diff --git a/apps/calculation/calculation.cpp b/apps/calculation/calculation.cpp
index a38f4ff36..dcb26d668 100644
--- a/apps/calculation/calculation.cpp
+++ b/apps/calculation/calculation.cpp
@@ -66,21 +66,18 @@ void Calculation::setContent(const char * c, Context * context, Expression * ans
 
 KDCoordinate Calculation::height(Context * context) {
   if (m_height < 0) {
-    ExpressionLayout * inputLayout = createInputLayout();
-    KDCoordinate inputHeight = inputLayout->size().height();
-    delete inputLayout;
-    Poincare::ExpressionLayout * approximateLayout = createApproximateOutputLayout(context);
-    KDCoordinate approximateOutputHeight = approximateLayout->size().height();
+    LayoutRef inputLayout = createInputLayout();
+    KDCoordinate inputHeight = inputLayout.layoutSize().height();
+    LayoutRef approximateLayout = createApproximateOutputLayout(context);
+    KDCoordinate approximateOutputHeight = approximateLayout.layoutSize().height();
     if (shouldOnlyDisplayApproximateOutput(context)) {
       m_height = inputHeight+approximateOutputHeight;
     } else {
-      Poincare::ExpressionLayout * exactLayout = createExactOutputLayout(context);
-      KDCoordinate exactOutputHeight = exactLayout->size().height();
-      KDCoordinate outputHeight = max(exactLayout->baseline(), approximateLayout->baseline()) + max(exactOutputHeight-exactLayout->baseline(), approximateOutputHeight-approximateLayout->baseline());
-      delete exactLayout;
+      LayoutRef exactLayout = createExactOutputLayout(context);
+      KDCoordinate exactOutputHeight = exactLayout.layoutSize().height();
+      KDCoordinate outputHeight = max(exactLayout.baseline(), approximateLayout.baseline()) + max(exactOutputHeight-exactLayout.baseline(), approximateOutputHeight-approximateLayout.baseline());
       m_height = inputHeight + outputHeight;
     }
-    delete approximateLayout;
   }
   return m_height;
 }
@@ -104,11 +101,11 @@ Expression * Calculation::input() {
   return m_input;
 }
 
-ExpressionLayout * Calculation::createInputLayout() {
+LayoutRef Calculation::createInputLayout() {
   if (input() != nullptr) {
     return input()->createLayout(PrintFloat::Mode::Decimal, Expression::ComplexFormat::Cartesian);
   }
-  return nullptr;
+  return LayoutRef(nullptr);
 }
 
 bool Calculation::isEmpty() {
@@ -156,11 +153,11 @@ Expression * Calculation::exactOutput(Context * context) {
   return m_exactOutput;
 }
 
-ExpressionLayout * Calculation::createExactOutputLayout(Context * context) {
+LayoutRef Calculation::createExactOutputLayout(Context * context) {
   if (exactOutput(context) != nullptr) {
     return exactOutput(context)->createLayout();
   }
-  return nullptr;
+  return LayoutRef(nullptr);
 }
 
 Expression * Calculation::approximateOutput(Context * context) {
@@ -178,11 +175,11 @@ Expression * Calculation::approximateOutput(Context * context) {
   return m_approximateOutput;
 }
 
-ExpressionLayout * Calculation::createApproximateOutputLayout(Context * context) {
+LayoutRef Calculation::createApproximateOutputLayout(Context * context) {
   if (approximateOutput(context) != nullptr) {
     return approximateOutput(context)->createLayout();
   }
-  return nullptr;
+  return LayoutRef(nullptr);
 }
 
 bool Calculation::shouldOnlyDisplayApproximateOutput(Context * context) {
diff --git a/apps/calculation/calculation.h b/apps/calculation/calculation.h
index 68f692876..f626207a5 100644
--- a/apps/calculation/calculation.h
+++ b/apps/calculation/calculation.h
@@ -29,11 +29,11 @@ public:
   const char * exactOutputText();
   const char * approximateOutputText();
   Poincare::Expression * input();
-  Poincare::ExpressionLayout * createInputLayout();
+  Poincare::LayoutRef createInputLayout();
   Poincare::Expression * approximateOutput(Poincare::Context * context);
   Poincare::Expression * exactOutput(Poincare::Context * context);
-  Poincare::ExpressionLayout * createExactOutputLayout(Poincare::Context * context);
-  Poincare::ExpressionLayout * createApproximateOutputLayout(Poincare::Context * context);
+  Poincare::LayoutRef createExactOutputLayout(Poincare::Context * context);
+  Poincare::LayoutRef createApproximateOutputLayout(Poincare::Context * context);
   bool isEmpty();
   void tidy();
   bool shouldOnlyDisplayApproximateOutput(Poincare::Context * context);
diff --git a/apps/calculation/history_view_cell.cpp b/apps/calculation/history_view_cell.cpp
index eea40852e..b6e4a645a 100644
--- a/apps/calculation/history_view_cell.cpp
+++ b/apps/calculation/history_view_cell.cpp
@@ -18,25 +18,10 @@ HistoryViewCell::HistoryViewCell(Responder * parentResponder) :
 {
 }
 
-HistoryViewCell::~HistoryViewCell() {
-  if (m_inputLayout != nullptr) {
-    delete m_inputLayout;
-    m_inputLayout = nullptr;
-  }
-  if (m_exactOutputLayout != nullptr) {
-    delete m_exactOutputLayout;
-    m_exactOutputLayout = nullptr;
-  }
-  if (m_approximateOutputLayout != nullptr) {
-    delete m_approximateOutputLayout;
-    m_approximateOutputLayout = nullptr;
-  }
-}
-
 Shared::ScrollableExactApproximateExpressionsView * HistoryViewCell::outputView() {
   return &m_scrollableOutputView;
-
 }
+
 void HistoryViewCell::setEven(bool even) {
   EvenOddCell::setEven(even);
   m_inputView.setBackgroundColor(backgroundColor());
@@ -57,11 +42,11 @@ void HistoryViewCell::setHighlighted(bool highlight) {
   reloadScroll();
 }
 
-Poincare::ExpressionLayout * HistoryViewCell::expressionLayout() const {
+Poincare::LayoutRef HistoryViewCell::layoutRef() const {
   if (m_selectedSubviewType == SubviewType::Input) {
     return m_inputLayout;
   } else {
-    return m_scrollableOutputView.expressionLayout();
+    return m_scrollableOutputView.layoutRef();
   }
 }
 
@@ -109,27 +94,20 @@ void HistoryViewCell::layoutSubviews() {
 }
 
 void HistoryViewCell::setCalculation(Calculation * calculation) {
-  if (m_inputLayout) {
-    delete m_inputLayout;
-  }
   m_inputLayout = calculation->createInputLayout();
-  m_inputView.setExpressionLayout(m_inputLayout);
+  m_inputView.setLayoutRef(m_inputLayout);
   App * calculationApp = (App *)app();
   /* Both output expressions have to be updated at the same time. Otherwise,
    * when updating one layout, if the second one still points to a deleted
    * layout, calling to layoutSubviews() would fail. */
-  if (m_exactOutputLayout) {
-    delete m_exactOutputLayout;
-    m_exactOutputLayout = nullptr;
+  if (m_exactOutputLayout.isDefined()) {
+    m_exactOutputLayout = Poincare::LayoutRef(nullptr);
   }
   if (!calculation->shouldOnlyDisplayApproximateOutput(calculationApp->localContext())) {
     m_exactOutputLayout = calculation->createExactOutputLayout(calculationApp->localContext());
   }
-  if (m_approximateOutputLayout) {
-    delete m_approximateOutputLayout;
-  }
   m_approximateOutputLayout = calculation->createApproximateOutputLayout(calculationApp->localContext());
-  Poincare::ExpressionLayout * outputExpressions[2] = {m_approximateOutputLayout, m_exactOutputLayout};
+  Poincare::LayoutRef outputExpressions[2] = {m_approximateOutputLayout, m_exactOutputLayout};
   m_scrollableOutputView.setExpressions(outputExpressions);
   I18n::Message equalMessage = calculation->exactAndApproximateDisplayedOutputsAreEqual(calculationApp->localContext()) == Calculation::EqualSign::Equal ? I18n::Message::Equal : I18n::Message::AlmostEqual;
   m_scrollableOutputView.setEqualMessage(equalMessage);
diff --git a/apps/calculation/history_view_cell.h b/apps/calculation/history_view_cell.h
index c581c3e21..4f7e060e6 100644
--- a/apps/calculation/history_view_cell.h
+++ b/apps/calculation/history_view_cell.h
@@ -15,7 +15,6 @@ public:
     Output
   };
   HistoryViewCell(Responder * parentResponder);
-  ~HistoryViewCell();
   void reloadCell() override;
   void reloadScroll();
   void setEven(bool even) override;
@@ -23,7 +22,7 @@ public:
   Responder * responder() override {
     return this;
   }
-  Poincare::ExpressionLayout * expressionLayout() const override;
+  Poincare::LayoutRef layoutRef() const override;
   KDColor backgroundColor() const override;
   void setCalculation(Calculation * calculation);
   int numberOfSubviews() const override;
@@ -37,9 +36,9 @@ public:
   Shared::ScrollableExactApproximateExpressionsView * outputView();
 private:
   constexpr static KDCoordinate k_resultWidth = 80;
-  Poincare::ExpressionLayout * m_inputLayout;
-  Poincare::ExpressionLayout * m_exactOutputLayout;
-  Poincare::ExpressionLayout * m_approximateOutputLayout;
+  Poincare::LayoutRef m_inputLayout;
+  Poincare::LayoutRef m_exactOutputLayout;
+  Poincare::LayoutRef m_approximateOutputLayout;
   ScrollableExpressionView m_inputView;
   Shared::ScrollableExactApproximateExpressionsView m_scrollableOutputView;
   SubviewType m_selectedSubviewType;
diff --git a/apps/calculation/scrollable_expression_view.cpp b/apps/calculation/scrollable_expression_view.cpp
index 70e10b526..a67639df0 100644
--- a/apps/calculation/scrollable_expression_view.cpp
+++ b/apps/calculation/scrollable_expression_view.cpp
@@ -10,8 +10,8 @@ ScrollableExpressionView::ScrollableExpressionView(Responder * parentResponder)
 {
 }
 
-void ScrollableExpressionView::setExpressionLayout(ExpressionLayout * expressionLayout) {
-  m_expressionView.setExpressionLayout(expressionLayout);
+void ScrollableExpressionView::setLayoutRef(LayoutRef layoutRef) {
+  m_expressionView.setLayoutRef(layoutRef);
   layoutSubviews();
 }
 
diff --git a/apps/calculation/scrollable_expression_view.h b/apps/calculation/scrollable_expression_view.h
index 38ae2d8d4..2e3281833 100644
--- a/apps/calculation/scrollable_expression_view.h
+++ b/apps/calculation/scrollable_expression_view.h
@@ -8,7 +8,7 @@ namespace Calculation {
 class ScrollableExpressionView : public ScrollableView, public ScrollViewDataSource {
 public:
   ScrollableExpressionView(Responder * parentResponder);
-  void setExpressionLayout(Poincare::ExpressionLayout * expressionLayout);
+  void setLayoutRef(Poincare::LayoutRef layoutRef);
   void setBackgroundColor(KDColor backgroundColor) override;
   KDSize minimalSizeForOptimalDisplay() const override;
 private:
diff --git a/apps/shared/expression_model.cpp b/apps/shared/expression_model.cpp
index b962212d5..edcce43ff 100644
--- a/apps/shared/expression_model.cpp
+++ b/apps/shared/expression_model.cpp
@@ -10,16 +10,15 @@ namespace Shared {
 ExpressionModel::ExpressionModel() :
   m_text{0},
   m_expression(nullptr),
-  m_layout(nullptr)
+  m_layoutRef(nullptr)
 {
 }
 
 ExpressionModel::~ExpressionModel() {
   /* We cannot call tidy here because tidy is a virtual function and does not
    * do the same thing for all children class. */
-  if (m_layout != nullptr) {
-    delete m_layout;
-    m_layout = nullptr;
+  if (m_layoutRef.isDefined()) {
+    m_layoutRef = LayoutRef(nullptr);
   }
   if (m_expression != nullptr) {
     delete m_expression;
@@ -44,15 +43,15 @@ Poincare::Expression * ExpressionModel::expression(Poincare::Context * context)
   return m_expression;
 }
 
-Poincare::ExpressionLayout * ExpressionModel::layout() {
-  if (m_layout == nullptr) {
+LayoutRef ExpressionModel::layoutRef() {
+  if (!m_layoutRef.isDefined()) {
     Expression * nonSimplifiedExpression = Expression::parse(m_text);
     if (nonSimplifiedExpression != nullptr) {
-      m_layout = nonSimplifiedExpression->createLayout(PrintFloat::Mode::Decimal);
+      m_layoutRef = nonSimplifiedExpression->createLayout(PrintFloat::Mode::Decimal);
       delete nonSimplifiedExpression;
     }
   }
-  return m_layout;
+  return m_layoutRef;
 }
 
 bool ExpressionModel::isDefined() {
@@ -68,9 +67,8 @@ void ExpressionModel::setContent(const char * c) {
   /* We cannot call tidy here because tidy is a virtual function and does not
    * do the same thing for all children class. And here we want to delete only
    * the m_layout and m_expression. */
-  if (m_layout != nullptr) {
-    delete m_layout;
-    m_layout = nullptr;
+  if (m_layoutRef.isDefined()) {
+    m_layoutRef = LayoutRef(nullptr);
   }
   if (m_expression != nullptr) {
     delete m_expression;
@@ -79,9 +77,8 @@ void ExpressionModel::setContent(const char * c) {
 }
 
 void ExpressionModel::tidy() {
-  if (m_layout != nullptr) {
-    delete m_layout;
-    m_layout = nullptr;
+  if (m_layoutRef.isDefined()) {
+    m_layoutRef = LayoutRef(nullptr);
   }
   if (m_expression != nullptr) {
     delete m_expression;
diff --git a/apps/shared/expression_model.h b/apps/shared/expression_model.h
index eca8b3c44..4ad4e9c0c 100644
--- a/apps/shared/expression_model.h
+++ b/apps/shared/expression_model.h
@@ -17,7 +17,7 @@ public:
   ExpressionModel(ExpressionModel&& other) = delete;
   const char * text() const;
   Poincare::Expression * expression(Poincare::Context * context) const;
-  Poincare::ExpressionLayout * layout();
+  Poincare::LayoutRef layoutRef();
   /* Here, isDefined is the exact contrary of isEmpty. However, for Sequence
    * inheriting from ExpressionModel, isEmpty and isDefined have not exactly
    * opposite meaning. For instance, u(n+1)=u(n) & u(0) = ... is not empty and
@@ -35,7 +35,7 @@ private:
   static_assert((k_dataLengthInBytes & 0x3) == 0, "The expression model data size is not a multiple of 4 bytes (cannot compute crc)"); // Assert that dataLengthInBytes is a multiple of 4
   char m_text[k_expressionBufferSize];
   mutable Poincare::Expression * m_expression;
-  mutable Poincare::ExpressionLayout * m_layout;
+  mutable Poincare::LayoutRef m_layoutRef;
 };
 
 }
diff --git a/apps/shared/expression_model_list_controller.cpp b/apps/shared/expression_model_list_controller.cpp
index 77b374454..3eb4ee778 100644
--- a/apps/shared/expression_model_list_controller.cpp
+++ b/apps/shared/expression_model_list_controller.cpp
@@ -23,17 +23,18 @@ KDCoordinate ExpressionModelListController::expressionRowHeight(int j) {
     return Metric::StoreRowHeight;
   }
   ExpressionModel * m = modelStore()->modelAtIndex(j);
-  if (m->layout() == nullptr) {
+  if (!m->layoutRef().isDefined()) {
     return Metric::StoreRowHeight;
   }
-  KDCoordinate modelSize = m->layout()->size().height();
+  KDCoordinate modelSize = m->layoutRef().layoutSize().height();
   return modelSize + Metric::StoreRowHeight - KDText::charSize().height();
 }
 
 void ExpressionModelListController::willDisplayExpressionCellAtIndex(HighlightCell * cell, int j) {
   EvenOddExpressionCell * myCell = (EvenOddExpressionCell *)cell;
   ExpressionModel * m = modelStore()->modelAtIndex(j);
-  myCell->setExpressionLayout(m->layout());
+  myCell->setExpressionLayout(nullptr); //TODO
+  //myCell->setExpressionLayout(m->layout());
 }
 
 /* Responder */
diff --git a/apps/shared/scrollable_exact_approximate_expressions_cell.h b/apps/shared/scrollable_exact_approximate_expressions_cell.h
index 0c49a48a7..0baaec24b 100644
--- a/apps/shared/scrollable_exact_approximate_expressions_cell.h
+++ b/apps/shared/scrollable_exact_approximate_expressions_cell.h
@@ -9,8 +9,8 @@ namespace Shared {
 class ScrollableExactApproximateExpressionsCell : public ::EvenOddCell, public Responder {
 public:
   ScrollableExactApproximateExpressionsCell(Responder * parentResponder = nullptr);
-  void setExpressions(Poincare::ExpressionLayout ** expressionsLayout) {
-    return m_view.setExpressions(expressionsLayout);
+  void setExpressions(Poincare::LayoutRef * layoutRefs) {
+    return m_view.setExpressions(layoutRefs); // TODO rename setLayouts
   }
   void setEqualMessage(I18n::Message equalSignMessage) {
     return m_view.setEqualMessage(equalSignMessage);
@@ -22,7 +22,7 @@ public:
   Responder * responder() override {
     return this;
   }
-  Poincare::ExpressionLayout * expressionLayout() const override { return m_view.expressionLayout(); }
+  Poincare::LayoutRef layoutRef() const override { return m_view.layoutRef(); }
   void didBecomeFirstResponder() override;
   constexpr static KDCoordinate k_margin = 5;
 private:
diff --git a/apps/shared/scrollable_exact_approximate_expressions_view.cpp b/apps/shared/scrollable_exact_approximate_expressions_view.cpp
index cb352ae6b..8276592b3 100644
--- a/apps/shared/scrollable_exact_approximate_expressions_view.cpp
+++ b/apps/shared/scrollable_exact_approximate_expressions_view.cpp
@@ -49,8 +49,8 @@ KDSize ScrollableExactApproximateExpressionsView::ContentCell::minimalSizeForOpt
     return approximateExpressionSize;
   }
   KDSize exactExpressionSize = m_exactExpressionView.minimalSizeForOptimalDisplay();
-  KDCoordinate exactBaseline = m_exactExpressionView.expressionLayout()->baseline();
-  KDCoordinate approximateBaseline = m_approximateExpressionView.expressionLayout()->baseline();
+  KDCoordinate exactBaseline = m_exactExpressionView.layoutRef().baseline();
+  KDCoordinate approximateBaseline = m_approximateExpressionView.layoutRef().baseline();
   KDCoordinate height = max(exactBaseline, approximateBaseline) + max(exactExpressionSize.height()-exactBaseline, approximateExpressionSize.height()-approximateBaseline);
   KDSize approximateSignSize = m_approximateSign.minimalSizeForOptimalDisplay();
   return KDSize(exactExpressionSize.width()+approximateSignSize.width()+approximateExpressionSize.width()+2*k_digitHorizontalMargin, height);
@@ -61,16 +61,16 @@ void ScrollableExactApproximateExpressionsView::ContentCell::setSelectedSubviewT
   setHighlighted(isHighlighted());
 }
 
-Poincare::ExpressionLayout * ScrollableExactApproximateExpressionsView::ContentCell::expressionLayout() const {
+Poincare::LayoutRef ScrollableExactApproximateExpressionsView::ContentCell::layoutRef() const {
   if (m_selectedSubviewType == SubviewType::ExactOutput) {
-    return m_exactExpressionView.expressionLayout();
+    return m_exactExpressionView.layoutRef();
   } else {
-    return m_approximateExpressionView.expressionLayout();
+    return m_approximateExpressionView.layoutRef();
   }
 }
 
 int ScrollableExactApproximateExpressionsView::ContentCell::numberOfSubviews() const {
-  if (m_exactExpressionView.expressionLayout() != nullptr) {
+  if (m_exactExpressionView.layoutRef().isDefined()) {
     return 3;
   }
   return 1;
@@ -88,8 +88,8 @@ void ScrollableExactApproximateExpressionsView::ContentCell::layoutSubviews() {
     m_approximateExpressionView.setFrame(KDRect(0, 0, approximateExpressionSize.width(), height));
     return;
   }
-  KDCoordinate exactBaseline = m_exactExpressionView.expressionLayout()->baseline();
-  KDCoordinate approximateBaseline = m_approximateExpressionView.expressionLayout()->baseline();
+  KDCoordinate exactBaseline = m_exactExpressionView.layoutRef().baseline();
+  KDCoordinate approximateBaseline = m_approximateExpressionView.layoutRef().baseline();
   KDCoordinate baseline = max(exactBaseline, approximateBaseline);
   KDSize exactExpressionSize = m_exactExpressionView.minimalSizeForOptimalDisplay();
   KDSize approximateSignSize = m_approximateSign.minimalSizeForOptimalDisplay();
@@ -103,9 +103,10 @@ ScrollableExactApproximateExpressionsView::ScrollableExactApproximateExpressions
   m_contentCell()
 {
 }
-void ScrollableExactApproximateExpressionsView::setExpressions(ExpressionLayout ** expressionsLayout) {
-  m_contentCell.approximateExpressionView()->setExpressionLayout(expressionsLayout[0]);
-  m_contentCell.exactExpressionView()->setExpressionLayout(expressionsLayout[1]);
+
+void ScrollableExactApproximateExpressionsView::setExpressions(Poincare::LayoutRef * layoutRefs) {
+  m_contentCell.approximateExpressionView()->setLayoutRef(layoutRefs[0]);
+  m_contentCell.exactExpressionView()->setLayoutRef(layoutRefs[1]);
   m_contentCell.layoutSubviews();
 }
 
@@ -114,7 +115,7 @@ void ScrollableExactApproximateExpressionsView::setEqualMessage(I18n::Message eq
 }
 
 void ScrollableExactApproximateExpressionsView::didBecomeFirstResponder() {
-  if (m_contentCell.exactExpressionView()->expressionLayout() == nullptr) {
+  if (!m_contentCell.exactExpressionView()->layoutRef().isDefined()) {
     setSelectedSubviewType(SubviewType::ApproximativeOutput);
   } else {
     setSelectedSubviewType(SubviewType::ExactOutput);
@@ -122,7 +123,7 @@ void ScrollableExactApproximateExpressionsView::didBecomeFirstResponder() {
 }
 
 bool ScrollableExactApproximateExpressionsView::handleEvent(Ion::Events::Event event) {
-  if (m_contentCell.exactExpressionView()->expressionLayout() == nullptr) {
+  if (!m_contentCell.exactExpressionView()->layoutRef().isDefined()) {
     return ScrollableView::handleEvent(event);
   }
   bool rightExpressionIsVisible = minimalSizeForOptimalDisplay().width() - m_contentCell.approximateExpressionView()->minimalSizeForOptimalDisplay().width() - m_manualScrollingOffset.x() < bounds().width()
diff --git a/apps/shared/scrollable_exact_approximate_expressions_view.h b/apps/shared/scrollable_exact_approximate_expressions_view.h
index 5a7081187..759d1c1e6 100644
--- a/apps/shared/scrollable_exact_approximate_expressions_view.h
+++ b/apps/shared/scrollable_exact_approximate_expressions_view.h
@@ -15,7 +15,7 @@ public:
   ::EvenOddCell * evenOddCell() {
     return &m_contentCell;
   }
-  void setExpressions(Poincare::ExpressionLayout ** expressionsLayout);
+  void setExpressions(Poincare::LayoutRef * layoutRefs);
   void setEqualMessage(I18n::Message equalSignMessage);
   SubviewType selectedSubviewType() {
     return m_contentCell.selectedSubviewType();
@@ -26,8 +26,8 @@ public:
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
   KDSize minimalSizeForOptimalDisplay() const override;
-  Poincare::ExpressionLayout * expressionLayout() const {
-    return m_contentCell.expressionLayout();
+  Poincare::LayoutRef layoutRef() const {
+    return m_contentCell.layoutRef();
   }
 private:
   class ContentCell : public ::EvenOddCell {
@@ -52,7 +52,7 @@ private:
     void setSelectedSubviewType(SubviewType subviewType);
     void layoutSubviews() override;
     int numberOfSubviews() const override;
-    Poincare::ExpressionLayout * expressionLayout() const override;
+    Poincare::LayoutRef layoutRef() const override;
   private:
     View * subviewAtIndex(int index) override;
     constexpr static KDCoordinate k_digitHorizontalMargin = 10;
diff --git a/apps/shared/sum_graph_controller.cpp b/apps/shared/sum_graph_controller.cpp
index 49a31a458..fcbff39a8 100644
--- a/apps/shared/sum_graph_controller.cpp
+++ b/apps/shared/sum_graph_controller.cpp
@@ -202,7 +202,7 @@ bool SumGraphController::handleEnter() {
 
 SumGraphController::LegendView::LegendView(SumGraphController * controller, char sumSymbol) :
   m_sum(0.0f, 0.5f, KDColorBlack, Palette::GreyMiddle),
-  m_sumLayout(nullptr),
+  m_sumLayoutRef(nullptr),
   m_legend(KDText::FontSize::Small, I18n::Message::Default, 0.0f, 0.5f, KDColorBlack, Palette::GreyMiddle),
   m_editableZone(controller, m_draftText, m_draftText, TextField::maxBufferSize(), controller, false, KDText::FontSize::Small, 0.0f, 0.5f, KDColorBlack, Palette::GreyMiddle),
   m_sumSymbol(sumSymbol)
@@ -210,13 +210,6 @@ SumGraphController::LegendView::LegendView(SumGraphController * controller, char
   m_draftText[0] = 0;
 }
 
-SumGraphController::LegendView::~LegendView() {
-  if (m_sumLayout != nullptr) {
-    delete m_sumLayout;
-    m_sumLayout = nullptr;
-  }
-}
-
 void SumGraphController::LegendView::drawRect(KDContext * ctx, KDRect rect) const {
   ctx->fillRect(bounds(), Palette::GreyMiddle);
 }
@@ -238,28 +231,26 @@ void SumGraphController::LegendView::setEditableZone(double d) {
 
 void SumGraphController::LegendView::setSumSymbol(Step step, double start, double end, double result, ExpressionLayout * functionLayout) {
   assert(step == Step::Result || functionLayout == nullptr);
-  if (m_sumLayout) {
-    delete m_sumLayout;
-    m_sumLayout = nullptr;
-  }
   const char sigma[] = {' ', m_sumSymbol};
   if (step == Step::FirstParameter) {
-    m_sumLayout = LayoutEngine::createStringLayout(sigma, sizeof(sigma));
+    m_sumLayoutRef = LayoutEngine::createStringLayout(sigma, sizeof(sigma));
   } else if (step == Step::SecondParameter) {
     char buffer[PrintFloat::bufferSizeForFloatsWithPrecision(Constant::MediumNumberOfSignificantDigits)];
     PrintFloat::convertFloatToText<double>(start, buffer, PrintFloat::bufferSizeForFloatsWithPrecision(Constant::MediumNumberOfSignificantDigits), Constant::MediumNumberOfSignificantDigits, PrintFloat::Mode::Decimal);
-    m_sumLayout = new CondensedSumLayout(
+    m_sumLayoutRef = LayoutEngine::createStringLayout(sigma, sizeof(sigma));/* TODO new CondensedSumLayout(
         LayoutEngine::createStringLayout(sigma, sizeof(sigma)),
         LayoutEngine::createStringLayout(buffer, strlen(buffer), KDText::FontSize::Small),
         new EmptyLayout(EmptyLayout::Color::Yellow, false, KDText::FontSize::Small, false),
-        false);
+        false); */
   } else {
+    m_sumLayoutRef = LayoutEngine::createStringLayout(sigma, sizeof(sigma));
+/* TODO
     char buffer[2+PrintFloat::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits)];
     PrintFloat::convertFloatToText<double>(start, buffer, PrintFloat::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits), Constant::LargeNumberOfSignificantDigits, PrintFloat::Mode::Decimal);
-    ExpressionLayout * start =  LayoutEngine::createStringLayout(buffer, strlen(buffer), KDText::FontSize::Small);
+    ExpressionLayout * start = LayoutEngine::createStringLayout(buffer, strlen(buffer), KDText::FontSize::Small);
     PrintFloat::convertFloatToText<double>(end, buffer, PrintFloat::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits), Constant::LargeNumberOfSignificantDigits, PrintFloat::Mode::Decimal);
-    ExpressionLayout * end =  LayoutEngine::createStringLayout(buffer, strlen(buffer), KDText::FontSize::Small);
-    m_sumLayout = new CondensedSumLayout(
+    ExpressionLayout * end = LayoutEngine::createStringLayout(buffer, strlen(buffer), KDText::FontSize::Small);
+    m_sumLayoutRef = new CondensedSumLayout(
         LayoutEngine::createStringLayout(sigma, sizeof(sigma)),
         start,
         end,
@@ -269,10 +260,10 @@ void SumGraphController::LegendView::setSumSymbol(Step step, double start, doubl
     PrintFloat::convertFloatToText<double>(result, buffer+2, PrintFloat::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits), Constant::LargeNumberOfSignificantDigits);
     childrenLayouts[2] = LayoutEngine::createStringLayout(buffer, strlen(buffer), KDText::FontSize::Small);
     childrenLayouts[1] = functionLayout;
-    childrenLayouts[0] = m_sumLayout;
-    m_sumLayout = new HorizontalLayout(childrenLayouts, 3, false);
+    childrenLayouts[0] = m_sumLayoutRef;
+    m_sumLayoutRef = new HorizontalLayout(childrenLayouts, 3, false);*/
   }
-  m_sum.setExpressionLayout(m_sumLayout);
+  m_sum.setLayoutRef(m_sumLayoutRef);
   if (step == Step::Result) {
     m_sum.setAlignment(0.5f, 0.5f);
   } else {
diff --git a/apps/shared/sum_graph_controller.h b/apps/shared/sum_graph_controller.h
index 98a110957..e40a74bf8 100644
--- a/apps/shared/sum_graph_controller.h
+++ b/apps/shared/sum_graph_controller.h
@@ -49,7 +49,6 @@ private:
   class LegendView : public View {
   public:
     LegendView(SumGraphController * controller, char sumSymbol);
-    ~LegendView();
     LegendView(const LegendView& other) = delete;
     LegendView(LegendView&& other) = delete;
     LegendView& operator=(const LegendView& other) = delete;
@@ -71,7 +70,7 @@ private:
     void layoutSubviews() override;
     void layoutSubviews(Step step);
     ExpressionView m_sum;
-    Poincare::ExpressionLayout * m_sumLayout;
+    Poincare::LayoutRef m_sumLayoutRef;
     MessageTextView m_legend;
     TextField m_editableZone;
     char m_draftText[TextField::maxBufferSize()];
diff --git a/apps/variable_box_controller.cpp b/apps/variable_box_controller.cpp
index 02a8ea27a..e17506dfc 100644
--- a/apps/variable_box_controller.cpp
+++ b/apps/variable_box_controller.cpp
@@ -148,16 +148,16 @@ void VariableBoxController::ContentViewController::willDisplayCellForIndex(Highl
   if (evaluation) {
     /* TODO: implement list contexts */
     // TODO: handle matrix and scalar!
-    ExpressionLayout * layout = expressionLayoutForIndex(index);
+    LayoutRef layoutR = layoutRefForIndex(index);
     const Matrix * matrixEvaluation = static_cast<const Matrix *>(evaluation);
-    myCell->setExpressionLayout(layout);
+    myCell->setLayoutRef(layoutR);
     char buffer[2*PrintFloat::bufferSizeForFloatsWithPrecision(2)+1];
     int numberOfChars = PrintFloat::convertFloatToText<float>(matrixEvaluation->numberOfRows(), buffer, PrintFloat::bufferSizeForFloatsWithPrecision(2), 2, PrintFloat::Mode::Decimal);
     buffer[numberOfChars++] = 'x';
     PrintFloat::convertFloatToText<float>(matrixEvaluation->numberOfColumns(), buffer+numberOfChars, PrintFloat::bufferSizeForFloatsWithPrecision(2), 2, PrintFloat::Mode::Decimal);
     myCell->setSubtitle(buffer);
   } else {
-    myCell->setExpressionLayout(nullptr);
+    myCell->setLayoutRef(LayoutRef(nullptr));
     myCell->setSubtitle(I18n::translate(I18n::Message::Empty));
   }
 }
@@ -166,9 +166,9 @@ KDCoordinate VariableBoxController::ContentViewController::rowHeight(int index)
   if (m_currentPage == Page::RootMenu || m_currentPage == Page::Scalar) {
     return Metric::ToolboxRowHeight;
   }
-  ExpressionLayout * expressionLayout = expressionLayoutForIndex(index);
-  if (expressionLayout) {
-    return expressionLayout->size().height()+k_leafMargin;
+  LayoutRef layoutR = layoutRefForIndex(index);
+  if (layoutR.isDefined()) {
+    return layoutR.layoutSize().height()+k_leafMargin;
   }
   return Metric::ToolboxRowHeight;
 }
@@ -252,10 +252,10 @@ const Expression * VariableBoxController::ContentViewController::expressionForIn
   return nullptr;
 }
 
-ExpressionLayout * VariableBoxController::ContentViewController::expressionLayoutForIndex(int index) {
+LayoutRef VariableBoxController::ContentViewController::layoutRefForIndex(int index) {
   if (m_currentPage == Page::Matrix) {
     const Symbol symbol = Symbol::matrixSymbol('0'+(char)index);
-    return m_context->expressionLayoutForSymbol(&symbol);
+    return m_context->layoutRefForSymbol(&symbol);
   }
 #if LIST_VARIABLES
   if (m_currentPage == Page::List) {
diff --git a/apps/variable_box_controller.h b/apps/variable_box_controller.h
index 2ada661ea..22c36e1b1 100644
--- a/apps/variable_box_controller.h
+++ b/apps/variable_box_controller.h
@@ -53,7 +53,7 @@ private:
     void putLabelAtIndexInBuffer(int index, char * buffer);
     I18n::Message nodeLabelAtIndex(int index);
     const Poincare::Expression * expressionForIndex(int index);
-    Poincare::ExpressionLayout * expressionLayoutForIndex(int index);
+    Poincare::LayoutRef layoutRefForIndex(int index);
     Poincare::GlobalContext * m_context;
     Responder * m_sender;
     int m_firstSelectedRow;
diff --git a/apps/variable_box_leaf_cell.cpp b/apps/variable_box_leaf_cell.cpp
index 2fe428367..6123ca501 100644
--- a/apps/variable_box_leaf_cell.cpp
+++ b/apps/variable_box_leaf_cell.cpp
@@ -76,8 +76,8 @@ void VariableBoxLeafCell::setSubtitle(const char * text) {
   layoutSubviews();
 }
 
-void VariableBoxLeafCell::setExpressionLayout(ExpressionLayout * expressionLayout) {
-  m_expressionView.setExpressionLayout(expressionLayout);
+void VariableBoxLeafCell::setLayoutRef(LayoutRef layoutRef) {
+  m_expressionView.setLayoutRef(layoutRef);
 }
 
 void VariableBoxLeafCell::drawRect(KDContext * ctx, KDRect rect) const {
diff --git a/apps/variable_box_leaf_cell.h b/apps/variable_box_leaf_cell.h
index dcff304ef..e021fab17 100644
--- a/apps/variable_box_leaf_cell.h
+++ b/apps/variable_box_leaf_cell.h
@@ -11,7 +11,7 @@ public:
   void reloadCell() override;
   void setLabel(const char * text);
   void setSubtitle(const char * text);
-  void setExpressionLayout(Poincare::ExpressionLayout * expressionLayout);
+  void setLayoutRef(Poincare::LayoutRef layoutRef);
   void drawRect(KDContext * ctx, KDRect rect) const override;
   const char * text() const override {
     return m_labelView.text();
diff --git a/escher/include/escher/clipboard.h b/escher/include/escher/clipboard.h
index ad7135cc6..0a9c5e58d 100644
--- a/escher/include/escher/clipboard.h
+++ b/escher/include/escher/clipboard.h
@@ -8,7 +8,7 @@ class Clipboard {
 public:
   static Clipboard * sharedClipboard();
   void store(const char * storedText);
-  void store(Poincare::ExpressionLayout * layout);
+  void store(Poincare::LayoutRef layoutR);
   const char * storedText();
   void reset();
 private:
diff --git a/escher/include/escher/even_odd_expression_cell.h b/escher/include/escher/even_odd_expression_cell.h
index dc6dd2e56..3d7380c8c 100644
--- a/escher/include/escher/even_odd_expression_cell.h
+++ b/escher/include/escher/even_odd_expression_cell.h
@@ -17,7 +17,7 @@ public:
   void setAlignment(float horizontalAlignment, float verticalAlignment);
   void setLeftMargin(KDCoordinate margin);
   void setRightMargin(KDCoordinate margin);
-  Poincare::ExpressionLayout * expressionLayout() const override { return m_expressionView.expressionLayout(); }
+  Poincare::LayoutRef layoutRef() const override { return m_expressionView.layoutRef(); }
   void drawRect(KDContext * ctx, KDRect rect) const override;
 protected:
   int numberOfSubviews() const override;
diff --git a/escher/include/escher/expression_table_cell.h b/escher/include/escher/expression_table_cell.h
index d0b9e01be..da87ab8ee 100644
--- a/escher/include/escher/expression_table_cell.h
+++ b/escher/include/escher/expression_table_cell.h
@@ -10,7 +10,7 @@ public:
   View * labelView() const override;
   void setHighlighted(bool highlight) override;
   void setExpressionLayout(Poincare::ExpressionLayout * expressionLayout);
-  Poincare::ExpressionLayout * expressionLayout() const override { return m_labelExpressionView.expressionLayout(); }
+  Poincare::LayoutRef layoutRef() const override { return m_labelExpressionView.layoutRef(); }
 private:
   ExpressionView m_labelExpressionView;
 };
diff --git a/escher/include/escher/highlight_cell.h b/escher/include/escher/highlight_cell.h
index 7f87db90b..a9ad67969 100644
--- a/escher/include/escher/highlight_cell.h
+++ b/escher/include/escher/highlight_cell.h
@@ -4,6 +4,7 @@
 #include <escher/view.h>
 #include <escher/responder.h>
 #include <poincare.h>
+#include <poincare/layout_reference.h>
 
 class HighlightCell : public View {
 public:
@@ -17,8 +18,8 @@ public:
   virtual const char * text() const {
     return nullptr;
   }
-  virtual Poincare::ExpressionLayout * expressionLayout() const {
-    return nullptr;
+  virtual Poincare::LayoutRef layoutRef() const {
+    return Poincare::LayoutRef(nullptr);
   }
 protected:
   bool m_highlighted;
diff --git a/escher/src/clipboard.cpp b/escher/src/clipboard.cpp
index 5d18289d9..9445e668d 100644
--- a/escher/src/clipboard.cpp
+++ b/escher/src/clipboard.cpp
@@ -10,8 +10,8 @@ void Clipboard::store(const char * storedText) {
   strlcpy(m_textBuffer, storedText, TextField::maxBufferSize());
 }
 
-void Clipboard::store(Poincare::ExpressionLayout * layout) {
-  layout->writeTextInBuffer(m_textBuffer, TextField::maxBufferSize(), Poincare::Preferences::sharedPreferences()->numberOfSignificantDigits());
+void Clipboard::store(Poincare::LayoutRef layoutR) {
+  layoutR.writeTextInBuffer(m_textBuffer, TextField::maxBufferSize(), Poincare::Preferences::sharedPreferences()->numberOfSignificantDigits());
 }
 
 const char * Clipboard::storedText() {
diff --git a/escher/src/layout_field.cpp b/escher/src/layout_field.cpp
index 031022da1..c3167b742 100644
--- a/escher/src/layout_field.cpp
+++ b/escher/src/layout_field.cpp
@@ -93,7 +93,8 @@ bool LayoutField::handleEventWithText(const char * text, bool indentation, bool
     } else if (resultLayoutRef.isHorizontal()) {
       /* If the layout is horizontal, pick the first open parenthesis. For now,
        * all horizontal layouts in MathToolbox have parentheses. */
-      for (LayoutRef l : resultLayoutRef.directChildren()) {
+      for (int i = 0; i < resultLayoutRef.numberOfChildren(); i++) {
+        LayoutRef l = resultLayoutRef.childAtIndex(i);
         if (l.isLeftParenthesis()) {
           pointedLayoutRef = l;
           break;
diff --git a/escher/src/selectable_table_view.cpp b/escher/src/selectable_table_view.cpp
index 58178070e..62ecf73ac 100644
--- a/escher/src/selectable_table_view.cpp
+++ b/escher/src/selectable_table_view.cpp
@@ -128,9 +128,9 @@ bool SelectableTableView::handleEvent(Ion::Events::Event event) {
       Clipboard::sharedClipboard()->store(text);
       return true;
     }
-    Poincare::ExpressionLayout * layout = cell->expressionLayout();
-    if (layout) {
-      Clipboard::sharedClipboard()->store(layout);
+    Poincare::LayoutRef layoutR = cell->layoutRef();
+    if (layoutR.isDefined()) {
+      Clipboard::sharedClipboard()->store(layoutR);
       return true;
     }
   }
diff --git a/poincare/include/poincare/absolute_value.h b/poincare/include/poincare/absolute_value.h
index c5b75d48d..7ea0090cb 100644
--- a/poincare/include/poincare/absolute_value.h
+++ b/poincare/include/poincare/absolute_value.h
@@ -16,7 +16,7 @@ public:
 private:
   Expression * setSign(Sign s, Context & context, AngleUnit angleUnit) override;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "abs");
   }
diff --git a/poincare/include/poincare/addition.h b/poincare/include/poincare/addition.h
index aa00d6313..00b8ad601 100644
--- a/poincare/include/poincare/addition.h
+++ b/poincare/include/poincare/addition.h
@@ -32,7 +32,7 @@ public:
 private:
   /* Layout */
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
     return LayoutEngine::createInfixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
diff --git a/poincare/include/poincare/arc_cosine.h b/poincare/include/poincare/arc_cosine.h
index 71ae77674..e3731a648 100644
--- a/poincare/include/poincare/arc_cosine.h
+++ b/poincare/include/poincare/arc_cosine.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/arc_sine.h b/poincare/include/poincare/arc_sine.h
index 3aa871d05..0ec4295da 100644
--- a/poincare/include/poincare/arc_sine.h
+++ b/poincare/include/poincare/arc_sine.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/arc_tangent.h b/poincare/include/poincare/arc_tangent.h
index e915ab332..dd0c197a4 100644
--- a/poincare/include/poincare/arc_tangent.h
+++ b/poincare/include/poincare/arc_tangent.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/binomial_coefficient.h b/poincare/include/poincare/binomial_coefficient.h
index b5085bb67..35b58a631 100644
--- a/poincare/include/poincare/binomial_coefficient.h
+++ b/poincare/include/poincare/binomial_coefficient.h
@@ -15,7 +15,7 @@ public:
 private:
   constexpr static int k_maxNValue = 300;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "binomial");
   }
diff --git a/poincare/include/poincare/ceiling.h b/poincare/include/poincare/ceiling.h
index e55e96f8c..3080c7ed9 100644
--- a/poincare/include/poincare/ceiling.h
+++ b/poincare/include/poincare/ceiling.h
@@ -14,7 +14,7 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
   }
diff --git a/poincare/include/poincare/char_layout_node.h b/poincare/include/poincare/char_layout_node.h
index c45796efb..37e2aa50a 100644
--- a/poincare/include/poincare/char_layout_node.h
+++ b/poincare/include/poincare/char_layout_node.h
@@ -2,7 +2,6 @@
 #define POINCARE_CHAR_LAYOUT_NODE_H
 
 #include <poincare/layout_cursor.h>
-#include <poincare/layout_engine.h>
 #include <poincare/layout_node.h>
 #include <poincare/layout_reference.h>
 
@@ -19,9 +18,7 @@ public:
   void setFontSize(KDText::FontSize fontSize) { m_fontSize = fontSize; }
 
   // LayoutNode
-  int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
-    return LayoutEngine::writeOneCharInBuffer(buffer, bufferSize, m_char);
-  }
+  int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   void moveCursorLeft(LayoutCursor * cursor, bool * shouldRecomputeLayout) override;
   void moveCursorRight(LayoutCursor * cursor, bool * shouldRecomputeLayout) override;
 
diff --git a/poincare/include/poincare/complex.h b/poincare/include/poincare/complex.h
index 47545eaa3..44b47aaf2 100644
--- a/poincare/include/poincare/complex.h
+++ b/poincare/include/poincare/complex.h
@@ -43,7 +43,7 @@ public:
 private:
   Complex(T a, T b);
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat) const override;
   /* Simplification */
   static Expression * CreateDecimal(T f);
   Expression * shallowReduce(Context & context, AngleUnit angleUnit) override;
@@ -54,8 +54,8 @@ private:
   /* convertComplexToText and convertFloatToTextPrivate return the string length
    * of the buffer (does not count the 0 last char)*/
   int convertComplexToText(char * buffer, int bufferSize, int numberOfSignificantDigits, PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, char multiplicationSign) const;
-  ExpressionLayout * createPolarLayout(PrintFloat::Mode floatDisplayMode) const;
-  ExpressionLayout * createCartesianLayout(PrintFloat::Mode floatDisplayMode) const;
+  //ExpressionLayout * createPolarLayout(PrintFloat::Mode floatDisplayMode) const;
+  //ExpressionLayout * createCartesianLayout(PrintFloat::Mode floatDisplayMode) const;
   T m_a;
   T m_b;
 };
diff --git a/poincare/include/poincare/complex_argument.h b/poincare/include/poincare/complex_argument.h
index 14d283528..02352b066 100644
--- a/poincare/include/poincare/complex_argument.h
+++ b/poincare/include/poincare/complex_argument.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/confidence_interval.h b/poincare/include/poincare/confidence_interval.h
index f4e815703..4acaf340a 100644
--- a/poincare/include/poincare/confidence_interval.h
+++ b/poincare/include/poincare/confidence_interval.h
@@ -3,6 +3,7 @@
 
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   int polynomialDegree(char symbolName) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/conjugate.h b/poincare/include/poincare/conjugate.h
index e43767171..db77c2994 100644
--- a/poincare/include/poincare/conjugate.h
+++ b/poincare/include/poincare/conjugate.h
@@ -14,7 +14,7 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "conj");
   }
diff --git a/poincare/include/poincare/cosine.h b/poincare/include/poincare/cosine.h
index b19ec7bad..8f059c4d0 100644
--- a/poincare/include/poincare/cosine.h
+++ b/poincare/include/poincare/cosine.h
@@ -6,6 +6,7 @@
 #include <poincare/approximation_engine.h>
 #include <poincare/trigonometry.h>
 #include <poincare/expression.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -19,8 +20,9 @@ public:
   template<typename T> static Complex<T> computeOnComplex(const Complex<T> c, AngleUnit angleUnit = AngleUnit::Radian);
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/decimal.h b/poincare/include/poincare/decimal.h
index 52f25d4ec..65d929039 100644
--- a/poincare/include/poincare/decimal.h
+++ b/poincare/include/poincare/decimal.h
@@ -31,7 +31,7 @@ private:
   int simplificationOrderSameType(const Expression * e, bool canBeInterrupted) const override;
   /* Layout */
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   /* Simplification */
   Expression * shallowReduce(Context& context, AngleUnit angleUnit) override;
   Expression * shallowBeautify(Context& context, AngleUnit angleUnit) override;
diff --git a/poincare/include/poincare/derivative.h b/poincare/include/poincare/derivative.h
index 85e10c3a4..9cc0d0f29 100644
--- a/poincare/include/poincare/derivative.h
+++ b/poincare/include/poincare/derivative.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/variable_context.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -15,8 +16,9 @@ public:
   int polynomialDegree(char symbolName) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/determinant.h b/poincare/include/poincare/determinant.h
index 7db860bc1..9cff27f3b 100644
--- a/poincare/include/poincare/determinant.h
+++ b/poincare/include/poincare/determinant.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/division.h b/poincare/include/poincare/division.h
index 0337ec310..460787667 100644
--- a/poincare/include/poincare/division.h
+++ b/poincare/include/poincare/division.h
@@ -20,7 +20,7 @@ public:
 private:
   /* Layout */
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writeInfixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "/");
   }
diff --git a/poincare/include/poincare/division_quotient.h b/poincare/include/poincare/division_quotient.h
index 318d09c0e..6747d284a 100644
--- a/poincare/include/poincare/division_quotient.h
+++ b/poincare/include/poincare/division_quotient.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
  /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/division_remainder.h b/poincare/include/poincare/division_remainder.h
index 05a79ea73..dce48e7c2 100644
--- a/poincare/include/poincare/division_remainder.h
+++ b/poincare/include/poincare/division_remainder.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+ // return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/empty_expression.h b/poincare/include/poincare/empty_expression.h
index 09d1cbb9d..495c13682 100644
--- a/poincare/include/poincare/empty_expression.h
+++ b/poincare/include/poincare/empty_expression.h
@@ -17,7 +17,7 @@ public:
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   /* Evaluation */
   Expression * privateApproximate(SinglePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<float>(context, angleUnit); }
   Expression * privateApproximate(DoublePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<double>(context, angleUnit); }
diff --git a/poincare/include/poincare/equal.h b/poincare/include/poincare/equal.h
index 14d775f23..7ff8d3e39 100644
--- a/poincare/include/poincare/equal.h
+++ b/poincare/include/poincare/equal.h
@@ -19,7 +19,7 @@ private:
   /* Simplification */
   Expression * shallowReduce(Context& context, AngleUnit angleUnit) override;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writeInfixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "=");
   }
diff --git a/poincare/include/poincare/expression.h b/poincare/include/poincare/expression.h
index 90cc058fa..3f100b2b5 100644
--- a/poincare/include/poincare/expression.h
+++ b/poincare/include/poincare/expression.h
@@ -1,7 +1,7 @@
 #ifndef POINCARE_EXPRESSION_H
 #define POINCARE_EXPRESSION_H
 
-#include <poincare/expression_layout.h>
+#include <poincare/layout_reference.h>
 #include <poincare/print_float.h>
 extern "C" {
 #include <assert.h>
@@ -249,7 +249,7 @@ public:
   bool isEqualToItsApproximationLayout(Expression * approximation, int bufferSize, int numberOfSignificantDigits, Context & context);
 
   /* Layout Engine */
-  ExpressionLayout * createLayout(PrintFloat::Mode floatDisplayMode = PrintFloat::Mode::Default, ComplexFormat complexFormat = ComplexFormat::Default) const; // Returned object must be deleted
+  LayoutRef createLayout(PrintFloat::Mode floatDisplayMode = PrintFloat::Mode::Default, ComplexFormat complexFormat = ComplexFormat::Default) const;
   virtual int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const = 0;
 
   /* Simplification */
@@ -315,7 +315,7 @@ private:
   //TODO: What should be the implementation for complex?
   virtual int simplificationOrderSameType(const Expression * e, bool canBeInterrupted) const { return 0; }
   /* Layout Engine */
-  virtual ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const = 0;
+  virtual LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const = 0;
   /* Simplification */
   Expression * deepBeautify(Context & context, AngleUnit angleUnit);
   Expression * deepReduce(Context & context, AngleUnit angleUnit);
diff --git a/poincare/include/poincare/factor.h b/poincare/include/poincare/factor.h
index 4ded7f021..8de7892b9 100644
--- a/poincare/include/poincare/factor.h
+++ b/poincare/include/poincare/factor.h
@@ -7,6 +7,7 @@
 #include <poincare/rational.h>
 #include <poincare/complex.h>
 #include <cmath>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -17,8 +18,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/factorial.h b/poincare/include/poincare/factorial.h
index 35c04b3fe..2f7842a69 100644
--- a/poincare/include/poincare/factorial.h
+++ b/poincare/include/poincare/factorial.h
@@ -15,7 +15,7 @@ private:
   constexpr static int k_maxOperandValue = 100;
   /* Layout */
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   /* Simplication */
   Expression * shallowReduce(Context& context, AngleUnit angleUnit) override;
diff --git a/poincare/include/poincare/floor.h b/poincare/include/poincare/floor.h
index 8a4196f32..c64bd8612 100644
--- a/poincare/include/poincare/floor.h
+++ b/poincare/include/poincare/floor.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,9 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
-    return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
+   return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
   }
   const char * name() const { return "floor"; }
   /* Simplification */
diff --git a/poincare/include/poincare/frac_part.h b/poincare/include/poincare/frac_part.h
index 2fb4f6d88..a55d70db6 100644
--- a/poincare/include/poincare/frac_part.h
+++ b/poincare/include/poincare/frac_part.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/global_context.h b/poincare/include/poincare/global_context.h
index d6c4d480a..e25775c1c 100644
--- a/poincare/include/poincare/global_context.h
+++ b/poincare/include/poincare/global_context.h
@@ -22,7 +22,7 @@ public:
   /* The expression recorded in global context is already a expression.
    * Otherwise, we would need the context and the angle unit to evaluate it */
   const Expression * expressionForSymbol(const Symbol * symbol) override;
-  ExpressionLayout * expressionLayoutForSymbol(const Symbol * symbol);
+  LayoutRef layoutRefForSymbol(const Symbol * symbol);
   void setExpressionForSymbolName(const Expression * expression, const Symbol * symbol, Context & context) override;
   static constexpr uint16_t k_maxNumberOfScalarExpressions = 26;
   static constexpr uint16_t k_maxNumberOfListExpressions = 10;
@@ -33,7 +33,7 @@ private:
   Complex<double> * m_expressions[k_maxNumberOfScalarExpressions];
   Matrix * m_matrixExpressions[k_maxNumberOfMatrixExpressions];
   /* Matrix layout memoization */
-  ExpressionLayout * m_matrixLayout[k_maxNumberOfMatrixExpressions];
+  LayoutRef m_matrixLayouts[k_maxNumberOfMatrixExpressions];
   Complex<double> m_pi;
   Complex<double> m_e;
   Complex<double> m_i;
diff --git a/poincare/include/poincare/great_common_divisor.h b/poincare/include/poincare/great_common_divisor.h
index 83d8f5d9e..0540535b4 100644
--- a/poincare/include/poincare/great_common_divisor.h
+++ b/poincare/include/poincare/great_common_divisor.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+ // return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/hyperbolic_arc_cosine.h b/poincare/include/poincare/hyperbolic_arc_cosine.h
index 8bc94757e..4ae9ec6e2 100644
--- a/poincare/include/poincare/hyperbolic_arc_cosine.h
+++ b/poincare/include/poincare/hyperbolic_arc_cosine.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+ // return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/hyperbolic_arc_sine.h b/poincare/include/poincare/hyperbolic_arc_sine.h
index 41f7ac7bc..2596b6b1d 100644
--- a/poincare/include/poincare/hyperbolic_arc_sine.h
+++ b/poincare/include/poincare/hyperbolic_arc_sine.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+ // return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/hyperbolic_arc_tangent.h b/poincare/include/poincare/hyperbolic_arc_tangent.h
index 1beaa2947..8cd59453f 100644
--- a/poincare/include/poincare/hyperbolic_arc_tangent.h
+++ b/poincare/include/poincare/hyperbolic_arc_tangent.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+ // return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/hyperbolic_cosine.h b/poincare/include/poincare/hyperbolic_cosine.h
index a3325b86f..aa21b03b8 100644
--- a/poincare/include/poincare/hyperbolic_cosine.h
+++ b/poincare/include/poincare/hyperbolic_cosine.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -15,8 +16,9 @@ public:
   template<typename T> static Complex<T> computeOnComplex(const Complex<T> c, AngleUnit angleUnit);
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+ // return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/hyperbolic_sine.h b/poincare/include/poincare/hyperbolic_sine.h
index 83b4c5f2f..f85dedca0 100644
--- a/poincare/include/poincare/hyperbolic_sine.h
+++ b/poincare/include/poincare/hyperbolic_sine.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -15,11 +16,12 @@ public:
   template<typename T> static Complex<T> computeOnComplex(const Complex<T> c, AngleUnit angleUnit);
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+    //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
-    return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
+   return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
   }
   const char * name() const { return "sinh"; }
   /* Simplification */
diff --git a/poincare/include/poincare/hyperbolic_tangent.h b/poincare/include/poincare/hyperbolic_tangent.h
index 4ec0dabed..e18ae5700 100644
--- a/poincare/include/poincare/hyperbolic_tangent.h
+++ b/poincare/include/poincare/hyperbolic_tangent.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -15,8 +16,9 @@ public:
   template<typename T> static Complex<T> computeOnComplex(const Complex<T> c, AngleUnit angleUnit);
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+      return CharLayoutRef('a'); //TODO
+ //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/imaginary_part.h b/poincare/include/poincare/imaginary_part.h
index 2c5757b7b..064c395a4 100644
--- a/poincare/include/poincare/imaginary_part.h
+++ b/poincare/include/poincare/imaginary_part.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+     return CharLayoutRef('a'); //TODO
+ // return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/integer.h b/poincare/include/poincare/integer.h
index af28e53c1..565d6267c 100644
--- a/poincare/include/poincare/integer.h
+++ b/poincare/include/poincare/integer.h
@@ -7,7 +7,9 @@
 namespace Poincare {
 
 class ExpressionLayout;
-
+/*class LayoutNode;
+class LayoutReference<LayoutNode>;
+*/
 /* All algorithm should be improved with:
  * Modern Computer Arithmetic, Richard P. Brent and Paul Zimmermann */
 
@@ -52,7 +54,7 @@ public:
 
   // Layout
   int writeTextInBuffer(char * buffer, int bufferSize) const;
-  ExpressionLayout * createLayout() const;
+  //LayoutReference<LayoutNode> createLayout() const;
 
   // Approximation
   template<typename T> T approximate() const;
diff --git a/poincare/include/poincare/integral.h b/poincare/include/poincare/integral.h
index 2c3ab3f98..0c24d7a05 100644
--- a/poincare/include/poincare/integral.h
+++ b/poincare/include/poincare/integral.h
@@ -16,7 +16,7 @@ public:
   int polynomialDegree(char symbolName) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "int");
   }
diff --git a/poincare/include/poincare/layout_engine.h b/poincare/include/poincare/layout_engine.h
index 1256621cc..8481c13f6 100644
--- a/poincare/include/poincare/layout_engine.h
+++ b/poincare/include/poincare/layout_engine.h
@@ -2,20 +2,20 @@
 #define POINCARE_LAYOUT_ENGINE_H
 
 #include <poincare/expression.h>
-#include <poincare/tree_reference.h>
+#include <poincare/layout_reference.h>
 
 namespace Poincare {
 
 class LayoutEngine {
 
 public:
-  /* Expression to ExpressionLayout */
-  static ExpressionLayout * createInfixLayout(const Expression * expression,  PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName);
-  static ExpressionLayout * createPrefixLayout(const Expression * expression, PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName);
+  /* Expression to LayoutRef */
+  static LayoutRef createInfixLayout(const Expression * expression,  PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName);
+  static LayoutRef createPrefixLayout(const Expression * expression, PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName);
 
   /* Create special layouts */
-  static ExpressionLayout * createParenthesedLayout(ExpressionLayout * layout, bool cloneLayout);
-  static ExpressionLayout * createStringLayout(const char * buffer, int bufferSize, KDText::FontSize fontSize = KDText::FontSize::Large);
+  static LayoutRef createParenthesedLayout(LayoutRef layout, bool cloneLayout);
+  static LayoutRef createStringLayout(const char * buffer, int bufferSize, KDText::FontSize fontSize = KDText::FontSize::Large);
   static ExpressionLayout * createLogLayout(ExpressionLayout * argument, ExpressionLayout * index);
 
   /* Expression to Text */
diff --git a/poincare/include/poincare/layout_node.h b/poincare/include/poincare/layout_node.h
index 13ad7061c..f93a4338c 100644
--- a/poincare/include/poincare/layout_node.h
+++ b/poincare/include/poincare/layout_node.h
@@ -25,6 +25,7 @@ public:
   virtual bool hasText() const { return false; } //TODO
   virtual char XNTChar() const { return 'x'; }
   virtual bool isHorizontal() const { return false; }
+  virtual bool isLeftParenthesis() const { return false; }
 
   // Rendering
   void draw(KDContext * ctx, KDPoint p, KDColor expressionColor = KDColorBlack, KDColor backgroundColor = KDColorWhite);
diff --git a/poincare/include/poincare/layout_reference.h b/poincare/include/poincare/layout_reference.h
index 90070ce42..5737ce1d3 100644
--- a/poincare/include/poincare/layout_reference.h
+++ b/poincare/include/poincare/layout_reference.h
@@ -44,6 +44,7 @@ public:
   }
 
   bool isHorizontal() const { return this->typedNode()->isHorizontal(); }
+  bool isLeftParenthesis() const { return this->typedNode()->isLeftParenthesis(); }
   bool hasText() { return this->typedNode()->hasText(); }
   char XNTChar() const { return this->typedNode()->XNTChar(); }
   KDSize layoutSize() { return this->typedNode()->layoutSize(); }
diff --git a/poincare/include/poincare/least_common_multiple.h b/poincare/include/poincare/least_common_multiple.h
index eddf83d93..8da3cef98 100644
--- a/poincare/include/poincare/least_common_multiple.h
+++ b/poincare/include/poincare/least_common_multiple.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+ //   return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/logarithm.h b/poincare/include/poincare/logarithm.h
index ded4cce79..aa4221d3d 100644
--- a/poincare/include/poincare/logarithm.h
+++ b/poincare/include/poincare/logarithm.h
@@ -15,7 +15,7 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "log");
   }
diff --git a/poincare/include/poincare/matrix.h b/poincare/include/poincare/matrix.h
index 4115b6b06..b7962e77b 100644
--- a/poincare/include/poincare/matrix.h
+++ b/poincare/include/poincare/matrix.h
@@ -41,7 +41,7 @@ private:
   /* rowCanonize turns a matrix in its reduced row echelon form. */
   void rowCanonize(Context & context, AngleUnit angleUnit, Multiplication * m = nullptr);
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   /* Evaluation */
   Expression * privateApproximate(SinglePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<float>(context, angleUnit); }
   Expression * privateApproximate(DoublePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<double>(context, angleUnit); }
diff --git a/poincare/include/poincare/matrix_dimension.h b/poincare/include/poincare/matrix_dimension.h
index f6b608b4c..71655e449 100644
--- a/poincare/include/poincare/matrix_dimension.h
+++ b/poincare/include/poincare/matrix_dimension.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+//    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/matrix_inverse.h b/poincare/include/poincare/matrix_inverse.h
index 0acae6ef6..675b56875 100644
--- a/poincare/include/poincare/matrix_inverse.h
+++ b/poincare/include/poincare/matrix_inverse.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Evaluation */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+//    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/matrix_trace.h b/poincare/include/poincare/matrix_trace.h
index 14b140ad6..710d3ce6a 100644
--- a/poincare/include/poincare/matrix_trace.h
+++ b/poincare/include/poincare/matrix_trace.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+ //   return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/matrix_transpose.h b/poincare/include/poincare/matrix_transpose.h
index 42ad6455a..c0b3e09db 100644
--- a/poincare/include/poincare/matrix_transpose.h
+++ b/poincare/include/poincare/matrix_transpose.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
  /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+    //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/multiplication.h b/poincare/include/poincare/multiplication.h
index 18ec2a876..d2edd226a 100644
--- a/poincare/include/poincare/multiplication.h
+++ b/poincare/include/poincare/multiplication.h
@@ -35,7 +35,7 @@ private:
   Expression * setSign(Sign s, Context & context, AngleUnit angleUnit) override;
   /* Layout */
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   /* Simplification */
   Expression * shallowReduce(Context& context, AngleUnit angleUnit) override;
diff --git a/poincare/include/poincare/naperian_logarithm.h b/poincare/include/poincare/naperian_logarithm.h
index 89a5173d1..244041555 100644
--- a/poincare/include/poincare/naperian_logarithm.h
+++ b/poincare/include/poincare/naperian_logarithm.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    return CharLayoutRef('a'); //TODO
+  //  return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/nth_root.h b/poincare/include/poincare/nth_root.h
index dfd8f5392..3a5c35c05 100644
--- a/poincare/include/poincare/nth_root.h
+++ b/poincare/include/poincare/nth_root.h
@@ -14,7 +14,7 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "root");
   }
diff --git a/poincare/include/poincare/opposite.h b/poincare/include/poincare/opposite.h
index 809aa4c43..a83dc3df4 100644
--- a/poincare/include/poincare/opposite.h
+++ b/poincare/include/poincare/opposite.h
@@ -18,7 +18,7 @@ public:
 private:
   /* Layout */
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   /* Simplification */
   Expression * shallowReduce(Context& context, AngleUnit angleUnit) override;
diff --git a/poincare/include/poincare/parenthesis.h b/poincare/include/poincare/parenthesis.h
index e3589c1d1..ee9965a67 100644
--- a/poincare/include/poincare/parenthesis.h
+++ b/poincare/include/poincare/parenthesis.h
@@ -15,7 +15,7 @@ public:
   int polynomialDegree(char symbolName) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, "");
   }
diff --git a/poincare/include/poincare/permute_coefficient.h b/poincare/include/poincare/permute_coefficient.h
index 63ad49a78..9ed509d0e 100644
--- a/poincare/include/poincare/permute_coefficient.h
+++ b/poincare/include/poincare/permute_coefficient.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -15,8 +16,9 @@ public:
 private:
   constexpr static int k_maxNValue = 100;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+//    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/power.h b/poincare/include/poincare/power.h
index a87b668dd..a074c0d9b 100644
--- a/poincare/include/poincare/power.h
+++ b/poincare/include/poincare/power.h
@@ -5,6 +5,7 @@
 #include <poincare/approximation_engine.h>
 #include <poincare/rational.h>
 #include <poincare/multiplication.h>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -30,7 +31,7 @@ private:
   /* Property */
   Expression * setSign(Sign s, Context & context, AngleUnit angleUnit) override;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   bool needParenthesisWithParent(const Expression * e) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writeInfixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/prediction_interval.h b/poincare/include/poincare/prediction_interval.h
index bccc77f8c..2f3fc7adb 100644
--- a/poincare/include/poincare/prediction_interval.h
+++ b/poincare/include/poincare/prediction_interval.h
@@ -3,6 +3,8 @@
 
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
+#include <poincare/char_layout_node.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -14,8 +16,9 @@ public:
   int polynomialDegree(char symbolName) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+  //  return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/randint.h b/poincare/include/poincare/randint.h
index 39d99e031..8eb650f8c 100644
--- a/poincare/include/poincare/randint.h
+++ b/poincare/include/poincare/randint.h
@@ -3,6 +3,8 @@
 
 #include <poincare/static_hierarchy.h>
 #include <poincare/layout_engine.h>
+#include <poincare/char_layout_node.h>
+#include <poincare/char_layout_node.h> //TODO remove
 
 namespace Poincare {
 
@@ -13,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    return CharLayoutRef('a'); //TODO
+//    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/random.h b/poincare/include/poincare/random.h
index 537b89106..1b61d1e0c 100644
--- a/poincare/include/poincare/random.h
+++ b/poincare/include/poincare/random.h
@@ -4,6 +4,7 @@
 #include <poincare/static_hierarchy.h>
 #include <poincare/layout_engine.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -17,8 +18,9 @@ public:
 private:
   Expression * setSign(Sign s, Context & context, AngleUnit angleUnit) override;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    return CharLayoutRef('a'); //TODO
+    /*return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());*/
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/rational.h b/poincare/include/poincare/rational.h
index 075a43060..13b8241b6 100644
--- a/poincare/include/poincare/rational.h
+++ b/poincare/include/poincare/rational.h
@@ -43,7 +43,7 @@ public:
   static int NaturalOrder(const Rational & i, const Rational & j);
 private:
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   Expression * privateApproximate(SinglePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<float>(context, angleUnit); }
   Expression * privateApproximate(DoublePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<double>(context, angleUnit); }
diff --git a/poincare/include/poincare/real_part.h b/poincare/include/poincare/real_part.h
index 16b6fdfd4..d4fe41f81 100644
--- a/poincare/include/poincare/real_part.h
+++ b/poincare/include/poincare/real_part.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    return CharLayoutRef('a'); //TODO
+    //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/round.h b/poincare/include/poincare/round.h
index fa0bd81da..cb26f2c48 100644
--- a/poincare/include/poincare/round.h
+++ b/poincare/include/poincare/round.h
@@ -4,6 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/complex.h>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -14,8 +15,9 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    return CharLayoutRef('a'); //TODO
+    //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/sequence.h b/poincare/include/poincare/sequence.h
index 6815ce4f4..88f1a0064 100644
--- a/poincare/include/poincare/sequence.h
+++ b/poincare/include/poincare/sequence.h
@@ -10,7 +10,7 @@ namespace Poincare {
 class Sequence : public StaticHierarchy<3>  {
   using StaticHierarchy<3>::StaticHierarchy;
 private:
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
   }
diff --git a/poincare/include/poincare/simplification_root.h b/poincare/include/poincare/simplification_root.h
index f692eda8c..049224c6c 100644
--- a/poincare/include/poincare/simplification_root.h
+++ b/poincare/include/poincare/simplification_root.h
@@ -20,8 +20,8 @@ public:
   Expression * clone() const override { return nullptr; }
   int polynomialDegree(char symbolName) const override { return -1; }
   Type type() const override { return Expression::Type::SimplificationRoot; }
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return nullptr;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    return LayoutRef(nullptr); //TODO
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override { return 0; }
   Expression * privateApproximate(SinglePrecision p, Context& context, AngleUnit angleUnit) const override {
diff --git a/poincare/include/poincare/sine.h b/poincare/include/poincare/sine.h
index 0c4fa57e3..da9e2debe 100644
--- a/poincare/include/poincare/sine.h
+++ b/poincare/include/poincare/sine.h
@@ -5,6 +5,7 @@
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
 #include <poincare/trigonometry.h>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -18,8 +19,9 @@ public:
   template<typename T> static Complex<T> computeOnComplex(const Complex<T> c, AngleUnit angleUnit = AngleUnit::Radian);
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    return CharLayoutRef('a'); //TODO
+//    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/square_root.h b/poincare/include/poincare/square_root.h
index 52b9f33f4..065b1541f 100644
--- a/poincare/include/poincare/square_root.h
+++ b/poincare/include/poincare/square_root.h
@@ -14,7 +14,7 @@ public:
   Expression * clone() const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   /* Simplification */
   Expression * shallowReduce(Context& context, AngleUnit angleUnit) override;
diff --git a/poincare/include/poincare/store.h b/poincare/include/poincare/store.h
index f47b8e342..1e0d915e9 100644
--- a/poincare/include/poincare/store.h
+++ b/poincare/include/poincare/store.h
@@ -18,7 +18,7 @@ private:
   /* Simplification */
   Expression * shallowReduce(Context& context, AngleUnit angleUnit) override;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   /* Evalutation */
   Expression * privateApproximate(SinglePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<float>(context, angleUnit); }
diff --git a/poincare/include/poincare/subtraction.h b/poincare/include/poincare/subtraction.h
index 6d611b6bb..223962455 100644
--- a/poincare/include/poincare/subtraction.h
+++ b/poincare/include/poincare/subtraction.h
@@ -4,6 +4,7 @@
 #include <poincare/static_hierarchy.h>
 #include <poincare/layout_engine.h>
 #include <poincare/approximation_engine.h>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -17,8 +18,9 @@ public:
 private:
   /* Layout */
   bool needParenthesisWithParent(const Expression * e) const override;
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createInfixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+  return CharLayoutRef('a'); //TODO
+ //   return LayoutEngine::createInfixLayout(this, floatDisplayMode, complexFormat, name());
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writeInfixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/symbol.h b/poincare/include/poincare/symbol.h
index edd1d1cd1..2cf4259f4 100644
--- a/poincare/include/poincare/symbol.h
+++ b/poincare/include/poincare/symbol.h
@@ -67,7 +67,7 @@ private:
   /* Comparison */
   int simplificationOrderSameType(const Expression * e, bool canBeInterrupted) const override;
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override;
   /* Evaluation */
   Expression * privateApproximate(SinglePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<float>(context, angleUnit); }
diff --git a/poincare/include/poincare/tangent.h b/poincare/include/poincare/tangent.h
index 640a2fad3..6606029b7 100644
--- a/poincare/include/poincare/tangent.h
+++ b/poincare/include/poincare/tangent.h
@@ -4,7 +4,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/static_hierarchy.h>
 #include <poincare/approximation_engine.h>
-
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -16,8 +16,9 @@ public:
   float characteristicXRange(Context & context, AngleUnit angleUnit = AngleUnit::Default) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
-    return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override {
+    //return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, name());
+  return CharLayoutRef('a'); //TODO
   }
   int writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits = PrintFloat::k_numberOfStoredSignificantDigits) const override {
     return LayoutEngine::writePrefixExpressionTextInBuffer(this, buffer, bufferSize, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/tree_reference.h b/poincare/include/poincare/tree_reference.h
index 78b37c5db..0ffead61e 100644
--- a/poincare/include/poincare/tree_reference.h
+++ b/poincare/include/poincare/tree_reference.h
@@ -65,6 +65,7 @@ public:
   int nodeRetainCount() const { return node()->retainCount(); }
   void incrementNumberOfChildren(int increment = 1) { return node()->incrementNumberOfChildren(increment); }
   void decrementNumberOfChildren(int decrement = 1) { return node()->decrementNumberOfChildren(decrement); }
+  int numberOfDescendants(bool includeSelf) const { return node()->numberOfDescendants(includeSelf);}
 
   // Serialization
   bool needsParenthesisWithParent(TreeReference<TreeNode> parentRef) { return node()->needsParenthesisWithParent(parentRef.node()); }
diff --git a/poincare/include/poincare/undefined.h b/poincare/include/poincare/undefined.h
index a0b1a0b24..857cbbb2c 100644
--- a/poincare/include/poincare/undefined.h
+++ b/poincare/include/poincare/undefined.h
@@ -14,7 +14,7 @@ public:
   int polynomialDegree(char symbolName) const override;
 private:
   /* Layout */
-  ExpressionLayout * privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
+  LayoutRef privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const override;
   /* Evaluation */
   Expression * privateApproximate(SinglePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<float>(context, angleUnit); }
   Expression * privateApproximate(DoublePrecision p, Context& context, AngleUnit angleUnit) const override { return templatedApproximate<double>(context, angleUnit); }
diff --git a/poincare/src/absolute_value.cpp b/poincare/src/absolute_value.cpp
index 5751149b8..773eac040 100644
--- a/poincare/src/absolute_value.cpp
+++ b/poincare/src/absolute_value.cpp
@@ -1,7 +1,7 @@
 #include <poincare/absolute_value.h>
 #include <poincare/complex.h>
 #include <poincare/simplification_engine.h>
-#include "layout/absolute_value_layout.h"
+#include <poincare/char_layout_node.h>
 
 extern "C" {
 #include <assert.h>
@@ -24,10 +24,10 @@ Expression * AbsoluteValue::setSign(Sign s, Context & context, AngleUnit angleUn
   return this;
 }
 
-ExpressionLayout * AbsoluteValue::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef AbsoluteValue::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
   assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
-  return new AbsoluteValueLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), false);
+  return CharLayoutRef('a'); //TODO
 }
 
 Expression * AbsoluteValue::shallowReduce(Context& context, AngleUnit angleUnit) {
diff --git a/poincare/src/binomial_coefficient.cpp b/poincare/src/binomial_coefficient.cpp
index 51c0c62ba..777cf4f94 100644
--- a/poincare/src/binomial_coefficient.cpp
+++ b/poincare/src/binomial_coefficient.cpp
@@ -3,6 +3,7 @@
 #include <poincare/complex.h>
 #include <poincare/rational.h>
 #include "layout/binomial_coefficient_layout.h"
+#include <poincare/char_layout_node.h>
 
 extern "C" {
 #include <stdlib.h>
@@ -72,14 +73,15 @@ Expression * BinomialCoefficient::shallowReduce(Context& context, AngleUnit angl
   return replaceWith(new Rational(result), true);
 }
 
-ExpressionLayout * BinomialCoefficient::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef BinomialCoefficient::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+    return CharLayoutRef('a'); //TODO
+ /*assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   return new BinomialCoefficientLayout(
       operand(0)->createLayout(floatDisplayMode, complexFormat),
       operand(1)->createLayout(floatDisplayMode, complexFormat),
       false);
-}
+*/}
 
 template<typename T>
 Expression * BinomialCoefficient::templatedApproximate(Context& context, AngleUnit angleUnit) const {
diff --git a/poincare/src/ceiling.cpp b/poincare/src/ceiling.cpp
index 4d8af70bb..a3feb6b03 100644
--- a/poincare/src/ceiling.cpp
+++ b/poincare/src/ceiling.cpp
@@ -8,6 +8,7 @@
 extern "C" {
 #include <assert.h>
 }
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -59,10 +60,11 @@ Complex<T> Ceiling::computeOnComplex(const Complex<T> c, AngleUnit angleUnit) {
   return Complex<T>::Float(std::ceil(c.a()));
 }
 
-ExpressionLayout * Ceiling::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Ceiling::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+    return CharLayoutRef('a'); //TODO
+ /*assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   return new CeilingLayout(m_operands[0]->createLayout(floatDisplayMode, complexFormat), false);
-}
+*/}
 
 }
diff --git a/poincare/src/char_layout_node.cpp b/poincare/src/char_layout_node.cpp
index 5bcaec05d..5723207f8 100644
--- a/poincare/src/char_layout_node.cpp
+++ b/poincare/src/char_layout_node.cpp
@@ -1,7 +1,13 @@
 #include <poincare/char_layout_node.h>
+#include <poincare/layout_engine.h>
 
 namespace Poincare {
 
+// LayoutNode
+int CharLayoutNode::writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits) const {
+  return LayoutEngine::writeOneCharInBuffer(buffer, bufferSize, m_char);
+}
+
 void CharLayoutNode::moveCursorLeft(LayoutCursor * cursor, bool * shouldRecomputeLayout) {
   if (cursor->position() == LayoutCursor::Position::Right) {
     cursor->setPosition(LayoutCursor::Position::Left);
diff --git a/poincare/src/complex.cpp b/poincare/src/complex.cpp
index 7ca360614..0f02dc3d6 100644
--- a/poincare/src/complex.cpp
+++ b/poincare/src/complex.cpp
@@ -20,6 +20,8 @@ extern "C" {
 #include <string.h>
 }
 
+#include <poincare/char_layout_node.h>
+
 namespace Poincare {
 
 template<typename T>
@@ -213,13 +215,14 @@ Complex<T>::Complex(T a, T b) :
 }
 
 template <class T>
-ExpressionLayout * Complex<T>::privateCreateLayout(PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Complex<T>::privateCreateLayout(PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+ /*  assert(floatDisplayMode != PrintFloat::Mode::Default);
   if (complexFormat == Expression::ComplexFormat::Polar) {
     return createPolarLayout(floatDisplayMode);
   }
   return createCartesianLayout(floatDisplayMode);
-}
+*/}
 
 template <class T>
 Expression * Complex<T>::CreateDecimal(T f) {
@@ -306,7 +309,7 @@ int Complex<T>::convertComplexToText(char * buffer, int bufferSize, int numberOf
   return numberOfChars;
 }
 
-template <class T>
+/*template <class T>
 ExpressionLayout * Complex<T>::createPolarLayout(PrintFloat::Mode floatDisplayMode) const {
   char bufferBase[PrintFloat::k_maxFloatBufferLength+2];
   int numberOfCharInBase = 0;
@@ -349,7 +352,7 @@ ExpressionLayout * Complex<T>::createCartesianLayout(PrintFloat::Mode floatDispl
   char buffer[PrintFloat::k_maxComplexBufferLength];
   int numberOfChars = convertComplexToText(buffer, PrintFloat::k_maxComplexBufferLength, Preferences::sharedPreferences()->numberOfSignificantDigits(), floatDisplayMode, Expression::ComplexFormat::Cartesian, Ion::Charset::MiddleDot);
   return LayoutEngine::createStringLayout(buffer, numberOfChars);
-}
+}*/
 
 template class Complex<float>;
 template class Complex<double>;
diff --git a/poincare/src/conjugate.cpp b/poincare/src/conjugate.cpp
index 57461ae00..d27f96ac6 100644
--- a/poincare/src/conjugate.cpp
+++ b/poincare/src/conjugate.cpp
@@ -2,6 +2,7 @@
 #include <poincare/complex.h>
 #include <poincare/simplification_engine.h>
 #include "layout/conjugate_layout.h"
+#include <poincare/char_layout_node.h>
 
 extern "C" {
 #include <assert.h>
@@ -19,11 +20,12 @@ Expression * Conjugate::clone() const {
   return a;
 }
 
-ExpressionLayout * Conjugate::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Conjugate::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+    return CharLayoutRef('a'); //TODO
+ /*assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   return new ConjugateLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), false);
-}
+*/}
 
 Expression * Conjugate::shallowReduce(Context& context, AngleUnit angleUnit) {
   Expression * e = Expression::shallowReduce(context, angleUnit);
diff --git a/poincare/src/decimal.cpp b/poincare/src/decimal.cpp
index 305049255..654d2c43a 100644
--- a/poincare/src/decimal.cpp
+++ b/poincare/src/decimal.cpp
@@ -9,6 +9,7 @@
 extern "C" {
 #include <assert.h>
 }
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -217,8 +218,9 @@ bool Decimal::needParenthesisWithParent(const Expression * e) const {
   return e->isOfType(types, 7);
 }
 
-ExpressionLayout * Decimal::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  char buffer[k_maxBufferSize];
+LayoutRef Decimal::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+   return CharLayoutRef('a'); //TODO
+ /*char buffer[k_maxBufferSize];
   int numberOfChars = convertToText(buffer, k_maxBufferSize, floatDisplayMode, PrintFloat::k_numberOfStoredSignificantDigits);
   return LayoutEngine::createStringLayout(buffer, numberOfChars);
 }
@@ -241,7 +243,7 @@ Expression * Decimal::shallowReduce(Context& context, AngleUnit angleUnit) {
   } else {
     denominator = Integer::Power(Integer(10), Integer(numberOfDigits-1-m_exponent));
   }
-  return replaceWith(new Rational(numerator, denominator), true);
+  return replaceWith(new Rational(numerator, denominator), true);*/
 }
 
 Expression * Decimal::shallowBeautify(Context & context, AngleUnit angleUnit) {
diff --git a/poincare/src/division.cpp b/poincare/src/division.cpp
index de9b576a8..4e54be4a7 100644
--- a/poincare/src/division.cpp
+++ b/poincare/src/division.cpp
@@ -97,13 +97,14 @@ Complex<T> Division::compute(const Complex<T> c, const Complex<T> d) {
   return Complex<T>::Cartesian((temp*aa + ab) / norm, (temp*bb + ba) / norm);
 }
 
-ExpressionLayout * Division::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Division::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+ /* assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   const Expression * numerator = operand(0)->type() == Type::Parenthesis ? operand(0)->operand(0) : operand(0);
   const Expression * denominator = operand(1)->type() == Type::Parenthesis ? operand(1)->operand(0) : operand(1);
   return new FractionLayout(numerator->createLayout(floatDisplayMode, complexFormat), denominator->createLayout(floatDisplayMode, complexFormat), false);
-}
+*/}
 
 template<typename T> Matrix * Division::computeOnComplexAndMatrix(const Complex<T> * c, const Matrix * n) {
   Matrix * inverse = n->createApproximateInverse<T>();
diff --git a/poincare/src/empty_expression.cpp b/poincare/src/empty_expression.cpp
index 9e416269c..13d22f174 100644
--- a/poincare/src/empty_expression.cpp
+++ b/poincare/src/empty_expression.cpp
@@ -2,6 +2,7 @@
 #include <poincare/layout_engine.h>
 #include <poincare/src/layout/empty_layout.h>
 #include <ion/charset.h>
+#include <poincare/char_layout_node.h>
 
 extern "C" {
 #include <math.h>
@@ -17,8 +18,9 @@ int EmptyExpression::writeTextInBuffer(char * buffer, int bufferSize, int number
   return LayoutEngine::writeOneCharInBuffer(buffer, bufferSize, Ion::Charset::Empty);
 }
 
-ExpressionLayout * EmptyExpression::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  return new EmptyLayout();
+LayoutRef EmptyExpression::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+ //  return new EmptyLayout();
 }
 
 template<typename T> Complex<T> * EmptyExpression::templatedApproximate(Context& context, AngleUnit angleUnit) const {
diff --git a/poincare/src/equal.cpp b/poincare/src/equal.cpp
index 58db799c9..ee9e35a3d 100644
--- a/poincare/src/equal.cpp
+++ b/poincare/src/equal.cpp
@@ -50,14 +50,15 @@ Expression * Equal::shallowReduce(Context& context, AngleUnit angleUnit) {
   return this;
 }
 
-ExpressionLayout * Equal::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Equal::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+    return CharLayoutRef('a'); //TODO
+ /*assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   HorizontalLayout * result = new HorizontalLayout();
   result->addOrMergeChildAtIndex(operand(0)->createLayout(floatDisplayMode, complexFormat), 0, false);
   result->addChildAtIndex(new CharLayout('='), result->numberOfChildren());
   result->addOrMergeChildAtIndex(operand(1)->createLayout(floatDisplayMode, complexFormat), result->numberOfChildren(), false);
-  return result;
+  return result;*/
 }
 
 template<typename T>
diff --git a/poincare/src/expression.cpp b/poincare/src/expression.cpp
index 22e30cfcd..6f3450c75 100644
--- a/poincare/src/expression.cpp
+++ b/poincare/src/expression.cpp
@@ -345,7 +345,7 @@ bool Expression::isEqualToItsApproximationLayout(Expression * approximation, int
 
 /* Layout */
 
-ExpressionLayout * Expression::createLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef Expression::createLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
   switch (floatDisplayMode) {
     case PrintFloat::Mode::Default:
       switch (complexFormat) {
diff --git a/poincare/src/factorial.cpp b/poincare/src/factorial.cpp
index bb1c048b7..983c4f6bc 100644
--- a/poincare/src/factorial.cpp
+++ b/poincare/src/factorial.cpp
@@ -11,6 +11,7 @@ extern "C" {
 #include <assert.h>
 }
 #include <cmath>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -92,13 +93,15 @@ Complex<T> Factorial::computeOnComplex(const Complex<T> c, AngleUnit angleUnit)
   return Complex<T>::Float(std::round(result));
 }
 
-ExpressionLayout * Factorial::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Factorial::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+    return CharLayoutRef('a'); //TODO
+ /*assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   HorizontalLayout * result = new HorizontalLayout();
   result->addOrMergeChildAtIndex(operand(0)->createLayout(floatDisplayMode, complexFormat), 0, false);
   result->addChildAtIndex(new CharLayout('!'), result->numberOfChildren());
   return result;
+*/
 }
 
 int Factorial::writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits) const {
diff --git a/poincare/src/floor.cpp b/poincare/src/floor.cpp
index fa9b02daa..a8302a05b 100644
--- a/poincare/src/floor.cpp
+++ b/poincare/src/floor.cpp
@@ -56,10 +56,11 @@ Complex<T> Floor::computeOnComplex(const Complex<T> c, AngleUnit angleUnit) {
   return Complex<T>::Float(std::floor(c.a()));
 }
 
-ExpressionLayout * Floor::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Floor::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+     return CharLayoutRef('a'); //TODO
+/*  assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
-  return new FloorLayout(m_operands[0]->createLayout(floatDisplayMode, complexFormat), false);
+  return new FloorLayout(m_operands[0]->createLayout(floatDisplayMode, complexFormat), false);*/
 }
 
 }
diff --git a/poincare/src/global_context.cpp b/poincare/src/global_context.cpp
index 479e61cfe..835eadf58 100644
--- a/poincare/src/global_context.cpp
+++ b/poincare/src/global_context.cpp
@@ -8,6 +8,17 @@
 namespace Poincare {
 
 GlobalContext::GlobalContext() :
+  m_matrixLayouts{
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr),
+    LayoutRef(nullptr)}, //TODO find better way to initialize
   m_pi(Complex<double>::Float(M_PI)),
   m_e(Complex<double>::Float(M_E)),
   m_i(Complex<double>::Cartesian(0.0, 1.0))
@@ -17,7 +28,6 @@ GlobalContext::GlobalContext() :
   }
   for (int i = 0; i < k_maxNumberOfMatrixExpressions ; i++) {
     m_matrixExpressions[i] = nullptr;
-    m_matrixLayout[i] = nullptr;
   }
 }
 
@@ -33,10 +43,6 @@ GlobalContext::~GlobalContext() {
       delete m_matrixExpressions[i];
     }
     m_matrixExpressions[i] = nullptr;
-    if (m_matrixLayout[i] != nullptr) {
-      delete m_matrixLayout[i];
-    }
-    m_matrixLayout[i] = nullptr;
   }
 }
 
@@ -78,13 +84,13 @@ const Expression * GlobalContext::expressionForSymbol(const Symbol * symbol) {
   return m_expressions[index];
 }
 
-ExpressionLayout * GlobalContext::expressionLayoutForSymbol(const Symbol * symbol) {
+LayoutRef GlobalContext::layoutRefForSymbol(const Symbol * symbol) {
   if (symbol->isMatrixSymbol()) {
     int index = symbolIndex(symbol);
-    if (m_matrixLayout[index] == nullptr && m_matrixExpressions[index] != nullptr) {
-      m_matrixLayout[index] = m_matrixExpressions[index]->createLayout();
+    if (!m_matrixLayouts[index].isDefined() && m_matrixExpressions[index] != nullptr) {
+      m_matrixLayouts[index] = m_matrixExpressions[index]->createLayout();
     }
-    return m_matrixLayout[index];
+    return m_matrixLayouts[index];
   }
   return nullptr;
 }
@@ -99,9 +105,8 @@ void GlobalContext::setExpressionForSymbolName(const Expression * expression, co
       delete m_matrixExpressions[indexMatrix];
       m_matrixExpressions[indexMatrix] = nullptr;
     }
-    if (m_matrixLayout[indexMatrix] != nullptr) {
-      delete m_matrixLayout[indexMatrix];
-      m_matrixLayout[indexMatrix] = nullptr;
+    if (m_matrixLayouts[indexMatrix] != nullptr) {
+      m_matrixLayouts[indexMatrix] = LayoutRef(nullptr);
     }
     if (evaluation != nullptr) {
       if (evaluation->type() == Expression::Type::Complex) {
diff --git a/poincare/src/integer.cpp b/poincare/src/integer.cpp
index a55a19dac..d69de58ed 100644
--- a/poincare/src/integer.cpp
+++ b/poincare/src/integer.cpp
@@ -2,6 +2,7 @@
 #include <poincare/complex.h>
 #include <poincare/ieee754.h>
 #include <poincare/layout_engine.h>
+#include <poincare/char_layout_node.h>
 #include <cmath>
 #include <utility>
 extern "C" {
@@ -600,11 +601,14 @@ int Integer::writeTextInBuffer(char * buffer, int bufferSize) const {
   return size;
 }
 
-ExpressionLayout * Integer::createLayout() const {
+/*LayoutRef Integer::createLayout() const {
+    return CharLayoutRef('a'); //TODO
+/*
   char buffer[255];
   int numberOfChars = writeTextInBuffer(buffer, 255);
   return LayoutEngine::createStringLayout(buffer, numberOfChars);
-}
+
+}*/
 
 template float Poincare::Integer::approximate<float>() const;
 template double Poincare::Integer::approximate<double>() const;
diff --git a/poincare/src/integral.cpp b/poincare/src/integral.cpp
index 3246ee5fd..2c24f3844 100644
--- a/poincare/src/integral.cpp
+++ b/poincare/src/integral.cpp
@@ -10,6 +10,7 @@ extern "C" {
 }
 #include "layout/integral_layout.h"
 #include "layout/horizontal_layout.h"
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -66,7 +67,9 @@ Complex<T> * Integral::templatedApproximate(Context & context, AngleUnit angleUn
   return new Complex<T>(Complex<T>::Float(result));
 }
 
-ExpressionLayout * Integral::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef Integral::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+    return CharLayoutRef('a'); //TODO
+ /*
   assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   return new IntegralLayout(
@@ -74,7 +77,7 @@ ExpressionLayout * Integral::privateCreateLayout(PrintFloat::Mode floatDisplayMo
       operand(1)->createLayout(floatDisplayMode, complexFormat),
       operand(2)->createLayout(floatDisplayMode, complexFormat),
       false);
-}
+*/}
 
 template<typename T>
 T Integral::functionValueAtAbscissa(T x, Context & context, AngleUnit angleUnit) const {
diff --git a/poincare/src/layout_engine.cpp b/poincare/src/layout_engine.cpp
index 8a82ba026..153177c0e 100644
--- a/poincare/src/layout_engine.cpp
+++ b/poincare/src/layout_engine.cpp
@@ -4,18 +4,29 @@
 #include "layout/left_parenthesis_layout.h"
 #include "layout/right_parenthesis_layout.h"
 #include "layout/vertical_offset_layout.h"
+#include <poincare/horizontal_layout_node.h>
+#include <poincare/char_layout_node.h>
+
 extern "C" {
 #include<assert.h>
 }
 
 namespace Poincare {
 
-ExpressionLayout * LayoutEngine::createInfixLayout(const Expression * expression, PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName) {
+LayoutRef LayoutEngine::createInfixLayout(const Expression * expression, PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName) {
   assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != Expression::ComplexFormat::Default);
   int numberOfOperands = expression->numberOfOperands();
   assert(numberOfOperands > 1);
-  HorizontalLayout * result = new HorizontalLayout();
+  HorizontalLayoutRef result;
+  result.addChildAtIndex(expression->operand(0)->createLayout(), 0);
+  for (int i = 1; i < numberOfOperands; i++) {
+    result.addChildAtIndex(createStringLayout(operatorName, strlen(operatorName)), result.numberOfChildren());
+    result.addChildAtIndex(
+        expression->operand(i)->createLayout(floatDisplayMode, complexFormat),
+        result.numberOfChildren());
+  }
+    /*
   result->addOrMergeChildAtIndex(expression->operand(0)->createLayout(), 0, true);
   for (int i = 1; i < numberOfOperands; i++) {
     result->addOrMergeChildAtIndex(createStringLayout(operatorName, strlen(operatorName)), result->numberOfChildren(), true);
@@ -24,16 +35,30 @@ ExpressionLayout * LayoutEngine::createInfixLayout(const Expression * expression
           createParenthesedLayout(expression->operand(i)->createLayout(floatDisplayMode, complexFormat), false) :
           expression->operand(i)->createLayout(floatDisplayMode, complexFormat),
         result->numberOfChildren(), true);
-  }
+  }*/
   return result;
 }
 
-ExpressionLayout * LayoutEngine::createPrefixLayout(const Expression * expression, PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName) {
+LayoutRef LayoutEngine::createPrefixLayout(const Expression * expression, PrintFloat::Mode floatDisplayMode, Expression::ComplexFormat complexFormat, const char * operatorName) {
   assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != Expression::ComplexFormat::Default);
-  HorizontalLayout * result = new HorizontalLayout();
-
+  HorizontalLayoutRef result;
   // Add the operator name.
+  result.addChildAtIndex(createStringLayout(operatorName, strlen(operatorName)), 0);
+
+  // Create the layout of arguments separated by commas.
+  HorizontalLayoutRef args;
+  int numberOfOperands = expression->numberOfOperands();
+  if (numberOfOperands > 0) {
+    args.addChildAtIndex(expression->operand(0)->createLayout(floatDisplayMode, complexFormat), 0);
+    for (int i = 1; i < numberOfOperands; i++) {
+      args.addChildAtIndex(CharLayoutRef(','), args.numberOfChildren());
+      args.addChildAtIndex(expression->operand(i)->createLayout(floatDisplayMode, complexFormat), args.numberOfChildren());
+    }
+  }
+  // Add the parenthesed arguments.
+  result.addChildAtIndex(createParenthesedLayout(args, false), result.numberOfChildren());
+  /*// Add the operator name.
   result->addOrMergeChildAtIndex(createStringLayout(operatorName, strlen(operatorName)), 0, true);
 
   // Create the layout of arguments separated by commas.
@@ -49,35 +74,36 @@ ExpressionLayout * LayoutEngine::createPrefixLayout(const Expression * expressio
     }
   }
   // Add the parenthesed arguments.
-  result->addOrMergeChildAtIndex(createParenthesedLayout(args, false), result->numberOfChildren(), true);
+  result->addOrMergeChildAtIndex(createParenthesedLayout(args, false), result->numberOfChildren(), true);*/
   return result;
 }
 
-ExpressionLayout * LayoutEngine::createParenthesedLayout(ExpressionLayout * layout, bool cloneLayout) {
-  HorizontalLayout * result = new HorizontalLayout();
-  result->addChildAtIndex(new LeftParenthesisLayout(), 0);
-  if (layout != nullptr) {
-    result->addOrMergeChildAtIndex(cloneLayout ? layout->clone() : layout, 1, true);
+LayoutRef LayoutEngine::createParenthesedLayout(LayoutRef layoutRef, bool cloneLayout) {
+  HorizontalLayoutRef result;
+  result.addChildAtIndex(CharLayoutRef('('), 0);
+  if (layoutRef.isDefined()) {
+    result.addChildAtIndex(cloneLayout ? layoutRef.clone() : layoutRef, 1);
   }
-  result->addChildAtIndex(new RightParenthesisLayout(), result->numberOfChildren());
+  result.addChildAtIndex(CharLayoutRef(')'), result.numberOfChildren());
   return result;
 }
 
-ExpressionLayout * LayoutEngine::createStringLayout(const char * buffer, int bufferSize, KDText::FontSize fontSize) {
+LayoutRef LayoutEngine::createStringLayout(const char * buffer, int bufferSize, KDText::FontSize fontSize) {
   assert(bufferSize > 0);
-  HorizontalLayout * resultLayout = new HorizontalLayout();
+  HorizontalLayoutRef resultLayout;
   for (int i = 0; i < bufferSize; i++) {
-    resultLayout->addChildAtIndex(new CharLayout(buffer[i], fontSize), i);
+    resultLayout.addChildAtIndex(CharLayoutRef(buffer[i], fontSize), i);
   }
   return resultLayout;
 }
 
 ExpressionLayout * LayoutEngine::createLogLayout(ExpressionLayout * argument, ExpressionLayout * index) {
-  HorizontalLayout * resultLayout = static_cast<HorizontalLayout *>(createStringLayout("log", 3));
+  return nullptr;
+  /*HorizontalLayout * resultLayout = static_cast<HorizontalLayout *>(createStringLayout("log", 3));
   VerticalOffsetLayout * offsetLayout = new VerticalOffsetLayout(index, VerticalOffsetLayout::Type::Subscript, false);
   resultLayout->addChildAtIndex(offsetLayout, resultLayout->numberOfChildren());
   resultLayout->addOrMergeChildAtIndex(createParenthesedLayout(argument, false), resultLayout->numberOfChildren(), true);
-  return resultLayout;
+  return resultLayout;*/
 }
 
 int LayoutEngine::writeInfixExpressionTextInBuffer(const Expression * expression, char * buffer, int bufferSize, int numberOfDigits, const char * operatorName) {
diff --git a/poincare/src/logarithm.cpp b/poincare/src/logarithm.cpp
index a8e979dc0..d7ddc1f53 100644
--- a/poincare/src/logarithm.cpp
+++ b/poincare/src/logarithm.cpp
@@ -228,13 +228,14 @@ Expression * Logarithm::templatedApproximate(Context& context, AngleUnit angleUn
   return new Complex<T>(result);
 }
 
-ExpressionLayout * Logarithm::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Logarithm::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+  /*assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   if (numberOfOperands() == 1) {
     return LayoutEngine::createPrefixLayout(this, floatDisplayMode, complexFormat, "log");
   }
-  return LayoutEngine::createLogLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), operand(1)->createLayout(floatDisplayMode, complexFormat));
+  return LayoutEngine::createLogLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), operand(1)->createLayout(floatDisplayMode, complexFormat));*/
 }
 
 }
diff --git a/poincare/src/matrix.cpp b/poincare/src/matrix.cpp
index 2b3e0f52f..e567f0e66 100644
--- a/poincare/src/matrix.cpp
+++ b/poincare/src/matrix.cpp
@@ -164,8 +164,9 @@ void Matrix::rowCanonize(Context & context, AngleUnit angleUnit, Multiplication
   }
 }
 
-ExpressionLayout * Matrix::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Matrix::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+ /* assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   ExpressionLayout ** childrenLayouts = new ExpressionLayout * [numberOfOperands()];
   for (int i = 0; i < numberOfOperands(); i++) {
@@ -173,7 +174,7 @@ ExpressionLayout * Matrix::privateCreateLayout(PrintFloat::Mode floatDisplayMode
   }
   ExpressionLayout * layout = new MatrixLayout(childrenLayouts, numberOfRows(), numberOfColumns(), false);
   delete [] childrenLayouts;
-  return layout;
+  return layout;*/
 }
 
 int Matrix::rank(Context & context, AngleUnit angleUnit, bool inPlace) {
diff --git a/poincare/src/multiplication.cpp b/poincare/src/multiplication.cpp
index 860f30ff4..532af5ad8 100644
--- a/poincare/src/multiplication.cpp
+++ b/poincare/src/multiplication.cpp
@@ -85,9 +85,12 @@ bool Multiplication::needParenthesisWithParent(const Expression * e) const {
   return e->isOfType(types, 3);
 }
 
-ExpressionLayout * Multiplication::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef Multiplication::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+/*
   const char middleDotString[] = {Ion::Charset::MiddleDot, 0};
   return LayoutEngine::createInfixLayout(this, floatDisplayMode, complexFormat, middleDotString);
+*/
 }
 
 int Multiplication::writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits) const {
diff --git a/poincare/src/nth_root.cpp b/poincare/src/nth_root.cpp
index 8f8005aec..3a32a88c6 100644
--- a/poincare/src/nth_root.cpp
+++ b/poincare/src/nth_root.cpp
@@ -38,10 +38,13 @@ Expression * NthRoot::shallowReduce(Context& context, AngleUnit angleUnit) {
   return p->shallowReduce(context, angleUnit);
 }
 
-ExpressionLayout * NthRoot::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef NthRoot::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+  /*
   assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   return new NthRootLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), operand(1)->createLayout(floatDisplayMode, complexFormat), false);
+*/
 }
 
 template<typename T>
diff --git a/poincare/src/opposite.cpp b/poincare/src/opposite.cpp
index 249ad84ce..dedce8527 100644
--- a/poincare/src/opposite.cpp
+++ b/poincare/src/opposite.cpp
@@ -12,6 +12,8 @@ extern "C" {
 #include <stdlib.h>
 }
 
+#include <poincare/char_layout_node.h>
+
 namespace Poincare {
 
 Expression::Type Opposite::type() const {
@@ -66,8 +68,9 @@ Expression * Opposite::shallowReduce(Context& context, AngleUnit angleUnit) {
   return m->shallowReduce(context, angleUnit);
 }
 
-ExpressionLayout * Opposite::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Opposite::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+/*  assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   HorizontalLayout * result = new HorizontalLayout(new CharLayout('-'), false);
   if (operand(0)->type() == Type::Opposite) {
@@ -76,7 +79,7 @@ ExpressionLayout * Opposite::privateCreateLayout(PrintFloat::Mode floatDisplayMo
     result->addOrMergeChildAtIndex(operand(0)->createLayout(floatDisplayMode, complexFormat), 1, false);
   }
   return result;
-
+*/
 }
 
 int Opposite::writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits) const {
diff --git a/poincare/src/parenthesis.cpp b/poincare/src/parenthesis.cpp
index 09240a108..e990da75d 100644
--- a/poincare/src/parenthesis.cpp
+++ b/poincare/src/parenthesis.cpp
@@ -1,4 +1,5 @@
 #include <poincare/parenthesis.h>
+#include <poincare/char_layout_node.h>
 
 extern "C" {
 #include <assert.h>
@@ -21,10 +22,12 @@ int Parenthesis::polynomialDegree(char symbolName) const {
   return operand(0)->polynomialDegree(symbolName);
 }
 
-ExpressionLayout * Parenthesis::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef Parenthesis::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('('); //TODO
+/*
   assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
-  return LayoutEngine::createParenthesedLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), false);
+  return LayoutEngine::createParenthesedLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), false);*/
 }
 
 Expression * Parenthesis::shallowReduce(Context& context, AngleUnit angleUnit) {
diff --git a/poincare/src/power.cpp b/poincare/src/power.cpp
index b20c500c4..28dcdcb34 100644
--- a/poincare/src/power.cpp
+++ b/poincare/src/power.cpp
@@ -175,8 +175,9 @@ bool Power::needParenthesisWithParent(const Expression * e) const {
   return e->isOfType(types, 2);
 }
 
-ExpressionLayout * Power::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Power::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+ /* assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   const Expression * indiceOperand = m_operands[1];
   // Delete eventual parentheses of the indice in the pretty print
@@ -190,7 +191,7 @@ ExpressionLayout * Power::privateCreateLayout(PrintFloat::Mode floatDisplayMode,
         VerticalOffsetLayout::Type::Superscript,
         false),
       result->numberOfChildren());
-  return result;
+  return result;*/
 }
 
 int Power::simplificationOrderSameType(const Expression * e, bool canBeInterrupted) const {
diff --git a/poincare/src/rational.cpp b/poincare/src/rational.cpp
index 03e9c1954..aa2117b9a 100644
--- a/poincare/src/rational.cpp
+++ b/poincare/src/rational.cpp
@@ -8,6 +8,7 @@ extern "C" {
 #include <poincare/arithmetic.h>
 #include <poincare/opposite.h>
 #include "layout/fraction_layout.h"
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -151,13 +152,15 @@ bool Rational::needParenthesisWithParent(const Expression * e) const {
   return e->isOfType(types, 3);
 }
 
-ExpressionLayout * Rational::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef Rational::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+  /*
   ExpressionLayout * numeratorLayout = m_numerator.createLayout();
   if (m_denominator.isOne()) {
     return numeratorLayout;
   }
   ExpressionLayout * denominatorLayout = m_denominator.createLayout();
-  return new FractionLayout(numeratorLayout, denominatorLayout, false);
+  return new FractionLayout(numeratorLayout, denominatorLayout, false);*/
 }
 
 int Rational::writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits) const {
diff --git a/poincare/src/sequence.cpp b/poincare/src/sequence.cpp
index 07aeb5159..d0dcef341 100644
--- a/poincare/src/sequence.cpp
+++ b/poincare/src/sequence.cpp
@@ -3,6 +3,7 @@
 #include <poincare/symbol.h>
 #include <poincare/undefined.h>
 #include <poincare/variable_context.h>
+#include <poincare/char_layout_node.h>
 extern "C" {
 #include <assert.h>
 #include <stdlib.h>
@@ -11,10 +12,12 @@ extern "C" {
 
 namespace Poincare {
 
-ExpressionLayout * Sequence::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Sequence::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+/*  assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   return createSequenceLayoutWithArgumentLayouts(operand(0)->createLayout(floatDisplayMode, complexFormat), operand(1)->createLayout(floatDisplayMode, complexFormat), operand(2)->createLayout(floatDisplayMode, complexFormat));
+*/
 }
 
 template<typename T>
diff --git a/poincare/src/square_root.cpp b/poincare/src/square_root.cpp
index 7b8105b7a..683137a27 100644
--- a/poincare/src/square_root.cpp
+++ b/poincare/src/square_root.cpp
@@ -8,6 +8,7 @@ extern "C" {
 }
 #include <cmath>
 #include <ion.h>
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -49,10 +50,12 @@ Expression * SquareRoot::shallowReduce(Context& context, AngleUnit angleUnit) {
   return p->shallowReduce(context, angleUnit);
 }
 
-ExpressionLayout * SquareRoot::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef SquareRoot::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+ /* assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   return new NthRootLayout(operand(0)->createLayout(floatDisplayMode, complexFormat), false);
+*/
 }
 
 }
diff --git a/poincare/src/store.cpp b/poincare/src/store.cpp
index 31164a008..098b69a3d 100644
--- a/poincare/src/store.cpp
+++ b/poincare/src/store.cpp
@@ -9,6 +9,7 @@ extern "C" {
 #include <poincare/context.h>
 #include "layout/char_layout.h"
 #include "layout/horizontal_layout.h"
+#include <poincare/char_layout_node.h>
 
 namespace Poincare {
 
@@ -34,14 +35,15 @@ Expression * Store::shallowReduce(Context& context, AngleUnit angleUnit) {
   return replaceWith(editableOperand(1), true)->shallowReduce(context, angleUnit);
 }
 
-ExpressionLayout * Store::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  assert(floatDisplayMode != PrintFloat::Mode::Default);
+LayoutRef Store::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+  /*assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   HorizontalLayout * result = new HorizontalLayout();
   result->addOrMergeChildAtIndex(value()->createLayout(floatDisplayMode, complexFormat), 0, false);
   result->addChildAtIndex(new CharLayout(Ion::Charset::Sto), result->numberOfChildren());
   result->addOrMergeChildAtIndex(symbol()->createLayout(floatDisplayMode, complexFormat), result->numberOfChildren(), false);
-  return result;
+  return result;*/
 }
 
 template<typename T>
diff --git a/poincare/src/symbol.cpp b/poincare/src/symbol.cpp
index 21a349b6a..9730df9df 100644
--- a/poincare/src/symbol.cpp
+++ b/poincare/src/symbol.cpp
@@ -12,6 +12,8 @@
 #include "layout/horizontal_layout.h"
 #include "layout/vertical_offset_layout.h"
 
+#include <poincare/char_layout_node.h>
+
 #include <ion.h>
 #include <cmath>
 
@@ -244,7 +246,9 @@ char Symbol::name() const {
   return m_name;
 }
 
-ExpressionLayout * Symbol::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+LayoutRef Symbol::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  return CharLayoutRef('a'); //TODO
+/*
   assert(floatDisplayMode != PrintFloat::Mode::Default);
   assert(complexFormat != ComplexFormat::Default);
   if (m_name == SpecialSymbols::Ans) {
@@ -289,7 +293,7 @@ ExpressionLayout * Symbol::privateCreateLayout(PrintFloat::Mode floatDisplayMode
   if (isMatrixSymbol() || isSeriesSymbol(m_name) || isRegressionSymbol(m_name)) {
     return LayoutEngine::createStringLayout(textForSpecialSymbols(m_name), 2);
   }
-  return LayoutEngine::createStringLayout(&m_name, 1);
+  return LayoutEngine::createStringLayout(&m_name, 1);*/
 }
 
 int Symbol::writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits) const {
diff --git a/poincare/src/undefined.cpp b/poincare/src/undefined.cpp
index c5600b15c..678854151 100644
--- a/poincare/src/undefined.cpp
+++ b/poincare/src/undefined.cpp
@@ -1,5 +1,6 @@
 #include <poincare/undefined.h>
 #include <poincare/layout_engine.h>
+#include <poincare/char_layout_node.h>
 
 extern "C" {
 #include <math.h>
@@ -24,10 +25,11 @@ template<typename T> Complex<T> * Undefined::templatedApproximate(Context& conte
   return new Complex<T>(Complex<T>::Float(NAN));
 }
 
-ExpressionLayout * Undefined::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
-  char buffer[16];
+LayoutRef Undefined::privateCreateLayout(PrintFloat::Mode floatDisplayMode, ComplexFormat complexFormat) const {
+  /*char buffer[16];
   int numberOfChars = PrintFloat::convertFloatToText<float>(NAN, buffer, 16, 1, floatDisplayMode);
-  return LayoutEngine::createStringLayout(buffer, numberOfChars);
+  return LayoutEngine::createStringLayout(buffer, numberOfChars);*/
+  return CharLayoutRef('a'); //TODO
 }
 
 int Undefined::writeTextInBuffer(char * buffer, int bufferSize, int numberOfSignificantDigits) const {