From e2e062e1288789c524aca417cb86be32ac485046 Mon Sep 17 00:00:00 2001
From: Gabriel Ozouf <gabriel.ozouf@numworks.com>
Date: Tue, 16 Jun 2020 10:34:41 +0200
Subject: [PATCH] [poincare/layout] Changed Fraction collapsing

Fraction are now only collapsed if they are the first thing to be
collapsed or if a parenthesis is open.

Change-Id: Ie7f3a99498b9981dff70221efd7de6bee6d0c379
---
 poincare/include/poincare/fraction_layout.h |  1 +
 poincare/src/fraction_layout.cpp            | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/poincare/include/poincare/fraction_layout.h b/poincare/include/poincare/fraction_layout.h
index 99a054aa2..8c6c4d101 100644
--- a/poincare/include/poincare/fraction_layout.h
+++ b/poincare/include/poincare/fraction_layout.h
@@ -22,6 +22,7 @@ public:
 
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
 
+  bool isCollapsable(int * numberOfOpenParenthesis, bool goingLeft) const override;
   bool shouldCollapseSiblingsOnLeft() const override { return true; }
   bool shouldCollapseSiblingsOnRight() const override { return true; }
   int leftCollapsingAbsorbingChildIndex() const override { return 0; }
diff --git a/poincare/src/fraction_layout.cpp b/poincare/src/fraction_layout.cpp
index 43dc8f7c3..ac035cf1b 100644
--- a/poincare/src/fraction_layout.cpp
+++ b/poincare/src/fraction_layout.cpp
@@ -161,6 +161,24 @@ LayoutNode * FractionLayoutNode::layoutToPointWhenInserting(Expression * corresp
   return this;
 }
 
+bool FractionLayoutNode::isCollapsable(int * numberOfOpenParenthesis, bool goingLeft) const {
+  if (*numberOfOpenParenthesis > 0) {
+    return true;
+  }
+
+  /* We do not want to absorb a fraction if something else is already being
+   * absorbed. This way, the user can write a product of fractions without
+   * typing the × sign. */
+  Layout p = Layout(parent());
+  assert(!p.isUninitialized() && p.type() == LayoutNode::Type::HorizontalLayout);
+  int indexInParent = p.indexOfChild(Layout(this));
+  int indexOfAbsorbingSibling = indexInParent + (goingLeft ? 1 : -1);
+  assert(indexOfAbsorbingSibling >= 0 && indexOfAbsorbingSibling < p.numberOfChildren());
+  Layout absorbingSibling = p.childAtIndex(indexOfAbsorbingSibling);
+  Layout absorbingChild = absorbingSibling.childAtIndex((goingLeft) ? absorbingSibling.leftCollapsingAbsorbingChildIndex() : absorbingSibling.rightCollapsingAbsorbingChildIndex());
+  return absorbingChild.type() == LayoutNode::Type::HorizontalLayout && absorbingChild.isEmpty();
+}
+
 void FractionLayoutNode::didCollapseSiblings(LayoutCursor * cursor) {
   if (cursor != nullptr) {
     cursor->setLayoutNode(denominatorLayout());