From 2d2aa03bcb8cb69b0235cc3ade4baad0f14cc5d2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Tue, 15 Nov 2016 11:57:40 +0100
Subject: [PATCH] [poincare] In context, return 0 if constant has not been
 assigned

Change-Id: I3a338a7de54c55500982a8a0dd32a1193f8db504
---
 poincare/include/poincare/context.h |  4 ++++
 poincare/src/context.cpp            | 12 +++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/poincare/include/poincare/context.h b/poincare/include/poincare/context.h
index 49160a702..81ad82af8 100644
--- a/poincare/include/poincare/context.h
+++ b/poincare/include/poincare/context.h
@@ -3,6 +3,9 @@
 
 #include <poincare/expression.h>
 #include <poincare/symbol.h>
+#include <poincare/float.h>
+
+class Integer;
 
 //TODO: We should probably make a COPY of the expressions we store
 
@@ -16,6 +19,7 @@ class Context {
     int symbolIndex(const Symbol * symbol) const;
     static constexpr uint16_t k_maxNumberOfExpressions = 26;
     Expression * m_expressions[k_maxNumberOfExpressions];
+    static Float * defaultExpression();
 };
 
 #endif
diff --git a/poincare/src/context.cpp b/poincare/src/context.cpp
index b2e65f126..4b51f1bbc 100644
--- a/poincare/src/context.cpp
+++ b/poincare/src/context.cpp
@@ -8,14 +8,24 @@ Context::Context()
   }
 }
 
+Float * Context::defaultExpression() {
+  static Float * defaultExpression = new Float(0);
+  return defaultExpression;
+}
+
 int Context::symbolIndex(const Symbol * symbol) const {
   int index = symbol->name() - 'A';
-  assert(index < k_maxNumberOfExpressions);
   return index;
 }
 
 const Expression * Context::expressionForSymbol(const Symbol * symbol) {
   int index = symbolIndex(symbol);
+  if (index < 0 || index >= k_maxNumberOfExpressions) {
+    return nullptr;
+  }
+  if (m_expressions[index] == nullptr) {
+    return defaultExpression();
+  }
   return m_expressions[index];
 }