[apps/probability] Create a class evaluate context for probability app

Change-Id: I38448ddeec25225edad1d96bf89d32d1eb86915d

apps/probability/Makefile

@@ -1,6 +1,7 @@
 app_objs += $(addprefix apps/probability/,\
   app.o\
   cell.o\
+  evaluate_context.o\
   law.o\
   law_controller.o\
   parameters_controller.o\

apps/probability/evaluate_context.cpp

@@ -0,0 +1,39 @@
+#include "evaluate_context.h"
+#include <string.h>
+
+namespace Probability {
+
+EvaluateContext::EvaluateContext(::Context * parentContext) :
+  m_tValue(Float(0.0f)),
+  m_firstParameterValue(Float(0.0f)),
+  m_secondParameterValue(Float(0.0f)),
+  m_context(parentContext)
+{
+}
+
+void EvaluateContext::setOverridenValueForSymbolT(float f) {
+  m_tValue = Float(f);
+}
+
+void EvaluateContext::setOverridenValueForFirstParameter(float f) {
+  m_firstParameterValue = Float(f);
+}
+
+void EvaluateContext::setOverridenValueForSecondParameter(float f) {
+  m_secondParameterValue = Float(f);
+}
+
+const Expression * EvaluateContext::expressionForSymbol(const Symbol * symbol) {
+  if (symbol->name() == 't') {
+    return &m_tValue;
+  }
+  if (symbol->name() == Symbol::SpecialSymbols::p1) {
+    return &m_firstParameterValue;
+  }
+  if (symbol->name() == Symbol::SpecialSymbols::p2) {
+    return &m_secondParameterValue;
+  }
+  return m_context->expressionForSymbol(symbol);
+}
+
+}

apps/probability/evaluate_context.h

@@ -0,0 +1,24 @@
+#ifndef PROBABILITY_EVALUATECONTEXT_H
+#define PROBABILITY_EVALUATECONTEXT_H
+
+#include <poincare.h>
+
+namespace Probability {
+
+class EvaluateContext : public ::Context {
+  public:
+    EvaluateContext(Context * parentContext);
+    void setOverridenValueForSymbolT(float f);
+    void setOverridenValueForFirstParameter(float f);
+    void setOverridenValueForSecondParameter(float f);
+    const Expression * expressionForSymbol(const Symbol * symbol) override;
+  private:
+    Float m_tValue;
+    Float m_firstParameterValue;
+    Float m_secondParameterValue;
+    ::Context * m_context;
+};
+
+}
+
+#endif

poincare/include/poincare/symbol.h

@@ -6,7 +6,9 @@
 class Symbol : public LeafExpression {
 public:
     enum SpecialSymbols : char {
-        Ans = '^'
+        Ans = '^',
+        p1 = '*',
+        p2 = '$'
     };
     Symbol(char name);
     ExpressionLayout * createLayout() const override;

poincare/src/expression_lexer.l

@@ -69,6 +69,8 @@
 [0-9]+ { poincare_expression_yylval.string = yytext; return(INTEGER); }
 [A-Zxnt] { poincare_expression_yylval.character = yytext[0]; return SYMBOL; }
 ans { poincare_expression_yylval.character = Symbol::Ans; return SYMBOL; }
+p1 { poincare_expression_yylval.character = Symbol::p1; return SYMBOL; }
+p2 { poincare_expression_yylval.character = Symbol::p2; return SYMBOL; }
 sin { poincare_expression_yylval.expression = new Sine(); return FUNCTION; }
 cos { poincare_expression_yylval.expression = new Cosine(); return FUNCTION; }
 tan { poincare_expression_yylval.expression = new Tangent(); return FUNCTION; }