[poincare] Implement factorial

Change-Id: I2344d12fdc9084db84247a096110efe0e909e32a

poincare/Makefile

@@ -23,6 +23,7 @@ objs += $(addprefix poincare/src/,\
   expression.o\
   expression_lexer.o\
   expression_parser.o\
+  factorial.o\
   floor.o\
   frac_part.o\
   fraction.o\

poincare/include/poincare.h

@@ -19,6 +19,7 @@
 #include <poincare/division_quotient.h>
 #include <poincare/division_remainder.h>
 #include <poincare/expression.h>
+#include <poincare/factorial.h>
 #include <poincare/floor.h>
 #include <poincare/frac_part.h>
 #include <poincare/fraction.h>

poincare/include/poincare/expression.h

@@ -27,6 +27,7 @@ public:
     Determinant,
     DivisionQuotient,
     DivisionRemainder,
+    Factorial,
     Float,
     Floor,
     FracPart,

poincare/include/poincare/factorial.h

@@ -0,0 +1,21 @@
+#ifndef POINCARE_FACTORIAL_H
+#define POINCARE_FACTORIAL_H
+
+#include <poincare/function.h>
+
+namespace Poincare {
+
+class Factorial : public Function {
+public:
+  Factorial(Expression * argument, bool clone = true);
+  Type type() const override;
+  Expression * cloneWithDifferentOperands(Expression ** newOperands,
+    int numberOfOperands, bool cloneOperands = true) const override;
+private:
+  float privateApproximate(Context & context, AngleUnit angleUnit) const override;
+  ExpressionLayout * privateCreateLayout(FloatDisplayMode floatDisplayMode, ComplexFormat complexFormat) const override;
+};
+
+}
+
+#endif

poincare/src/expression_lexer.l

@@ -145,6 +145,7 @@ inf { poincare_expression_yylval.expression = new Complex(Complex::Float(INFINIT
 \* { return MULTIPLY; }
 \/ { return DIVIDE; }
 \^ { return POW; }
+\! { return BANG; }
 \( { return LEFT_PARENTHESIS; }
 \) { return RIGHT_PARENTHESIS; }
 \{ { return LEFT_BRACE; }

poincare/src/expression_parser.y

@@ -58,6 +58,7 @@ void poincare_expression_yyerror(Poincare::Expression ** expressionOutput, char
 %token MULTIPLY
 %token DIVIDE
 %token POW
+%token BANG
 %token LEFT_PARENTHESIS
 %token RIGHT_PARENTHESIS
 %token LEFT_BRACE
@@ -89,6 +90,7 @@ void poincare_expression_yyerror(Poincare::Expression ** expressionOutput, char
 %left MULTIPLY
 %left DIVIDE
 %left POW
+%left BANG
 
 /* The "exp" symbol uses the "expression" part of the union. */
 %type <expression> exp;
@@ -131,7 +133,8 @@ symb:
 
 exp:
   UNDEFINED        { $$ = $1; }
-  | exp STO symb   {$$ = new Poincare::Store($3, $1, false); }
+  | exp BANG       { $$ = new Poincare::Factorial($1, false); }
+  | exp STO symb   { $$ = new Poincare::Store($3, $1, false); }
   | number             { $$ = $1; }
   | ICOMPLEX         { $$ = new Poincare::Complex(Poincare::Complex::Cartesian(0.0f, 1.0f)); }
   | symb           { $$ = $1; }

poincare/src/factorial.cpp

@@ -0,0 +1,53 @@
+#include <poincare/factorial.h>
+#include "layout/string_layout.h"
+#include "layout/horizontal_layout.h"
+extern "C" {
+#include <assert.h>
+#include <math.h>
+}
+
+namespace Poincare {
+
+Factorial::Factorial(Expression * argument, bool clone) :
+  Function("fact")
+{
+  setArgument(&argument, 1, clone);
+}
+
+Expression::Type Factorial::type() const {
+  return Type::Factorial;
+}
+
+Expression * Factorial::cloneWithDifferentOperands(Expression** newOperands,
+        int numberOfOperands, bool cloneOperands) const {
+  assert(newOperands != nullptr);
+  Factorial * f = new Factorial(newOperands[0], cloneOperands);
+  return f;
+}
+
+float Factorial::privateApproximate(Context& context, AngleUnit angleUnit) const {
+  assert(angleUnit != AngleUnit::Default);
+  float n = m_args[0]->approximate(context, angleUnit);
+  if (isnan(n) || n != (int)n || n < 0.0f) {
+    return NAN;
+  }
+  float result = 1.0f;
+  for (int i = 1; i <= (int)n; i++) {
+    result *= (float)i;
+    if (isinf(result)) {
+      return result;
+    }
+  }
+  return roundf(result);
+}
+
+ExpressionLayout * Factorial::privateCreateLayout(FloatDisplayMode floatDisplayMode, ComplexFormat complexFormat) const {
+  assert(floatDisplayMode != FloatDisplayMode::Default);
+  assert(complexFormat != ComplexFormat::Default);
+  ExpressionLayout * childrenLayouts[2];
+  childrenLayouts[0] = m_args[0]->createLayout(floatDisplayMode, complexFormat);
+  childrenLayouts[1] = new StringLayout("!", 1);
+  return new HorizontalLayout(childrenLayouts, 2);
+}
+
+}