[poincare] Parse variables

poincare/Makefile

@@ -1,5 +1,5 @@
 SFLAGS += -Ipoincare/include
-objs += $(addprefix poincare/src/, addition.o expression.o integer.o fraction.o expression_lexer.o expression_parser.o)
+objs += $(addprefix poincare/src/, addition.o expression.o integer.o fraction.o expression_lexer.o expression_parser.o variable.o)
 objs += $(addprefix poincare/src/layout/, expression_layout.o fraction_layout.o horizontal_layout.o string_layout.o)
 tests += $(addprefix poincare/test/, integer.cpp)
 

poincare/include/poincare.h

@@ -6,5 +6,6 @@
 #include <poincare/fraction.h>
 #include <poincare/integer.h>
 #include <poincare/power.h>
+#include <poincare/variable.h>
 
 #endif

poincare/include/poincare/variable.h

@@ -0,0 +1,21 @@
+#ifndef POINCARE_VARIABLE_H
+#define POINCARE_VARIABLE_H
+
+#include <poincare/expression.h>
+
+class Variable : public Expression {
+  public:
+    Variable(char * name);
+    ~Variable();
+    static Variable * VariableNamed(char * name);
+    ExpressionLayout * createLayout(ExpressionLayout * parent) override;
+    float approximate() override;
+    void setValue(float value);
+  private:
+    static void RegisterVariable(Variable * v);
+    static void UnregisterVariable(Variable * v);
+    char * m_name;
+    float m_value;
+};
+
+#endif

poincare/src/expression_lexer.l

@@ -52,6 +52,7 @@
 \/ { return(DIVIDE); }
 \^ { return(POW); }
 \+ { return(PLUS); }
+[A-Za-z]+ { yylval->string = yytext; return(SYMBOL); }
 
 %%
 

poincare/src/expression_parser.y

@@ -55,6 +55,7 @@ void poincare_expression_yyerror(yyscan_t scanner, Expression ** expressionOutpu
 
 /* The INTEGER token uses the "string" part of the union to store its value */
 %token <string> INTEGER
+%token <string> SYMBOL
 
 /* The DIVIDE and POW tokens use no value */
 %token DIVIDE
@@ -92,6 +93,7 @@ Root:
 
 exp:
   INTEGER          { $$ = new Integer($1);     }
+  | SYMBOL           { $$ = new Variable($1);    }
   | exp DIVIDE exp { $$ = new Fraction($1,$3); }
   | exp PLUS exp   { $$ = new Addition($1,$3); }
 /*  | exp POW exp    { $$ = new Power($1,$3); } */

poincare/src/variable.cpp

@@ -0,0 +1,55 @@
+#include <poincare/variable.h>
+#include <stdlib.h>
+#include "layout/string_layout.h"
+
+Variable ** sRegisteredVariables = NULL;
+int16_t sRegisteredVariableCount = 0;
+#define MAX_REGISTERED_VARIABLES 10
+
+Variable::Variable(char * name) :
+m_value(0.0f) {
+  size_t length = strlen(name);
+  m_name = (char *)malloc(sizeof(char)*length+1);
+  memcpy(m_name, name, length);
+  m_name[length] = 0;
+  RegisterVariable(this);
+}
+
+Variable::~Variable() {
+  UnregisterVariable(this);
+  free(m_name);
+}
+
+float Variable::approximate() {
+  return m_value;
+}
+
+ExpressionLayout * Variable::createLayout(ExpressionLayout * parent) {
+  size_t length = strlen(m_name);
+  return new StringLayout(parent, m_name, length);
+}
+
+Variable * Variable::VariableNamed(char * name) {
+  for (int16_t i=0; i<sRegisteredVariableCount; i++) {
+    Variable * currentVariable = sRegisteredVariables[i];
+    if (strcmp(currentVariable->m_name, name) == 0) {
+      return currentVariable;
+    }
+  }
+  return NULL;
+}
+
+void Variable::setValue(float value) {
+  m_value = value;
+}
+
+void Variable::RegisterVariable(Variable * v) {
+  if (sRegisteredVariables == NULL) {
+    sRegisteredVariables = (Variable **)malloc(MAX_REGISTERED_VARIABLES*sizeof(Variable *));
+  }
+  sRegisteredVariables[sRegisteredVariableCount++] = v;
+}
+
+void Variable::UnregisterVariable(Variable * v) {
+  // TODO!
+}