1 files changed, 67 insertions, 0 deletions
diff --git a/c_parser/src/c_parser.y b/c_parser/src/c_parser.y
new file mode 100644
index 0000000..9ef385f
--- /dev/null
+++ b/c_parser/src/c_parser.y
@@ -0,0 +1,67 @@
+%code requires{
+
+  #include <cassert>
+
+  extern const Expression *g_root; // A way of getting the AST out
+
+  //! This is to fix problems when generating C++
+  // We are declaring the functions provided by Flex, so
+  // that Bison generated code can call them.
+  int yylex(void);
+  void yyerror(const char *);
+}
+
+// Represents the value associated with any kind of
+// AST node.
+%union{
+  const Expression *expr;
+  double number;
+  std::string *string;
+}
+
+%token T_TIMES T_PLUS T_DIVIDE T_MINUS T_LBRACKET T_RBRACKET T_LOG T_EXP T_SQRT T_NUMBER T_VARIABLE
+
+%type <expr> EXPR TERM FACTOR
+%type <number> T_NUMBER
+%type <string> T_VARIABLE T_LOG T_EXP T_SQRT FUNCTION_NAME
+
+%start ROOT
+
+%%
+
+ROOT : EXPR { g_root = $1; }
+
+EXPR : TERM                 { $$ = $1; }
+     | EXPR T_PLUS TERM     { $$ = new AddOperator($1, $3); }
+     | EXPR T_MINUS TERM    { $$ = new SubOperator($1, $3); }
+
+TERM : FACTOR               { $$ = $1; }
+     | TERM T_TIMES FACTOR  { $$ = new MulOperator($1, $3); }
+     | TERM T_DIVIDE FACTOR { $$ = new DivOperator($1, $3); }
+
+FACTOR : T_NUMBER           { $$ = new Number( $1 ); }
+       | T_VARIABLE         { $$ = new Variable( *$1 ); }
+       | T_LBRACKET EXPR T_RBRACKET { $$ = $2; }
+       | FUNCTION_NAME FACTOR {
+          if(*$1 == "log") {
+              $$ = new LogFunction($2);
+          } else if(*$1 == "exp") {
+              $$ = new ExpFunction($2);
+          } else {
+              $$ = new SqrtFunction($2);
+       }}
+
+FUNCTION_NAME : T_LOG   { $$ = new std::string("log"); }
+              | T_EXP   { $$ = new std::string("exp"); }
+              | T_SQRT  { $$ = new std::string("sqrt"); }
+
+%%
+
+const Expression *g_root; // Definition of variable (to match declaration earlier)
+
+const Expression *parseAST()
+{
+  g_root=0;
+  yyparse();
+  return g_root;
+}