testing why grammar does not work

calc.h

@@ -0,0 +1,48 @@
+/* Function type. */
+typedef double (func_t) (double);
+/* Data type for links in the chain of symbols. */
+struct symrec
+{
+  char *name;  /* name of symbol */
+  int type;    /* type of symbol: either VAR or FUN */
+  union
+  {
+    double var;    /* value of a VAR */
+    func_t *fun;   /* value of a FUN */
+  } value;
+  struct symrec *next;  /* link field */
+};
+typedef struct symrec symrec;
+
+/* The symbol table: a chain of 'struct symrec'. */
+extern symrec *sym_table;
+
+symrec *putsym (char const *name, int sym_type);
+symrec *getsym (char const *name);
+struct init
+{
+  char const *name;
+  func_t *fun;
+};
+struct init const funs[] =
+{
+  { "atan", atan },
+  { "cos",  cos  },
+  { "exp",  exp  },
+  { "ln",   log  },
+  { "sin",  sin  },
+  { "sqrt", sqrt },
+  { 0, 0 },
+};
+/* The symbol table: a chain of 'struct symrec'. */
+symrec *sym_table;
+/* Put functions in table. */
+static void
+init_table (void)
+{
+  for (int i = 0; funs[i].name; i++)
+    {
+      symrec *ptr = putsym (funs[i].name, FUN);
+      ptr->value.fun = funs[i].fun;
+    }
+}

grammar.y

@@ -8,9 +8,9 @@
   extern int yylex(void);
   void yyerror(const char *err);
 %}
-/*
+
 %token ID 101
-%token T_INTEGER 201
+%token T_INTEGER
 %token T_ADDRESS 202
 %token T_BOOLEAN 203
 %token T_CHARACTER 204
@@ -54,10 +54,19 @@
 %token DOT 612
 %token RESERVE 613
 %token RELEASE 614
-%token COMMENT 700 */
+%token COMMENT 700
 %%
 
-start: /*empty for now*/
+input: /*empty for now*/
+	OPTIONAL;
+	
+OPTIONAL_OPTIONAL: 
+	OPTIONAL
+	| OPTIONAL_OPTIONAL OPTIONAL		{printf("expansion\n");};
+
+OPTIONAL:
+	'['		{printf("success");}
+	|%empty
 	;
 // B : '{'{CreateScope(cur,line,column)} E '}'; //Braced Expressions can have braces removed to get regular expressions
 // D : '[' l ']'; //Declaration Lists Brackets can be taken out to get a list of Declarations

lexicalStructure.lex

@@ -6,7 +6,7 @@
 %option header-file="flex.h"
 %{
 	#include <stdbool.h>
-	#include "typedefs.h"
+	//#include "typedefs.h"
 	#include "grammar.tab.h"
 	int line_number = 1, column_number = 1;
 	#ifndef DEBUG

testGrammar.y

@@ -0,0 +1,41 @@
+%{
+  #include <stdio.h>  /* For printf, etc. */
+  #include <math.h>   /* For pow, used in the grammar. */
+  #include "calc.h"   /* Contains definition of 'symrec'. */
+  int yylex (void);
+  void yyerror (char const *);
+%}
+%define api.value.type union /* Generate YYSTYPE from these types: */
+%token <double>  NUM     /* Double precision number. */
+%token <symrec*> VAR FUN /* Symbol table pointer: variable/function. */
+%nterm <double>  exp
+%precedence '='
+%left '-' '+'
+%left '*' '/'
+%precedence NEG /* negation--unary minus */
+%right '^'      /* exponentiation */
+%% /* The grammar follows. */
+input:
+  %empty
+| input line
+;
+line:
+  '\n'
+| exp '\n'   { printf ("%.10g\n", $1); }
+| error '\n' { yyerrok;                }
+;
+exp:
+  NUM
+| VAR                { $$ = $1->value.var;              }
+| VAR '=' exp        { $$ = $3; $1->value.var = $3;     }
+| FUN '(' exp ')'    { $$ = $1->value.fun ($3);         }
+| exp '+' exp        { $$ = $1 + $3;                    }
+| exp '-' exp        { $$ = $1 - $3;                    }
+| exp '*' exp        { $$ = $1 * $3;                    }
+| exp '/' exp        { $$ = $1 / $3;                    }
+| '-' exp  %prec NEG { $$ = -$2;                        }
+| exp '^' exp        { $$ = pow ($1, $3);               }
+| '(' exp ')'        { $$ = $2;                         }
+;
+/* End of grammar. */
+%%