Wrote push_env_table() and pop_env_table()

intmdt_code_gen.c

@@ -35,12 +35,18 @@ intmdt_code_t *init_code() {
 /* 
    Initialize the environment variable for the program.
 */
-env_t *init_env(hash_table_t *table) {
+env_t *init_env() {
   env_t *temp = malloc( sizeof(env_t ));
   if (temp == NULL) {
     fprintf(stderr, "Error: failed to malloc env_t in init_env()\n");
     exit(1);
   }
+
+  hash_table_t *table = hash_table_init(cmp_string, string_hasher);
+  if (table == NULL) {
+    fprintf(stderr, "Error: failed to malloc hash_table_t in init_env()\n");
+  }
+
   temp->prev = NULL;
   temp->table = table;
   return temp;
@@ -276,3 +282,36 @@ void print_id_type (void *id) {
     printf(",%p}", (void *) ((id_type_t *)id)->supersize);
   }
 }
+
+/*  
+    Generates and pushes a new symbol table onto the environment.
+    Returns a pointer to the new top of the stack.
+*/
+env_t *push_env_table(env_t *env) {
+  env_t *top = init_env();
+
+  top->table = hash_table_init(cmp_string ,string_hasher);
+  top->prev = env;
+
+  return top;
+}
+
+/* 
+   Pops the top symbol table off the environment.
+   Returns a pointer to the new top of the stack.
+*/
+env_t *pop_env_table(env_t *env) {
+  if (env == NULL) {
+    fprintf(stderr, "Attempted to pop from a null environment\n");
+    exit(1);
+  }
+
+  hash_table_delete(env->table);
+
+  env_t *temp = env->prev;
+
+  free (env);
+
+  return temp;
+
+}

intmdt_code_gen.h

@@ -48,9 +48,9 @@ typedef struct {
 } intmdt_code_t;
 
 
-typedef struct {
+typedef struct env_t {
   hash_table_t *table;
-  hash_table_t *prev;
+  struct env_t *prev;
 } env_t;
 
 
@@ -81,3 +81,8 @@ intmdt_code_t *init_code();
 env_t *init_env();
 
 void print_intmdt_code(intmdt_code_t *code);
+
+env_t *push_env_table(env_t *env);
+
+env_t *pop_env_table(env_t *env);
+

parser.yacc

@@ -17,8 +17,6 @@
 
   void *install_id (char *, struct id_type_t *);
 
-  hash_table_t *sym_table; 
-
   intmdt_code_t *intermediate_code;
   env_t *env;
 
@@ -123,7 +121,7 @@ loc : loc '[' bool ']'     {printf("loc-> loc [ bool ]\n");
 			     $$ = $1;
 			    /* TODO: figure out what the value of the bool is and pass it */ }
     | ID                   {printf("loc->ID\n");
-                            id_type_t *id = hash_table_search(sym_table, $1);
+                            id_type_t *id = hash_table_search(env->table, $1);
 			    if (id == NULL) {
 			      fprintf(stderr, "Error: symbol '%s' was not previously defined.\n", (char*)$1);
 			      exit(1);
@@ -272,7 +270,7 @@ factor : '(' bool ')'      {printf("factor->( bool )\n");
     but does not GC the original string. Beware.
 */
 void *install_id (char *token, id_type_t *type_info) {
-  if (!hash_table_search(sym_table, token)) {
+  if (!hash_table_search(env->table, token)) {
     char *tempstr = malloc (sizeof(char) + strlen(token));
     strcpy (tempstr, token);
     return hash_table_insert(env->table, (void *)tempstr, type_info);
@@ -297,24 +295,22 @@ void print_str (void *str) {
 */
 void yyerror (char const * s) {
   fprintf (stderr, "%s\n", s);
-  hash_pretty_print (sym_table, print_str, print_id_type);
+  hash_pretty_print (env->table, print_str, print_id_type);
 }
 
 
 int main () {
   yyin = fopen("test.code", "r");
 
-  sym_table = hash_table_init(cmp_string,string_hasher);
-
   intermediate_code = init_code();
-  env = init_env(sym_table);
+  env = init_env();
 
 
 
   yyparse();
 
   printf("\n\n");
-  hash_pretty_print (sym_table, print_str, print_id_type);
+  hash_pretty_print (env->table, print_str, print_id_type);
 
   intmdt_code_print(intermediate_code);