Added initial support for variables.

They are now parsed correctly, though they cannot be defined manually
and all have a value of 42.42.

src/ast.c

@@ -27,6 +27,7 @@ void ast_destroy(AST* ast) {
     switch (ast->type) {
         case AST_TYPE_NUM:  ast_num_data_destroy(ast->data); break;
         case AST_TYPE_CALL: ast_call_data_destroy(ast->data); break;
+        case AST_TYPE_VREF: ast_vref_data_destroy(ast->data); break;
         default:
             log_dbgf("Unknown ast type %d (max: %d)", ast->type, AST_TYPE_MAX);
     }
@@ -103,9 +104,18 @@ void ast_call_print(ASTCallData* data, int i) {
     INDENT_END;
 }
 
-ASTVrefData* ast_vref_data_init(char* to) {}
+ASTVrefData* ast_vref_data_init(char* to) {
+    talloc(ASTVrefData, vref);
 
-void ast_vref_data_destroy(ASTVrefData* vref) {}
+    vref->to = to;
+
+    return vref;
+}
+
+void ast_vref_data_destroy(ASTVrefData* vref) {
+    free(vref->to);
+    free(vref);
+}
 
 void ast_vref_print(ASTVrefData* data, int i) {
     INDENT_BEGIN(i);

src/exec.c

@@ -13,6 +13,7 @@ ASTNumData exec_exp(AST* ast) {
     switch (ast->type) {
         case AST_TYPE_CALL: return exec_call(ast);
         case AST_TYPE_NUM:  return *(ASTNumData*)ast->data;
+        case AST_TYPE_VREF: return exec_vref(ast);
         default:            printf("what\n");
                             exit(1);
     }
@@ -67,4 +68,8 @@ ASTNumData exec_call(AST* ast) {
     return -1000;
 }
 
+ASTNumData exec_vref(AST* ast) {
+    return *ast_num_data_init(42.42);
+}
+
 void exec_print(double n) { printf("= %lf\n", n); }

src/grammar.y

@@ -84,7 +84,9 @@ exp:
     | LGROUP exp RGROUP { $$ = $2; }
 
     // Variable reference.
-    //| WORD
+    | WORD {
+        $$ = ast_init(AST_TYPE_VREF, ast_vref_data_init($1));
+    }
 
     | WORD LGROUP arg RGROUP {
         size_t argc = $3->ln;

src/include/exec.h

@@ -5,6 +5,7 @@
 
 ASTNumData exec_exp(AST* ast);
 ASTNumData exec_call(AST* ast);
+ASTNumData exec_vref(AST* ast);
 void exec_print(double n);
 
 #endif