Scope works.

src/exec.c

@@ -33,61 +33,68 @@ ASTNumData exec_start(AST* ast) {
     // Push global namespace to `scope`.
     stack_push(scope, global);
 
-    return exec_exp(ast, scope);
+    return exec_exp(ast);
 }
 
-ASTNumData exec_exp(AST* ast, Stack* scope) {
+ASTNumData exec_exp(AST* ast) {
     log_dbg("Started execution.");
     switch (ast->type) {
-        case AST_TYPE_BLOCK: return exec_block(ast, scope);
-        case AST_TYPE_CALL:  return exec_call(ast, scope);
+        case AST_TYPE_BLOCK: return exec_block(ast);
+        case AST_TYPE_CALL:  return exec_call(ast);
         case AST_TYPE_NUM:   return *(ASTNumData*)ast->data;
-        case AST_TYPE_VREF:  return exec_vref(ast, scope);
-        case AST_TYPE_VDEF:  return exec_vdef(ast, scope);
+        case AST_TYPE_VREF:  return exec_vref(ast);
+        case AST_TYPE_VDEF:  return exec_vdef(ast);
         default:             printf("what\n"); exit(1);
     }
 }
 
-ASTNumData exec_block(AST* ast, Stack* scope) {
+ASTNumData exec_block(AST* ast) {
     ASTBlockData* block = (ASTBlockData*)ast->data;
 
-    // Loop through all but last ast.
-    for (int i = 0; i < block->ln - 1; i++) exec_exp(block->inside[i], scope);
+    HTab* local = htab_init();
+    stack_push(scope, local);
 
-    return exec_exp(block->inside[block->ln - 1], scope);
+    // Loop through all but last ast.
+    for (int i = 0; i < block->ln - 1; i++) exec_exp(block->inside[i]);
+    ASTNumData last = exec_exp(block->inside[block->ln - 1]);
+
+    stack_pop(scope);
+    htab_destroy(local);
+
+    return last;
 }
 
-ASTNumData exec_call(AST* ast, Stack* scope) {
+ASTNumData exec_call(AST* ast) {
     log_dbg("Started call execution.");
     fflush(stdout);
     ASTCallData* calldata = (ASTCallData*)ast->data;
     if (calldata->argc >= 1) {
         if (!strcmp(calldata->to, "sum")) {
-            double total = exec_exp(calldata->argv[0], scope);
+            double total = exec_exp(calldata->argv[0]);
 
             for (size_t i = 1; i < calldata->argc;
-                 total += exec_exp(calldata->argv[i++], scope));
+                 total += exec_exp(calldata->argv[i++]));
 
             return total;
         } else if (!strcmp(calldata->to, "sub")) {
-            double total = exec_exp(calldata->argv[0], scope);
+            double total = exec_exp(calldata->argv[0]);
 
             for (size_t i = 1; i < calldata->argc;
-                 total -= exec_exp(calldata->argv[i++], scope));
+                 total -= exec_exp(calldata->argv[i++]));
 
             return total;
         } else if (!strcmp(calldata->to, "mul")) {
-            double total = exec_exp(calldata->argv[0], scope);
+            double total = exec_exp(calldata->argv[0]);
 
             for (size_t i = 1; i < calldata->argc;
-                 total *= exec_exp(calldata->argv[i++], scope));
+                 total *= exec_exp(calldata->argv[i++]));
 
             return total;
         } else if (!strcmp(calldata->to, "div")) {
-            double total = exec_exp(calldata->argv[0], scope);
+            double total = exec_exp(calldata->argv[0]);
 
             for (size_t i = 1; i < calldata->argc;
-                 total /= exec_exp(calldata->argv[i++], scope));
+                 total /= exec_exp(calldata->argv[i++]));
 
             return total;
         }
@@ -95,26 +102,32 @@ ASTNumData exec_call(AST* ast, Stack* scope) {
     return -1000;
 }
 
-ASTNumData exec_vdef(AST* ast, Stack* scope) {
+AST* exec_find(char* name) {
+    AST* val = NULL;
+
+    for (int i = scope->ln - 1; i >= 0; i--) {
+        HTab* lvl = scope->buf[i];
+        val = htab_get(lvl, name);
+        if (val != NULL) return val;
+    }
+
+    log_dbgf("Could not find var %s", name);
+    exit(1);
+}
+
+ASTNumData exec_vdef(AST* ast) {
     ASTVDefData* data = (ASTVDefData*)ast->data;
     AST* val = data->val;
     char* key = data->name;
-    htab_ins(scope->val[0], key, val);
-    return exec_exp(val, scope);
+    htab_ins(scope->buf[scope->ln - 1], key, val);
+    return exec_exp(val);
 }
 
-ASTNumData exec_vref(AST* ast, Stack* scope) {
+ASTNumData exec_vref(AST* ast) {
     log_dbg("attempting to reference var");
     ASTVrefData* vref = (ASTVrefData*)ast->data;
 
-    char* key = vref->to;
-    AST* val;
-
-    val = htab_get(scope->val[0], key);
-    if (val != NULL) return exec_exp(val, scope);
-    else log_dbg("didn't find def");
-
-    return *ast_num_data_init(101.0);
+    return exec_exp(exec_find(vref->to));
 }
 
 void exec_print(double n) { printf("= %lf\n", n); }

src/grammar.y

@@ -196,3 +196,4 @@ exp:
         $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
     }
 %%
+

src/include/exec.h

@@ -9,11 +9,11 @@ extern Stack* scope;
 
 // Start executing at the root of the AST. Initialize the `scope`.
 ASTNumData exec_start(AST* ast);
-ASTNumData exec_exp(AST* ast, Stack* scope);
-ASTNumData exec_block(AST* ast, Stack* scope);
-ASTNumData exec_call(AST* ast, Stack* scope);
-ASTNumData exec_vref(AST* ast, Stack* scope);
-ASTNumData exec_vdef(AST* ast, Stack* scope);
+ASTNumData exec_exp(AST* ast);
+ASTNumData exec_block(AST* ast);
+ASTNumData exec_call(AST* ast);
+ASTNumData exec_vref(AST* ast);
+ASTNumData exec_vdef(AST* ast);
 void exec_print(double n);
 
 #endif

src/include/stack.h

@@ -6,8 +6,8 @@
 #define STACK_MAX 64
 
 typedef struct {
-    size_t i;               // Current index in the stack.
-    void* val[STACK_MAX];   // The stack itself.
+    size_t ln;            // The length of the stack (i.e., how many elements).
+    void* buf[STACK_MAX]; // The stack itself.
 } Stack;
 
 // Create a `Stack`.

src/stack.c

@@ -8,33 +8,34 @@
 Stack* stack_init() {
     talloc(Stack, stack);
 
-    memset(stack->val, 0, sizeof(void*) * STACK_MAX);
-    stack->i = 0;
+    memset(stack->buf, 0, sizeof(void*) * STACK_MAX);
+    stack->ln = 0;
 
     return stack;
 }
 
 void stack_destroy(Stack* stack) {
     // Can only free an empty stack.
-    assert(stack->i == 0);
+    assert(stack->ln == 0);
     free(stack);
 }
 
 void stack_push(Stack* stack, void* val) {
-    if (stack->i >= STACK_MAX) {
+    log_dbgf("pushed to stack, inc ln to %ld", stack->ln);
+    if (stack->ln >= STACK_MAX) {
         log_dbgf("Ran out of stack (max: %d)", STACK_MAX);
         return;
     }
 
-    stack->val[stack->i] = val;
-    stack->i++;
+    stack->buf[stack->ln] = val;
+    stack->ln++;
 }
 
 void* stack_pop(Stack* stack) {
-    if (stack->i <= 0) {
+    if (stack->ln <= 0) {
         log_dbg("Can't pop empty stack.");
         return (void*)-1;
     }
 
-    return stack->val[--stack->i];
+    return stack->buf[--stack->ln];
 }