feat: implement address deferencing

include/common/fzl_opcodes.h

@@ -25,6 +25,7 @@ typedef enum
   FZL_OPCODE_GET_FIELD     = 0xFA0002, // Get field N of an object at dstack
   FZL_OPCODE_SET_FIELD     = 0xFA0003, // Set field N of an object at dstack
   FZL_OPCODE_ESCAPE_OBJECT = 0xFA0004, // Make parent envtable as owner
+  FZL_OPCODE_DEREFERENCE   = 0xFA0005, // Dereference address
 
   FZL_OPCODE_ADD = 0xA00001, // Sum two numbers in dstack
   FZL_OPCODE_SUB = 0xA00002, // Subract two numbers in dstack

src/compiler/fzl_walker.c

@@ -942,6 +942,7 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           fzl_token_t *tok = node->token;
           push_op(walker, FZL_OPCODE_PUSHNUM);
           push_word(walker, 0);
+          push_op(walker, FZL_OPCODE_DEREFERENCE);
           current_res = (fzl_walk_res_t){
               .type = FZL_TYPE_OBJECT, .error = false, .classname = null_name};
         }

src/vm/fzl_vm.c

@@ -279,6 +279,37 @@ int fzl_vm_run(fzl_vm_t *vm)
 
     switch (opcode)
     {
+      case FZL_OPCODE_DEREFERENCE:
+      {
+        if (vm->dtop < 1)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected value in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+
+        fzl_value_t addr = vm->dstack[--vm->dtop];
+        if (addr.type < FZL_TYPE_INT8)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected address");
+          print_err_data(vm);
+          return -1;
+        }
+
+        if (addr.as.u == 0)
+        {
+          vm->dstack[vm->dtop++] =
+              (fzl_value_t){.type = FZL_TYPE_OBJECT, .as.obj = NULL};
+          break;
+        }
+
+        vm->dstack[vm->dtop++] = (fzl_value_t){
+            .type = FZL_TYPE_OBJECT, .as.obj = (fzl_vm_object_t *)addr.as.u};
+        break;
+      }
+
       case FZL_OPCODE_CMP_EQ_STR:
       {
         if (vm->dtop < 2)
@@ -359,7 +390,7 @@ int fzl_vm_run(fzl_vm_t *vm)
           return -1;
         }
         fzl_value_t obj = vm->dstack[--vm->dtop];
-        if (obj.type != FZL_TYPE_OBJECT && obj.type < FZL_TYPE_INT8)
+        if (obj.type != FZL_TYPE_OBJECT)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - cannot escape non-object type");
@@ -679,8 +710,21 @@ int fzl_vm_run(fzl_vm_t *vm)
         fzl_value_t writevar = vm->dstack[--vm->dtop];
         fzl_value_t value    = vm->dstack[--vm->dtop];
 
-        fzl_vm_env_wresult_t wresult = fzl_env_writevalue(
-            vm->estack[vm->etop - 1], (char *)writevar.as.s.value, value);
+        char *wrname = (char *)writevar.as.s.value;
+        bool wrfound;
+        fzl_value_t wrenv;
+        ssize_t wrlvl = -1;
+        for (ssize_t i = vm->etop - 1; i >= 0; i--)
+        {
+          if ((wrfound = fzl_env_lookup(vm->estack[i], wrname, &wrenv)))
+          {
+            wrlvl = i;
+            break;
+          }
+        }
+
+        fzl_vm_env_wresult_t wresult =
+            fzl_env_writevalue(vm->estack[wrlvl], (char *)wrname, value);
         if (wresult != FZL_VM_ENV_WRESULT_OK)
         {
           switch (wresult)

src/vm/fzl_vm_debug.c

@@ -20,6 +20,10 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
 
     switch (vm->ops[i])
     {
+      case FZL_OPCODE_DEREFERENCE:
+        printf("DEREFERENCE\n");
+        break;
+
       case FZL_OPCODE_CMP_EQ_STR:
         printf("CMP_EQ_STR\n");
         break;