Introduce dom_stack_code enum and use it for push_dom_node()

src/dom/select.c

@@ -506,7 +506,7 @@ parse_dom_select(struct dom_select *select, struct dom_stack *stack,
 			select->selector = select_node;
 		}
 
-		if (!push_dom_node(stack, &select_node->node))
+		if (push_dom_node(stack, &select_node->node) != DOM_STACK_CODE_OK)
 			return DOM_ERR_INVALID_STATE;
 
 		if (select_node->node.type != DOM_NODE_ELEMENT)
@@ -1070,7 +1070,7 @@ select_dom_nodes(struct dom_select *select, struct dom_node *root)
 			      &dom_select_data_context_info);
 	add_dom_stack_tracer(&select_data.stack, "select-match: ");
 
-	if (push_dom_node(&select_data.stack, &select->selector->node)) {
+	if (push_dom_node(&select_data.stack, &select->selector->node) == DOM_STACK_CODE_OK) {
 		get_dom_stack_top(&select_data.stack)->immutable = 1;
 		walk_dom_nodes(&stack, root);
 	}

src/dom/sgml/parser.c

@@ -39,7 +39,10 @@ add_sgml_document(struct dom_stack *stack, struct dom_string *string)
 {
 	struct dom_node *node = init_dom_node(DOM_NODE_DOCUMENT, string);
 
-	return node ? push_dom_node(stack, node) : NULL;
+	if (node && push_dom_node(stack, node) == DOM_STACK_CODE_OK)
+		return node;
+
+	return NULL;
 }
 
 static inline struct dom_node *
@@ -58,7 +61,7 @@ add_sgml_element(struct dom_stack *stack, struct dom_scanner_token *token)
 	node_info = get_sgml_node_info(parser->info->elements, node);
 	node->data.element.type = node_info->type;
 
-	if (!push_dom_node(stack, node))
+	if (push_dom_node(stack, node) != DOM_STACK_CODE_OK)
 		return NULL;
 
 	state = get_dom_stack_top(stack);
@@ -92,7 +95,7 @@ add_sgml_attribute(struct dom_stack *stack,
 	if (valtoken && valtoken->type == SGML_TOKEN_STRING)
 		node->data.attribute.quoted = 1;
 
-	if (!node || !push_dom_node(stack, node))
+	if (!node || push_dom_node(stack, node) != DOM_STACK_CODE_OK)
 		return;
 
 	pop_dom_node(stack);
@@ -119,7 +122,10 @@ add_sgml_proc_instruction(struct dom_stack *stack, struct dom_scanner_token *tar
 		node->data.proc_instruction.type = DOM_PROC_INSTRUCTION;
 	}
 
-	return push_dom_node(stack, node);
+	if (push_dom_node(stack, node) == DOM_STACK_CODE_OK)
+		return node;
+
+	return NULL;
 }
 
 static inline void
@@ -133,7 +139,7 @@ add_sgml_node(struct dom_stack *stack, enum dom_node_type type, struct dom_scann
 	if (token->type == SGML_TOKEN_SPACE)
 		node->data.text.only_space = 1;
 
-	if (push_dom_node(stack, node))
+	if (push_dom_node(stack, node) == DOM_STACK_CODE_OK)
 		pop_dom_node(stack);
 }
 
@@ -403,7 +409,7 @@ parse_sgml(struct sgml_parser *parser, unsigned char *buf, size_t bufsize,
 	}
 
 	node = init_dom_node(DOM_NODE_TEXT, &source);
-	if (!node || !push_dom_node(&parser->parsing, node))
+	if (!node || push_dom_node(&parser->parsing, node) != DOM_STACK_CODE_OK)
 		return SGML_PARSER_CODE_MEM_ALLOC;
 
 	pop_dom_node(&parser->parsing);

src/dom/stack.c

@@ -154,7 +154,7 @@ call_dom_stack_callbacks(struct dom_stack *stack, struct dom_stack_state *state,
 	}
 }
 
-struct dom_node *
+enum dom_stack_code
 push_dom_node(struct dom_stack *stack, struct dom_node *node)
 {
 	struct dom_stack_state *state;
@@ -164,13 +164,13 @@ push_dom_node(struct dom_stack *stack, struct dom_node *node)
 	assert(0 < node->type && node->type < DOM_NODES);
 
 	if (stack->depth > DOM_STACK_MAX_DEPTH) {
-		return NULL;
+		return DOM_STACK_CODE_ERROR_MAX_DEPTH;
 	}
 
 	state = realloc_dom_stack_states(&stack->states, stack->depth);
 	if (!state) {
 		done_dom_node(node);
-		return NULL;
+		return DOM_STACK_CODE_ERROR_MEM_ALLOC;
 	}
 
 	state += stack->depth;
@@ -181,7 +181,7 @@ push_dom_node(struct dom_stack *stack, struct dom_node *node)
 		if (context->info->object_size
 		    && !realloc_dom_stack_state_objects(context, stack->depth)) {
 			done_dom_node(node);
-			return NULL;
+			return DOM_STACK_CODE_ERROR_MEM_ALLOC;
 		}
 	}
 
@@ -193,7 +193,7 @@ push_dom_node(struct dom_stack *stack, struct dom_node *node)
 	stack->depth++;
 	call_dom_stack_callbacks(stack, state, DOM_STACK_PUSH);
 
-	return node;
+	return DOM_STACK_CODE_OK;
 }
 
 void
@@ -349,7 +349,8 @@ walk_dom_nodes(struct dom_stack *stack, struct dom_node *root)
 	if (!context)
 		return;
 
-	push_dom_node(stack, root);
+	if (push_dom_node(stack, root) != DOM_STACK_CODE_OK)
+		return;
 
 	while (!dom_stack_is_empty(stack)) {
 		struct dom_stack_state *state = get_dom_stack_top(stack);

src/dom/stack.h

@@ -9,6 +9,16 @@ struct dom_stack;
 
 /* API Doc :: dom-stack */
 
+/** DOM stack code
+ *
+ * Codes used by the DOM stack to indicate states.
+ */
+enum dom_stack_code {
+	DOM_STACK_CODE_OK,		/*: All is well */
+	DOM_STACK_CODE_ERROR_MEM_ALLOC,	/*: Memory allocation failure */
+	DOM_STACK_CODE_ERROR_MAX_DEPTH,	/*: Stack max depth reached */
+};
+
 /** DOM stack callback
  *
  * Used by contexts, for 'hooking' into the node traversing. */
@@ -230,7 +240,7 @@ void done_dom_stack_context(struct dom_stack *stack, struct dom_stack_context *c
  *
  * If an error occurs the node is released with ref:[done_dom_node] and NULL is
  * returned. Else the pushed node is returned. */
-struct dom_node *push_dom_node(struct dom_stack *stack, struct dom_node *node);
+enum dom_stack_code push_dom_node(struct dom_stack *stack, struct dom_node *node);
 
 /** Pop the top stack state
  *