lang: ast: add a BLOCK ast node to hold lists of expressions

lang/ast/msgh.c

@@ -30,6 +30,24 @@ static struct token_parse_result parse_expr(
 	return PARSE_RESULT(IVY_OK, PARSE_REPEAT_TOKEN);
 }
 
+
+static struct token_parse_result parse_bang(
+	struct ivy_parser *ctx, struct ivy_token *tok)
+{
+	struct msgh_parser_state *state
+		= parser_get_state(ctx, struct msgh_parser_state);
+
+	struct ivy_ast_msgh_node *msgh
+		= (struct ivy_ast_msgh_node *)state->s_base.s_node;
+
+	if (!msgh->n_sel || state->s_oneline) {
+		return PARSE_RESULT(IVY_ERR_BAD_SYNTAX, 0);
+	}
+
+	parser_pop_state(ctx, STATE_ADD_NODE_TO_PARENT);
+	return PARSE_RESULT(IVY_OK, 0);
+}
+
 static enum ivy_status add_child(
 	struct ivy_ast_node *parent, struct ivy_ast_node *child)
 {
@@ -40,7 +58,11 @@ static enum ivy_status add_child(
 		return IVY_OK;
 	}
 
-	b_queue_push_back(&msgh->n_body, &child->n_entry);
+	if (child->n_type == IVY_AST_BLOCK && !msgh->n_body) {
+		msgh->n_body = child;
+		return IVY_OK;
+	}
+
 	return IVY_OK;
 }
 
@@ -61,5 +83,8 @@ struct ast_node_type msgh_node_ops = {
         .n_node_size = sizeof(struct ivy_ast_msgh_node),
 	.n_expr_parser = {
 		.expr_begin = parse_expr,
-	}
+	},
+	.n_symbol_parsers = {
+		[IVY_SYM_BANG] = parse_bang,
+	},
 };