Merge branch 'dev' into debugging-client

doc/en/scripting/ui.md

@@ -37,6 +37,7 @@ Properties that apply to all elements:
 | Name          | Type    | Read | Write | Description                                 |
 | ------------- | ------- | ---- | ----- | ------------------------------------------- |
 | id            | string  | yes  | *no*  | element id                                  |
+| exists        | bool    | yes  | *no*  | checks if element exists                    |
 | pos           | vec2    | yes  | yes   | element position inside a container         |
 | wpos          | vec2    | yes  | yes   | element position inside the window          |
 | size          | vec2    | yes  | yes   | element size                                |

doc/ru/scripting/ui.md

@@ -37,6 +37,7 @@ document["worlds-panel"]:clear()
 | Название      | Тип     | Чтение | Запись | Описание                                  |
 | ------------- | ------- | ------ | ------ | ----------------------------------------- |
 | id            | string  | да     | *нет*  | идентификатор элемента                    |
+| exists        | bool    | да     | *нет*  | проверяет, существует ли элемент          |
 | pos           | vec2    | да     | да     | позиция элемента внутри контейнера        |
 | wpos          | vec2    | да     | да     | позиция элемента в окне                   |
 | size          | vec2    | да     | да     | размер элемента                           |

src/frontend/hud.cpp

@@ -469,6 +469,7 @@ void Hud::showExchangeSlot() {
         gui,
         SlotLayout(-1, glm::vec2(), false, false, nullptr, nullptr, nullptr)
     );
+    exchangeSlot->setId("hud.exchange-slot");
     exchangeSlot->bind(exchangeSlotInv->getId(), exchangeSlotInv->getSlot(0), &content);
     exchangeSlot->setColor(glm::vec4());
     exchangeSlot->setInteractive(false);

src/logic/scripting/lua/libs/libgui.cpp

@@ -30,14 +30,17 @@ using namespace gui;
 using namespace scripting;
 
 static DocumentNode get_document_node_impl(
-    lua::State*, const std::string& name, const std::string& nodeName
+    lua::State*, const std::string& name, const std::string& nodeName, bool throwable=true
 ) {
     auto doc = engine->getAssets()->get<UiDocument>(name);
     if (doc == nullptr) {
-        throw std::runtime_error("document '" + name + "' not found");
+        if (throwable) {
+            throw std::runtime_error("document '" + name + "' not found");
+        }
+        return {nullptr, nullptr};
     }
     auto node = doc->get(nodeName);
-    if (node == nullptr) {
+    if (node == nullptr && throwable) {
         throw std::runtime_error(
             "document '" + name + "' has no element with id '" + nodeName + "'"
         );
@@ -459,6 +462,9 @@ static int p_get_content_offset(UINode* node, lua::State* L) {
     return lua::pushvec(L, node->getContentOffset());
 }
 static int p_get_id(UINode* node, lua::State* L) {
+    if (node == nullptr) {
+        return 0;
+    }
     return lua::pushstring(L, node->getId());
 }
 static int p_get_color(UINode* node, lua::State* L) {
@@ -540,6 +546,14 @@ static int p_get_options(UINode* node, lua::State* L) {
     return 0;
 }
 
+static int p_is_exists(UINode* node, lua::State* L) {
+    return lua::pushboolean(L, node != nullptr);
+}
+
+static bool is_node_required(std::string_view attr) {
+    return attr != "exists";
+}
+
 static int l_gui_getattr(lua::State* L) {
     if (!lua::isstring(L, 1)) {
         throw std::runtime_error("document name is not a string");
@@ -568,12 +582,14 @@ static int l_gui_getattr(lua::State* L) {
         throw std::runtime_error("attribute name is not a string");
     }
     auto attr = lua::require_string(L, 3);
+    bool required = is_node_required(attr);
 
     static const std::unordered_map<
         std::string_view,
         std::function<int(UINode*, lua::State*)>>
         getters {
             {"id", p_get_id},
+            {"exists", p_is_exists},
             {"color", p_get_color},
             {"hoverColor", p_get_hover_color},
             {"pressedColor", p_get_pressed_color},
@@ -630,7 +646,7 @@ static int l_gui_getattr(lua::State* L) {
         };
     auto func = getters.find(attr);
     if (func != getters.end()) {
-        auto docnode = get_document_node_impl(L, docname, element);
+        auto docnode = get_document_node_impl(L, docname, element, required);
         auto node = docnode.node;
         return func->second(node.get(), L);
     }