Fix failure to load document if template has not script defined (#7)

Allow copying `ImVue::Document` + test for it.
Old implementation also would allow copy but everything will crash if
you do that.

Author: Unix4ever

src/imvue.cpp

@@ -92,11 +92,27 @@ namespace ImVue {
     : mDocument(0)
     , mRawData(NULL)
     , mMounted(false)
+    , mRefs((int*)ImGui::MemAlloc(sizeof(int)))
   {
+    *mRefs = 1;
   }
 
   ComponentContainer::~ComponentContainer()
   {
+    if((*mRefs) > 1) {
+      mChildren.clear();
+    }
+    destroy();
+  }
+
+  void ComponentContainer::destroy()
+  {
+    if(!mRefs || --(*mRefs) > 0) {
+      return;
+    }
+
+    ImGui::MemFree(mRefs);
+
     fireCallback(ScriptState::BEFORE_DESTROY);
     removeChildren();
 

src/imvue.h

@@ -101,6 +101,8 @@ namespace ImVue {
 
     protected:
 
+      void destroy();
+
       virtual bool build();
 
       /**
@@ -119,10 +121,43 @@ namespace ImVue {
       char* mRawData;
       bool mMounted;
 
+      /**
+       * Override copy constructor and assignment
+       */
+      ComponentContainer& operator=(ComponentContainer& other)
+      {
+        if(mRefs != other.mRefs) {
+          destroy();
+        }
+
+        ComponentContainer tmp(other);
+        swap(*this, tmp);
+        return *this;
+      }
+
+      ComponentContainer(ComponentContainer& other)
+        : ContainerElement(other)
+        , mDocument(other.mDocument)
+        , mRawData(other.mRawData)
+        , mMounted(other.mMounted)
+        , mRefs(other.mRefs)
+      {
+        (*mRefs)++;
+      }
+
     private:
 
+      friend void swap(ComponentContainer& first, ComponentContainer& second) // nothrow
+      {
+        std::swap(first.mRefs, second.mRefs);
+        std::swap(first.mDocument, second.mDocument);
+        std::swap(first.mRawData, second.mRawData);
+        std::swap(first.mMounted, second.mMounted);
+      }
+
       typedef std::unordered_map<ImU32, ComponentFactory> ComponentFactories;
       ComponentFactories mComponents;
+      int* mRefs;
 
   };
 

src/lua/script.cpp

@@ -1125,6 +1125,10 @@ extern "C" {
 
   void LuaScriptState::eval(const char* str, std::string* retval, Fields* fields, ScriptState::Context* ctx)
   {
+    if(!mImVue) {
+      return;
+    }
+
     StackGuard g(mLuaState);
     std::stringstream script;
     std::string data(str);
@@ -1180,7 +1184,7 @@ extern "C" {
   Object LuaScriptState::getObject(const char* str, Fields* fields, ScriptState::Context* ctx)
   {
     StackGuard g(mLuaState);
-    if(str[0] == '\0') {
+    if(str[0] == '\0' || !mImVue) {
       return Object();
     }
 

tests/unit/parser.cpp

@@ -1,6 +1,7 @@
 
 #include <gtest/gtest.h>
 #include "imvue.h"
+#include "imvue_generated.h"
 #include "imvue_errors.h"
 #include "utils.h"
 
@@ -70,3 +71,23 @@ TEST(DocumentParser, BadScript)
   document.parse(badScript);
   renderDocument(document);
 }
+
+/**
+ * Create document and copy it, should delete, ctx and other pointers only once
+ */
+TEST(DocumentParser, DocumentCopy)
+{
+  ImVue::Context* ctx = ImVue::createContext(
+      ImVue::createElementFactory()
+  );
+  ImVue::Document document(ctx);
+  document.parse(simple);
+  renderDocument(document);
+
+  ImVue::Document copied(document);
+  renderDocument(document);
+  renderDocument(copied);
+
+  ImVue::Document duplicate = document;
+  renderDocument(duplicate);
+}