Add XMLUtils.cpp and XMLUtils.h

These XML functions will be useful for de-duplicating copy-pasted XML
handling code, while also making it so elements will get updated in
place instead of being thrown out and starting from scratch every time a
file is saved.

desktop_version/CMakeLists.txt

@@ -105,6 +105,7 @@ SET(VVV_SRC
 	src/Tower.cpp
 	src/UtilityClass.cpp
 	src/WarpClass.cpp
+	src/XMLUtils.cpp
 	src/main.cpp
 	src/Network.c
 )

desktop_version/src/XMLUtils.cpp

@@ -0,0 +1,142 @@
+#include <SDL.h>
+#include <tinyxml2.h>
+
+namespace xml
+{
+
+// Helper functions for these utils (not exported)
+
+static inline tinyxml2::XMLDocument& get_document(tinyxml2::XMLNode* parent)
+{
+    return *(parent->GetDocument());
+}
+
+
+// EXPORTED FUNCTIONS
+
+
+// Create a new element if it doesn't exist. Returns the element.
+tinyxml2::XMLElement* update_element(tinyxml2::XMLNode* parent, const char* name)
+{
+    if (parent == NULL)
+    {
+        return NULL;
+    }
+
+    tinyxml2::XMLDocument& doc = get_document(parent);
+
+    tinyxml2::XMLElement* element = parent->FirstChildElement(name);
+    if (element == NULL)
+    {
+        // It doesn't exist, so create a new one
+        element = doc.NewElement(name);
+        parent->LinkEndChild(element);
+    }
+
+    return element;
+}
+
+// Same thing as above, but takes &parent instead of *parent
+tinyxml2::XMLElement* update_element(tinyxml2::XMLNode& parent, const char* name)
+{
+    return update_element(&parent, name);
+}
+
+// Same thing as above, but deletes the content inside the element, too.
+tinyxml2::XMLElement* update_element_delete_contents(tinyxml2::XMLNode* parent, const char* name)
+{
+    tinyxml2::XMLDocument& doc = get_document(parent);
+
+    tinyxml2::XMLElement* element = update_element(parent, name);
+
+    for (tinyxml2::XMLNode* node = element->FirstChild();
+    node != NULL;
+    /* Increment code handled separately */)
+    {
+        // Unfortunately, element->DeleteNode() is private
+        // Can't just doc.DeleteNode(node) and then go to next,
+        // node->NextSiblingElement() will be NULL.
+        // Instead, store pointer of node we want to delete. Then increment
+        // `node`. And THEN delete the node.
+        tinyxml2::XMLNode* delete_this = node;
+
+        node = node->NextSiblingElement();
+
+        doc.DeleteNode(delete_this);
+    }
+
+    return element;
+}
+
+// Call update_element_delete_contents(), then immediately set its value to a
+// string. Returns the element.
+tinyxml2::XMLElement* update_tag(tinyxml2::XMLNode* parent, const char* name, const char* value)
+{
+    tinyxml2::XMLElement* element = update_element_delete_contents(parent, name);
+
+    element->InsertNewText(value);
+
+    return element;
+}
+
+// Same as above, but takes an int instead, and automatically converts it to a
+// string.
+tinyxml2::XMLElement* update_tag(tinyxml2::XMLNode* parent, const char* name, const int value)
+{
+    char string[16];
+    SDL_snprintf(string, sizeof(string), "%i", value);
+
+    return update_tag(parent, name, string);
+}
+
+// Delete the declaration, if it exists. Then create a new declaration.
+// Returns the declaration.
+tinyxml2::XMLDeclaration* update_declaration(tinyxml2::XMLDocument& doc)
+{
+    if (doc.FirstChild() != NULL)
+    {
+        tinyxml2::XMLDeclaration* decl = doc.FirstChild()->ToDeclaration();
+
+        if (decl != NULL)
+        {
+            doc.DeleteNode(decl);
+        }
+    }
+
+    tinyxml2::XMLDeclaration* decl = doc.NewDeclaration();
+    doc.InsertFirstChild(decl);
+
+    return decl;
+}
+
+// Create a new comment if the first child of the node isn't a comment.
+// Returns the comment.
+tinyxml2::XMLComment* update_comment(tinyxml2::XMLNode* parent, const char* text)
+{
+    if (parent == NULL)
+    {
+        return NULL;
+    }
+
+    tinyxml2::XMLDocument& doc = get_document(parent);
+
+    if (parent->FirstChild() == NULL)
+    {
+        return NULL;
+    }
+
+    tinyxml2::XMLComment* comment = parent->FirstChild()->ToComment();
+
+    if (comment == NULL)
+    {
+        // It doesn't exist, so create a new one
+        comment = doc.NewComment(text);
+        parent->InsertFirstChild(comment);
+    }
+
+    return comment;
+}
+
+
+
+} // namespace xml

desktop_version/src/XMLUtils.h

@@ -0,0 +1,27 @@
+// Forward decl, avoid including tinyxml2.h
+namespace tinyxml2
+{
+    class XMLComment;
+    class XMLDocument;
+    class XMLDeclaration;
+    class XMLElement;
+    class XMLNode;
+}
+
+namespace xml
+{
+
+tinyxml2::XMLElement* update_element(tinyxml2::XMLNode* parent, const char* name);
+// Same thing as above, but takes &parent instead of *parent
+tinyxml2::XMLElement* update_element(tinyxml2::XMLNode& parent, const char* name);
+
+tinyxml2::XMLElement* update_element_delete_contents(tinyxml2::XMLNode* parent, const char* name);
+
+tinyxml2::XMLElement* update_tag(tinyxml2::XMLNode* parent, const char* name, const char* value);
+tinyxml2::XMLElement* update_tag(tinyxml2::XMLNode* parent, const char* name, const int value);
+
+tinyxml2::XMLDeclaration* update_declaration(tinyxml2::XMLDocument& doc);
+
+tinyxml2::XMLComment* update_comment(tinyxml2::XMLNode* parent, const char* text);
+
+} // namespace xml