C++: Remove class/function/enum extraction from CppLocatorData.

With every single change in a document the corresponding IndexItem
elements were extracted and put into an vector. The locator filters
then used these lists to iterate over and filter them.

This change removes that extraction, and the filtering now directly
iterates over the IndexItem elements with a callback.

The exception is the current document filter, because it also queries
for all declarations. Adding this to the model would result in a higher
memory usage, while that information is only used by this filter.

Change-Id: Ibe445cc11e9f68b5d807348fd46c7cac4aff4c85
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/plugins/cpptools/indexitem.h

@@ -38,6 +38,8 @@
 #include <QSharedPointer>
 #include <QMetaType>
 
+#include <functional>
+
 namespace CppTools {
 
 class CPPTOOLS_EXPORT IndexItem
@@ -45,7 +47,14 @@ class CPPTOOLS_EXPORT IndexItem
     Q_DISABLE_COPY(IndexItem)
 
 public:
-    enum ItemType { Enum, Class, Function, Declaration };
+    enum ItemType {
+        Enum        = 1 << 0,
+        Class       = 1 << 1,
+        Function    = 1 << 2,
+        Declaration = 1 << 3,
+
+        All = Enum | Class | Function | Declaration
+    };
 
 private:
     IndexItem(const QString &symbolName,
@@ -139,7 +148,34 @@ public:
     void addChild(IndexItem::Ptr childItem) { m_children.append(childItem); }
     void squeeze();
 
-    void visitAllChildren(std::function<void (const IndexItem::Ptr &)> f) const;
+    enum VisitorResult {
+        Break, /// terminates traversal
+        Continue, /// continues traversal with the next sibling
+        Recurse, /// continues traversal with the children
+    };
+
+    typedef std::function<VisitorResult (const IndexItem::Ptr &)> Visitor;
+
+    VisitorResult visitAllChildren(Visitor callback) const
+    {
+        VisitorResult result = Recurse;
+        foreach (const IndexItem::Ptr &child, m_children) {
+            result = callback(child);
+            switch (result) {
+            case Break:
+                return Break;
+            case Continue:
+                continue;
+            case Recurse:
+                if (!child->m_children.isEmpty()) {
+                    result = child->visitAllChildren(callback);
+                    if (result == Break)
+                        return Break;
+                }
+            }
+        }
+        return result;
+    }
 
 private:
     QString m_symbolName; // as found in the code, therefore might be qualified