Iterators.h

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#pragma once
 
#include <iterator>
 
#include "Node.h"
#include "ScreenGraph.h"
 
namespace bWidgets {
namespace bwScreenGraph {
 
class PreOrderIterator {
 public:
  PreOrderIterator();
  PreOrderIterator(Node& node);
  ~PreOrderIterator();
 
  // Delete copy but keep move constructor for now. We store a parent path
  // below which would require deep copying. So prefer move over copy.
  PreOrderIterator(const PreOrderIterator&) = delete;
  PreOrderIterator(PreOrderIterator&&);
 
  auto operator!=(const PreOrderIterator&) const -> bool;
  auto operator*() -> Node&;
  auto operator++() -> PreOrderIterator&;
 
 private:
  void triggerIterationEnd();
  bool hasExceededLastSibling();
 
  union {
    Node* node;
    Node::ChildList::iterator node_iter;
  };
 
  Node* root = nullptr;
  bool is_root = true;
  // Ancestors up to (but excluding!) node that started iteration.
  std::list<Node::ChildList::iterator> ancestors;
};
 
/* PreOrderIterator is the default iterator (implicitly chosen when passing a
 * node as range-expression for range-based foor loops) */
auto begin(Node&) -> PreOrderIterator;
auto end(Node&) -> PreOrderIterator;
auto begin(ScreenGraph& screen_graph) -> PreOrderIterator;
auto end(ScreenGraph& screen_graph) -> PreOrderIterator;
 
}  // namespace bwScreenGraph
}  // namespace bWidgets