Add utility class btree_detail::key_value_extractor

persistent-data/data-structures/btree_key_value_extractor.h

@@ -0,0 +1,39 @@
+#ifndef PERSISTENT_DATA_DATA_STRUCTURES_BTREE_KEY_VALUE_EXTRACTOR_H
+#define PERSISTENT_DATA_DATA_STRUCTURES_BTREE_KEY_VALUE_EXTRACTOR_H
+
+#include "persistent-data/data-structures/btree_damage_visitor.h"
+#include <map>
+
+namespace persistent_data {
+	namespace btree_detail {
+		template <typename ValueType>
+		class key_value_extractor {
+			typedef typename std::map<uint64_t, ValueType> MapType;
+		public:
+			key_value_extractor(MapType &map): map_(map) {
+			}
+
+			virtual ~key_value_extractor() {
+			}
+
+			virtual void visit(btree_path const &path, ValueType const &v) {
+				map_.insert(std::make_pair(path.back(), v));
+			}
+		private:
+			MapType &map_;
+		};
+
+		template <unsigned Levels, typename ValueTraits>
+		void btree_extract_key_values(btree<Levels, ValueTraits> const &tree,
+					      std::map<uint64_t, typename ValueTraits::value_type> &map) {
+			typedef key_value_extractor<typename ValueTraits::value_type> KeyValueExtractor;
+			KeyValueExtractor kve(map);
+			noop_damage_visitor noop_dv;
+			btree_detail::btree_damage_visitor<KeyValueExtractor, noop_damage_visitor, Levels, ValueTraits>
+				v(kve, noop_dv);
+			tree.visit_depth_first(v);
+		}
+	}
+}
+
+#endif