ceph/src/rocksdb/table/iter_heap.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under the BSD-style license found in the
   3 //  LICENSE file in the root directory of this source tree. An additional grant
   4 //  of patent rights can be found in the PATENTS file in the same directory.
   5 //
   6
   7 #pragma once
   8
   9 #include "rocksdb/comparator.h"
  10 #include "table/iterator_wrapper.h"
  11
  12 namespace rocksdb {
  13
  14 // When used with std::priority_queue, this comparison functor puts the
  15 // iterator with the max/largest key on top.
  16 class MaxIteratorComparator {
  17  public:
  18   MaxIteratorComparator(const Comparator* comparator) :
  19     comparator_(comparator) {}
  20
  21   bool operator()(IteratorWrapper* a, IteratorWrapper* b) const {
  22     return comparator_->Compare(a->key(), b->key()) < 0;
  23   }
  24  private:
  25   const Comparator* comparator_;
  26 };
  27
  28 // When used with std::priority_queue, this comparison functor puts the
  29 // iterator with the min/smallest key on top.
  30 class MinIteratorComparator {
  31  public:
  32   MinIteratorComparator(const Comparator* comparator) :
  33     comparator_(comparator) {}
  34
  35   bool operator()(IteratorWrapper* a, IteratorWrapper* b) const {
  36     return comparator_->Compare(a->key(), b->key()) > 0;
  37   }
  38  private:
  39   const Comparator* comparator_;
  40 };
  41
  42 }  // namespace rocksdb