// util/const-integer-set.h

// Copyright 2009-2011     Microsoft Corporation

// See ../../COPYING for clarification regarding multiple authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
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// MERCHANTABLITY OR NON-INFRINGEMENT.
// See the Apache 2 License for the specific language governing permissions and
// limitations under the License.

#ifndef KALDI_UTIL_CONST_INTEGER_SET_H_
#define KALDI_UTIL_CONST_INTEGER_SET_H_
#include <algorithm>
#include <cassert>
#include <limits>
#include <set>
#include <vector>
#include "util/stl-utils.h"

/* ConstIntegerSet is a way to efficiently test whether something is in a
   supplied set of integers.  It can be initialized from a vector or set, but
   never changed after that. It either uses a sorted vector or an array of
   bool, depending on the input.  It behaves like a const version of an STL set,
   with only a subset of the functionality, except all the member functions are
   upper-case.

   Note that we could get rid of the member slow_set_, but we'd have to
   do more work to implement an iterator type.  This would save memory.
*/

namespace kaldi {

template <class I>
class ConstIntegerSet {
 public:
  ConstIntegerSet() : lowest_member_(1), highest_member_(0) {}

  void Init(const std::vector<I> &input) {
    slow_set_ = input;
    SortAndUniq(&slow_set_);
    InitInternal();
  }

  void Init(const std::set<I> &input) {
    CopySetToVector(input, &slow_set_);
    InitInternal();
  }

  explicit ConstIntegerSet(const std::vector<I> &input) : slow_set_(input) {
    SortAndUniq(&slow_set_);
    InitInternal();
  }
  explicit ConstIntegerSet(const std::set<I> &input) {
    CopySetToVector(input, &slow_set_);
    InitInternal();
  }
  explicit ConstIntegerSet(const ConstIntegerSet<I> &other)
      : slow_set_(other.slow_set_) {
    InitInternal();
  }

  int count(I i) const;  // returns 1 or 0.

  typedef typename std::vector<I>::const_iterator iterator;
  iterator begin() const { return slow_set_.begin(); }
  iterator end() const { return slow_set_.end(); }
  size_t size() const { return slow_set_.size(); }
  bool empty() const { return slow_set_.empty(); }

  void Write(std::ostream &os, bool binary) const;
  void Read(std::istream &is, bool binary);

 private:
  I lowest_member_;
  I highest_member_;
  bool contiguous_;
  bool quick_;
  std::vector<bool> quick_set_;
  std::vector<I> slow_set_;
  void InitInternal();
};

}  // end namespace kaldi

#include "util/const-integer-set-inl.h"

#endif  // KALDI_UTIL_CONST_INTEGER_SET_H_
