llvm-mirror/include/llvm/ADT/MapVector.h

//===- llvm/ADT/MapVector.h - Map with deterministic value order *- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a map that provides insertion order iteration. The
// interface is purposefully minimal. The key is assumed to be cheap to copy
// and 2 copies are kept, one for indexing in a DenseMap, one for iteration in
// a std::vector.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_MAPVECTOR_H
#define LLVM_ADT_MAPVECTOR_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include <vector>

namespace llvm {

/// This class implements a map that also provides access to all stored values
/// in a deterministic order. The values are kept in a std::vector and the
/// mapping is done with DenseMap from Keys to indexes in that vector.
template<typename KeyT, typename ValueT>
class MapVector {
  typedef llvm::DenseMap<KeyT, unsigned> MapType;
  typedef std::vector<std::pair<KeyT, ValueT> > VectorType;
  typedef typename VectorType::size_type SizeType;

  MapType Map;
  VectorType Vector;

public:
  typedef typename VectorType::iterator iterator;
  typedef typename VectorType::const_iterator const_iterator;

  SizeType size() const {
    return Vector.size();
  }

  iterator begin() {
    return Vector.begin();
  }

  const_iterator begin() const {
    return Vector.begin();
  }

  iterator end() {
    return Vector.end();
  }

  const_iterator end() const {
    return Vector.end();
  }

  bool empty() const {
    return Vector.empty();
  }

  ValueT &operator[](const KeyT &Key) {
    std::pair<KeyT, unsigned> Pair = std::make_pair(Key, 0);
    std::pair<typename MapType::iterator, bool> Result = Map.insert(Pair);
    unsigned &I = Result.first->second;
    if (Result.second) {
      Vector.push_back(std::make_pair(Key, ValueT()));
      I = Vector.size() - 1;
    }
    return Vector[I].second;
  }
};

}

#endif