swift-mirror/include/swift/Basic/BlotMapVector.h

//===- BlotMapVector.h - Map vector with "blot" operation  -----*- C++ -*--===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#ifndef SWIFT_BASIC_BLOTMAPVECTOR_H
#define SWIFT_BASIC_BLOTMAPVECTOR_H

#include "llvm/ADT/DenseMap.h"
#include "swift/Basic/Range.h"
#include <vector>

namespace swift {
  /// \brief An associative container with fast insertion-order (deterministic)
  /// iteration over its elements. Plus the special blot operation.
template<typename KeyT, typename ValueT,
         typename MapTy=llvm::DenseMap<KeyT, size_t>,
         typename VectorTy=std::vector<std::pair<KeyT, ValueT>>>
  class BlotMapVector {
    /// Map keys to indices in Vector.
    MapTy Map;

    /// Keys and values.
    VectorTy Vector;

  public:
    typedef typename VectorTy::iterator iterator;
    typedef typename VectorTy::const_iterator const_iterator;
    iterator begin() { return Vector.begin(); }
    iterator end() { return Vector.end(); }
    const_iterator begin() const { return Vector.begin(); }
    const_iterator end() const { return Vector.end(); }

    Range<iterator> getItems() { return swift::make_range(begin(), end()); }

#ifdef XDEBUG
    ~BlotMapVector() {
      assert(Vector.size() >= Map.size()); // May differ due to blotting.
      for (typename MapTy::const_iterator I = Map.begin(), E = Map.end();
           I != E; ++I) {
        assert(I->second < Vector.size());
        assert(Vector[I->second].first == I->first);
      }
      for (typename VectorTy::const_iterator I = Vector.begin(),
           E = Vector.end(); I != E; ++I)
        assert(!I->first ||
               (Map.count(I->first) &&
                Map[I->first] == size_t(I - Vector.begin())));
    }
#endif

    ValueT &operator[](const KeyT &Arg) {
      std::pair<typename MapTy::iterator, bool> Pair =
        Map.insert(std::make_pair(Arg, size_t(0)));
      if (Pair.second) {
        size_t Num = Vector.size();
        Pair.first->second = Num;
        Vector.push_back(std::make_pair(Arg, ValueT()));
        return Vector[Num].second;
      }
      return Vector[Pair.first->second].second;
    }

    std::pair<iterator, bool>
    insert(const std::pair<KeyT, ValueT> &InsertPair) {
      std::pair<typename MapTy::iterator, bool> Pair =
        Map.insert(std::make_pair(InsertPair.first, size_t(0)));
      if (Pair.second) {
        size_t Num = Vector.size();
        Pair.first->second = Num;
        Vector.push_back(InsertPair);
        return std::make_pair(Vector.begin() + Num, true);
      }
      return std::make_pair(Vector.begin() + Pair.first->second, false);
    }

    iterator find(const KeyT &Key) {
      typename MapTy::iterator It = Map.find(Key);
      if (It == Map.end()) return Vector.end();
      return Vector.begin() + It->second;
    }

    const_iterator find(const KeyT &Key) const {
      typename MapTy::const_iterator It = Map.find(Key);
      if (It == Map.end()) return Vector.end();
      return Vector.begin() + It->second;
    }

    /// This is similar to erase, but instead of removing the element from the
    /// vector, it just zeros out the key in the vector. This leaves iterators
    /// intact, but clients must be prepared for zeroed-out keys when iterating.
    void blot(const KeyT &Key) {
      typename MapTy::iterator It = Map.find(Key);
      if (It == Map.end()) return;
      Vector[It->second].first = KeyT();
      Map.erase(It);
    }

    void clear() {
      Map.clear();
      Vector.clear();
    }
  };
} // end namespace swift

#endif