base/stl_util.h

// Copyright 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MINI_CHROMIUM_BASE_STL_UTIL_H_
#define MINI_CHROMIUM_BASE_STL_UTIL_H_

#include <algorithm>
#include <functional>
#include <iterator>
#include <string>
#include <vector>

#include "base/logging.h"

namespace base {

template <class T>
void STLClearObject(T* obj) {
  T tmp;
  tmp.swap(*obj);
  obj->reserve(0);
}

template <class ForwardIterator>
void STLDeleteContainerPointers(ForwardIterator begin, ForwardIterator end) {
  while (begin != end) {
    ForwardIterator temp = begin;
    ++begin;
    delete *temp;
  }
}

template <class ForwardIterator>
void STLDeleteContainerPairPointers(ForwardIterator begin,
                                    ForwardIterator end) {
  while (begin != end) {
    ForwardIterator temp = begin;
    ++begin;
    delete temp->first;
    delete temp->second;
  }
}

template <class ForwardIterator>
void STLDeleteContainerPairFirstPointers(ForwardIterator begin,
                                         ForwardIterator end) {
  while (begin != end) {
    ForwardIterator temp = begin;
    ++begin;
    delete temp->first;
  }
}

template <class ForwardIterator>
void STLDeleteContainerPairSecondPointers(ForwardIterator begin,
                                          ForwardIterator end) {
  while (begin != end) {
    ForwardIterator temp = begin;
    ++begin;
    delete temp->second;
  }
}

template <typename Container, typename T>
typename std::iterator_traits<
    typename Container::const_iterator>::difference_type
STLCount(const Container& container, const T& val) {
  return std::count(container.begin(), container.end(), val);
}

inline char* string_as_array(std::string* str) {
  return str->empty() ? NULL : &*str->begin();
}

template <class T>
void STLDeleteElements(T* container) {
  if (!container) {
    return;
  }

  STLDeleteContainerPointers(container->begin(), container->end());
  container->clear();
}

template <class T>
void STLDeleteValues(T* container) {
  if (!container) {
    return;
  }

  STLDeleteContainerPairSecondPointers(container->begin(), container->end());
  container->clear();
}

template <class T>
class STLElementDeleter {
 public:
  STLElementDeleter<T>(T* container) : container_(container) {}
  ~STLElementDeleter<T>() { STLDeleteElements(container_); }

 private:
  T* container_;
};

template <class T>
class STLValueDeleter {
 public:
  STLValueDeleter<T>(T* container) : container_(container) {}
  ~STLValueDeleter<T>() { STLDeleteValues(container_); }

 private:
  T* container_;
};

template <typename Collection, typename Key>
bool ContainsKey(const Collection& collection, const Key& key) {
  return collection.find(key) != collection.end();
}

template <typename Collection, typename Value>
bool ContainsValue(const Collection& collection, const Value& value) {
  return std::find(collection.begin(), collection.end(), value) !=
         collection.end();
}

template <typename Container>
bool STLIsSorted(const Container& cont) {
  return std::adjacent_find(cont.rbegin(),
                            cont.rend(),
                            std::less<typename Container::value_type>()) ==
         cont.rend();
}

template <typename ResultType, typename Arg1, typename Arg2>
ResultType STLSetDifference(const Arg1& a1, const Arg2& a2) {
  DCHECK(STLIsSorted(a1));
  DCHECK(STLIsSorted(a2));

  ResultType difference;
  std::set_difference(a1.begin(),
                      a1.end(),
                      a2.begin(),
                      a2.end(),
                      std::inserter(difference, difference.end()));
  return difference;
}

template <typename ResultType, typename Arg1, typename Arg2>
ResultType STLSetUnion(const Arg1& a1, const Arg2& a2) {
  DCHECK(STLIsSorted(a1));
  DCHECK(STLIsSorted(a2));

  ResultType result;
  std::set_union(a1.begin(),
                 a1.end(),
                 a2.begin(),
                 a2.end(),
                 std::inserter(result, result.end()));
  return result;
}

template <typename ResultType, typename Arg1, typename Arg2>
ResultType STLSetIntersection(const Arg1& a1, const Arg2& a2) {
  DCHECK(STLIsSorted(a1));
  DCHECK(STLIsSorted(a2));

  ResultType result;
  std::set_intersection(a1.begin(),
                        a1.end(),
                        a2.begin(),
                        a2.end(),
                        std::inserter(result, result.end()));
  return result;
}

template <typename Arg1, typename Arg2>
bool STLIncludes(const Arg1& a1, const Arg2& a2) {
  DCHECK(STLIsSorted(a1));
  DCHECK(STLIsSorted(a2));

  return std::includes(a1.begin(), a1.end(), a2.begin(), a2.end());
}

}  // namespace base

#endif  // MINI_CHROMIUM_BASE_STL_UTIL_H_