base/stl_util.h - chromium/src - Git at Google

 // Copyright (c) 2011 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.

 // Derived from google3/util/gtl/stl_util.h

 #ifndef BASE_STL_UTIL_H_
 #define BASE_STL_UTIL_H_

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

 #include "base/logging.h"

 // Clears internal memory of an STL object.
 // STL clear()/reserve(0) does not always free internal memory allocated
 // This function uses swap/destructor to ensure the internal memory is freed.
 template<class T>
 void STLClearObject(T* obj) {
   T tmp;
   tmp.swap(*obj);
   // Sometimes "T tmp" allocates objects with memory (arena implementation?).
   // Hence using additional reserve(0) even if it doesn't always work.
   obj->reserve(0);
 }

 // For a range within a container of pointers, calls delete (non-array version)
 // on these pointers.
 // NOTE: for these three functions, we could just implement a DeleteObject
 // functor and then call for_each() on the range and functor, but this
 // requires us to pull in all of algorithm.h, which seems expensive.
 // For hash_[multi]set, it is important that this deletes behind the iterator
 // because the hash_set may call the hash function on the iterator when it is
 // advanced, which could result in the hash function trying to deference a
 // stale pointer.
 template <class ForwardIterator>
 void STLDeleteContainerPointers(ForwardIterator begin, ForwardIterator end) {
   while (begin != end) {
     ForwardIterator temp = begin;
     ++begin;
     delete *temp;
   }
 }

 // For a range within a container of pairs, calls delete (non-array version) on
 // BOTH items in the pairs.
 // NOTE: Like STLDeleteContainerPointers, it is important that this deletes
 // behind the iterator because if both the key and value are deleted, the
 // container may call the hash function on the iterator when it is advanced,
 // which could result in the hash function trying to dereference a stale
 // pointer.
 template <class ForwardIterator>
 void STLDeleteContainerPairPointers(ForwardIterator begin,
                                     ForwardIterator end) {
   while (begin != end) {
     ForwardIterator temp = begin;
     ++begin;
     delete temp->first;
     delete temp->second;
   }
 }

 // For a range within a container of pairs, calls delete (non-array version) on
 // the FIRST item in the pairs.
 // NOTE: Like STLDeleteContainerPointers, deleting behind the iterator.
 template <class ForwardIterator>
 void STLDeleteContainerPairFirstPointers(ForwardIterator begin,
                                          ForwardIterator end) {
   while (begin != end) {
     ForwardIterator temp = begin;
     ++begin;
     delete temp->first;
   }
 }

 // For a range within a container of pairs, calls delete.
 // NOTE: Like STLDeleteContainerPointers, deleting behind the iterator.
 // Deleting the value does not always invalidate the iterator, but it may
 // do so if the key is a pointer into the value object.
 template <class ForwardIterator>
 void STLDeleteContainerPairSecondPointers(ForwardIterator begin,
                                           ForwardIterator end) {
   while (begin != end) {
     ForwardIterator temp = begin;
     ++begin;
     delete temp->second;
   }
 }

 // To treat a possibly-empty vector as an array, use these functions.
 // If you know the array will never be empty, you can use &*v.begin()
 // directly, but that is undefined behaviour if |v| is empty.
 template<typename T>
 inline T* vector_as_array(std::vector<T>* v) {
   return v->empty() ? NULL : &*v->begin();
 }

 template<typename T>
 inline const T* vector_as_array(const std::vector<T>* v) {
   return v->empty() ? NULL : &*v->begin();
 }

 // Return a mutable char* pointing to a string's internal buffer,
 // which may not be null-terminated. Writing through this pointer will
 // modify the string.
 //
 // string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
 // next call to a string method that invalidates iterators.
 //
 // As of 2006-04, there is no standard-blessed way of getting a
 // mutable reference to a string's internal buffer. However, issue 530
 // (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#530)
 // proposes this as the method. According to Matt Austern, this should
 // already work on all current implementations.
 inline char* string_as_array(std::string* str) {
   // DO NOT USE const_cast<char*>(str->data())
   return str->empty() ? NULL : &*str->begin();
 }

 // The following functions are useful for cleaning up STL containers whose
 // elements point to allocated memory.

 // STLDeleteElements() deletes all the elements in an STL container and clears
 // the container.  This function is suitable for use with a vector, set,
 // hash_set, or any other STL container which defines sensible begin(), end(),
 // and clear() methods.
 //
 // If container is NULL, this function is a no-op.
 //
 // As an alternative to calling STLDeleteElements() directly, consider
 // STLElementDeleter (defined below), which ensures that your container's
 // elements are deleted when the STLElementDeleter goes out of scope.
 template <class T>
 void STLDeleteElements(T* container) {
   if (!container)
     return;
   STLDeleteContainerPointers(container->begin(), container->end());
   container->clear();
 }

 // Given an STL container consisting of (key, value) pairs, STLDeleteValues
 // deletes all the "value" components and clears the container.  Does nothing
 // in the case it's given a NULL pointer.
 template <class T>
 void STLDeleteValues(T* container) {
   if (!container)
     return;
   for (typename T::iterator i(container->begin()); i != container->end(); ++i)
     delete i->second;
   container->clear();
 }


 // The following classes provide a convenient way to delete all elements or
 // values from STL containers when they goes out of scope.  This greatly
 // simplifies code that creates temporary objects and has multiple return
 // statements.  Example:
 //
 // vector<MyProto *> tmp_proto;
 // STLElementDeleter<vector<MyProto *> > d(&tmp_proto);
 // if (...) return false;
 // ...
 // return success;

 // Given a pointer to an STL container this class will delete all the element
 // pointers when it goes out of scope.
 template<class T>
 class STLElementDeleter {
  public:
   STLElementDeleter<T>(T* container) : container_(container) {}
   ~STLElementDeleter<T>() { STLDeleteElements(container_); }

  private:
   T* container_;
 };

 // Given a pointer to an STL container this class will delete all the value
 // pointers when it goes out of scope.
 template<class T>
 class STLValueDeleter {
  public:
   STLValueDeleter<T>(T* container) : container_(container) {}
   ~STLValueDeleter<T>() { STLDeleteValues(container_); }

  private:
   T* container_;
 };

 // Test to see if a set, map, hash_set or hash_map contains a particular key.
 // Returns true if the key is in the collection.
 template <typename Collection, typename Key>
 bool ContainsKey(const Collection& collection, const Key& key) {
   return collection.find(key) != collection.end();
 }

 namespace base {

 // Returns true if the container is sorted.
 template <typename Container>
 bool STLIsSorted(const Container& cont) {
   // Note: Use reverse iterator on container to ensure we only require
   // value_type to implement operator<.
   return std::adjacent_find(cont.rbegin(), cont.rend(),
                             std::less<typename Container::value_type>())
       == cont.rend();
 }

 // Returns a new ResultType containing the difference of two sorted containers.
 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;
 }

 // Returns a new ResultType containing the union of two sorted containers.
 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;
 }

 // Returns a new ResultType containing the intersection of two sorted
 // containers.
 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;
 }

 // Returns true if the sorted container |a1| contains all elements of the sorted
 // container |a2|.
 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  // BASE_STL_UTIL_H_
	// Copyright (c) 2011 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.

	// Derived from google3/util/gtl/stl_util.h

	#ifndef BASE_STL_UTIL_H_
	#define BASE_STL_UTIL_H_

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

	#include "base/logging.h"

	// Clears internal memory of an STL object.
	// STL clear()/reserve(0) does not always free internal memory allocated
	// This function uses swap/destructor to ensure the internal memory is freed.
	template<class T>
	void STLClearObject(T* obj) {
	T tmp;
	tmp.swap(*obj);
	// Sometimes "T tmp" allocates objects with memory (arena implementation?).
	// Hence using additional reserve(0) even if it doesn't always work.
	obj->reserve(0);
	}

	// For a range within a container of pointers, calls delete (non-array version)
	// on these pointers.
	// NOTE: for these three functions, we could just implement a DeleteObject
	// functor and then call for_each() on the range and functor, but this
	// requires us to pull in all of algorithm.h, which seems expensive.
	// For hash_[multi]set, it is important that this deletes behind the iterator
	// because the hash_set may call the hash function on the iterator when it is
	// advanced, which could result in the hash function trying to deference a
	// stale pointer.
	template <class ForwardIterator>
	void STLDeleteContainerPointers(ForwardIterator begin, ForwardIterator end) {
	while (begin != end) {
	ForwardIterator temp = begin;
	++begin;
	delete *temp;
	}
	}

	// For a range within a container of pairs, calls delete (non-array version) on
	// BOTH items in the pairs.
	// NOTE: Like STLDeleteContainerPointers, it is important that this deletes
	// behind the iterator because if both the key and value are deleted, the
	// container may call the hash function on the iterator when it is advanced,
	// which could result in the hash function trying to dereference a stale
	// pointer.
	template <class ForwardIterator>
	void STLDeleteContainerPairPointers(ForwardIterator begin,
	ForwardIterator end) {
	while (begin != end) {
	ForwardIterator temp = begin;
	++begin;
	delete temp->first;
	delete temp->second;
	}
	}

	// For a range within a container of pairs, calls delete (non-array version) on
	// the FIRST item in the pairs.
	// NOTE: Like STLDeleteContainerPointers, deleting behind the iterator.
	template <class ForwardIterator>
	void STLDeleteContainerPairFirstPointers(ForwardIterator begin,
	ForwardIterator end) {
	while (begin != end) {
	ForwardIterator temp = begin;
	++begin;
	delete temp->first;
	}
	}

	// For a range within a container of pairs, calls delete.
	// NOTE: Like STLDeleteContainerPointers, deleting behind the iterator.
	// Deleting the value does not always invalidate the iterator, but it may
	// do so if the key is a pointer into the value object.
	template <class ForwardIterator>
	void STLDeleteContainerPairSecondPointers(ForwardIterator begin,
	ForwardIterator end) {
	while (begin != end) {
	ForwardIterator temp = begin;
	++begin;
	delete temp->second;
	}
	}

	// To treat a possibly-empty vector as an array, use these functions.
	// If you know the array will never be empty, you can use &*v.begin()
	// directly, but that is undefined behaviour if \|v\| is empty.
	template<typename T>
	inline T* vector_as_array(std::vector<T>* v) {
	return v->empty() ? NULL : &*v->begin();
	}

	template<typename T>
	inline const T* vector_as_array(const std::vector<T>* v) {
	return v->empty() ? NULL : &*v->begin();
	}

	// Return a mutable char* pointing to a string's internal buffer,
	// which may not be null-terminated. Writing through this pointer will
	// modify the string.
	//
	// string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
	// next call to a string method that invalidates iterators.
	//
	// As of 2006-04, there is no standard-blessed way of getting a
	// mutable reference to a string's internal buffer. However, issue 530
	// (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#530)
	// proposes this as the method. According to Matt Austern, this should
	// already work on all current implementations.
	inline char* string_as_array(std::string* str) {
	// DO NOT USE const_cast<char*>(str->data())
	return str->empty() ? NULL : &*str->begin();
	}

	// The following functions are useful for cleaning up STL containers whose
	// elements point to allocated memory.

	// STLDeleteElements() deletes all the elements in an STL container and clears
	// the container. This function is suitable for use with a vector, set,
	// hash_set, or any other STL container which defines sensible begin(), end(),
	// and clear() methods.
	//
	// If container is NULL, this function is a no-op.
	//
	// As an alternative to calling STLDeleteElements() directly, consider
	// STLElementDeleter (defined below), which ensures that your container's
	// elements are deleted when the STLElementDeleter goes out of scope.
	template <class T>
	void STLDeleteElements(T* container) {
	if (!container)
	return;
	STLDeleteContainerPointers(container->begin(), container->end());
	container->clear();
	}

	// Given an STL container consisting of (key, value) pairs, STLDeleteValues
	// deletes all the "value" components and clears the container. Does nothing
	// in the case it's given a NULL pointer.
	template <class T>
	void STLDeleteValues(T* container) {
	if (!container)
	return;
	for (typename T::iterator i(container->begin()); i != container->end(); ++i)
	delete i->second;
	container->clear();
	}


	// The following classes provide a convenient way to delete all elements or
	// values from STL containers when they goes out of scope. This greatly
	// simplifies code that creates temporary objects and has multiple return
	// statements. Example:
	//
	// vector<MyProto *> tmp_proto;
	// STLElementDeleter<vector<MyProto *> > d(&tmp_proto);
	// if (...) return false;
	// ...
	// return success;

	// Given a pointer to an STL container this class will delete all the element
	// pointers when it goes out of scope.
	template<class T>
	class STLElementDeleter {
	public:
	STLElementDeleter<T>(T* container) : container_(container) {}
	~STLElementDeleter<T>() { STLDeleteElements(container_); }

	private:
	T* container_;
	};

	// Given a pointer to an STL container this class will delete all the value
	// pointers when it goes out of scope.
	template<class T>
	class STLValueDeleter {
	public:
	STLValueDeleter<T>(T* container) : container_(container) {}
	~STLValueDeleter<T>() { STLDeleteValues(container_); }

	private:
	T* container_;
	};

	// Test to see if a set, map, hash_set or hash_map contains a particular key.
	// Returns true if the key is in the collection.
	template <typename Collection, typename Key>
	bool ContainsKey(const Collection& collection, const Key& key) {
	return collection.find(key) != collection.end();
	}

	namespace base {

	// Returns true if the container is sorted.
	template <typename Container>
	bool STLIsSorted(const Container& cont) {
	// Note: Use reverse iterator on container to ensure we only require
	// value_type to implement operator<.
	return std::adjacent_find(cont.rbegin(), cont.rend(),
	std::less<typename Container::value_type>())
	== cont.rend();
	}

	// Returns a new ResultType containing the difference of two sorted containers.
	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;
	}

	// Returns a new ResultType containing the union of two sorted containers.
	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;
	}

	// Returns a new ResultType containing the intersection of two sorted
	// containers.
	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;
	}

	// Returns true if the sorted container \|a1\| contains all elements of the sorted
	// container \|a2\|.
	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 // BASE_STL_UTIL_H_