michael@0: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: // STL utility functions.  Usually, these replace built-in, but slow(!),
michael@0: // STL functions with more efficient versions.
michael@0: 
michael@0: #ifndef BASE_STL_UTIL_INL_H_
michael@0: #define BASE_STL_UTIL_INL_H_
michael@0: 
michael@0: #include <string.h>  // for memcpy
michael@0: #include <functional>
michael@0: #include <set>
michael@0: #include <string>
michael@0: #include <vector>
michael@0: #include <cassert>
michael@0: 
michael@0: // Clear internal memory of an STL object.
michael@0: // STL clear()/reserve(0) does not always free internal memory allocated
michael@0: // This function uses swap/destructor to ensure the internal memory is freed.
michael@0: template<class T> void STLClearObject(T* obj) {
michael@0:   T tmp;
michael@0:   tmp.swap(*obj);
michael@0:   obj->reserve(0);  // this is because sometimes "T tmp" allocates objects with
michael@0:                     // memory (arena implementation?).  use reserve()
michael@0:                     // to clear() even if it doesn't always work
michael@0: }
michael@0: 
michael@0: // Reduce memory usage on behalf of object if it is using more than
michael@0: // "bytes" bytes of space.  By default, we clear objects over 1MB.
michael@0: template <class T> inline void STLClearIfBig(T* obj, size_t limit = 1<<20) {
michael@0:   if (obj->capacity() >= limit) {
michael@0:     STLClearObject(obj);
michael@0:   } else {
michael@0:     obj->clear();
michael@0:   }
michael@0: }
michael@0: 
michael@0: // Reserve space for STL object.
michael@0: // STL's reserve() will always copy.
michael@0: // This function avoid the copy if we already have capacity
michael@0: template<class T> void STLReserveIfNeeded(T* obj, int new_size) {
michael@0:   if (obj->capacity() < new_size)   // increase capacity
michael@0:     obj->reserve(new_size);
michael@0:   else if (obj->size() > new_size)  // reduce size
michael@0:     obj->resize(new_size);
michael@0: }
michael@0: 
michael@0: // STLDeleteContainerPointers()
michael@0: //  For a range within a container of pointers, calls delete
michael@0: //  (non-array version) on these pointers.
michael@0: // NOTE: for these three functions, we could just implement a DeleteObject
michael@0: // functor and then call for_each() on the range and functor, but this
michael@0: // requires us to pull in all of algorithm.h, which seems expensive.
michael@0: // For hash_[multi]set, it is important that this deletes behind the iterator
michael@0: // because the hash_set may call the hash function on the iterator when it is
michael@0: // advanced, which could result in the hash function trying to deference a
michael@0: // stale pointer.
michael@0: template <class ForwardIterator>
michael@0: void STLDeleteContainerPointers(ForwardIterator begin,
michael@0:                                 ForwardIterator end) {
michael@0:   while (begin != end) {
michael@0:     ForwardIterator temp = begin;
michael@0:     ++begin;
michael@0:     delete *temp;
michael@0:   }
michael@0: }
michael@0: 
michael@0: // STLDeleteContainerPairPointers()
michael@0: //  For a range within a container of pairs, calls delete
michael@0: //  (non-array version) on BOTH items in the pairs.
michael@0: // NOTE: Like STLDeleteContainerPointers, it is important that this deletes
michael@0: // behind the iterator because if both the key and value are deleted, the
michael@0: // container may call the hash function on the iterator when it is advanced,
michael@0: // which could result in the hash function trying to dereference a stale
michael@0: // pointer.
michael@0: template <class ForwardIterator>
michael@0: void STLDeleteContainerPairPointers(ForwardIterator begin,
michael@0:                                     ForwardIterator end) {
michael@0:   while (begin != end) {
michael@0:     ForwardIterator temp = begin;
michael@0:     ++begin;
michael@0:     delete temp->first;
michael@0:     delete temp->second;
michael@0:   }
michael@0: }
michael@0: 
michael@0: // STLDeleteContainerPairFirstPointers()
michael@0: //  For a range within a container of pairs, calls delete (non-array version)
michael@0: //  on the FIRST item in the pairs.
michael@0: // NOTE: Like STLDeleteContainerPointers, deleting behind the iterator.
michael@0: template <class ForwardIterator>
michael@0: void STLDeleteContainerPairFirstPointers(ForwardIterator begin,
michael@0:                                          ForwardIterator end) {
michael@0:   while (begin != end) {
michael@0:     ForwardIterator temp = begin;
michael@0:     ++begin;
michael@0:     delete temp->first;
michael@0:   }
michael@0: }
michael@0: 
michael@0: // STLDeleteContainerPairSecondPointers()
michael@0: //  For a range within a container of pairs, calls delete
michael@0: //  (non-array version) on the SECOND item in the pairs.
michael@0: template <class ForwardIterator>
michael@0: void STLDeleteContainerPairSecondPointers(ForwardIterator begin,
michael@0:                                           ForwardIterator end) {
michael@0:   while (begin != end) {
michael@0:     delete begin->second;
michael@0:     ++begin;
michael@0:   }
michael@0: }
michael@0: 
michael@0: template<typename T>
michael@0: inline void STLAssignToVector(std::vector<T>* vec,
michael@0:                               const T* ptr,
michael@0:                               size_t n) {
michael@0:   vec->resize(n);
michael@0:   memcpy(&vec->front(), ptr, n*sizeof(T));
michael@0: }
michael@0: 
michael@0: /***** Hack to allow faster assignment to a vector *****/
michael@0: 
michael@0: // This routine speeds up an assignment of 32 bytes to a vector from
michael@0: // about 250 cycles per assignment to about 140 cycles.
michael@0: //
michael@0: // Usage:
michael@0: //      STLAssignToVectorChar(&vec, ptr, size);
michael@0: //      STLAssignToString(&str, ptr, size);
michael@0: 
michael@0: inline void STLAssignToVectorChar(std::vector<char>* vec,
michael@0:                                   const char* ptr,
michael@0:                                   size_t n) {
michael@0:   STLAssignToVector(vec, ptr, n);
michael@0: }
michael@0: 
michael@0: inline void STLAssignToString(std::string* str, const char* ptr, size_t n) {
michael@0:   str->resize(n);
michael@0:   memcpy(&*str->begin(), ptr, n);
michael@0: }
michael@0: 
michael@0: // To treat a possibly-empty vector as an array, use these functions.
michael@0: // If you know the array will never be empty, you can use &*v.begin()
michael@0: // directly, but that is allowed to dump core if v is empty.  This
michael@0: // function is the most efficient code that will work, taking into
michael@0: // account how our STL is actually implemented.  THIS IS NON-PORTABLE
michael@0: // CODE, so call us instead of repeating the nonportable code
michael@0: // everywhere.  If our STL implementation changes, we will need to
michael@0: // change this as well.
michael@0: 
michael@0: template<typename T>
michael@0: inline T* vector_as_array(std::vector<T>* v) {
michael@0: # ifdef NDEBUG
michael@0:   return &*v->begin();
michael@0: # else
michael@0:   return v->empty() ? NULL : &*v->begin();
michael@0: # endif
michael@0: }
michael@0: 
michael@0: template<typename T>
michael@0: inline const T* vector_as_array(const std::vector<T>* v) {
michael@0: # ifdef NDEBUG
michael@0:   return &*v->begin();
michael@0: # else
michael@0:   return v->empty() ? NULL : &*v->begin();
michael@0: # endif
michael@0: }
michael@0: 
michael@0: // Return a mutable char* pointing to a string's internal buffer,
michael@0: // which may not be null-terminated. Writing through this pointer will
michael@0: // modify the string.
michael@0: //
michael@0: // string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
michael@0: // next call to a string method that invalidates iterators.
michael@0: //
michael@0: // As of 2006-04, there is no standard-blessed way of getting a
michael@0: // mutable reference to a string's internal buffer. However, issue 530
michael@0: // (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#530)
michael@0: // proposes this as the method. According to Matt Austern, this should
michael@0: // already work on all current implementations.
michael@0: inline char* string_as_array(std::string* str) {
michael@0:   // DO NOT USE const_cast<char*>(str->data())! See the unittest for why.
michael@0:   return str->empty() ? NULL : &*str->begin();
michael@0: }
michael@0: 
michael@0: // These are methods that test two hash maps/sets for equality.  These exist
michael@0: // because the == operator in the STL can return false when the maps/sets
michael@0: // contain identical elements.  This is because it compares the internal hash
michael@0: // tables which may be different if the order of insertions and deletions
michael@0: // differed.
michael@0: 
michael@0: template <class HashSet>
michael@0: inline bool
michael@0: HashSetEquality(const HashSet& set_a,
michael@0:                 const HashSet& set_b) {
michael@0:   if (set_a.size() != set_b.size()) return false;
michael@0:   for (typename HashSet::const_iterator i = set_a.begin();
michael@0:        i != set_a.end();
michael@0:        ++i) {
michael@0:     if (set_b.find(*i) == set_b.end())
michael@0:       return false;
michael@0:   }
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: template <class HashMap>
michael@0: inline bool
michael@0: HashMapEquality(const HashMap& map_a,
michael@0:                 const HashMap& map_b) {
michael@0:   if (map_a.size() != map_b.size()) return false;
michael@0:   for (typename HashMap::const_iterator i = map_a.begin();
michael@0:        i != map_a.end(); ++i) {
michael@0:     typename HashMap::const_iterator j = map_b.find(i->first);
michael@0:     if (j == map_b.end()) return false;
michael@0:     if (i->second != j->second) return false;
michael@0:   }
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // The following functions are useful for cleaning up STL containers
michael@0: // whose elements point to allocated memory.
michael@0: 
michael@0: // STLDeleteElements() deletes all the elements in an STL container and clears
michael@0: // the container.  This function is suitable for use with a vector, set,
michael@0: // hash_set, or any other STL container which defines sensible begin(), end(),
michael@0: // and clear() methods.
michael@0: //
michael@0: // If container is NULL, this function is a no-op.
michael@0: //
michael@0: // As an alternative to calling STLDeleteElements() directly, consider
michael@0: // STLElementDeleter (defined below), which ensures that your container's
michael@0: // elements are deleted when the STLElementDeleter goes out of scope.
michael@0: template <class T>
michael@0: void STLDeleteElements(T *container) {
michael@0:   if (!container) return;
michael@0:   STLDeleteContainerPointers(container->begin(), container->end());
michael@0:   container->clear();
michael@0: }
michael@0: 
michael@0: // Given an STL container consisting of (key, value) pairs, STLDeleteValues
michael@0: // deletes all the "value" components and clears the container.  Does nothing
michael@0: // in the case it's given a NULL pointer.
michael@0: 
michael@0: template <class T>
michael@0: void STLDeleteValues(T *v) {
michael@0:   if (!v) return;
michael@0:   for (typename T::iterator i = v->begin(); i != v->end(); ++i) {
michael@0:     delete i->second;
michael@0:   }
michael@0:   v->clear();
michael@0: }
michael@0: 
michael@0: 
michael@0: // The following classes provide a convenient way to delete all elements or
michael@0: // values from STL containers when they goes out of scope.  This greatly
michael@0: // simplifies code that creates temporary objects and has multiple return
michael@0: // statements.  Example:
michael@0: //
michael@0: // vector<MyProto *> tmp_proto;
michael@0: // STLElementDeleter<vector<MyProto *> > d(&tmp_proto);
michael@0: // if (...) return false;
michael@0: // ...
michael@0: // return success;
michael@0: 
michael@0: // Given a pointer to an STL container this class will delete all the element
michael@0: // pointers when it goes out of scope.
michael@0: 
michael@0: template<class STLContainer> class STLElementDeleter {
michael@0:  public:
michael@0:   STLElementDeleter(STLContainer *ptr) : container_ptr_(ptr) {}
michael@0:   ~STLElementDeleter() { STLDeleteElements(container_ptr_); }
michael@0:  private:
michael@0:   STLContainer *container_ptr_;
michael@0: };
michael@0: 
michael@0: // Given a pointer to an STL container this class will delete all the value
michael@0: // pointers when it goes out of scope.
michael@0: 
michael@0: template<class STLContainer> class STLValueDeleter {
michael@0:  public:
michael@0:   STLValueDeleter(STLContainer *ptr) : container_ptr_(ptr) {}
michael@0:   ~STLValueDeleter() { STLDeleteValues(container_ptr_); }
michael@0:  private:
michael@0:   STLContainer *container_ptr_;
michael@0: };
michael@0: 
michael@0: 
michael@0: // Forward declare some callback classes in callback.h for STLBinaryFunction
michael@0: template <class R, class T1, class T2>
michael@0: class ResultCallback2;
michael@0: 
michael@0: // STLBinaryFunction is a wrapper for the ResultCallback2 class in callback.h
michael@0: // It provides an operator () method instead of a Run method, so it may be
michael@0: // passed to STL functions in <algorithm>.
michael@0: //
michael@0: // The client should create callback with NewPermanentCallback, and should
michael@0: // delete callback after it is done using the STLBinaryFunction.
michael@0: 
michael@0: template <class Result, class Arg1, class Arg2>
michael@0: class STLBinaryFunction : public std::binary_function<Arg1, Arg2, Result> {
michael@0:  public:
michael@0:   typedef ResultCallback2<Result, Arg1, Arg2> Callback;
michael@0: 
michael@0:   STLBinaryFunction(Callback* callback)
michael@0:     : callback_(callback) {
michael@0:     assert(callback_);
michael@0:   }
michael@0: 
michael@0:   Result operator() (Arg1 arg1, Arg2 arg2) {
michael@0:     return callback_->Run(arg1, arg2);
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   Callback* callback_;
michael@0: };
michael@0: 
michael@0: // STLBinaryPredicate is a specialized version of STLBinaryFunction, where the
michael@0: // return type is bool and both arguments have type Arg.  It can be used
michael@0: // wherever STL requires a StrictWeakOrdering, such as in sort() or
michael@0: // lower_bound().
michael@0: //
michael@0: // templated typedefs are not supported, so instead we use inheritance.
michael@0: 
michael@0: template <class Arg>
michael@0: class STLBinaryPredicate : public STLBinaryFunction<bool, Arg, Arg> {
michael@0:  public:
michael@0:   typedef typename STLBinaryPredicate<Arg>::Callback Callback;
michael@0:   STLBinaryPredicate(Callback* callback)
michael@0:     : STLBinaryFunction<bool, Arg, Arg>(callback) {
michael@0:   }
michael@0: };
michael@0: 
michael@0: // Functors that compose arbitrary unary and binary functions with a
michael@0: // function that "projects" one of the members of a pair.
michael@0: // Specifically, if p1 and p2, respectively, are the functions that
michael@0: // map a pair to its first and second, respectively, members, the
michael@0: // table below summarizes the functions that can be constructed:
michael@0: //
michael@0: // * UnaryOperate1st<pair>(f) returns the function x -> f(p1(x))
michael@0: // * UnaryOperate2nd<pair>(f) returns the function x -> f(p2(x))
michael@0: // * BinaryOperate1st<pair>(f) returns the function (x,y) -> f(p1(x),p1(y))
michael@0: // * BinaryOperate2nd<pair>(f) returns the function (x,y) -> f(p2(x),p2(y))
michael@0: //
michael@0: // A typical usage for these functions would be when iterating over
michael@0: // the contents of an STL map. For other sample usage, see the unittest.
michael@0: 
michael@0: template<typename Pair, typename UnaryOp>
michael@0: class UnaryOperateOnFirst
michael@0:     : public std::unary_function<Pair, typename UnaryOp::result_type> {
michael@0:  public:
michael@0:   UnaryOperateOnFirst() {
michael@0:   }
michael@0: 
michael@0:   UnaryOperateOnFirst(const UnaryOp& f) : f_(f) {
michael@0:   }
michael@0: 
michael@0:   typename UnaryOp::result_type operator()(const Pair& p) const {
michael@0:     return f_(p.first);
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   UnaryOp f_;
michael@0: };
michael@0: 
michael@0: template<typename Pair, typename UnaryOp>
michael@0: UnaryOperateOnFirst<Pair, UnaryOp> UnaryOperate1st(const UnaryOp& f) {
michael@0:   return UnaryOperateOnFirst<Pair, UnaryOp>(f);
michael@0: }
michael@0: 
michael@0: template<typename Pair, typename UnaryOp>
michael@0: class UnaryOperateOnSecond
michael@0:     : public std::unary_function<Pair, typename UnaryOp::result_type> {
michael@0:  public:
michael@0:   UnaryOperateOnSecond() {
michael@0:   }
michael@0: 
michael@0:   UnaryOperateOnSecond(const UnaryOp& f) : f_(f) {
michael@0:   }
michael@0: 
michael@0:   typename UnaryOp::result_type operator()(const Pair& p) const {
michael@0:     return f_(p.second);
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   UnaryOp f_;
michael@0: };
michael@0: 
michael@0: template<typename Pair, typename UnaryOp>
michael@0: UnaryOperateOnSecond<Pair, UnaryOp> UnaryOperate2nd(const UnaryOp& f) {
michael@0:   return UnaryOperateOnSecond<Pair, UnaryOp>(f);
michael@0: }
michael@0: 
michael@0: template<typename Pair, typename BinaryOp>
michael@0: class BinaryOperateOnFirst
michael@0:     : public std::binary_function<Pair, Pair, typename BinaryOp::result_type> {
michael@0:  public:
michael@0:   BinaryOperateOnFirst() {
michael@0:   }
michael@0: 
michael@0:   BinaryOperateOnFirst(const BinaryOp& f) : f_(f) {
michael@0:   }
michael@0: 
michael@0:   typename BinaryOp::result_type operator()(const Pair& p1,
michael@0:                                             const Pair& p2) const {
michael@0:     return f_(p1.first, p2.first);
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   BinaryOp f_;
michael@0: };
michael@0: 
michael@0: template<typename Pair, typename BinaryOp>
michael@0: BinaryOperateOnFirst<Pair, BinaryOp> BinaryOperate1st(const BinaryOp& f) {
michael@0:   return BinaryOperateOnFirst<Pair, BinaryOp>(f);
michael@0: }
michael@0: 
michael@0: template<typename Pair, typename BinaryOp>
michael@0: class BinaryOperateOnSecond
michael@0:     : public std::binary_function<Pair, Pair, typename BinaryOp::result_type> {
michael@0:  public:
michael@0:   BinaryOperateOnSecond() {
michael@0:   }
michael@0: 
michael@0:   BinaryOperateOnSecond(const BinaryOp& f) : f_(f) {
michael@0:   }
michael@0: 
michael@0:   typename BinaryOp::result_type operator()(const Pair& p1,
michael@0:                                             const Pair& p2) const {
michael@0:     return f_(p1.second, p2.second);
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   BinaryOp f_;
michael@0: };
michael@0: 
michael@0: template<typename Pair, typename BinaryOp>
michael@0: BinaryOperateOnSecond<Pair, BinaryOp> BinaryOperate2nd(const BinaryOp& f) {
michael@0:   return BinaryOperateOnSecond<Pair, BinaryOp>(f);
michael@0: }
michael@0: 
michael@0: // Translates a set into a vector.
michael@0: template<typename T>
michael@0: std::vector<T> SetToVector(const std::set<T>& values) {
michael@0:   std::vector<T> result;
michael@0:   result.reserve(values.size());
michael@0:   result.insert(result.begin(), values.begin(), values.end());
michael@0:   return result;
michael@0: }
michael@0: 
michael@0: #endif  // BASE_STL_UTIL_INL_H_