base: Clean up stl_util.h style issues.

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_
 #pragma once
 
 #include <string>
 #include <vector>
 
-// Clear internal memory of an STL object.
+// 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) {
+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);
 }
 
-// STLDeleteContainerPointers()
-//  For a range within a container of pointers, calls delete
-//  (non-array version) on these pointers.
+// 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;
   }
 }
 
-// STLDeleteContainerPairPointers()
-//  For a range within a container of pairs, calls delete
-//  (non-array version) on BOTH items in the pairs.
+// 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;
   }
 }
 
-// STLDeleteContainerPairFirstPointers()
-//  For a range within a container of pairs, calls delete (non-array version)
-//  on the FIRST item in the pairs.
+// 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;
   }
 }
 
-// STLDeleteContainerPairSecondPointers()
-//  For a range within a container of pairs, calls delete
+// 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.
-//  (non-array version) on the SECOND item in the pairs.
 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.
-
+// 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.
+// 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;
+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 *v) {
-  if (!v) return;
-  for (typename T::iterator i = v->begin(); i != v->end(); ++i) {
+void STLDeleteValues(T* container) {
+  if (!container)
+    return;
+  for (typename T::iterator i(container->begin()); i != container->end(); ++i)
     delete i->second;
-  }
-  v->clear();
+  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_); }
 
-template<class STLContainer> class STLElementDeleter {
- public:
-  STLElementDeleter<STLContainer>(STLContainer *ptr) : container_ptr_(ptr) {}
-  ~STLElementDeleter<STLContainer>() { STLDeleteElements(container_ptr_); }
  private:
-  STLContainer *container_ptr_;
+  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_); }
 
-template<class STLContainer> class STLValueDeleter {
- public:
-  STLValueDeleter<STLContainer>(STLContainer *ptr) : container_ptr_(ptr) {}
-  ~STLValueDeleter<STLContainer>() { STLDeleteValues(container_ptr_); }
  private:
-  STLContainer *container_ptr_;
+  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();
 }
 
 #endif  // BASE_STL_UTIL_H_