1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc.  All rights reserved.
3// http://code.google.com/p/protobuf/
4//
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6// modification, are permitted provided that the following conditions are
7// met:
8//
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18//
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20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31// from google3/util/gtl/stl_util.h
32
33#ifndef GOOGLE_PROTOBUF_STUBS_STL_UTIL_H__
34#define GOOGLE_PROTOBUF_STUBS_STL_UTIL_H__
35
36#include <google/protobuf/stubs/common.h>
37
38namespace google {
39namespace protobuf {
40
41// STLDeleteContainerPointers()
42//  For a range within a container of pointers, calls delete
43//  (non-array version) on these pointers.
44// NOTE: for these three functions, we could just implement a DeleteObject
45// functor and then call for_each() on the range and functor, but this
46// requires us to pull in all of algorithm.h, which seems expensive.
47// For hash_[multi]set, it is important that this deletes behind the iterator
48// because the hash_set may call the hash function on the iterator when it is
49// advanced, which could result in the hash function trying to deference a
50// stale pointer.
51template <class ForwardIterator>
52void STLDeleteContainerPointers(ForwardIterator begin,
53                                ForwardIterator end) {
54  while (begin != end) {
55    ForwardIterator temp = begin;
56    ++begin;
57    delete *temp;
58  }
59}
60
61// Inside Google, this function implements a horrible, disgusting hack in which
62// we reach into the string's private implementation and resize it without
63// initializing the new bytes.  In some cases doing this can significantly
64// improve performance.  However, since it's totally non-portable it has no
65// place in open source code.  Feel free to fill this function in with your
66// own disgusting hack if you want the perf boost.
67inline void STLStringResizeUninitialized(string* s, size_t new_size) {
68  s->resize(new_size);
69}
70
71// Return a mutable char* pointing to a string's internal buffer,
72// which may not be null-terminated. Writing through this pointer will
73// modify the string.
74//
75// string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
76// next call to a string method that invalidates iterators.
77//
78// As of 2006-04, there is no standard-blessed way of getting a
79// mutable reference to a string's internal buffer. However, issue 530
80// (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#530)
81// proposes this as the method. According to Matt Austern, this should
82// already work on all current implementations.
83inline char* string_as_array(string* str) {
84  // DO NOT USE const_cast<char*>(str->data())! See the unittest for why.
85  return str->empty() ? NULL : &*str->begin();
86}
87
88// STLDeleteElements() deletes all the elements in an STL container and clears
89// the container.  This function is suitable for use with a vector, set,
90// hash_set, or any other STL container which defines sensible begin(), end(),
91// and clear() methods.
92//
93// If container is NULL, this function is a no-op.
94//
95// As an alternative to calling STLDeleteElements() directly, consider
96// ElementDeleter (defined below), which ensures that your container's elements
97// are deleted when the ElementDeleter goes out of scope.
98template <class T>
99void STLDeleteElements(T *container) {
100  if (!container) return;
101  STLDeleteContainerPointers(container->begin(), container->end());
102  container->clear();
103}
104
105// Given an STL container consisting of (key, value) pairs, STLDeleteValues
106// deletes all the "value" components and clears the container.  Does nothing
107// in the case it's given a NULL pointer.
108
109template <class T>
110void STLDeleteValues(T *v) {
111  if (!v) return;
112  for (typename T::iterator i = v->begin(); i != v->end(); ++i) {
113    delete i->second;
114  }
115  v->clear();
116}
117
118}  // namespace protobuf
119}  // namespace google
120
121#endif  // GOOGLE_PROTOBUF_STUBS_STL_UTIL_H__
122