1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc. All rights reserved.
3// https://developers.google.com/protocol-buffers/
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are
7// met:
8//
9// * Redistributions of source code must retain the above copyright
10// notice, this list of conditions and the following disclaimer.
11// * Redistributions in binary form must reproduce the above
12// copyright notice, this list of conditions and the following disclaimer
13// in the documentation and/or other materials provided with the
14// distribution.
15// * Neither the name of Google Inc. nor the names of its
16// contributors may be used to endorse or promote products derived from
17// this software without specific prior written permission.
18//
19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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
38#include <algorithm>
39
40// Must be last.
41#include <google/protobuf/port_def.inc> // NOLINT
42
43namespace google {
44namespace protobuf {
45
46// Inside Google, this function implements a horrible, disgusting hack in which
47// we reach into the string's private implementation and resize it without
48// initializing the new bytes. In some cases doing this can significantly
49// improve performance. However, since it's totally non-portable it has no
50// place in open source code. Feel free to fill this function in with your
51// own disgusting hack if you want the perf boost.
52inline void STLStringResizeUninitialized(std::string* s, size_t new_size) {
53 s->resize(n: new_size);
54}
55
56// As above, but we make sure to follow amortized growth in which we always
57// increase the capacity by at least a constant factor >1.
58inline void STLStringResizeUninitializedAmortized(std::string* s,
59 size_t new_size) {
60 const size_t cap = s->capacity();
61 if (new_size > cap) {
62 // Make sure to always grow by at least a factor of 2x.
63 s->reserve(res_arg: std::max<size_t>(new_size, 2 * cap));
64 }
65 STLStringResizeUninitialized(s, new_size);
66}
67
68// Return a mutable char* pointing to a string's internal buffer,
69// which may not be null-terminated. Writing through this pointer will
70// modify the string.
71//
72// string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
73// next call to a string method that invalidates iterators.
74//
75// As of 2006-04, there is no standard-blessed way of getting a
76// mutable reference to a string's internal buffer. However, issue 530
77// (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#530)
78// proposes this as the method. According to Matt Austern, this should
79// already work on all current implementations.
80inline char* string_as_array(std::string* str) {
81 // DO NOT USE const_cast<char*>(str->data())! See the unittest for why.
82 return str->empty() ? nullptr : &*str->begin();
83}
84
85} // namespace protobuf
86} // namespace google
87
88#include <google/protobuf/port_undef.inc> // NOLINT
89
90#endif // GOOGLE_PROTOBUF_STUBS_STL_UTIL_H__
91