libstdc++: streambuf.tcc Source File

libstdc++

streambuf.tcc
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1// Stream buffer classes -*- C++ -*-
2
3// Copyright (C) 1997-2026 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file bits/streambuf.tcc
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{streambuf}
28 */
29
30//
31// ISO C++ 14882: 27.5 Stream buffers
32//
33
34#ifndef _STREAMBUF_TCC
35#define _STREAMBUF_TCC 1
36
37#ifdef _GLIBCXX_SYSHDR
38#pragma GCC system_header
39#endif
40
41#pragma GCC diagnostic push
42#pragma GCC diagnostic ignored "-Wc++11-extensions" // extern template
43
44namespace std _GLIBCXX_VISIBILITY(default)
45{
46_GLIBCXX_BEGIN_NAMESPACE_VERSION
47
48 template<typename _CharT, typename _Traits>
49 streamsize
50 basic_streambuf<_CharT, _Traits>::
51 xsgetn(char_type* __s, streamsize __n)
52 {
53 streamsize __ret = 0;
54 while (__ret < __n)
55 {
56 const streamsize __buf_len = this->egptr() - this->gptr();
57 if (__buf_len)
58 {
59 const streamsize __remaining = __n - __ret;
60 const streamsize __len = std::min(__buf_len, __remaining);
61 traits_type::copy(__s, this->gptr(), __len);
62 __ret += __len;
63 __s += __len;
64 this->__safe_gbump(__len);
65 }
66
67 if (__ret < __n)
68 {
69 const int_type __c = this->uflow();
70 if (!traits_type::eq_int_type(__c, traits_type::eof()))
71 {
72 traits_type::assign(*__s++, traits_type::to_char_type(__c));
73 ++__ret;
74 }
75 else
76 break;
77 }
78 }
79 return __ret;
80 }
81
82 template<typename _CharT, typename _Traits>
83 streamsize
84 basic_streambuf<_CharT, _Traits>::
85 xsputn(const char_type* __s, streamsize __n)
86 {
87 streamsize __ret = 0;
88 while (__ret < __n)
89 {
90 const streamsize __buf_len = this->epptr() - this->pptr();
91 if (__buf_len)
92 {
93 const streamsize __remaining = __n - __ret;
94 const streamsize __len = std::min(__buf_len, __remaining);
95 traits_type::copy(this->pptr(), __s, __len);
96 __ret += __len;
97 __s += __len;
98 this->__safe_pbump(__len);
99 }
100
101 if (__ret < __n)
102 {
103 int_type __c = this->overflow(traits_type::to_int_type(*__s));
104 if (!traits_type::eq_int_type(__c, traits_type::eof()))
105 {
106 ++__ret;
107 ++__s;
108 }
109 else
110 break;
111 }
112 }
113 return __ret;
114 }
115
116 // Conceivably, this could be used to implement buffer-to-buffer
117 // copies, if this was ever desired in an un-ambiguous way by the
118 // standard.
119 template<typename _CharT, typename _Traits>
120 streamsize
121 __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>* __sbin,
122 basic_streambuf<_CharT, _Traits>* __sbout,
123 bool& __ineof)
124 {
125 streamsize __ret = 0;
126 __ineof = true;
127 typename _Traits::int_type __c = __sbin->sgetc();
128 while (!_Traits::eq_int_type(__c, _Traits::eof()))
129 {
130 __c = __sbout->sputc(_Traits::to_char_type(__c));
131 if (_Traits::eq_int_type(__c, _Traits::eof()))
132 {
133 __ineof = false;
134 break;
135 }
136 ++__ret;
137 __c = __sbin->snextc();
138 }
139 return __ret;
140 }
141
142 template<typename _CharT, typename _Traits>
143 inline streamsize
144 __copy_streambufs(basic_streambuf<_CharT, _Traits>* __sbin,
145 basic_streambuf<_CharT, _Traits>* __sbout)
146 {
147 bool __ineof;
148 return __copy_streambufs_eof(__sbin, __sbout, __ineof);
149 }
150
151 // Inhibit implicit instantiations for required instantiations,
152 // which are defined via explicit instantiations elsewhere.
153#if _GLIBCXX_EXTERN_TEMPLATE
154 extern template class basic_streambuf<char>;
155
156 extern template
157 streamsize
158 __copy_streambufs(basic_streambuf<char>*,
159 basic_streambuf<char>*);
160
161#ifdef _GLIBCXX_USE_WCHAR_T
162 extern template class basic_streambuf<wchar_t>;
163
164 extern template
165 streamsize
166 __copy_streambufs(basic_streambuf<wchar_t>*,
167 basic_streambuf<wchar_t>*);
168#endif
169#endif
170
171_GLIBCXX_END_NAMESPACE_VERSION
172} // namespace std
173
174#pragma GCC diagnostic pop
175#endif
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition stl_algobase.h:232
std
ISO C++ entities toplevel namespace is std.
std::streamsize
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition postypes.h:73
std::basic_streambuf
The actual work of input and output (interface).
Definition streambuf:127
std::basic_streambuf::int_type
traits_type::int_type int_type
Definition streambuf:137
std::basic_streambuf::epptr
char_type * epptr() const
Access to the put area.
Definition streambuf:549
std::basic_streambuf::overflow
virtual int_type overflow(int_type __c=traits_type::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition streambuf:782
std::basic_streambuf::xsputn
virtual streamsize xsputn(const char_type *__s, streamsize __n)
Multiple character insertion.
Definition streambuf.tcc:85
std::basic_streambuf::pptr
char_type * pptr() const
Access to the put area.
Definition streambuf:546
std::basic_streambuf::char_type
_CharT char_type
Definition streambuf:135
std::basic_streambuf::uflow
virtual int_type uflow()
Fetches more data from the controlled sequence.
Definition streambuf:714
std::basic_streambuf::egptr
char_type * egptr() const
Access to the get area.
Definition streambuf:501
std::basic_streambuf::gptr
char_type * gptr() const
Access to the get area.
Definition streambuf:498
std::basic_streambuf::xsgetn
virtual streamsize xsgetn(char_type *__s, streamsize __n)
Multiple character extraction.
Definition streambuf.tcc:51
std::basic_streambuf::snextc
int_type snextc()
Getting the next character.
Definition streambuf:307
std::basic_streambuf::sgetc
int_type sgetc()
Getting the next character.
Definition streambuf:347
std::basic_streambuf::sputc
int_type sputc(char_type __c)
Entry point for all single-character output functions.
Definition streambuf:433