1// ----------------------------------------------------------------------------
2// internals.hpp : internal structs : stream_format_state, format_item.
3// included by format.hpp
4// ----------------------------------------------------------------------------
5
6// Copyright Samuel Krempp 2003. Use, modification, and distribution are
7// subject to the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9
10// See http://www.boost.org/libs/format for library home page
11
12// ----------------------------------------------------------------------------
13
14#ifndef BOOST_FORMAT_INTERNALS_HPP
15#define BOOST_FORMAT_INTERNALS_HPP
16
17
18#include <string>
19#include <boost/assert.hpp>
20#include <boost/optional.hpp>
21#include <boost/limits.hpp>
22#include <boost/format/detail/compat_workarounds.hpp>
23#include <boost/format/alt_sstream.hpp> // used as a dummy stream
24
25namespace boost {
26namespace io {
27namespace detail {
28
29
30//---- stream_format_state --------------------------------------------------//
31
32// set of params that define the format state of a stream
33 template<class Ch, class Tr>
34 struct stream_format_state
35 {
36 typedef BOOST_IO_STD basic_ios<Ch, Tr> basic_ios;
37
38 stream_format_state(Ch fill) { reset(fill); }
39// stream_format_state(const basic_ios& os) { set_by_stream(os); }
40
41 void reset(Ch fill); //- sets to default state.
42 void set_by_stream(const basic_ios& os); //- sets to os's state.
43 void apply_on(basic_ios & os, //- applies format_state to the stream
44 boost::io::detail::locale_t * loc_default = 0) const;
45 template<class T>
46 void apply_manip(T manipulator) //- modifies state by applying manipulator
47 { apply_manip_body<Ch, Tr, T>( *this, manipulator) ; }
48
49 // --- data ---
50 std::streamsize width_;
51 std::streamsize precision_;
52 Ch fill_;
53 std::ios_base::fmtflags flags_;
54 std::ios_base::iostate rdstate_;
55 std::ios_base::iostate exceptions_;
56 boost::optional<boost::io::detail::locale_t> loc_;
57 };
58
59
60//---- format_item ---------------------------------------------------------//
61
62// stores all parameters that can be specified in format strings
63 template<class Ch, class Tr, class Alloc>
64 struct format_item
65 {
66 enum pad_values { zeropad = 1, spacepad =2, centered=4, tabulation = 8 };
67 // 1. if zeropad is set, all other bits are not,
68 // 2. if tabulation is set, all others are not.
69 // centered and spacepad can be mixed freely.
70 enum arg_values { argN_no_posit = -1, // non-positional directive. will set argN later
71 argN_tabulation = -2, // tabulation directive. (no argument read)
72 argN_ignored = -3 // ignored directive. (no argument read)
73 };
74 typedef BOOST_IO_STD basic_ios<Ch, Tr> basic_ios;
75 typedef detail::stream_format_state<Ch, Tr> stream_format_state;
76 typedef ::std::basic_string<Ch, Tr, Alloc> string_type;
77
78 format_item(Ch fill) :argN_(argN_no_posit), fmtstate_(fill),
79 truncate_(max_streamsize()), pad_scheme_(0) {}
80 void reset(Ch fill);
81 void compute_states(); // sets states according to truncate and pad_scheme.
82
83 static std::streamsize max_streamsize() {
84 return (std::numeric_limits<std::streamsize>::max)();
85 }
86
87 // --- data ---
88 int argN_; //- argument number (starts at 0, eg : %1 => argN=0)
89 // negative values for items that don't process an argument
90 string_type res_; //- result of the formatting of this item
91 string_type appendix_; //- piece of string between this item and the next
92
93 stream_format_state fmtstate_;// set by parsing, is only affected by modify_item
94
95 std::streamsize truncate_;//- is set for directives like %.5s that ask truncation
96 unsigned int pad_scheme_;//- several possible padding schemes can mix. see pad_values
97 };
98
99
100
101//--- Definitions ------------------------------------------------------------
102
103// - stream_format_state:: -------------------------------------------------
104 template<class Ch, class Tr>
105 void stream_format_state<Ch,Tr>:: apply_on (basic_ios & os,
106 boost::io::detail::locale_t * loc_default) const {
107 // If a locale is available, set it first. "os.fill(fill_);" may chrash otherwise.
108#if !defined(BOOST_NO_STD_LOCALE)
109 if(loc_)
110 os.imbue(loc_.get());
111 else if(loc_default)
112 os.imbue(*loc_default);
113#else
114 (void) loc_default; // keep compiler quiet if we don't support locales
115#endif
116 // set the state of this stream according to our params
117 if(width_ != -1)
118 os.width(width_);
119 if(precision_ != -1)
120 os.precision(precision_);
121 if(fill_ != 0)
122 os.fill(fill_);
123 os.flags(flags_);
124 os.clear(rdstate_);
125 os.exceptions(exceptions_);
126 }
127
128 template<class Ch, class Tr>
129 void stream_format_state<Ch,Tr>:: set_by_stream(const basic_ios& os) {
130 // set our params according to the state of this stream
131 flags_ = os.flags();
132 width_ = os.width();
133 precision_ = os.precision();
134 fill_ = os.fill();
135 rdstate_ = os.rdstate();
136 exceptions_ = os.exceptions();
137 }
138
139
140 template<class Ch, class Tr, class T>
141 void apply_manip_body( stream_format_state<Ch, Tr>& self,
142 T manipulator) {
143 // modify our params according to the manipulator
144 basic_oaltstringstream<Ch, Tr> ss;
145 self.apply_on( ss );
146 ss << manipulator;
147 self.set_by_stream( ss );
148 }
149
150 template<class Ch, class Tr> inline
151 void stream_format_state<Ch,Tr>:: reset(Ch fill) {
152 // set our params to standard's default state. cf 27.4.4.1 of the C++ norm
153 width_=0; precision_=6;
154 fill_=fill; // default is widen(' '), but we cant compute it without the locale
155 flags_ = std::ios_base::dec | std::ios_base::skipws;
156 // the adjust_field part is left equal to 0, which means right.
157 exceptions_ = std::ios_base::goodbit;
158 rdstate_ = std::ios_base::goodbit;
159 }
160
161
162// --- format_item:: --------------------------------------------------------
163
164 template<class Ch, class Tr, class Alloc>
165 void format_item<Ch, Tr, Alloc>::
166 reset (Ch fill) {
167 argN_=argN_no_posit; truncate_ = max_streamsize(); pad_scheme_ =0;
168 res_.resize(0); appendix_.resize(0);
169 fmtstate_.reset(fill);
170 }
171
172 template<class Ch, class Tr, class Alloc>
173 void format_item<Ch, Tr, Alloc>::
174 compute_states() {
175 // reflect pad_scheme_ on fmt_state_
176 // because some pad_schemes has complex consequences on several state params.
177 if(pad_scheme_ & zeropad) {
178 // ignore zeropad in left alignment :
179 if(fmtstate_.flags_ & std::ios_base::left) {
180 BOOST_ASSERT(!(fmtstate_.flags_ &(std::ios_base::adjustfield ^std::ios_base::left)));
181 // only left bit might be set. (not right, nor internal)
182 pad_scheme_ = pad_scheme_ & (~zeropad);
183 }
184 else {
185 pad_scheme_ &= ~spacepad; // printf ignores spacepad when zeropadding
186 fmtstate_.fill_='0';
187 fmtstate_.flags_ = (fmtstate_.flags_ & ~std::ios_base::adjustfield)
188 | std::ios_base::internal;
189 // removes all adjustfield bits, and adds internal.
190 }
191 }
192 if(pad_scheme_ & spacepad) {
193 if(fmtstate_.flags_ & std::ios_base::showpos)
194 pad_scheme_ &= ~spacepad;
195 }
196 }
197
198
199} } } // namespaces boost :: io :: detail
200
201
202#endif // BOOST_FORMAT_INTERNALS_HPP
203

source code of boost/boost/format/internals.hpp