1// ----------------------------------------------------------------------------
2// sample_userType.cc : example usage of format with a user-defined type
3// ----------------------------------------------------------------------------
4
5// Copyright Samuel Krempp 2003. Use, modification, and distribution are
6// subject to the Boost Software License, Version 1.0. (See accompanying
7// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8
9// See http://www.boost.org/libs/format for library home page
10
11// ----------------------------------------------------------------------------
12
13
14#include <iostream>
15#include <iomanip>
16#include "boost/format.hpp"
17#include <boost/cast.hpp>
18
19#if !(BOOST_WORKAROUND(__GNUC__, < 3) && defined(__STL_CONFIG_H) )
20 // not for broken gcc stdlib
21#include <boost/io/ios_state.hpp>
22
23#else
24// not as complete, but compatible with gcc-2.95 :
25
26void copyfmt(ios& left, const ios& right) {
27 left.fill(right.fill());
28 left.flags(right.flags() );
29 left.exceptions(right.exceptions());
30 left.width(right.width());
31 left.precision(right.precision());
32}
33
34namespace boost { namespace io {
35class ios_all_saver {
36 std::basic_ios<char> ios_;
37 std::ios & target_r;
38public:
39 ios_all_saver(std::ios& right) : ios_(0), target_r(right) {
40 copyfmt(ios_, right);
41 }
42 ~ios_all_saver() {
43 copyfmt(target_r, ios_);
44 }
45};
46
47} } // N.S. boost::io
48
49
50// define showpos and noshowpos :
51class ShowPos {
52public:
53 bool showpos_;
54 ShowPos(bool v) : showpos_(v) {}
55};
56std::ostream& operator<<(std::ostream& os, const ShowPos& x) {
57 if(x.showpos_)
58 os.setf(ios_base:: showpos);
59 else
60 os.unsetf(ios_base:: showpos);
61 return os;
62}
63ShowPos noshowpos(false);
64ShowPos showpos(true);
65
66#endif // -end gcc-2.95 workarounds
67
68
69
70//---------------------------------------------------------------------------//
71// *** an exemple of UDT : a Rational class ****
72class Rational {
73public:
74 Rational(int n, unsigned int d) : n_(n), d_(d) {}
75 Rational(int n, int d); // convert denominator to unsigned
76 friend std::ostream& operator<<(std::ostream&, const Rational&);
77private:
78 int n_; // numerator
79 unsigned int d_; // denominator
80};
81
82Rational::Rational(int n, int d) : n_(n)
83{
84 if(d < 0) { n_ = -n_; d=-d; } // make the denominator always non-negative.
85 d_ = static_cast<unsigned int>(d);
86}
87
88std::ostream& operator<<(std::ostream& os, const Rational& r) {
89 using namespace std;
90 streamsize n, s1, s2, s3;
91 streamsize w = os.width(wide: 0); // width has to be zeroed before saving state.
92// boost::io::ios_all_saver bia_saver (os);
93
94 boost::io::basic_oaltstringstream<char> oss;
95 oss.copyfmt(rhs: os );
96 oss << r.n_;
97 s1 = oss.size();
98 oss << "/" << noshowpos; // a rational number needs only one sign !
99 s2 = oss.size();
100 oss << r.d_ ;
101 s3 = oss.size();
102
103 n = w - s3;
104 if(n <= 0) {
105 os.write(s: oss.begin(), n: oss.size());
106 }
107 else if(os.flags() & std::ios_base::internal) {
108 std::streamsize n1 = w/2, n2 = w - n1, t;
109 t = (s3-s1) - n2; // is 2d part '/nnn' bigger than 1/2 w ?
110 if(t > 0) {
111 n1 = w -(s3-s1); // put all paddings on first part.
112 n2 = 0; // minimal width (s3-s2)
113 }
114 else {
115 n2 -= s2-s1; // adjust for '/', n2 is still w/2.
116 }
117 os << setw(n1) << r.n_ << "/" << noshowpos << setw(n2) << r.d_;
118 }
119 else {
120 if(! (os.flags() & std::ios_base::left)) {
121 // -> right align. (right bit is set, or no bit is set)
122 os << string(boost::numeric_cast<std::string::size_type>(arg: n), ' ');
123 }
124 os.write(s: oss.begin(), n: s3);
125 if( os.flags() & std::ios_base::left ) {
126 os << string(boost::numeric_cast<std::string::size_type>(arg: n), ' ');
127 }
128 }
129
130 return os;
131}
132
133
134
135int main(){
136 using namespace std;
137 using boost::format;
138 using boost::io::group;
139 using boost::io::str;
140 string s;
141
142 Rational r(16, 9);
143
144 cout << "bonjour ! " << endl;
145 // "bonjour !"
146
147 cout << r << endl;
148 // "16/9"
149
150 cout << showpos << r << ", " << 5 << endl;
151 // "+16/9, +5"
152
153 cout << format("%02d : [%0+9d] \n") % 1 % r ;
154 // "01 : [+016 / 0009]"
155
156 cout << format("%02d : [%_+9d] \n") % 2 % Rational(9,160);
157 // "02 : [+9 / 160]"
158
159 cout << format("%02d : [%_+9d] \n") % 3 % r;
160 // "03 : [+16 / 9]"
161
162 cout << format("%02d : [%_9d] \n") % 4 % Rational(8,1234);
163 // "04 : [8 / 1234]"
164
165 cout << format("%02d : [%_9d] \n") % 5 % Rational(1234,8);
166 // "05 : [1234 / 8]"
167
168 cout << format("%02d : [%09d] \n") % 6 % Rational(8,1234);
169 // "06 : [0008 / 1234]"
170
171 cout << format("%02d : [%0+9d] \n") % 7 % Rational(1234,8);
172 // "07 : [+1234 / 008]"
173
174 cout << format("%02d : [%0+9d] \n") % 8 % Rational(7,12345);
175 // "08 : [+07 / 12345]"
176
177
178 cerr << "\n\nEverything went OK, exiting. \n";
179 return 0;
180}
181

source code of boost/libs/format/example/sample_userType.cpp