1// Copyright 2010 The Kyua Authors.
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met:
7//
8// * Redistributions of source code must retain the above copyright
9//   notice, this list of conditions and the following disclaimer.
10// * Redistributions in binary form must reproduce the above copyright
11//   notice, this list of conditions and the following disclaimer in the
12//   documentation and/or other materials provided with the distribution.
13// * Neither the name of Google Inc. nor the names of its contributors
14//   may be used to endorse or promote products derived from this software
15//   without specific prior written permission.
16//
17// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29/// \file utils/format/formatter.hpp
30/// Provides the definition of the utils::format::formatter class.
31///
32/// The utils::format::formatter class is a poor man's replacement for the
33/// Boost.Format library, as it is much simpler and has less dependencies.
34///
35/// Be aware that the formatting supported by this module is NOT compatible
36/// with printf(3) nor with Boost.Format.  The general syntax for a
37/// placeholder in a formatting string is:
38///
39///     %[0][width][.precision]s
40///
41/// In particular, note that the only valid formatting specifier is %s: the
42/// library deduces what to print based on the type of the variable passed
43/// in, not based on what the format string says.  Also, note that the only
44/// valid padding character is 0.
45
46#if !defined(UTILS_FORMAT_FORMATTER_HPP)
47#define UTILS_FORMAT_FORMATTER_HPP
48
49#include "utils/format/formatter_fwd.hpp"
50
51#include <sstream>
52#include <string>
53
54namespace utils {
55namespace format {
56
57
58/// Mechanism to format strings similar to printf.
59///
60/// A formatter always maintains the original format string but also holds a
61/// partial expansion.  The partial expansion is immutable in the context of a
62/// formatter instance, but calls to operator% return new formatter objects with
63/// one less formatting placeholder.
64///
65/// In general, one can format a string in the following manner:
66///
67/// \code
68/// const std::string s = (formatter("%s %s") % "foo" % 5).str();
69/// \endcode
70///
71/// which, following the explanation above, would correspond to:
72///
73/// \code
74/// const formatter f1("%s %s");
75/// const formatter f2 = f1 % "foo";
76/// const formatter f3 = f2 % 5;
77/// const std::string s = f3.str();
78/// \endcode
79class formatter {
80    /// The original format string provided by the user.
81    std::string _format;
82
83    /// The current "expansion" of the format string.
84    ///
85    /// This field gets updated on every call to operator%() to have one less
86    /// formatting placeholder.
87    std::string _expansion;
88
89    /// The position of _expansion from which to scan for placeholders.
90    std::string::size_type _last_pos;
91
92    /// The position of the first placeholder in the current expansion.
93    std::string::size_type _placeholder_pos;
94
95    /// The first placeholder in the current expansion.
96    std::string _placeholder;
97
98    /// Stream used to format any possible argument supplied by operator%().
99    std::ostringstream* _oss;
100
101    formatter replace(const std::string&) const;
102
103    void init(void);
104    formatter(const std::string&, const std::string&,
105              const std::string::size_type);
106
107public:
108    explicit formatter(const std::string&);
109    ~formatter(void);
110
111    const std::string& str(void) const;
112    operator const std::string&(void) const;
113
114    template< typename Type > formatter operator%(const Type&) const;
115    formatter operator%(const bool&) const;
116};
117
118
119}  // namespace format
120}  // namespace utils
121
122
123#endif  // !defined(UTILS_FORMAT_FORMATTER_HPP)
124