1// Copyright 2010 Google Inc. 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 <sstream> 50#include <string> 51 52namespace utils { 53namespace format { 54 55 56/// Mechanism to format strings similar to printf. 57/// 58/// A formatter always maintains the original format string but also holds a 59/// partial expansion. The partial expansion is immutable in the context of a 60/// formatter instance, but calls to operator% return new formatter objects with 61/// one less formatting placeholder. 62/// 63/// In general, one can format a string in the following manner: 64/// 65/// \code 66/// const std::string s = (formatter("%s %s") % "foo" % 5).str(); 67/// \endcode 68/// 69/// which, following the explanation above, would correspond to: 70/// 71/// \code 72/// const formatter f1("%s %s"); 73/// const formatter f2 = f1 % "foo"; 74/// const formatter f3 = f2 % 5; 75/// const std::string s = f3.str(); 76/// \endcode 77class formatter { 78 /// The original format string provided by the user. 79 std::string _format; 80 81 /// The current "expansion" of the format string. 82 /// 83 /// This field gets updated on every call to operator%() to have one less 84 /// formatting placeholder. 85 std::string _expansion; 86 87 /// The position of _expansion from which to scan for placeholders. 88 std::string::size_type _last_pos; 89 90 /// The position of the first placeholder in the current expansion. 91 std::string::size_type _placeholder_pos; 92 93 /// The first placeholder in the current expansion. 94 std::string _placeholder; 95 96 /// Stream used to format any possible argument supplied by operator%(). 97 std::ostringstream* _oss; 98 99 formatter replace(const std::string&) const; 100 101 void init(void); 102 formatter(const std::string&, const std::string&, 103 const std::string::size_type); 104 105public: 106 explicit formatter(const std::string&); 107 ~formatter(void); 108 109 const std::string& str(void) const; 110 operator const std::string&(void) const; 111 112 template< typename Type > formatter operator%(const Type&) const; 113 formatter operator%(const bool&) const; 114}; 115 116 117} // namespace format 118} // namespace utils 119 120 121#endif // !defined(UTILS_FORMAT_FORMATTER_HPP) 122