external/bsd/kyua-cli/dist/utils/format/formatter.hpp

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  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
  52 namespace utils {
  53 namespace 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
  77 class 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
 105 public:
 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)