1 2 #ifndef DATE_TIME_SPECIAL_VALUES_PARSER_HPP__ 3 #define DATE_TIME_SPECIAL_VALUES_PARSER_HPP__ 4 5 /* Copyright (c) 2005 CrystalClear Software, Inc. 6 * Use, modification and distribution is subject to the 7 * Boost Software License, Version 1.0. (See accompanying 8 * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) 9 * Author: Jeff Garland, Bart Garst 10 * $Date: 11 */ 12 13 14 #include "boost/date_time/string_parse_tree.hpp" 15 #include "boost/date_time/special_defs.hpp" 16 #include <string> 17 #include <vector> 18 19 namespace boost { namespace date_time { 20 21 //! Class for special_value parsing 22 /*! 23 * TODO: add doc-comments for which elements can be changed 24 * Parses input stream for strings representing special_values. 25 * Special values parsed are: 26 * - not_a_date_time 27 * - neg_infin 28 * - pod_infin 29 * - min_date_time 30 * - max_date_time 31 */ 32 template<class date_type, typename charT> 33 class special_values_parser 34 { 35 public: 36 typedef std::basic_string<charT> string_type; 37 typedef std::basic_stringstream<charT> stringstream_type; 38 typedef std::istreambuf_iterator<charT> stream_itr_type; 39 typedef typename date_type::duration_type duration_type; 40 typedef string_parse_tree<charT> parse_tree_type; 41 typedef typename parse_tree_type::parse_match_result_type match_results; 42 typedef std::vector<std::basic_string<charT> > collection_type; 43 44 typedef charT char_type; 45 static const char_type nadt_string[16]; 46 static const char_type neg_inf_string[10]; 47 static const char_type pos_inf_string[10]; 48 static const char_type min_date_time_string[18]; 49 static const char_type max_date_time_string[18]; 50 51 //! Creates a special_values_parser with the default set of "sv_strings" special_values_parser()52 special_values_parser() 53 { 54 sv_strings(string_type(nadt_string), 55 string_type(neg_inf_string), 56 string_type(pos_inf_string), 57 string_type(min_date_time_string), 58 string_type(max_date_time_string)); 59 } 60 61 //! Creates a special_values_parser using a user defined set of element strings special_values_parser(const string_type & nadt_str,const string_type & neg_inf_str,const string_type & pos_inf_str,const string_type & min_dt_str,const string_type & max_dt_str)62 special_values_parser(const string_type& nadt_str, 63 const string_type& neg_inf_str, 64 const string_type& pos_inf_str, 65 const string_type& min_dt_str, 66 const string_type& max_dt_str) 67 { 68 sv_strings(nadt_str, neg_inf_str, pos_inf_str, min_dt_str, max_dt_str); 69 } 70 special_values_parser(typename collection_type::iterator beg,typename collection_type::iterator end)71 special_values_parser(typename collection_type::iterator beg, typename collection_type::iterator end) 72 { 73 collection_type phrases; 74 std::copy(beg, end, std::back_inserter(phrases)); 75 m_sv_strings = parse_tree_type(phrases, static_cast<int>(not_a_date_time)); 76 } 77 78 //! Replace special value strings sv_strings(const string_type & nadt_str,const string_type & neg_inf_str,const string_type & pos_inf_str,const string_type & min_dt_str,const string_type & max_dt_str)79 void sv_strings(const string_type& nadt_str, 80 const string_type& neg_inf_str, 81 const string_type& pos_inf_str, 82 const string_type& min_dt_str, 83 const string_type& max_dt_str) 84 { 85 collection_type phrases; 86 phrases.push_back(nadt_str); 87 phrases.push_back(neg_inf_str); 88 phrases.push_back(pos_inf_str); 89 phrases.push_back(min_dt_str); 90 phrases.push_back(max_dt_str); 91 m_sv_strings = parse_tree_type(phrases, static_cast<int>(not_a_date_time)); 92 } 93 94 //! The parser is expensive to create, and not thread-safe so it cannot be static 95 //! therefore given a string, determine if it is likely to be a special value. 96 //! A negative response is a definite no, whereas a positive is only likely and 97 //! match() should be called and return value checked. 98 //! \param[in] str the string to check 99 //! \returns false if it is definitely not a special value likely(const string_type & str)100 static bool likely(const string_type& str) 101 { 102 if (!str.empty()) { 103 switch (str[0]) { 104 // See string definitions at the end of this class.. 105 case '+': 106 case '-': 107 case 'n': 108 case 'm': 109 return true; 110 111 default: 112 break; 113 } 114 } 115 116 return false; 117 } 118 119 //! Given an input iterator, attempt to match it to a known special value 120 //! \param[in] sitr the start iterator 121 //! \param[in] str_end the end iterator 122 //! \param[out] mr the match result: 123 //! mr.current_match is set to the corresponding special_value or -1 124 //! \returns whether something matched match(stream_itr_type & sitr,stream_itr_type & str_end,match_results & mr) const125 bool match(stream_itr_type& sitr, 126 stream_itr_type& str_end, 127 match_results& mr) const 128 { 129 unsigned int level = 0; 130 m_sv_strings.match(sitr, str_end, mr, level); 131 return (mr.current_match != match_results::PARSE_ERROR); 132 } 133 134 private: 135 parse_tree_type m_sv_strings; 136 137 }; 138 139 template<class date_type, class CharT> 140 const typename special_values_parser<date_type, CharT>::char_type 141 special_values_parser<date_type, CharT>::nadt_string[16] = 142 {'n','o','t','-','a','-','d','a','t','e','-','t','i','m','e'}; 143 template<class date_type, class CharT> 144 const typename special_values_parser<date_type, CharT>::char_type 145 special_values_parser<date_type, CharT>::neg_inf_string[10] = 146 {'-','i','n','f','i','n','i','t','y'}; 147 template<class date_type, class CharT> 148 const typename special_values_parser<date_type, CharT>::char_type 149 special_values_parser<date_type, CharT>::pos_inf_string[10] = 150 {'+','i','n','f','i','n','i','t','y'}; 151 template<class date_type, class CharT> 152 const typename special_values_parser<date_type, CharT>::char_type 153 special_values_parser<date_type, CharT>::min_date_time_string[18] = 154 {'m','i','n','i','m','u','m','-','d','a','t','e','-','t','i','m','e'}; 155 template<class date_type, class CharT> 156 const typename special_values_parser<date_type, CharT>::char_type 157 special_values_parser<date_type, CharT>::max_date_time_string[18] = 158 {'m','a','x','i','m','u','m','-','d','a','t','e','-','t','i','m','e'}; 159 160 } } //namespace 161 162 #endif // DATE_TIME_SPECIAL_VALUES_PARSER_HPP__ 163 164