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
19namespace 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"
52 special_values_parser()
53 {
54 sv_strings(nadt_str: string_type(nadt_string),
55 neg_inf_str: string_type(neg_inf_string),
56 pos_inf_str: string_type(pos_inf_string),
57 min_dt_str: string_type(min_date_time_string),
58 max_dt_str: string_type(max_date_time_string));
59 }
60
61 //! Creates a special_values_parser using a user defined set of element strings
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
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
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
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
125 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

source code of include/boost/date_time/special_values_parser.hpp