1 | #ifndef BOOST_DATE_TIME_STRING_PARSE_TREE___HPP__
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2 | #define BOOST_DATE_TIME_STRING_PARSE_TREE___HPP__
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3 |
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4 | /* Copyright (c) 2004-2005 CrystalClear Software, Inc.
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5 | * Use, modification and distribution is subject to the
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6 | * Boost Software License, Version 1.0. (See accompanying
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7 | * file LICENSE-1.0 or http://www.boost.org/LICENSE-1.0)
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8 | * Author: Jeff Garland, Bart Garst
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9 | * $Date: 2005/07/01 02:58:57 $
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10 | */
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11 |
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12 |
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13 | #include "boost/lexical_cast.hpp" //error without?
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14 | #include "boost/algorithm/string/case_conv.hpp"
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15 | #include <map>
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16 | #include <string>
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17 | #include <vector>
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18 | #include <algorithm>
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19 |
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20 | namespace boost { namespace date_time {
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21 |
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22 |
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23 | template<typename charT>
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24 | struct parse_match_result
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25 | {
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26 | parse_match_result() :
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27 | match_depth(0),
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28 | current_match(-1)// -1 is match_not-found value
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29 | {}
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30 | typedef std::basic_string<charT> string_type;
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31 | string_type remaining() const
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32 | {
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33 | if (match_depth == cache.size()) {
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34 | return string_type();
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35 | }
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36 | if (current_match == -1) {
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37 | return cache;
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38 | }
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39 | //some of the cache was used return the rest
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40 | return string_type(cache, match_depth);
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41 | }
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42 | charT last_char() const
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43 | {
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44 | return cache[cache.size()-1];
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45 | }
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46 | //! Returns true if more characters were parsed than was necessary
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47 | /*! Should be used in conjunction with last_char()
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48 | * to get the remaining character. */
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49 | bool has_remaining() const
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50 | {
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51 | return (cache.size() > match_depth);
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52 | }
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53 |
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54 | // cache will hold characters that have been read from the stream
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55 | string_type cache;
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56 | unsigned short match_depth;
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57 | short current_match;
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58 | static const short PARSE_ERROR;
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59 | };
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60 | template<typename charT>
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61 | const short parse_match_result<charT>::PARSE_ERROR = -1;
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62 |
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63 | //for debug -- really only char streams...
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64 | template<typename charT>
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65 | std::basic_ostream<charT>&
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66 | operator<<(std::basic_ostream<charT>& os, parse_match_result<charT>& mr)
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67 | {
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68 | os << "cm: " << mr.current_match
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69 | << " C: '" << mr.cache
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70 | << "' md: " << mr.match_depth
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71 | << " R: " << mr.remaining();
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72 | return os;
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73 | }
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74 |
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75 |
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76 |
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77 | //! Recursive data structure to allow efficient parsing of various strings
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78 | /*! This class provides a quick lookup by building what amounts to a
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79 | * tree data structure. It also features a match function which can
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80 | * can handle nasty input interators by caching values as it recurses
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81 | * the tree so that it can backtrack as needed.
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82 | */
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83 | template<typename charT>
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84 | struct string_parse_tree
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85 | {
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86 | typedef std::multimap<charT, string_parse_tree> ptree_coll;
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87 | typedef typename ptree_coll::value_type value_type;
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88 | typedef typename ptree_coll::iterator iterator;
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89 | typedef typename ptree_coll::const_iterator const_iterator;
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90 | typedef std::basic_string<charT> string_type;
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91 | typedef std::vector<std::basic_string<charT> > collection_type;
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92 | typedef parse_match_result<charT> parse_match_result_type;
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93 |
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94 | /*! Parameter "starting_point" desingates where the numbering begins.
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95 | * A starting_point of zero will start the numbering at zero
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96 | * (Sun=0, Mon=1, ...) were a starting_point of one starts the
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97 | * numbering at one (Jan=1, Feb=2, ...). The default is zero,
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98 | * negative vaules are not allowed */
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99 | string_parse_tree(collection_type names, unsigned int starting_point=0)
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100 | {
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101 | // iterate thru all the elements and build the tree
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102 | unsigned short index = 0;
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103 | while (index != names.size() ) {
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104 | string_type s = boost::algorithm::to_lower_copy(names[index]);
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105 | insert(s, static_cast<unsigned short>(index + starting_point));
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106 | index++;
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107 | }
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108 | //set the last tree node = index+1 indicating a value
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109 | index++;
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110 | }
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111 |
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112 |
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113 | string_parse_tree(short value = -1) :
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114 | m_value(value)
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115 | {}
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116 | ptree_coll m_next_chars;
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117 | short m_value;
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118 |
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119 | void insert(const string_type& s, unsigned short value)
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120 | {
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121 | unsigned int i = 0;
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122 | iterator ti;
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123 | while(i < s.size()) {
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124 | if (i==0) {
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125 | if (i == (s.size()-1)) {
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126 | ti = m_next_chars.insert(value_type(s[i],
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127 | string_parse_tree<charT>(value)));
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128 | }
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129 | else {
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130 | ti = m_next_chars.insert(value_type(s[i],
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131 | string_parse_tree<charT>()));
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132 | }
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133 | }
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134 | else {
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135 | if (i == (s.size()-1)) {
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136 | ti = ti->second.m_next_chars.insert(value_type(s[i],
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137 | string_parse_tree<charT>(value)));
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138 | }
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139 |
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140 | else {
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141 | ti = ti->second.m_next_chars.insert(value_type(s[i],
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142 | string_parse_tree<charT>()));
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143 | }
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144 |
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145 | }
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146 | i++;
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147 | }
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148 | }
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149 |
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150 |
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151 | //! Recursive function that finds a matching string in the tree.
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152 | /*! Must check match_results::has_remaining() after match() is
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153 | * called. This is required so the user can determine if
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154 | * stream iterator is already pointing to the expected
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155 | * character or not (match() might advance sitr to next char in stream).
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156 | *
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157 | * A parse_match_result that has been returned from a failed match
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158 | * attempt can be sent in to the match function of a different
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159 | * string_parse_tree to attempt a match there. Use the iterators
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160 | * for the partially consumed stream, the parse_match_result object,
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161 | * and '0' for the level parameter. */
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162 | short
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163 | match(std::istreambuf_iterator<charT>& sitr,
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164 | std::istreambuf_iterator<charT>& stream_end,
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165 | parse_match_result_type& result,
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166 | unsigned int& level) const
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167 | {
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168 |
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169 | level++;
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170 | charT c;
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171 | // if we conditionally advance sitr, we won't have
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172 | // to consume the next character past the input
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173 | bool adv_itr = true;
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174 | if (level > result.cache.size()) {
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175 | if (sitr == stream_end) return 0; //bail - input exhausted
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176 | c = static_cast<charT>(std::tolower(*sitr));
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177 | //result.cache += c;
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178 | //sitr++;
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179 | }
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180 | else {
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181 | // if we're looking for characters from the cache,
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182 | // we don't want to increment sitr
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183 | adv_itr = false;
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184 | c = static_cast<charT>(std::tolower(result.cache[level-1]));
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185 | }
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186 | const_iterator litr = m_next_chars.lower_bound(c);
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187 | const_iterator uitr = m_next_chars.upper_bound(c);
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188 | while (litr != uitr) { // equal if not found
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189 | if(adv_itr) {
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190 | sitr++;
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191 | result.cache += c;
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192 | }
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193 | if (litr->second.m_value != -1) { // -1 is default value
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194 | if (result.match_depth < level) {
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195 | result.current_match = litr->second.m_value;
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196 | result.match_depth = static_cast<unsigned short>(level);
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197 | }
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198 | litr->second.match(sitr, stream_end,
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199 | result, level);
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200 | level--;
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201 | }
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202 | else {
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203 | litr->second.match(sitr, stream_end,
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204 | result, level);
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205 | level--;
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206 | }
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207 |
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208 | if(level <= result.cache.size()) {
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209 | adv_itr = false;
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210 | }
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211 |
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212 | litr++;
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213 | }
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214 | return result.current_match;
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215 |
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216 | }
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217 |
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218 | /*! Must check match_results::has_remaining() after match() is
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219 | * called. This is required so the user can determine if
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220 | * stream iterator is already pointing to the expected
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221 | * character or not (match() might advance sitr to next char in stream).
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222 | */
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223 | parse_match_result_type
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224 | match(std::istreambuf_iterator<charT>& sitr,
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225 | std::istreambuf_iterator<charT>& stream_end) const
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226 | {
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227 | // lookup to_lower of char in tree.
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228 | unsigned int level = 0;
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229 | // string_type cache;
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230 | parse_match_result_type result;
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231 | match(sitr, stream_end, result, level);
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232 | return result;
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233 | }
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234 |
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235 | void printme(std::ostream& os, int& level)
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236 | {
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237 | level++;
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238 | iterator itr = m_next_chars.begin();
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239 | iterator end = m_next_chars.end();
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240 | // os << "starting level: " << level << std::endl;
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241 | while (itr != end) {
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242 | os << "level: " << level
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243 | << " node: " << itr->first
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244 | << " value: " << itr->second.m_value
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245 | << std::endl;
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246 | itr->second.printme(os, level);
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247 | itr++;
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248 | }
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249 | level--;
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250 | }
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251 |
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252 | void print(std::ostream& os)
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253 | {
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254 | int level = 0;
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255 | printme(os, level);
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256 | }
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257 |
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258 | void printmatch(std::ostream& os, charT c)
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259 | {
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260 | iterator litr = m_next_chars.lower_bound(c);
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261 | iterator uitr = m_next_chars.upper_bound(c);
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262 | os << "matches for: " << c << std::endl;
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263 | while (litr != uitr) {
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264 | os << " node: " << litr->first
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265 | << " value: " << litr->second.m_value
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266 | << std::endl;
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267 | litr++;
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268 | }
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269 | }
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270 |
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271 | };
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272 |
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273 |
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274 | } } //namespace
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275 | #endif
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