279 lines
8.2 KiB
C++
279 lines
8.2 KiB
C++
#ifndef BOOST_DATE_TIME_STRING_PARSE_TREE___HPP__
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#define BOOST_DATE_TIME_STRING_PARSE_TREE___HPP__
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/* Copyright (c) 2004-2005 CrystalClear Software, Inc.
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* Use, modification and distribution is subject to the
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* Boost Software License, Version 1.0. (See accompanying
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* file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
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* Author: Jeff Garland, Bart Garst
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* $Date: 2008-11-12 11:37:53 -0800 (Wed, 12 Nov 2008) $
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*/
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#include "boost/lexical_cast.hpp" //error without?
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#include "boost/algorithm/string/case_conv.hpp"
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#include <map>
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#include <string>
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#include <vector>
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#include <algorithm>
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namespace boost { namespace date_time {
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template<typename charT>
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struct parse_match_result
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{
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parse_match_result() :
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match_depth(0),
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current_match(-1)// -1 is match_not-found value
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{}
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typedef std::basic_string<charT> string_type;
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string_type remaining() const
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{
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if (match_depth == cache.size()) {
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return string_type();
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}
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if (current_match == -1) {
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return cache;
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}
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//some of the cache was used return the rest
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return string_type(cache, match_depth);
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}
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charT last_char() const
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{
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return cache[cache.size()-1];
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}
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//! Returns true if more characters were parsed than was necessary
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/*! Should be used in conjunction with last_char()
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* to get the remaining character.
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*/
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bool has_remaining() const
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{
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return (cache.size() > match_depth);
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}
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// cache will hold characters that have been read from the stream
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string_type cache;
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unsigned short match_depth;
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short current_match;
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enum PARSE_STATE { PARSE_ERROR= -1 };
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};
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//for debug -- really only char streams...
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template<typename charT>
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std::basic_ostream<charT>&
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operator<<(std::basic_ostream<charT>& os, parse_match_result<charT>& mr)
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{
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os << "cm: " << mr.current_match
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<< " C: '" << mr.cache
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<< "' md: " << mr.match_depth
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<< " R: " << mr.remaining();
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return os;
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}
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//! Recursive data structure to allow efficient parsing of various strings
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/*! This class provides a quick lookup by building what amounts to a
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* tree data structure. It also features a match function which can
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* can handle nasty input interators by caching values as it recurses
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* the tree so that it can backtrack as needed.
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*/
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template<typename charT>
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struct string_parse_tree
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{
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#if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581) )
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typedef std::multimap<charT, string_parse_tree< charT> > ptree_coll;
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#else
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typedef std::multimap<charT, string_parse_tree > ptree_coll;
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#endif
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typedef typename ptree_coll::value_type value_type;
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typedef typename ptree_coll::iterator iterator;
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typedef typename ptree_coll::const_iterator const_iterator;
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typedef std::basic_string<charT> string_type;
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typedef std::vector<std::basic_string<charT> > collection_type;
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typedef parse_match_result<charT> parse_match_result_type;
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/*! Parameter "starting_point" designates where the numbering begins.
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* A starting_point of zero will start the numbering at zero
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* (Sun=0, Mon=1, ...) were a starting_point of one starts the
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* numbering at one (Jan=1, Feb=2, ...). The default is zero,
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* negative vaules are not allowed */
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string_parse_tree(collection_type names, unsigned int starting_point=0)
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{
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// iterate thru all the elements and build the tree
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unsigned short index = 0;
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while (index != names.size() ) {
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string_type s = boost::algorithm::to_lower_copy(names[index]);
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insert(s, static_cast<unsigned short>(index + starting_point));
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index++;
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}
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//set the last tree node = index+1 indicating a value
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index++;
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}
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string_parse_tree(short value = -1) :
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m_value(value)
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{}
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ptree_coll m_next_chars;
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short m_value;
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void insert(const string_type& s, unsigned short value)
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{
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unsigned int i = 0;
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iterator ti;
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while(i < s.size()) {
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if (i==0) {
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if (i == (s.size()-1)) {
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ti = m_next_chars.insert(value_type(s[i],
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string_parse_tree<charT>(value)));
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}
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else {
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ti = m_next_chars.insert(value_type(s[i],
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string_parse_tree<charT>()));
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}
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}
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else {
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if (i == (s.size()-1)) {
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ti = ti->second.m_next_chars.insert(value_type(s[i],
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string_parse_tree<charT>(value)));
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}
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else {
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ti = ti->second.m_next_chars.insert(value_type(s[i],
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string_parse_tree<charT>()));
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}
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}
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i++;
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}
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}
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//! Recursive function that finds a matching string in the tree.
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/*! Must check match_results::has_remaining() after match() is
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* called. This is required so the user can determine if
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* stream iterator is already pointing to the expected
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* character or not (match() might advance sitr to next char in stream).
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*
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* A parse_match_result that has been returned from a failed match
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* attempt can be sent in to the match function of a different
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* string_parse_tree to attempt a match there. Use the iterators
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* for the partially consumed stream, the parse_match_result object,
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* and '0' for the level parameter. */
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short
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match(std::istreambuf_iterator<charT>& sitr,
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std::istreambuf_iterator<charT>& stream_end,
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parse_match_result_type& result,
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unsigned int& level) const
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{
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level++;
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charT c;
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// if we conditionally advance sitr, we won't have
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// to consume the next character past the input
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bool adv_itr = true;
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if (level > result.cache.size()) {
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if (sitr == stream_end) return 0; //bail - input exhausted
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c = static_cast<charT>(std::tolower(*sitr));
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//result.cache += c;
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//sitr++;
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}
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else {
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// if we're looking for characters from the cache,
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// we don't want to increment sitr
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adv_itr = false;
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c = static_cast<charT>(std::tolower(result.cache[level-1]));
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}
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const_iterator litr = m_next_chars.lower_bound(c);
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const_iterator uitr = m_next_chars.upper_bound(c);
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while (litr != uitr) { // equal if not found
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if(adv_itr) {
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sitr++;
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result.cache += c;
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}
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if (litr->second.m_value != -1) { // -1 is default value
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if (result.match_depth < level) {
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result.current_match = litr->second.m_value;
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result.match_depth = static_cast<unsigned short>(level);
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}
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litr->second.match(sitr, stream_end,
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result, level);
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level--;
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}
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else {
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litr->second.match(sitr, stream_end,
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result, level);
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level--;
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}
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if(level <= result.cache.size()) {
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adv_itr = false;
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}
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litr++;
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}
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return result.current_match;
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}
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/*! Must check match_results::has_remaining() after match() is
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* called. This is required so the user can determine if
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* stream iterator is already pointing to the expected
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* character or not (match() might advance sitr to next char in stream).
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*/
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parse_match_result_type
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match(std::istreambuf_iterator<charT>& sitr,
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std::istreambuf_iterator<charT>& stream_end) const
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{
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// lookup to_lower of char in tree.
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unsigned int level = 0;
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// string_type cache;
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parse_match_result_type result;
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match(sitr, stream_end, result, level);
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return result;
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}
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void printme(std::ostream& os, int& level)
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{
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level++;
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iterator itr = m_next_chars.begin();
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iterator end = m_next_chars.end();
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// os << "starting level: " << level << std::endl;
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while (itr != end) {
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os << "level: " << level
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<< " node: " << itr->first
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<< " value: " << itr->second.m_value
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<< std::endl;
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itr->second.printme(os, level);
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itr++;
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}
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level--;
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}
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void print(std::ostream& os)
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{
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int level = 0;
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printme(os, level);
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}
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void printmatch(std::ostream& os, charT c)
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{
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iterator litr = m_next_chars.lower_bound(c);
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iterator uitr = m_next_chars.upper_bound(c);
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os << "matches for: " << c << std::endl;
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while (litr != uitr) {
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os << " node: " << litr->first
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<< " value: " << litr->second.m_value
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<< std::endl;
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litr++;
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}
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}
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};
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} } //namespace
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#endif
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