#ifndef BOOST_DATE_TIME_STRING_PARSE_TREE___HPP__
#define BOOST_DATE_TIME_STRING_PARSE_TREE___HPP__
/* Copyright (c) 2004-2005 CrystalClear Software, Inc.
* Use, modification and distribution is subject to the
* Boost Software License, Version 1.0. (See accompanying
* file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
* Author: Jeff Garland, Bart Garst
* $Date: 2008-11-12 14:37:53 -0500 (Wed, 12 Nov 2008) $
*/
#include "boost/lexical_cast.hpp" //error without?
#include "boost/algorithm/string/case_conv.hpp"
#include <map>
#include <string>
#include <vector>
#include <algorithm>
namespace boost { namespace date_time {
template<typename charT>
struct parse_match_result
{
parse_match_result() :
match_depth(0),
current_match(-1)// -1 is match_not-found value
{}
typedef std::basic_string<charT> string_type;
string_type remaining() const
{
if (match_depth == cache.size()) {
return string_type();
}
if (current_match == -1) {
return cache;
}
//some of the cache was used return the rest
return string_type(cache, match_depth);
}
charT last_char() const
{
return cache[cache.size()-1];
}
//! Returns true if more characters were parsed than was necessary
/*! Should be used in conjunction with last_char()
* to get the remaining character.
*/
bool has_remaining() const
{
return (cache.size() > match_depth);
}
// cache will hold characters that have been read from the stream
string_type cache;
unsigned short match_depth;
short current_match;
enum PARSE_STATE { PARSE_ERROR= -1 };
};
//for debug -- really only char streams...
template<typename charT>
std::basic_ostream<charT>&
operator<<(std::basic_ostream<charT>& os, parse_match_result<charT>& mr)
{
os << "cm: " << mr.current_match
<< " C: '" << mr.cache
<< "' md: " << mr.match_depth
<< " R: " << mr.remaining();
return os;
}
//! Recursive data structure to allow efficient parsing of various strings
/*! This class provides a quick lookup by building what amounts to a
* tree data structure. It also features a match function which can
* can handle nasty input interators by caching values as it recurses
* the tree so that it can backtrack as needed.
*/
template<typename charT>
struct string_parse_tree
{
#if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581) )
typedef std::multimap<charT, string_parse_tree< charT> > ptree_coll;
#else
typedef std::multimap<charT, string_parse_tree > ptree_coll;
#endif
typedef typename ptree_coll::value_type value_type;
typedef typename ptree_coll::iterator iterator;
typedef typename ptree_coll::const_iterator const_iterator;
typedef std::basic_string<charT> string_type;
typedef std::vector<std::basic_string<charT> > collection_type;
typedef parse_match_result<charT> parse_match_result_type;
/*! Parameter "starting_point" designates where the numbering begins.
* A starting_point of zero will start the numbering at zero
* (Sun=0, Mon=1, ...) were a starting_point of one starts the
* numbering at one (Jan=1, Feb=2, ...). The default is zero,
* negative vaules are not allowed */
string_parse_tree(collection_type names, unsigned int starting_point=0)
{
// iterate thru all the elements and build the tree
unsigned short index = 0;
while (index != names.size() ) {
string_type s = boost::algorithm::to_lower_copy(names[index]);
insert(s, static_cast<unsigned short>(index + starting_point));
index++;
}
//set the last tree node = index+1 indicating a value
index++;
}
string_parse_tree(short value = -1) :
m_value(value)
{}
ptree_coll m_next_chars;
short m_value;
void insert(const string_type& s, unsigned short value)
{
unsigned int i = 0;
iterator ti;
while(i < s.size()) {
if (i==0) {
if (i == (s.size()-1)) {
ti = m_next_chars.insert(value_type(s[i],
string_parse_tree<charT>(value)));
}
else {
ti = m_next_chars.insert(value_type(s[i],
string_parse_tree<charT>()));
}
}
else {
if (i == (s.size()-1)) {
ti = ti->second.m_next_chars.insert(value_type(s[i],
string_parse_tree<charT>(value)));
}
else {
ti = ti->second.m_next_chars.insert(value_type(s[i],
string_parse_tree<charT>()));
}
}
i++;
}
}
//! Recursive function that finds a matching string in the tree.
/*! Must check match_results::has_remaining() after match() is
* called. This is required so the user can determine if
* stream iterator is already pointing to the expected
* character or not (match() might advance sitr to next char in stream).
*
* A parse_match_result that has been returned from a failed match
* attempt can be sent in to the match function of a different
* string_parse_tree to attempt a match there. Use the iterators
* for the partially consumed stream, the parse_match_result object,
* and '0' for the level parameter. */
short
match(std::istreambuf_iterator<charT>& sitr,
std::istreambuf_iterator<charT>& stream_end,
parse_match_result_type& result,
unsigned int& level) const
{
level++;
charT c;
// if we conditionally advance sitr, we won't have
// to consume the next character past the input
bool adv_itr = true;
if (level > result.cache.size()) {
if (sitr == stream_end) return 0; //bail - input exhausted
c = static_cast<charT>(std::tolower(*sitr));
//result.cache += c;
//sitr++;
}
else {
// if we're looking for characters from the cache,
// we don't want to increment sitr
adv_itr = false;
c = static_cast<charT>(std::tolower(result.cache[level-1]));
}
const_iterator litr = m_next_chars.lower_bound(c);
const_iterator uitr = m_next_chars.upper_bound(c);
while (litr != uitr) { // equal if not found
if(adv_itr) {
sitr++;
result.cache += c;
}
if (litr->second.m_value != -1) { // -1 is default value
if (result.match_depth < level) {
result.current_match = litr->second.m_value;
result.match_depth = static_cast<unsigned short>(level);
}
litr->second.match(sitr, stream_end,
result, level);
level--;
}
else {
litr->second.match(sitr, stream_end,
result, level);
level--;
}
if(level <= result.cache.size()) {
adv_itr = false;
}
litr++;
}
return result.current_match;
}
/*! Must check match_results::has_remaining() after match() is
* called. This is required so the user can determine if
* stream iterator is already pointing to the expected
* character or not (match() might advance sitr to next char in stream).
*/
parse_match_result_type
match(std::istreambuf_iterator<charT>& sitr,
std::istreambuf_iterator<charT>& stream_end) const
{
// lookup to_lower of char in tree.
unsigned int level = 0;
// string_type cache;
parse_match_result_type result;
match(sitr, stream_end, result, level);
return result;
}
void printme(std::ostream& os, int& level)
{
level++;
iterator itr = m_next_chars.begin();
iterator end = m_next_chars.end();
// os << "starting level: " << level << std::endl;
while (itr != end) {
os << "level: " << level
<< " node: " << itr->first
<< " value: " << itr->second.m_value
<< std::endl;
itr->second.printme(os, level);
itr++;
}
level--;
}
void print(std::ostream& os)
{
int level = 0;
printme(os, level);
}
void printmatch(std::ostream& os, charT c)
{
iterator litr = m_next_chars.lower_bound(c);
iterator uitr = m_next_chars.upper_bound(c);
os << "matches for: " << c << std::endl;
while (litr != uitr) {
os << " node: " << litr->first
<< " value: " << litr->second.m_value
<< std::endl;
litr++;
}
}
};
} } //namespace
#endif
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