std::regex_token_iterator
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<tbody> </tbody> template< class BidirIt, class CharT = typename std::iterator_traits<BidirIt>::value_type, class Traits = std::regex_traits<CharT> > class regex_token_iterator |
( C++11) | |
std::regex_token_iterator ForwardIterator, - . , (, Tokenizer).:
std::regex_token_iterator is a read-only ForwardIterator that accesses the individual sub-matches of every match of a regular expression within the underlying character sequence. It can also be used to access the parts of the sequence that were not matched by the given regular expression (e.g. as a tokenizer). , std::regex_iterator match_results, regex_iterator, .
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On construction, it constructs an std::regex_iterator and on every increment it steps through the requested sub-matches from the current match_results, incrementing the underlying regex_iterator when incrementing away from the last submatch.
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std::regex_token_iterator . std::regex_token_iterator , . .:
The default-constructed
std::regex_token_iterator is the end-of-sequence iterator. When a valid std::regex_token_iterator is incremented after reaching the last submatch of the last match, it becomes equal to the end-of-sequence iterator. Dereferencing or incrementing it further invokes undefined behavior., , std::regex_token_iterator ' ,
-1 ( ) . , , match_results .:
Just before becoming the end-of-sequence iterator, a std::regex_token_iterator may become a suffix iterator, if the index
-1 (non-matched fragment) appears in the list of the requested submatch indexes. Such iterator, if dereferenced, returns a match_results corresponding to the sequence of characters between the last match and the end of sequence.std::regex_token_iterator std::regex_iterator, (, std::vector<int>) , , , std::match_results, , std::match_results , ( Tokenizer ).:
A typical implementation of
std::regex_token_iterator holds the underlying std::regex_iterator, a container (e.g. std::vector<int>) of the requested submatch indexes, the internal counter equal to the index of the submatch, a pointer to std::match_results, pointing at the current submatch of the current match, and a std::match_results object containing the last non-matched character sequence (used in tokenizer mode).-BidirIt BidirectionalIterator.
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<regex> | |
| Definition | |
cregex_token_iterator
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regex_token_iterator<const char*>
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wcregex_token_iterator
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regex_token_iterator<const wchar_t*>
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sregex_token_iterator
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regex_token_iterator<std::string::const_iterator>
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wsregex_token_iterator
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regex_token_iterator<std::wstring::const_iterator>
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value_type
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std::sub_match<BidirIt>
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difference_type
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std::ptrdiff_t |
pointer
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const value_type*
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reference
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const value_type&
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iterator_category
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std::forward_iterator_tag |
regex_type
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basic_regex<CharT, Traits>
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regex_token_iterator (public -) | |
() ( ) |
destructs a regex_token_iterator, including the cached value (public -) |
regex_token_iterator (public -) | |
regex_token_iterators (public -) | |
accsses (public -) | |
regex_token_iterator (public -) |
, std::basic_regex , . std::regex_iterator, , .
:
It is the programmer's responsibility to ensure that the std::basic_regex object passed to the iterator's constructor outlives the iterator. Because the iterator stores a std::regex_iterator which stores a pointer to the regex, incrementing the iterator after the regex was destroyed results in undefined behavior.
#include <fstream>
#include <iostream>
#include <algorithm>
#include <iterator>
#include <regex>
int main()
{
std::string text = "Quick brown fox.";
// tokenization (non-matched fragments)
// Note that regex is matched only two times: when the third value is obtained
// the iterator is a suffix iterator.
std::regex ws_re("\\s+"); // whitespace
std::copy( std::sregex_token_iterator(text.begin(), text.end(), ws_re, -1),
std::sregex_token_iterator(),
std::ostream_iterator<std::string>(std::cout, "\n"));
// iterating the first submatches
std::string html = "<p><a href=\"http://google.com\">google</a> "
"< a HREF =\"http://cppreference.com\">cppreference</a>\n</p>";
std::regex url_re("<\\s*A\\s+[^>]*href\\s*=\\s*\"([^\"]*)\"", std::regex::icase);
std::copy( std::sregex_token_iterator(html.begin(), html.end(), url_re, 1),
std::sregex_token_iterator(),
std::ostream_iterator<std::string>(std::cout, "\n"));
}
:
Quick
brown
fox.
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