Difference between revisions of "cpp/regex/match results"
m (patrial undo: back to std::pmr, but accepting BidirIt since that's whats listed under type requirements lower) |
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| Line 11: | Line 11: | ||
{{dcl|num=2|since=c++17|1= | {{dcl|num=2|since=c++17|1= | ||
namespace pmr { | namespace pmr { | ||
| − | template <class | + | template <class > |
using match_results = std::match_results<BidirIt, | using match_results = std::match_results<BidirIt, | ||
| − | + | std::polymorphic_allocator< | |
| + | std::sub_match<BidirIt>>>; | ||
} | } | ||
}} | }} | ||
| Line 55: | Line 56: | ||
{{dsc | {{tt|const_reference}} | {{c|const value_type&}}}} | {{dsc | {{tt|const_reference}} | {{c|const value_type&}}}} | ||
{{dsc | {{tt|reference}} | {{c|value_type&}}}} | {{dsc | {{tt|reference}} | {{c|value_type&}}}} | ||
| − | {{dsc | {{tt|const_iterator}} | | + | {{dsc | {{tt|const_iterator}} | depends on the underlying container}} |
{{dsc | {{tt|iterator}} | {{c|const_iterator}}}} | {{dsc | {{tt|iterator}} | {{c|const_iterator}}}} | ||
{{dsc | {{tt|difference_type}} | {{c|std::iterator_traits<BidirIt>::difference_type}}}} | {{dsc | {{tt|difference_type}} | {{c|std::iterator_traits<BidirIt>::difference_type}}}} | ||
Revision as of 14:18, 27 January 2017
| Defined in header <regex>
|
||
| template< class BidirIt, |
(1) | (since C++11) |
| namespace pmr { template <class BidirIt> |
(2) | (since C++17) |
The class template std::match_results holds a collection of character sequences that represent the result of a regular expression match.
This is a specialized allocator-aware container. It can only be default created, obtained from std::regex_iterator, or modified by std::regex_search or std::regex_match. Because std::match_results holds std::sub_matches, each of which is a pair of iterators into the original character sequence that was matched, it's undefined behavior to examine std::match_results if the original character sequence was destroyed or iterators to it were invalidated for other reasons.
The first sub_match (index 0) contained in a match_result always represents the full match within a target sequence made by a regex, and subsequent sub_matches represent sub-expression matches corresponding in sequence to the left parenthesis delimiting the sub-expression in the regex.
std::match_results meets the requirements of a constant Template:concept and of a constant Template:concept, except that the semantics of comparison functions are different from those required for a container.
Contents |
Type requirements
Specializations
Several specializations for common character sequence types are provided:
| Defined in header
<regex> | |
| Type | Definition |
std::cmatch
|
std::match_results<const char*> |
std::wcmatch
|
std::match_results<const wchar_t*> |
std::smatch
|
std::match_results<std::string::const_iterator> |
std::wsmatch
|
std::match_results<std::wstring::const_iterator> |
std::pmr::cmatch (C++17)
|
std::pmr::match_results<const char*> |
std::pmr::wcmatch (C++17)
|
std::pmr::match_results<const wchar_t*> |
std::pmr::smatch (C++17)
|
std::pmr::match_results<std::string::const_iterator> |
std::pmr::wsmatch (C++17)
|
std::pmr::match_results<std::wstring::const_iterator> |
Member types
| Member type | Definition |
allocator_type
|
Allocator |
value_type
|
std::sub_match<BidirIt> |
const_reference
|
const value_type& |
reference
|
value_type& |
const_iterator
|
implementation defined (depends on the underlying container) |
iterator
|
const_iterator |
difference_type
|
std::iterator_traits<BidirIt>::difference_type |
size_type
|
std::allocator_traits<Alloc>::size_type |
char_type
|
std::iterator_traits<BidirIt>::value_type |
string_type
|
std::basic_string<char_type> |
Member functions
| constructs the object (public member function) | |
| destructs the object (public member function) | |
| assigns the contents (public member function) | |
| returns the associated allocator (public member function) | |
State | |
| checks if the results are available (public member function) | |
Size | |
| checks whether the match was successful (public member function) | |
| returns the number of matches in a fully-established result state (public member function) | |
| returns the maximum possible number of sub-matches (public member function) | |
Element access | |
| returns the length of the particular sub-match (public member function) | |
| returns the position of the first character of the particular sub-match (public member function) | |
| returns the sequence of characters for the particular sub-match (public member function) | |
| returns specified sub-match (public member function) | |
| returns sub-sequence between the beginning of the target sequence and the beginning of the full match (public member function) | |
| returns sub-sequence between the end of the full match and the end of the target sequence (public member function) | |
Iterators | |
| returns iterator to the beginning of the list of sub-matches (public member function) | |
| returns iterator to the end of the list of sub-matches (public member function) | |
Format | |
| formats match results for output (public member function) | |
Modifiers | |
| swaps the contents (public member function) | |
Non-member functions
| (removed in C++20) |
lexicographically compares the values in the two match result (function template) |
| specializes the std::swap algorithm (function template) |
