31 Regular expressions library [re]

31.11 Regular expression algorithms [re.alg]

31.11.3 regex_­search [re.alg.search]

template <class BidirectionalIterator, class Allocator, class charT, class traits> bool regex_search(BidirectionalIterator first, BidirectionalIterator last, match_results<BidirectionalIterator, Allocator>& m, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
Requires: Type BidirectionalIterator shall satisfy the requirements of a Bidirectional Iterator.
Effects: Determines whether there is some sub-sequence within [first, last) that matches the regular expression e.
The parameter flags is used to control how the expression is matched against the character sequence.
Returns true if such a sequence exists, false otherwise.
Postconditions: m.ready() == true in all cases.
If the function returns false, then the effect on parameter m is unspecified except that m.size() returns 0 and m.empty() returns true.
Otherwise the effects on parameter m are given in Table 136.
Table 136 — Effects of regex_­search algorithm
Element
Value
m.size()
1 + e.mark_­count()
m.empty()
false
m.prefix().first
first
m.prefix().second
m[0].first
m.prefix().matched
m.prefix().first != m.prefix().second
m.suffix().first
m[0].second
m.suffix().second
last
m.suffix().matched
m.suffix().first != m.suffix().second
m[0].first
The start of the sequence of characters that matched the regular expression
m[0].second
The end of the sequence of characters that matched the regular expression
m[0].matched
true
m[n].first
For all integers 0 < n < m.size(), the start of the sequence that matched sub-expression n.
Alternatively, if sub-expression n did not participate in the match, then last.
m[n].second
For all integers 0 < n < m.size(), the end of the sequence that matched sub-expression n.
Alternatively, if sub-expression n did not participate in the match, then last .
m[n].matched
For all integers 0 < n < m.size(), true if sub-expression n participated in the match, false otherwise.
template <class charT, class Allocator, class traits> bool regex_search(const charT* str, match_results<const charT*, Allocator>& m, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
Returns: regex_­search(str, str + char_­traits<charT>​::​length(str), m, e, flags).
template <class ST, class SA, class Allocator, class charT, class traits> bool regex_search(const basic_string<charT, ST, SA>& s, match_results<typename basic_string<charT, ST, SA>::const_iterator, Allocator>& m, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
Returns: regex_­search(s.begin(), s.end(), m, e, flags).
template <class BidirectionalIterator, class charT, class traits> bool regex_search(BidirectionalIterator first, BidirectionalIterator last, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
Effects: Behaves “as if” by constructing an object what of type match_­results<BidirectionalIterator> and returning regex_­search(first, last, what, e, flags).
template <class charT, class traits> bool regex_search(const charT* str, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
Returns: regex_­search(str, str + char_­traits<charT>​::​length(str), e, flags).
template <class ST, class SA, class charT, class traits> bool regex_search(const basic_string<charT, ST, SA>& s, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
Returns: regex_­search(s.begin(), s.end(), e, flags).