std::sub_match<BidirIt>::swap
From cppreference.com
void swap( sub_match& s ) noexcept(/* see below */);
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(since C++11) | |
Exchanges the contents of two sub-match objects. Equivalent to
this->pair<BidirIt, BidirIt>::swap(s);std::swap(matched, s.matched);
Parameters
| s | - | a sub_match to swap with
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| Type requirements | ||
-BidirIt must meet the requirements of LegacySwappable.
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Exceptions
noexcept specification:
noexcept(std::is_nothrow_swappable_v<BidirIt>)
Example
Run this code
#include <cassert>
#include <iostream>
#include <regex>
int main()
{
const char* s = "Quick red cat";
std::sub_match<const char*> x, y;
x.first = &s[0];
x.second = &s[5];
x.matched = false;
y.first = &s[012];
y.second = &s[13];
y.matched = true;
std::cout << "Before swap:\n";
std::cout << "x.str() = [" << x.str() << "]\n";
std::cout << "y.str() = [" << y.str() << "]\n";
assert(!x.matched and y.matched);
x.swap(y);
std::cout << "After swap:\n";
std::cout << "x.str() = [" << x.str() << "]\n";
std::cout << "y.str() = [" << y.str() << "]\n";
assert(x.matched and !y.matched);
}
Output:
Before swap:
x.str() = []
y.str() = [cat]
After swap:
x.str() = [cat]
y.str() = []
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 3204 | C++11 | std::sub_match used inherited std::pair::swap(pair&)which led to a slicing |
std::sub_match::swap(sub_match&) is added
|