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std::ranges:: replace_copy, std::ranges:: replace_copy_if, std::ranges:: replace_copy_result, std::ranges:: replace_copy_if_result

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C++
Algorithm library
Constrained algorithms and algorithms on ranges (C++20)
Constrained algorithms, e.g. ranges::copy , ranges::sort , ...
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(C++17)
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(C++11)
(C++11)
(C++11)
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(until C++17) (C++11)
(C++20) (C++20)
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(C++17)

Sorting and related operations
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(on partitioned ranges)
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(C++20)
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C library
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All names in this menu belong to namespace std::ranges
Non-modifying sequence operations
Modifying sequence operations
Partitioning operations
Sorting operations
Binary search operations (on sorted ranges)
Set operations (on sorted ranges)
Heap operations
Minimum/maximum operations
Permutation operations
Fold operations
Operations on uninitialized storage
Return types
Definiert im Header <algorithm>
Aufrufsignatur
(1)
template < std:: input_iterator I, std:: sentinel_for < I > S, class T1, class T2,

std:: output_iterator < const T2 & > O, class Proj = std:: identity >
erfordert std:: indirectly_copyable < I, O > &&
std:: indirect_binary_predicate
< ranges:: equal_to , std :: projected < I, Proj > , const T1 * >
constexpr replace_copy_result < I, O >
replace_copy ( I first, S last, O result, const T1 & old_value,

const T2 & new_value, Proj proj = { } ) ;
(seit C++20)
(bis C++26)
template < std:: input_iterator I, std:: sentinel_for < I > S,

class O, class Proj = std:: identity ,
class T1 = std :: projected_value_t < I, Proj > ,
class T2 = std:: iter_value_t < O > >
erfordert std:: indirectly_copyable < I, O > &&
std:: indirect_binary_predicate
< ranges:: equal_to , std :: projected < I, Proj > , const T1 * > &&
std:: output_iterator < O, const T2 & >
constexpr replace_copy_result < I, O >
replace_copy ( I first, S last, O result, const T1 & old_value,

const T2 & new_value, Proj proj = { } ) ;
(seit C++26)
(2)
template < ranges:: input_range R, class T1, class T2,

std:: output_iterator < const T2 & > O, class Proj = std:: identity >
erfordert std:: indirectly_copyable < ranges:: iterator_t < R > , O > &&
std:: indirect_binary_predicate
< ranges:: equal_to ,
std :: projected < ranges:: iterator_t < R > , Proj > , const T1 * >
constexpr replace_copy_result < ranges:: borrowed_iterator_t < R > , O >
replace_copy ( R && r, O result, const T1 & old_value,

const T2 & new_value, Proj proj = { } ) ;
(seit C++20)
(bis C++26)
template < ranges:: input_range R,

class O, class Proj = std:: identity ,
class T1 = std :: projected_value_t < ranges:: iterator_t < R > , Proj > ,
class T2 = std:: iter_value_t < O > >
erfordert std:: indirectly_copyable < ranges:: iterator_t < R > , O > &&
std:: indirect_binary_predicate
< ranges:: equal_to ,
std :: projected < ranges:: iterator_t < R > , Proj > , const T1 * > &&
std:: output_iterator < O, const T2 & >
constexpr replace_copy_result < ranges:: borrowed_iterator_t < R > , O >
replace_copy ( R && r, O result, const T1 & old_value,

const T2 & new_value, Proj proj = { } ) ;
(seit C++26)
(3)
template < std:: input_iterator I, std:: sentinel_for < I > S,

class T, std:: output_iterator < const T & > O,
class Proj = std:: identity ,
std:: indirect_unary_predicate < std :: projected < I, Proj >> Pred >
requires std:: indirectly_copyable < I, O >
constexpr replace_copy_if_result < I, O >
replace_copy_if ( I first, S last, O result, Pred pred,

const T & new_value, Proj proj = { } ) ;
(seit C++20)
(bis C++26)
template < std:: input_iterator I, std:: sentinel_for < I > S,

class O, class T = std:: iter_value_t < O >
class Proj = std:: identity ,
std:: indirect_unary_predicate < std :: projected < I, Proj >> Pred >
requires std:: indirectly_copyable < I, O > && std:: output_iterator < O, const T & >
constexpr replace_copy_if_result < I, O >
replace_copy_if ( I first, S last, O result, Pred pred,

const T & new_value, Proj proj = { } ) ;
(seit C++26)
(4)
template < ranges:: input_range R,

class T, std:: output_iterator < const T & > O,
class Proj = std:: identity ,
std:: indirect_unary_predicate
< std :: projected < ranges:: iterator_t < R > , Proj >> Pred >
requires std:: indirectly_copyable < ranges:: iterator_t < R > , O >
constexpr replace_copy_if_result < ranges:: borrowed_iterator_t < R > , O >
replace_copy_if ( R && r, O result, Pred pred,

const T & new_value, Proj proj = { } ) ;
(seit C++20)
(bis C++26)
template < ranges:: input_range R,

class O, class T = std:: iter_value_t < O >
class Proj = std:: identity ,
std:: indirect_unary_predicate
< std :: projected < ranges:: iterator_t < R > , Proj >> Pred >
requires std:: indirectly_copyable < ranges:: iterator_t < R > , O > &&
std:: output_iterator < O, const T & >
constexpr replace_copy_if_result < ranges:: borrowed_iterator_t < R > , O >
replace_copy_if ( R && r, O result, Pred pred,

const T & new_value, Proj proj = { } ) ;
(seit C++26)
Hilfstypen
template < class I, class O >
using replace_copy_result = ranges:: in_out_result < I, O > ;
(5) (seit C++20)
template < class I, class O >
using replace_copy_if_result = ranges:: in_out_result < I, O > ;
(6) (seit C++20)

Kopiert die Elemente aus dem Quellbereich [ first , last ) in den Zielbereich beginnend bei result und ersetzt alle Elemente, die bestimmte Kriterien erfüllen, durch new_value . Das Verhalten ist undefiniert, wenn sich Quell- und Zielbereich überlappen.

1) Ersetzt alle Elemente, die gleich old_value sind, unter Verwendung von std:: invoke ( proj, * ( first + ( i - result ) ) ) == old_value für den Vergleich.
3) Ersetzt alle Elemente, für die das Prädikat pred zu true ausgewertet wird, wobei der auszuwertende Ausdruck std:: invoke ( pred, std:: invoke ( proj, * ( first + ( i - result ) ) ) ) ist.
2,4) Gleich wie (1,3) , verwendet jedoch r als Quellbereich, als ob ranges:: begin ( r ) als first und ranges:: end ( r ) als last verwendet würde.

Die auf dieser Seite beschriebenen funktionsähnlichen Entitäten sind Algorithm Function Objects (informell bekannt als Niebloids ), das heißt:

Inhaltsverzeichnis

Parameter

first, last - das Iterator-Sentinel-Paar, das den Bereich der zu kopierenden Elemente definiert
r - der Bereich der zu kopierenden Elemente
result - der Anfang des Zielbereichs
old_value - der Wert der zu ersetzenden Elemente
new_value - der Wert, der als Ersatz verwendet werden soll
pred - Prädikat, das auf die projizierten Elemente angewendet wird
proj - Projektion, die auf die Elemente angewendet wird

Rückgabewert

{ last, result + N } , wobei

1,3) N = ranges:: distance ( first, last ) ;
2,4) N = ranges:: distance ( r ) .

Komplexität

Genau N Anwendungen des entsprechenden Prädikats comp und beliebiger Projektionen proj .

Mögliche Implementierung

replace_copy (1,2) 
struct replace_copy_fn
{
    template<std::input_iterator I, std::sentinel_for<I> S,
             class O, class Proj = std::identity,
             class T1 = std::projected_value_t<I, Proj>,
             class T2 = std::iter_value_t<O>>
    requires std::indirectly_copyable<I, O> &&
             std::indirect_binary_predicate
                 <ranges::equal_to, std::projected<I, Proj>, const T1*> &&
             std::output_iterator<O, const T2&>
    constexpr ranges::replace_copy_result<I, O>
        operator()(I first, S last, O result, const T1& old_value,
                   const T2& new_value, Proj proj = {}) const
    {
        for (; first != last; ++first, ++result)
            *result = (std::invoke(proj, *first) == old_value) ? new_value : *first;
        return {std::move(first), std::move(result)};
    }
    template<ranges::input_range R, class O, class Proj = std::identity,
             class T1 = std::projected_value_t<ranges::iterator_t<R>, Proj>,
             class T2 = std::iter_value_t<O>>
    requires std::indirectly_copyable<ranges::iterator_t<R>, O> &&
             std::indirect_binary_predicate
                 <ranges::equal_to,
                  std::projected<ranges::iterator_t<R>, Proj>, const T1*>
    constexpr ranges::replace_copy_result<ranges::borrowed_iterator_t<R>, O>
        operator()(R&& r, O result, const T1& old_value,
                   const T2& new_value, Proj proj = {}) const
    {
        return (*this)(ranges::begin(r), ranges::end(r), std::move(result),
                       old_value, new_value, std::move(proj));
    }
};
inline constexpr replace_copy_fn replace_copy {};
replace_copy_if (3,4) 
struct replace_copy_if_fn
{
    template<std::input_iterator I, std::sentinel_for<I> S,
             class O, class T = std::iter_value_t<O>
             class Proj = std::identity,
             std::indirect_unary_predicate<std::projected<I, Proj>> Pred>
    requires std::indirectly_copyable<I, O> && std::output_iterator<O, const T&>
    constexpr ranges::replace_copy_if_result<I, O>
        operator()(I first, S last, O result, Pred pred,
                   const T& new_value, Proj proj = {}) const
    {
        for (; first != last; ++first, ++result)
             *result = std::invoke(pred, std::invoke(proj, *first)) ? new_value : *first;
        return {std::move(first), std::move(result)};
    }
    template<ranges::input_range R, class O, class T = std::iter_value_t<O>
             class Proj = std::identity,
             std::indirect_unary_predicate
                 <std::projected<ranges::iterator_t<R>, Proj>> Pred>
    requires std::indirectly_copyable<ranges::iterator_t<R>, O> &&
             std::output_iterator<O, const T&>
    constexpr ranges::replace_copy_if_result<ranges::borrowed_iterator_t<R>, O>
        operator()(R&& r, O result, Pred pred,
                   const T& new_value, Proj proj = {}) const
    {
        return (*this)(ranges::begin(r), ranges::end(r), std::move(result),
                       std::move(pred), new_value, std::move(proj));
    }
};
inline constexpr replace_copy_if_fn replace_copy_if {};

Hinweise

Feature-Test Makro Wert Std Funktion
__cpp_lib_algorithm_default_value_type 202403 (C++26) Listeninitialisierung für Algorithmen ( 1-4 )

Beispiel

Diesen Code ausführen 
#include <algorithm>
#include <array>
#include <complex>
#include <iostream>
#include <vector>
void println(const auto rem, const auto& v)
{
    for (std::cout << rem << ": "; const auto& e : v)
        std::cout << e << ' ';
    std::cout << '\n';
}
int main()
{    
    std::vector<int> o;
    std::array p{1, 6, 1, 6, 1, 6};
    o.resize(p.size());
    println("p", p);
    std::ranges::replace_copy(p, o.begin(), 6, 9);
    println("o", o);
    std::array q{1, 2, 3, 6, 7, 8, 4, 5};
    o.resize(q.size());
    println("q", q);
    std::ranges::replace_copy_if(q, o.begin(), [](int x) { return 5 < x; }, 5);
    println("o", o);
    std::vector<std::complex<short>> r{{1, 3}, {2, 2}, {4, 8}};
    std::vector<std::complex<float>> s(r.size());
    println("r", r);
    #ifdef __cpp_lib_algorithm_default_value_type
        std::ranges::replace_copy(r, s.begin(),
                                  {1, 3}, // T1 wird abgeleitet
                                  {2.2, 4.8}); // T2 wird abgeleitet
    #else
        std::ranges::replace_copy(r, s.begin(),
                                  std::complex<short>{1, 3},
                                  std::complex<float>{2.2, 4.8});
    #endif
    println("s", s);
    std::vector<std::complex<double>> b{{1, 3}, {2, 2}, {4, 8}},
                                      d(b.size());
    println("b", b);
    #ifdef __cpp_lib_algorithm_default_value_type
        std::ranges::replace_copy_if(b, d.begin(),
            [](std::complex<double> z){ return std::abs(z) < 5; },
            {4, 2}); // Möglich, da T abgeleitet wird.
    #else
        std::ranges::replace_copy_if(b, d.begin(),
            [](std::complex<double> z){ return std::abs(z) < 5; },
            std::complex<double>{4, 2});
    #endif
    println("d", d);
}

Ausgabe: 

p: 1 6 1 6 1 6
o: 1 9 1 9 1 9
q: 1 2 3 6 7 8 4 5
o: 1 2 3 5 5 5 4 5
r: (1,3) (2,2) (4,8)
s: (2.2,4.8) (2,2) (4,8)
b: (1,3) (2,2) (4,8)
d: (4,2) (4,2) (4,8)

Siehe auch

(C++20) (C++20)
ersetzt alle Werte, die bestimmte Kriterien erfüllen, durch einen anderen Wert
(Algorithmus-Funktionsobjekt)
kopiert einen Bereich und ersetzt Elemente, die bestimmte Kriterien erfüllen, durch einen anderen Wert
(Funktionstemplate)