std:: indirect_unary_predicate

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indirectly_readable (C++20)
indirectly_writable (C++20)
weakly_incrementable (C++20)
incrementable (C++20)
is-integer-like is-signed-integer-like (C++20) (C++20)

sentinel_for (C++20)
sized_sentinel_for (C++20)
input_iterator (C++20)
output_iterator (C++20)
input_or_output_iterator (C++20)

forward_iterator (C++20)
bidirectional_iterator (C++20)
random_access_iterator (C++20)
contiguous_iterator (C++20)

Iterator primitives

input_iterator_tag output_iterator_tag forward_iterator_tag bidirectional_iterator_tag random_access_iterator_tag contiguous_iterator_tag

(C++20)

iter_value_t iter_difference_t iter_reference_t iter_const_reference_t iter_rvalue_reference_t iter_common_reference_t

(C++20) (C++20) (C++20) (C++23) (C++20) (C++20)

iterator (deprecated in C++17)
iterator_traits
incrementable_traits (C++20)
indirectly_readable_traits (C++20)

Algorithm concepts and utilities

Indirect callable concepts

indirectly_unary_invocable indirectly_regular_unary_invocable

(C++20) (C++20)

indirect_unary_predicate (C++20)
indirect_binary_predicate (C++20)

indirect_equivalence_relation (C++20)
indirect_strict_weak_order (C++20)

Common algorithm requirements

indirectly_movable (C++20)
indirectly_movable_storable (C++20)
indirectly_copyable (C++20)

indirectly_copyable_storable (C++20)
indirectly_swappable (C++20)
indirectly_comparable (C++20)

permutable (C++20)
mergeable (C++20)
sortable (C++20)

Utilities

indirect_result_t

(C++20)

projected

(C++20)

projected_value_t

(C++26)

Iterator adaptors

reverse_iterator
make_reverse_iterator (C++14)
move_iterator (C++11)
make_move_iterator (C++11)
default_sentinel_t default_sentinel (C++20) (C++20)
unreachable_sentinel_t unreachable_sentinel (C++20) (C++20)

front_insert_iterator
back_insert_iterator
inserter
insert_iterator
front_inserter
back_inserter
move_sentinel (C++20)

common_iterator (C++20)
counted_iterator (C++20)
basic_const_iterator (C++23)
const_iterator (C++23)
const_sentinel (C++23)
make_const_iterator (C++23)
make_const_sentinel (C++23)

Stream iterators

istream_iterator
ostream_iterator

istreambuf_iterator
ostreambuf_iterator

Iterator customization points
ranges::iter_move (C++20)
ranges::iter_swap (C++20)

Iterator operations

advance
distance
prev (C++11)
next (C++11)

ranges::advance (C++20)
ranges::distance (C++20)
ranges::prev (C++20)
ranges::next (C++20)

Range access

begin cbegin (C++11) (C++14)
rbegin crbegin (C++14) (C++14)

end cend (C++11) (C++14)
rend crend (C++14) (C++14)

size ssize (C++17) (C++20)
empty (C++17)
data (C++17)

定义于头文件 `<iterator>`
template < class F, class I > concept indirect_unary_predicate = std:: indirectly_readable < I > && std:: copy_constructible < F > && std:: predicate < F & , /indirect-value-t/ < I >> && std:: predicate < F & , std:: iter_reference_t < I >> ;		(C++20 起)

概念 indirect_unary_predicate 规定了算法调用一元谓词作为参数时的要求。该概念与 std::predicate 的关键区别在于：它适用于 I 所引用的类型，而非 I 本身。

缺陷报告

下列行为变更缺陷报告被追溯应用于先前发布的 C++ 标准。

缺陷报告	适用范围	发布时的行为	正确行为
P2609R3	C++20	其中一项要求基于 std:: iter_value_t < I > & 定义，错误处理了投影导致与谓词 F & 不兼容	基于 /indirect-value-t/ < I > 定义以正确处理此类投影
P2997R1	C++20	`indirect_unary_predicate` 要求 F & 满足与 std:: iter_common_reference_t < I > 的 `predicate` 要求	不再要求

Compiler support
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Language
Standard library
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Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Diagnostics library
Memory management library
Metaprogramming library (C++11)
General utilities library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
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External libraries

cppreference.net

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Variants

std:: indirect_unary_predicate

缺陷报告