From Jason Turner

[string.cons]

C++20 → C++23 2.3 KB 38 lines
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Archived: C++20 | C++23
Markdown: C++20 | C++23
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  1. tmp/tmppqg9full/{from.md → to.md} +29 -5
tmp/tmppqg9full/{from.md → to.md} RENAMED
@@ -20,17 +20,33 @@ state.
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  ``` cpp
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  constexpr basic_string(const basic_string& str, size_type pos,
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  const Allocator& a = Allocator());
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  constexpr basic_string(const basic_string& str, size_type pos, size_type n,
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  const Allocator& a = Allocator());
 
 
 
 
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  ```
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- *Effects:* Let `n` be `npos` for the first overload. Equivalent to:
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- ``` cpp
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- basic_string(basic_string_view<charT, traits>(str).substr(pos, n), a)
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- ```
 
 
 
 
 
 
 
 
 
 
 
 
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  ``` cpp
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  template<class T>
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  constexpr basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator());
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  ```
@@ -105,11 +121,19 @@ template<class InputIterator>
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  *Constraints:* `InputIterator` is a type that qualifies as an input
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  iterator [[container.requirements.general]].
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  *Effects:* Constructs a string from the values in the range \[`begin`,
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- `end`), as indicated in [[container.seq.req]].
 
 
 
 
 
 
 
 
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  ``` cpp
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  constexpr basic_string(initializer_list<charT> il, const Allocator& a = Allocator());
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  ```
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  ``` cpp
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  constexpr basic_string(const basic_string& str, size_type pos,
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  const Allocator& a = Allocator());
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  constexpr basic_string(const basic_string& str, size_type pos, size_type n,
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  const Allocator& a = Allocator());
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+ constexpr basic_string(basic_string&& str, size_type pos,
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+ const Allocator& a = Allocator());
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+ constexpr basic_string(basic_string&& str, size_type pos, size_type n,
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+ const Allocator& a = Allocator());
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  ```
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+ Let
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+ - `s` be the value of `str` prior to this call and
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+ - `rlen` be `pos + min(n, s.size() - pos)` for the overloads with
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+ parameter `n`, and `s.size()` otherwise.
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+
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+ *Effects:* Constructs an object whose initial value is the range
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+ \[`s.data() + pos`, `s.data() + rlen`).
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+
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+ *Throws:* `out_of_range` if `pos > s.size()`.
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+
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+ *Remarks:* For the overloads with a `basic_string&&` parameter, `str` is
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+ left in a valid but unspecified state.
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+
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+ *Recommended practice:* For the overloads with a `basic_string&&`
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+ parameter, implementations should avoid allocation if
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+ `s.get_allocator() == a` is `true`.
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  ``` cpp
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  template<class T>
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  constexpr basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator());
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  ```
 
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  *Constraints:* `InputIterator` is a type that qualifies as an input
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  iterator [[container.requirements.general]].
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  *Effects:* Constructs a string from the values in the range \[`begin`,
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+ `end`), as specified in [[sequence.reqmts]].
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+
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+ ``` cpp
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+ template<container-compatible-range<charT> R>
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+ constexpr basic_string(from_range_t, R&& rg, const Allocator& = Allocator());
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+ ```
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+
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+ *Effects:* Constructs a string from the values in the range `rg`, as
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+ specified in [[sequence.reqmts]].
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  ``` cpp
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  constexpr basic_string(initializer_list<charT> il, const Allocator& a = Allocator());
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  ```
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