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Make the result of reserve_hint implementation-defined #135

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Merged
ednolan merged 1 commit into from
Nov 2, 2025
Merged

Make the result of reserve_hint implementation-defined #135

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4 changes: 2 additions & 2 deletions include/beman/utf_view/to_utf_view.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -186,14 +186,14 @@ class exposition_only_to_utf_view_impl {

/* !PAPER */
#if defined(__cpp_lib_ranges_reserve_hint)
/* PAPER */
/* PAPER: constexpr auto reserve_hint() requires approximately_sized_range<V>; */
constexpr auto reserve_hint() requires std::ranges::approximately_sized_range<V> {
return std::ranges::reserve_hint(base_);
}
/* PAPER: constexpr auto reserve_hint() const requires approximately_sized_range<const V>; */
constexpr auto reserve_hint() const requires std::ranges::approximately_sized_range<const V>; {
return std::ranges::reserve_hint(base_);
}
/* !PAPER */
#endif
/* PAPER */
};
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18 changes: 13 additions & 5 deletions paper/P2728.md
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Original file line number Diff line number Diff line change
Expand Up @@ -625,12 +625,8 @@ public:

constexpr bool empty() const { return empty(@*base_*@); }

constexpr auto reserve_hint() requires approximately_sized_range<V>
{
return reserve_hint(@*base_*@);
}
constexpr auto reserve_hint() requires approximately_sized_range<V>;
constexpr auto reserve_hint() const requires approximately_sized_range<const V>;
{ return reserve_hint(@*base_*@); }
};
```

Expand All @@ -648,6 +644,18 @@ _Returns:_ `{*this, std::ranges::begin(base_)}`

_Remarks:_ In order to provide the amortized constant time complexity required by the `range` concept when `@*to-utf-view-impl*@` transcodes from UTF-8 or UTF-16, this function caches the result within the `@*to-utf-view-impl*@` for use on subsequent calls.

```cpp
constexpr auto reserve_hint() requires approximately_sized_range<V>;
```

_Returns:_ The result is implementation-defined.

```cpp
constexpr auto reserve_hint() const requires approximately_sized_range<const V>;
```

_Returns:_ The result is implementation-defined.

::: note

The implementation of the `empty()` member function provided by the
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