tmp/tmp9e9my7zr/{from.md → to.md}
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| 1 |
+
#### Swap <a id="expected.object.swap">[[expected.object.swap]]</a>
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| 3 |
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``` cpp
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constexpr void swap(expected& rhs) noexcept(see below);
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| 5 |
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```
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*Constraints:*
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- `is_swappable_v<T>` is `true` and
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- `is_swappable_v<E>` is `true` and
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- `is_move_constructible_v<T> && is_move_constructible_v<E>` is `true`,
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and
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- `is_nothrow_move_constructible_v<T> || is_nothrow_move_constructible_v<E>`
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is `true`.
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*Effects:* See [[expected.object.swap]].
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**Table: `swap(expected&)` effects** <a id="expected.object.swap">[expected.object.swap]</a>
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| \topline | `this->has_value()` | `!this->has_value()` |
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| -------- | ------------------- | -------------------- |
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For the case where `rhs.value()` is `false` and `this->has_value()` is
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`true`, equivalent to:
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``` cpp
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if constexpr (is_nothrow_move_constructible_v<E>) {
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E tmp(std::move(rhs.unex));
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| 30 |
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destroy_at(addressof(rhs.unex));
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| 31 |
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try {
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construct_at(addressof(rhs.val), std::move(val));
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destroy_at(addressof(val));
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construct_at(addressof(unex), std::move(tmp));
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} catch(...) {
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| 36 |
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construct_at(addressof(rhs.unex), std::move(tmp));
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| 37 |
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throw;
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| 38 |
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}
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| 39 |
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} else {
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T tmp(std::move(val));
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| 41 |
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destroy_at(addressof(val));
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| 42 |
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try {
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| 43 |
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construct_at(addressof(unex), std::move(rhs.unex));
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| 44 |
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destroy_at(addressof(rhs.unex));
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| 45 |
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construct_at(addressof(rhs.val), std::move(tmp));
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| 46 |
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} catch (...) {
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| 47 |
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construct_at(addressof(val), std::move(tmp));
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throw;
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}
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}
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has_val = false;
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rhs.has_val = true;
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| 53 |
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```
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| 54 |
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| 55 |
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*Throws:* Any exception thrown by the expressions in the *Effects*.
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| 56 |
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*Remarks:* The exception specification is equivalent to:
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``` cpp
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is_nothrow_move_constructible_v<T> && is_nothrow_swappable_v<T> &&
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is_nothrow_move_constructible_v<E> && is_nothrow_swappable_v<E>
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| 62 |
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```
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``` cpp
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friend constexpr void swap(expected& x, expected& y) noexcept(noexcept(x.swap(y)));
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| 66 |
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```
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*Effects:* Equivalent to `x.swap(y)`.
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