mirror of
https://github.com/boostorg/optional.git
synced 2025-07-29 12:07:21 +02:00
More restrictive assignment from optional<U>
This commit is contained in:
Andrzej Krzemienski
@ -808,30 +808,74 @@
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is <a href="../../../../../utility/CopyConstructible.html" target="_top"><code class="computeroutput"><span class="identifier">CopyConstructible</span></code></a> and <code class="computeroutput"><span class="identifier">CopyAssignable</span></code>.
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</li>
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<li class="listitem">
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<p class="simpara">
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<span class="bold"><strong>Effects:</strong></span>
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<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
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<li class="listitem">
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If <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
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<span class="special">&&</span> <span class="special">!</span><span class="identifier">rhs</span></code> no effect, otherwise
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</li>
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<li class="listitem">
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if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
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<span class="special">&&</span> <span class="special">!</span><span class="identifier">rhs</span></code>, destroys the contained value
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by calling <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>, otherwise
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</li>
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<li class="listitem">
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if <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
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<span class="special">&&</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>, initializes the contained value
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as if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
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with <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>,
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otherwise
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</li>
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<li class="listitem">
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(if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
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<span class="special">&&</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>) assigns <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code> to the contained value.
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</li>
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</ul></div>
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</li>
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</p>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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</th>
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<th>
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<p>
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<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
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contains a value
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</p>
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</th>
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<th>
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<p>
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<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
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does not contain a value
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<code class="computeroutput"><span class="identifier">rhs</span></code> contains
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a value
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</p>
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</td>
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<td>
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<p>
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assigns <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>
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to the contained value
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</p>
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</td>
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<td>
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<p>
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initializes the contained value as if direct-initializing an
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object of type <code class="computeroutput"><span class="identifier">T</span></code>
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with <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<code class="computeroutput"><span class="identifier">rhs</span></code> does not
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contain a value
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</p>
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</td>
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<td>
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<p>
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destroys the contained value by calling <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>
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</p>
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</td>
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<td>
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<p>
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no effect
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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</li>
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<li class="listitem">
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<span class="bold"><strong>Returns:</strong></span> <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>;
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</li>
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@ -919,30 +963,73 @@
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and <code class="computeroutput"><span class="identifier">MoveAssignable</span></code>.
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</li>
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<li class="listitem">
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<p class="simpara">
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<span class="bold"><strong>Effects:</strong></span>
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<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
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<li class="listitem">
|
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If <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
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<span class="special">&&</span> <span class="special">!</span><span class="identifier">rhs</span></code> no effect, otherwise
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</li>
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<li class="listitem">
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if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
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<span class="special">&&</span> <span class="special">!</span><span class="identifier">rhs</span></code>, destroys the contained value
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by calling <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>, otherwise
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</li>
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<li class="listitem">
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if <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
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<span class="special">&&</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>, initializes the contained value
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as if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
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with <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code>,
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otherwise
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</li>
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<li class="listitem">
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(if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
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<span class="special">&&</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>) assigns <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code> to the contained value.
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</li>
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</ul></div>
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</li>
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</p>
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<div class="informaltable"><table class="table">
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||||
<colgroup>
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||||
<col>
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||||
<col>
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||||
<col>
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||||
</colgroup>
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||||
<thead><tr>
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||||
<th>
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||||
</th>
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||||
<th>
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||||
<p>
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<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
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contains a value
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</p>
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</th>
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<th>
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<p>
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<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
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does not contain a value
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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||||
<td>
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||||
<p>
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<code class="computeroutput"><span class="identifier">rhs</span></code> contains
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a value
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</p>
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</td>
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<td>
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<p>
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assigns <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code> to the contained value
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</p>
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</td>
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<td>
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<p>
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initializes the contained value as if direct-initializing an
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object of type <code class="computeroutput"><span class="identifier">T</span></code>
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with <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code>
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<code class="computeroutput"><span class="identifier">rhs</span></code> does not
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contain a value
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</p>
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</td>
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<td>
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<p>
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destroys the contained value by calling <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>
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</p>
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</td>
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<td>
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<p>
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no effect
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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</li>
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<li class="listitem">
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<span class="bold"><strong>Returns:</strong></span> <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>;
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</li>
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@ -997,40 +1084,88 @@
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</p></blockquote></div>
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<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
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<li class="listitem">
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<span class="bold"><strong>Effect:</strong></span> Assigns another convertible
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optional to an optional.
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<p class="simpara">
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<span class="bold"><strong>Effect:</strong></span>
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||||
</p>
|
||||
<div class="informaltable"><table class="table">
|
||||
<colgroup>
|
||||
<col>
|
||||
<col>
|
||||
<col>
|
||||
</colgroup>
|
||||
<thead><tr>
|
||||
<th>
|
||||
</th>
|
||||
<th>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
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contains a value
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</p>
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</th>
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<th>
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<p>
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<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
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does not contain a value
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</p>
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</th>
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||||
</tr></thead>
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<tbody>
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<tr>
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||||
<td>
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||||
<p>
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<code class="computeroutput"><span class="identifier">rhs</span></code> contains
|
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a value
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</p>
|
||||
</td>
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||||
<td>
|
||||
<p>
|
||||
assigns <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>
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to the contained value
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||||
</p>
|
||||
</td>
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||||
<td>
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||||
<p>
|
||||
initializes the contained value as if direct-initializing an
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object of type <code class="computeroutput"><span class="identifier">T</span></code>
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with <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>
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</p>
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||||
</td>
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||||
</tr>
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||||
<tr>
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||||
<td>
|
||||
<p>
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<code class="computeroutput"><span class="identifier">rhs</span></code> does not
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contain a value
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||||
</p>
|
||||
</td>
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||||
<td>
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||||
<p>
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||||
destroys the contained value by calling <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
no effect
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table></div>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Returns:</strong></span> <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Postconditions:</strong></span> If <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
is initialized, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
is initialized and its value is a <span class="emphasis"><em>copy</em></span> of the value
|
||||
of <code class="computeroutput"><span class="identifier">rhs</span></code> <span class="emphasis"><em>converted</em></span>
|
||||
to type <code class="computeroutput"><span class="identifier">T</span></code>; else <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
is uninitialized.
|
||||
<span class="bold"><strong>Postconditions:</strong></span> <code class="computeroutput"><span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span> <span class="special">==</span> <span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span></code>.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Throws:</strong></span> Whatever <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">U</span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span></code> or <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="identifier">T</span><span class="special">(</span> <span class="identifier">U</span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span></code> throws.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Notes:</strong></span> If both <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and rhs are initially initialized,
|
||||
<code class="computeroutput"><span class="identifier">T</span></code>'s <span class="emphasis"><em>assignment
|
||||
operator</em></span> (from <code class="computeroutput"><span class="identifier">U</span></code>)
|
||||
is used. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
is initially initialized but <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
is uninitialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
<span class="emphasis"><em>destructor</em></span> is called. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is initially uninitialized but rhs
|
||||
is initialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
<span class="emphasis"><em>converting constructor</em></span> (from <code class="computeroutput"><span class="identifier">U</span></code>)
|
||||
is called.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Exception Safety:</strong></span> In the event of an
|
||||
exception, the initialization state of <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is unchanged and its value unspecified
|
||||
as far as optional is concerned (it is up to <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
<code class="computeroutput"><span class="keyword">operator</span><span class="special">=()</span></code>).
|
||||
If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
is initially uninitialized and <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
converting constructor fails, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is left properly uninitialized.
|
||||
<span class="bold"><strong>Exception Safety:</strong></span> If any exception is
|
||||
thrown, the result of the expression <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span></code> remains unchanged. If an exception is
|
||||
thrown during the call to <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
constructor, no effect. If an exception is thrown during the call to
|
||||
<code class="computeroutput"><span class="identifier">T</span></code>'s assignment, the state
|
||||
of its contained value is as defined by the exception safety guarantee
|
||||
of <code class="computeroutput"><span class="identifier">T</span></code>'s copy assignment.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Example:</strong></span>
|
||||
@ -1053,36 +1188,87 @@
|
||||
</p></blockquote></div>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Effect:</strong></span> Move-assigns another convertible
|
||||
optional to an optional.
|
||||
<p class="simpara">
|
||||
<span class="bold"><strong>Effect:</strong></span>
|
||||
</p>
|
||||
<div class="informaltable"><table class="table">
|
||||
<colgroup>
|
||||
<col>
|
||||
<col>
|
||||
<col>
|
||||
</colgroup>
|
||||
<thead><tr>
|
||||
<th>
|
||||
</th>
|
||||
<th>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
contains a value
|
||||
</p>
|
||||
</th>
|
||||
<th>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
does not contain a value
|
||||
</p>
|
||||
</th>
|
||||
</tr></thead>
|
||||
<tbody>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="identifier">rhs</span></code> contains
|
||||
a value
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
assigns <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code> to the contained value
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
initializes the contained value as if direct-initializing an
|
||||
object of type <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
with <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code>
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="identifier">rhs</span></code> does not
|
||||
contain a value
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
destroys the contained value by calling <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
no effect
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table></div>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Returns:</strong></span> <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Postconditions:</strong></span> If <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
is initialized, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
is initialized and its value is moved from the value of <code class="computeroutput"><span class="identifier">rhs</span></code>; else <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is uninitialized.
|
||||
<span class="bold"><strong>Postconditions:</strong></span> <code class="computeroutput"><span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span> <span class="special">==</span> <span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span></code>.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Throws:</strong></span> Whatever <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">U</span><span class="special">&&</span> <span class="special">)</span></code>
|
||||
or <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="identifier">T</span><span class="special">(</span> <span class="identifier">U</span><span class="special">&&</span>
|
||||
<span class="special">)</span></code> throws.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Notes:</strong></span> If both <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
are initially initialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
<span class="emphasis"><em>assignment operator</em></span> (from <code class="computeroutput"><span class="identifier">U</span><span class="special">&&</span></code>) is used. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
is initially initialized but <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
is uninitialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
<span class="emphasis"><em>destructor</em></span> is called. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is initially uninitialized but <code class="computeroutput"><span class="identifier">rhs</span></code> is initialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
<span class="emphasis"><em>converting constructor</em></span> (from <code class="computeroutput"><span class="identifier">U</span><span class="special">&&</span></code>) is called.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Exception Safety:</strong></span> In the event of an
|
||||
exception, the initialization state of <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is unchanged and its value unspecified
|
||||
as far as optional is concerned (it is up to <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
<code class="computeroutput"><span class="keyword">operator</span><span class="special">=()</span></code>).
|
||||
If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
is initially uninitialized and <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
converting constructor fails, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is left properly uninitialized.
|
||||
<span class="bold"><strong>Exception Safety:</strong></span> If any exception is
|
||||
thrown, the result of the expression <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span></code> remains unchanged. If an exception is
|
||||
thrown during the call to <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
constructor, no effect. If an exception is thrown during the call to
|
||||
<code class="computeroutput"><span class="identifier">T</span></code>'s assignment, the state
|
||||
of its contained value is as defined by the exception safety guarantee
|
||||
of <code class="computeroutput"><span class="identifier">T</span></code>'s copy assignment.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Example:</strong></span>
|
||||
@ -2019,35 +2205,81 @@
|
||||
<span class="bold"><strong>Requires:</strong></span> Lvalues of type <code class="computeroutput"><span class="identifier">T</span></code> shall be swappable and <code class="computeroutput"><span class="identifier">T</span></code> shall be <code class="computeroutput"><span class="identifier">MoveConstructible</span></code>.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<p class="simpara">
|
||||
<span class="bold"><strong>Effects:</strong></span>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
|
||||
<li class="listitem">
|
||||
If <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
|
||||
<span class="special">&&</span> <span class="special">!</span><span class="identifier">rhs</span></code>, no effect, otherwise
|
||||
</li>
|
||||
<li class="listitem">
|
||||
if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
|
||||
<span class="special">&&</span> <span class="special">!</span><span class="identifier">rhs</span></code>, initializes the contained
|
||||
value of <code class="computeroutput"><span class="identifier">rhs</span></code> as
|
||||
if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
with the expression <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*(*</span><span class="keyword">this</span><span class="special">))</span></code>, followed by <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> does not contain a value and
|
||||
<code class="computeroutput"><span class="identifier">rhs</span></code> contains a
|
||||
value, otherwise
|
||||
</li>
|
||||
<li class="listitem">
|
||||
if <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
|
||||
<span class="special">&&</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>, initializes the contained value
|
||||
of <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
as if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
with the expression <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code>, followed by <code class="computeroutput"><span class="identifier">rhs</span><span class="special">.</span><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> contains a value and <code class="computeroutput"><span class="identifier">rhs</span></code> does not contain a value,
|
||||
otherwise
|
||||
</li>
|
||||
<li class="listitem">
|
||||
(if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
|
||||
<span class="special">&&</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>) calls <code class="computeroutput"><span class="identifier">swap</span><span class="special">(*(*</span><span class="keyword">this</span><span class="special">),</span> <span class="special">*</span><span class="identifier">rhs</span><span class="special">)</span></code>.
|
||||
</li>
|
||||
</ul></div>
|
||||
</li>
|
||||
</p>
|
||||
<div class="informaltable"><table class="table">
|
||||
<colgroup>
|
||||
<col>
|
||||
<col>
|
||||
<col>
|
||||
</colgroup>
|
||||
<thead><tr>
|
||||
<th>
|
||||
</th>
|
||||
<th>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
contains a value
|
||||
</p>
|
||||
</th>
|
||||
<th>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
does not contain a value
|
||||
</p>
|
||||
</th>
|
||||
</tr></thead>
|
||||
<tbody>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="identifier">rhs</span></code> contains
|
||||
a value
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
calls <code class="computeroutput"><span class="identifier">swap</span><span class="special">(*(*</span><span class="keyword">this</span><span class="special">),</span> <span class="special">*</span><span class="identifier">rhs</span><span class="special">)</span></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
initializes the contained value of <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> as if direct-initializing
|
||||
an object of type <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
with the expression <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code>, followed by <code class="computeroutput"><span class="identifier">rhs</span><span class="special">.</span><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>,
|
||||
<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
contains a value and <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
does not contain a value
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="identifier">rhs</span></code> does not
|
||||
contain a value
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
initializes the contained value of <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
as if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
with the expression <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*(*</span><span class="keyword">this</span><span class="special">))</span></code>, followed by <code class="computeroutput"><span class="identifier">val</span><span class="special">-></span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>,
|
||||
<code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
|
||||
does not contain a value and <code class="computeroutput"><span class="identifier">rhs</span></code>
|
||||
contains a value
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
no effect
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table></div>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Postconditions:</strong></span> The states of <code class="computeroutput"><span class="identifier">x</span></code> and <code class="computeroutput"><span class="identifier">y</span></code>
|
||||
interchanged.
|
||||
|
||||
@ -52,6 +52,10 @@
|
||||
This can be used to work around <a href="https://svn.boost.org/trac/boost/ticket/10399" target="_top">Trac
|
||||
#10399</a>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
It is no longer possible to assign <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">U</span><span class="special">></span></code> to <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> when <code class="computeroutput"><span class="identifier">U</span></code>
|
||||
is not assignable or convertible to <code class="computeroutput"><span class="identifier">T</span></code>.
|
||||
</li>
|
||||
</ul></div>
|
||||
<h4>
|
||||
<a name="boost_optional.relnotes.h1"></a>
|
||||
|
||||
Reference in New Issue
Block a user