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Fix tuple_cat example a bit

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Peter Dimov
2017-05-19 01:43:30 +03:00
parent 3cc44323e9
commit 7d91a174a2
2 changed files with 11 additions and 11 deletions
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12
doc/html/mp11.html
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@@ -474,7 +474,7 @@
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span> <span class="number">2</span><span class="special">&gt;</span> <span class="identifier">t1</span><span class="special">{</span> <span class="number">1</span><span class="special">,</span> <span class="number">2</span> <span class="special">};</span> <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span> <span class="number">2</span><span class="special">&gt;</span> <span class="identifier">t1</span><span class="special">{</span> <span class="number">1</span><span class="special">,</span> <span class="number">2</span> <span class="special">};</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special">&lt;</span><span class="keyword">float</span><span class="special">,</span> <span class="number">3</span><span class="special">&gt;</span> <span class="identifier">t2</span><span class="special">{</span> <span class="number">3.0f</span><span class="special">,</span> <span class="number">4.0f</span><span class="special">,</span> <span class="number">5.0f</span> <span class="special">};</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special">&lt;</span><span class="keyword">float</span><span class="special">,</span> <span class="number">3</span><span class="special">&gt;</span> <span class="identifier">t2</span><span class="special">{</span> <span class="number">3.0f</span><span class="special">,</span> <span class="number">4.0f</span><span class="special">,</span> <span class="number">5.0f</span> <span class="special">};</span>
<span class="keyword">auto</span> <span class="identifier">result</span> <span class="special">=</span> <span class="special">::</span><span class="identifier">tuple_cat</span><span class="special">(</span> <span class="identifier">t1</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span> <span class="identifier">t2</span> <span class="special">)</span> <span class="special">);</span> <span class="keyword">auto</span> <span class="identifier">result</span> <span class="special">=</span> <span class="special">::</span><span class="identifier">tuple_cat</span><span class="special">(</span> <span class="identifier">t1</span><span class="special">,</span> <span class="identifier">t2</span> <span class="special">);</span>
</pre> </pre>
<p> <p>
Let's fix these one by one. Support for move-only types is easy, if one knows Let's fix these one by one. Support for move-only types is easy, if one knows
@@ -542,11 +542,11 @@
<p> <p>
What we need is, given a tuple-like type <code class="computeroutput"><span class="identifier">Tp</span></code>, What we need is, given a tuple-like type <code class="computeroutput"><span class="identifier">Tp</span></code>,
to obtain <code class="computeroutput"><span class="identifier">mp_list</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="number">0</span><span class="special">,</span> to obtain <code class="computeroutput"><span class="identifier">mp_list</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="number">0</span><span class="special">,</span>
<span class="identifier">Tp</span><span class="special">&gt;,</span> <span class="identifier">Tp</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="number">1</span><span class="special">,</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="number">1</span><span class="special">,</span> <span class="identifier">Tp</span><span class="special">&gt;,</span> <span class="special">...,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="identifier">N</span><span class="special">-</span><span class="number">1</span><span class="special">,</span> <span class="identifier">Tp</span><span class="special">&gt;&gt;</span></code>, where <code class="computeroutput"><span class="identifier">N</span></code> <span class="identifier">Tp</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">,</span> <span class="special">...,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="identifier">N</span><span class="special">-</span><span class="number">1</span><span class="special">,</span> <span class="identifier">Tp</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span></code>, where <code class="computeroutput"><span class="identifier">N</span></code>
is <code class="computeroutput"><span class="identifier">tuple_size</span><span class="special">&lt;</span><span class="identifier">Tp</span><span class="special">&gt;::</span><span class="identifier">value</span></code>. Here's one way to do it: is <code class="computeroutput"><span class="identifier">tuple_size</span><span class="special">&lt;</span><span class="identifier">Tp</span><span class="special">&gt;::</span><span class="identifier">value</span></code>. Here's one way to do it:
</p> </p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">I</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">tuple_element</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element_t</span><span class="special">&lt;</span><span class="identifier">I</span><span class="special">::</span><span class="identifier">value</span><span class="special">,</span> <span class="identifier">T</span><span class="special">&gt;;</span> <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">I</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">tuple_element</span> <span class="special">=</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="identifier">I</span><span class="special">::</span><span class="identifier">value</span><span class="special">,</span> <span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">from_tuple_like</span> <span class="special">=</span> <span class="identifier">mp_product</span><span class="special">&lt;</span><span class="identifier">tuple_element</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;,</span> <span class="identifier">mp_iota</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_size</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;&gt;&gt;;</span> <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">from_tuple_like</span> <span class="special">=</span> <span class="identifier">mp_product</span><span class="special">&lt;</span><span class="identifier">tuple_element</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;,</span> <span class="identifier">mp_iota</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_size</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;&gt;&gt;;</span>
</pre> </pre>
<p> <p>
@@ -591,7 +591,7 @@
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">remove_cv_ref</span> <span class="special">=</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">remove_cv</span><span class="special">&lt;</span> <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">remove_cv_ref</span> <span class="special">=</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">remove_cv</span><span class="special">&lt;</span>
<span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">remove_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">;</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">remove_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">I</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">tuple_element</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element_t</span><span class="special">&lt;</span><span class="identifier">I</span><span class="special">::</span><span class="identifier">value</span><span class="special">,</span> <span class="identifier">T</span><span class="special">&gt;;</span> <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">I</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">tuple_element</span> <span class="special">=</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special">&lt;</span><span class="identifier">I</span><span class="special">::</span><span class="identifier">value</span><span class="special">,</span> <span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">from_tuple_like</span> <span class="special">=</span> <span class="identifier">mp_product</span><span class="special">&lt;</span><span class="identifier">tuple_element</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;,</span> <span class="identifier">mp_iota</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_size</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;&gt;&gt;;</span> <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">from_tuple_like</span> <span class="special">=</span> <span class="identifier">mp_product</span><span class="special">&lt;</span><span class="identifier">tuple_element</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;,</span> <span class="identifier">mp_iota</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_size</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;&gt;&gt;;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span><span class="special">...</span> <span class="identifier">Tp</span><span class="special">,</span> <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span><span class="special">...</span> <span class="identifier">Tp</span><span class="special">,</span>
@@ -2317,7 +2317,7 @@
</div> </div>
</div> </div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: May 18, 2017 at 11:57:59 GMT</small></p></td> <td align="left"><p><small>Last revised: May 18, 2017 at 22:41:31 GMT</small></p></td>
<td align="right"><div class="copyright-footer"></div></td> <td align="right"><div class="copyright-footer"></div></td>
</tr></table> </tr></table>
<hr> <hr>

10
doc/mp11/examples.qbk
View File

@@ -148,7 +148,7 @@ that support `tuple_size`, `tuple_element`, and `get`), while our implementation
std::array<int, 2> t1{ 1, 2 }; std::array<int, 2> t1{ 1, 2 };
std::array<float, 3> t2{ 3.0f, 4.0f, 5.0f }; std::array<float, 3> t2{ 3.0f, 4.0f, 5.0f };
auto result = ::tuple_cat( t1, std::move( t2 ) ); auto result = ::tuple_cat( t1, t2 );
Let's fix these one by one. Support for move-only types is easy, if one knows where to look. The problem is Let's fix these one by one. Support for move-only types is easy, if one knows where to look. The problem is
that `Tp` that we're passing to the helper `tuple_cat_` is (correctly) `tuple<unique_ptr<int>&&, unique_ptr<float>&&>`, that `Tp` that we're passing to the helper `tuple_cat_` is (correctly) `tuple<unique_ptr<int>&&, unique_ptr<float>&&>`,
@@ -193,10 +193,10 @@ the corresponding `mp_list`.
Technically, a more principled approach would've been to return `std::tuple`, but here `mp_list` will prove more Technically, a more principled approach would've been to return `std::tuple`, but here `mp_list` will prove more
convenient. convenient.
What we need is, given a tuple-like type `Tp`, to obtain `mp_list<std::tuple_element<0, Tp>, std::tuple_element<1, Tp>, What we need is, given a tuple-like type `Tp`, to obtain `mp_list<std::tuple_element<0, Tp>::type, std::tuple_element<1, Tp>::type,
..., std::tuple_element<N-1, Tp>>`, where `N` is `tuple_size<Tp>::value`. Here's one way to do it: ..., std::tuple_element<N-1, Tp>::type>`, where `N` is `tuple_size<Tp>::value`. Here's one way to do it:
template<class T, class I> using tuple_element = std::tuple_element_t<I::value, T>; template<class T, class I> using tuple_element = typename std::tuple_element<I::value, T>::type;
template<class T> using from_tuple_like = mp_product<tuple_element, mp_list<T>, mp_iota<std::tuple_size<T>>>; template<class T> using from_tuple_like = mp_product<tuple_element, mp_list<T>, mp_iota<std::tuple_size<T>>>;
(`mp_iota<N>` is an algorithm that returns an `mp_list` with elements `mp_size_t<0>`, `mp_size_t<1>`, ..., `mp_size_t<N-1>`.) (`mp_iota<N>` is an algorithm that returns an `mp_list` with elements `mp_size_t<0>`, `mp_size_t<1>`, ..., `mp_size_t<N-1>`.)
@@ -224,7 +224,7 @@ With all these fixes applied, our fully operational `tuple_cat` now looks like t
template<class T> using remove_cv_ref = typename std::remove_cv< template<class T> using remove_cv_ref = typename std::remove_cv<
typename std::remove_reference<T>::type>::type; typename std::remove_reference<T>::type>::type;
template<class T, class I> using tuple_element = std::tuple_element_t<I::value, T>; template<class T, class I> using tuple_element = typename std::tuple_element<I::value, T>::type;
template<class T> using from_tuple_like = mp_product<tuple_element, mp_list<T>, mp_iota<std::tuple_size<T>>>; template<class T> using from_tuple_like = mp_product<tuple_element, mp_list<T>, mp_iota<std::tuple_size<T>>>;
template<class... Tp, template<class... Tp,