forked from boostorg/mp11
Add more examples
This commit is contained in:
Peter Dimov
+349
-1
@@ -38,6 +38,7 @@
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<dd><dl>
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<dt><span class="section"><a href="mp11.html#mp11.examples.generating_test_cases">Generating Test
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Cases</a></span></dt>
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<dt><span class="section"><a href="mp11.html#mp11.examples.fixing_tuple_cat">Fixing <code class="computeroutput"><span class="identifier">tuple_cat</span></code></a></span></dt>
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<dt><span class="section"><a href="mp11.html#mp11.examples.computing_return_types">Computing Return
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Types</a></span></dt>
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</dl></dd>
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@@ -366,6 +367,258 @@
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<span class="identifier">boost</span><span class="special">::</span><span class="identifier">tuple_for_each</span><span class="special">(</span> <span class="identifier">mp_product</span><span class="special"><</span><span class="identifier">mp_list</span><span class="special">,</span> <span class="identifier">L</span><span class="special">,</span> <span class="identifier">L</span><span class="special">>(),</span> <span class="special">[](</span><span class="keyword">auto</span><span class="special">&&</span> <span class="identifier">x</span><span class="special">){</span> <span class="identifier">test_result</span><span class="special">(</span><span class="identifier">x</span><span class="special">);</span> <span class="special">}</span> <span class="special">);</span>
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<span class="special">}</span>
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</pre>
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<p>
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How does it work?
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</p>
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<p>
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<code class="computeroutput"><span class="identifier">mp_product</span><span class="special"><</span><span class="identifier">F</span><span class="special">,</span> <span class="identifier">L1</span><span class="special">,</span> <span class="identifier">L2</span><span class="special">></span></code>
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calls <code class="computeroutput"><span class="identifier">F</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">></span></code> where <code class="computeroutput"><span class="identifier">T1</span></code>
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varies over the elements of <code class="computeroutput"><span class="identifier">L1</span></code>
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and <code class="computeroutput"><span class="identifier">T2</span></code> varies over the elements
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of <code class="computeroutput"><span class="identifier">L2</span></code>, as if by executing
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two nested loops. It then returns a list of these results, of the same type
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as <code class="computeroutput"><span class="identifier">L1</span></code>.
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</p>
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<p>
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In our case, both lists are the same <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span></code>,
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and <code class="computeroutput"><span class="identifier">F</span></code> is <code class="computeroutput"><span class="identifier">mp_list</span></code>,
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so <code class="computeroutput"><span class="identifier">mp_product</span><span class="special"><</span><span class="identifier">mp_list</span><span class="special">,</span> <span class="identifier">L</span><span class="special">,</span> <span class="identifier">L</span><span class="special">></span></code> will get us <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span>
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<span class="keyword">char</span><span class="special">>,</span>
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<span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="keyword">short</span><span class="special">>,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span>
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<span class="keyword">int</span><span class="special">>,</span>
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<span class="special">...,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">unsigned</span> <span class="keyword">long</span><span class="special">,</span> <span class="keyword">long</span><span class="special">>,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">unsigned</span> <span class="keyword">long</span><span class="special">,</span> <span class="keyword">unsigned</span>
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<span class="keyword">long</span><span class="special">>></span></code>.
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</p>
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<p>
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We then default-construct this tuple and pass it to <code class="computeroutput"><span class="identifier">tuple_for_each</span></code>.
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<code class="computeroutput"><span class="identifier">tuple_for_each</span><span class="special">(</span><span class="identifier">tp</span><span class="special">,</span> <span class="identifier">f</span><span class="special">)</span></code> calls <code class="computeroutput"><span class="identifier">f</span></code>
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for every tuple element; we use a (C++14) lambda that calls <code class="computeroutput"><span class="identifier">test_result</span></code>. (In pure C++11, we'd need
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to make <code class="computeroutput"><span class="identifier">test_result</span></code> a function
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object with a templated <code class="computeroutput"><span class="keyword">operator</span><span class="special">()</span></code> and pass that to <code class="computeroutput"><span class="identifier">tuple_for_each</span></code>
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directly.)
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</p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="mp11.examples.fixing_tuple_cat"></a><a class="link" href="mp11.html#mp11.examples.fixing_tuple_cat" title="Fixing tuple_cat">Fixing <code class="computeroutput"><span class="identifier">tuple_cat</span></code></a>
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</h3></div></div></div>
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<p>
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The article <a href="http://pdimov.com/cpp2/simple_cxx11_metaprogramming.html" target="_top">Simple
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C++11 metaprogramming</a> builds an implementation of the standard function
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<code class="computeroutput"><span class="identifier">tuple_cat</span></code>, with the end result
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given below:
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</p>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">L</span><span class="special">></span> <span class="keyword">using</span> <span class="identifier">F</span> <span class="special">=</span> <span class="identifier">mp_iota</span><span class="special"><</span><span class="identifier">mp_size</span><span class="special"><</span><span class="identifier">L</span><span class="special">>>;</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span><span class="identifier">Is</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Ks</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tp</span><span class="special">></span>
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<span class="identifier">R</span> <span class="identifier">tuple_cat_</span><span class="special">(</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">Is</span><span class="special">...>,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">Ks</span><span class="special">...>,</span> <span class="identifier">Tp</span> <span class="identifier">tp</span> <span class="special">)</span>
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<span class="special">{</span>
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<span class="keyword">return</span> <span class="identifier">R</span><span class="special">{</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Ks</span><span class="special">::</span><span class="identifier">value</span><span class="special">>(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Is</span><span class="special">::</span><span class="identifier">value</span><span class="special">>(</span><span class="identifier">tp</span><span class="special">))...</span> <span class="special">};</span>
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<span class="special">}</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">...</span> <span class="identifier">Tp</span><span class="special">,</span>
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<span class="keyword">class</span> <span class="identifier">R</span> <span class="special">=</span> <span class="identifier">mp_append</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</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"><</span><span class="identifier">Tp</span><span class="special">>::</span><span class="identifier">type</span><span class="special">...>></span>
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<span class="identifier">R</span> <span class="identifier">tuple_cat</span><span class="special">(</span> <span class="identifier">Tp</span> <span class="special">&&...</span> <span class="identifier">tp</span> <span class="special">)</span>
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<span class="special">{</span>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="keyword">const</span> <span class="identifier">N</span> <span class="special">=</span> <span class="keyword">sizeof</span><span class="special">...(</span><span class="identifier">Tp</span><span class="special">);</span>
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<span class="comment">// inner</span>
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<span class="keyword">using</span> <span class="identifier">list1</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">mp_rename</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"><</span><span class="identifier">Tp</span><span class="special">>::</span><span class="identifier">type</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special">>...>;</span>
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<span class="keyword">using</span> <span class="identifier">list2</span> <span class="special">=</span> <span class="identifier">mp_iota_c</span><span class="special"><</span><span class="identifier">N</span><span class="special">>;</span>
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<span class="keyword">using</span> <span class="identifier">list3</span> <span class="special">=</span> <span class="identifier">mp_transform</span><span class="special"><</span><span class="identifier">mp_fill</span><span class="special">,</span> <span class="identifier">list1</span><span class="special">,</span> <span class="identifier">list2</span><span class="special">>;</span>
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<span class="keyword">using</span> <span class="identifier">inner</span> <span class="special">=</span> <span class="identifier">mp_apply</span><span class="special"><</span><span class="identifier">mp_append</span><span class="special">,</span> <span class="identifier">list3</span><span class="special">>;</span>
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<span class="comment">// outer</span>
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<span class="keyword">using</span> <span class="identifier">list4</span> <span class="special">=</span> <span class="identifier">mp_transform</span><span class="special"><</span><span class="identifier">F</span><span class="special">,</span> <span class="identifier">list1</span><span class="special">>;</span>
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<span class="keyword">using</span> <span class="identifier">outer</span> <span class="special">=</span> <span class="identifier">mp_apply</span><span class="special"><</span><span class="identifier">mp_append</span><span class="special">,</span> <span class="identifier">list4</span><span class="special">>;</span>
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<span class="comment">//</span>
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<span class="keyword">return</span> <span class="identifier">tuple_cat_</span><span class="special"><</span><span class="identifier">R</span><span class="special">>(</span> <span class="identifier">inner</span><span class="special">(),</span> <span class="identifier">outer</span><span class="special">(),</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">forward_as_tuple</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">>(</span><span class="identifier">tp</span><span class="special">)...</span> <span class="special">)</span> <span class="special">);</span>
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<span class="special">}</span>
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</pre>
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<p>
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This function, however, is not entirely correct, in that it doesn't handle
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some cases properly. For example, trying to concatenate tuples containing
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move-only elements such as <code class="computeroutput"><span class="identifier">unique_ptr</span></code>
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fails:
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</p>
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<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">unique_ptr</span><span class="special"><</span><span class="keyword">int</span><span class="special">>></span> <span class="identifier">t1</span><span class="special">;</span>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">unique_ptr</span><span class="special"><</span><span class="keyword">float</span><span class="special">>></span> <span class="identifier">t2</span><span class="special">;</span>
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<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">std</span><span class="special">::</span><span class="identifier">move</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>
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</pre>
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<p>
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Trying to concatenate <code class="computeroutput"><span class="keyword">const</span></code>
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tuples fails:
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</p>
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<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="keyword">const</span> <span class="identifier">t1</span><span class="special">;</span>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">></span> <span class="keyword">const</span> <span class="identifier">t2</span><span class="special">;</span>
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<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>
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</pre>
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<p>
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And finally, the standard <code class="computeroutput"><span class="identifier">tuple_cat</span></code>
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is specified to work on arbitrary tuple-like types (that is, all types that
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support <code class="computeroutput"><span class="identifier">tuple_size</span></code>, <code class="computeroutput"><span class="identifier">tuple_element</span></code>, and <code class="computeroutput"><span class="identifier">get</span></code>),
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while our implementation only works with <code class="computeroutput"><span class="identifier">tuple</span></code>
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and <code class="computeroutput"><span class="identifier">pair</span></code>. <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span></code>,
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for example, fails:
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</p>
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<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="number">2</span><span class="special">></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>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="number">3</span><span class="special">></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>
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<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>
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</pre>
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<p>
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Let's fix these one by one. Support for move-only types is easy, if one knows
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where to look. The problem is that <code class="computeroutput"><span class="identifier">Tp</span></code>
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that we're passing to the helper <code class="computeroutput"><span class="identifier">tuple_cat_</span></code>
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is (correctly) <code class="computeroutput"><span class="identifier">tuple</span><span class="special"><</span><span class="identifier">unique_ptr</span><span class="special"><</span><span class="keyword">int</span><span class="special">>&&,</span>
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<span class="identifier">unique_ptr</span><span class="special"><</span><span class="keyword">float</span><span class="special">>&&></span></code>,
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but <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">get</span><span class="special"><</span><span class="number">0</span><span class="special">>(</span><span class="identifier">tp</span><span class="special">)</span></code> still returns <code class="computeroutput"><span class="identifier">unique_ptr</span><span class="special"><</span><span class="keyword">int</span><span class="special">>&</span></code>,
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because <code class="computeroutput"><span class="identifier">tp</span></code> is an lvalue.
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This behavior is a bit surprising, but consistent with how rvalue reference
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members are treated by the language.
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</p>
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<p>
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Long story short, we need <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">tp</span><span class="special">)</span></code>
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in <code class="computeroutput"><span class="identifier">tuple_cat_</span></code> to make <code class="computeroutput"><span class="identifier">tp</span></code> an rvalue:
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</p>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span><span class="identifier">Is</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Ks</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tp</span><span class="special">></span>
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<span class="identifier">R</span> <span class="identifier">tuple_cat_</span><span class="special">(</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">Is</span><span class="special">...>,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">Ks</span><span class="special">...>,</span> <span class="identifier">Tp</span> <span class="identifier">tp</span> <span class="special">)</span>
|
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<span class="special">{</span>
|
||||
<span class="keyword">return</span> <span class="identifier">R</span><span class="special">{</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Ks</span><span class="special">::</span><span class="identifier">value</span><span class="special">>(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Is</span><span class="special">::</span><span class="identifier">value</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">tp</span><span class="special">)))...</span> <span class="special">};</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
Next, <code class="computeroutput"><span class="keyword">const</span></code>-qualified tuples.
|
||||
The issue here is that we're stripping references from the input tuples,
|
||||
but not <code class="computeroutput"><span class="keyword">const</span></code>. As a result,
|
||||
we're trying to manipulate types such as <code class="computeroutput"><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span>
|
||||
<span class="keyword">const</span></code> with Mp11 algorithms, and these
|
||||
types do not fit the list concept. We just need to strip qualifiers as well,
|
||||
by defining the useful <code class="computeroutput"><span class="identifier">remove_cv_ref</span></code>
|
||||
primitive that is inexplicably missing from the standard library:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></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"><</span>
|
||||
<span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">remove_reference</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span><span class="special">>::</span><span class="identifier">type</span><span class="special">;</span>
|
||||
</pre>
|
||||
<p>
|
||||
and then by using <code class="computeroutput"><span class="identifier">remove_cv_ref</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">></span></code> in place of <code class="computeroutput"><span class="keyword">typename</span>
|
||||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">remove_reference</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">>::</span><span class="identifier">type</span></code>:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">...</span> <span class="identifier">Tp</span><span class="special">,</span>
|
||||
<span class="keyword">class</span> <span class="identifier">R</span> <span class="special">=</span> <span class="identifier">mp_append</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><>,</span> <span class="identifier">remove_cv_ref</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">>...>></span>
|
||||
<span class="identifier">R</span> <span class="identifier">tuple_cat</span><span class="special">(</span> <span class="identifier">Tp</span> <span class="special">&&...</span> <span class="identifier">tp</span> <span class="special">)</span>
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="keyword">const</span> <span class="identifier">N</span> <span class="special">=</span> <span class="keyword">sizeof</span><span class="special">...(</span><span class="identifier">Tp</span><span class="special">);</span>
|
||||
|
||||
<span class="comment">// inner</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">list1</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">mp_rename</span><span class="special"><</span><span class="identifier">remove_cv_ref</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">>,</span> <span class="identifier">mp_list</span><span class="special">>...>;</span>
|
||||
|
||||
<span class="comment">// ...</span>
|
||||
</pre>
|
||||
<p>
|
||||
Finally, tuple-like types. We've so far exploited the fact that <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code>
|
||||
and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span></code> are valid Mp11 lists, but in general,
|
||||
arbitrary tuple-like types aren't, so we need to convert them into such.
|
||||
For that, we'll need to define a metafunction <code class="computeroutput"><span class="identifier">from_tuple_like</span></code>
|
||||
that will take an arbitrary tuple-like type and will return, in our case,
|
||||
the corresponding <code class="computeroutput"><span class="identifier">mp_list</span></code>.
|
||||
</p>
|
||||
<p>
|
||||
Technically, a more principled approach would've been to return <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span></code>,
|
||||
but here <code class="computeroutput"><span class="identifier">mp_list</span></code> will prove
|
||||
more convenient.
|
||||
</p>
|
||||
<p>
|
||||
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"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special"><</span><span class="number">0</span><span class="special">,</span>
|
||||
<span class="identifier">Tp</span><span class="special">>,</span>
|
||||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_element</span><span class="special"><</span><span class="number">1</span><span class="special">,</span> <span class="identifier">Tp</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"><</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">>></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"><</span><span class="identifier">Tp</span><span class="special">>::</span><span class="identifier">value</span></code>. Here's one way to do it:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</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">></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"><</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">>;</span>
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></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"><</span><span class="identifier">tuple_element</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">T</span><span class="special">>,</span> <span class="identifier">mp_iota</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_size</span><span class="special"><</span><span class="identifier">T</span><span class="special">>>>;</span>
|
||||
</pre>
|
||||
<p>
|
||||
(<code class="computeroutput"><span class="identifier">mp_iota</span><span class="special"><</span><span class="identifier">N</span><span class="special">></span></code> is
|
||||
an algorithm that returns an <code class="computeroutput"><span class="identifier">mp_list</span></code>
|
||||
with elements <code class="computeroutput"><span class="identifier">mp_size_t</span><span class="special"><</span><span class="number">0</span><span class="special">></span></code>, <code class="computeroutput"><span class="identifier">mp_size_t</span><span class="special"><</span><span class="number">1</span><span class="special">></span></code>, ...,
|
||||
<code class="computeroutput"><span class="identifier">mp_size_t</span><span class="special"><</span><span class="identifier">N</span><span class="special">-</span><span class="number">1</span><span class="special">></span></code>.)
|
||||
</p>
|
||||
<p>
|
||||
Remember that <code class="computeroutput"><span class="identifier">mp_product</span><span class="special"><</span><span class="identifier">F</span><span class="special">,</span>
|
||||
<span class="identifier">L1</span><span class="special">,</span> <span class="identifier">L2</span><span class="special">></span></code>
|
||||
performs the equivalent of two nested loops over the elements of <code class="computeroutput"><span class="identifier">L1</span></code> and <code class="computeroutput"><span class="identifier">L2</span></code>,
|
||||
applying <code class="computeroutput"><span class="identifier">F</span></code> to the two variables
|
||||
and gathering the result. In our case <code class="computeroutput"><span class="identifier">L1</span></code>
|
||||
consists of the single element <code class="computeroutput"><span class="identifier">T</span></code>,
|
||||
so only the second loop (over <code class="computeroutput"><span class="identifier">mp_iota</span><span class="special"><</span><span class="identifier">N</span><span class="special">></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"><</span><span class="identifier">T</span><span class="special">></span></code>),
|
||||
remains, and we get a list of the same type as <code class="computeroutput"><span class="identifier">L1</span></code>
|
||||
(an <code class="computeroutput"><span class="identifier">mp_list</span></code>) with contents
|
||||
<code class="computeroutput"><span class="identifier">tuple_element</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">mp_size_t</span><span class="special"><</span><span class="number">0</span><span class="special">>></span></code>,
|
||||
<code class="computeroutput"><span class="identifier">tuple_element</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">mp_size_t</span><span class="special"><</span><span class="number">1</span><span class="special">>></span></code>,
|
||||
..., <code class="computeroutput"><span class="identifier">tuple_element</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">mp_size_t</span><span class="special"><</span><span class="identifier">N</span><span class="special">-</span><span class="number">1</span><span class="special">>></span></code>.
|
||||
</p>
|
||||
<p>
|
||||
For completeness's sake, here's another, more traditional way to achieve
|
||||
the same result:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">using</span> <span class="identifier">from_tuple_like</span> <span class="special">=</span> <span class="identifier">mp_transform_q</span><span class="special"><</span><span class="identifier">mp_bind_front</span><span class="special"><</span><span class="identifier">tuple_element</span><span class="special">,</span> <span class="identifier">T</span><span class="special">>,</span> <span class="identifier">mp_iota</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_size</span><span class="special"><</span><span class="identifier">T</span><span class="special">>>>;</span>
|
||||
</pre>
|
||||
<p>
|
||||
With all these fixes applied, our fully operational <code class="computeroutput"><span class="identifier">tuple_cat</span></code>
|
||||
now looks like this:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">L</span><span class="special">></span> <span class="keyword">using</span> <span class="identifier">F</span> <span class="special">=</span> <span class="identifier">mp_iota</span><span class="special"><</span><span class="identifier">mp_size</span><span class="special"><</span><span class="identifier">L</span><span class="special">>>;</span>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span><span class="identifier">Is</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Ks</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tp</span><span class="special">></span>
|
||||
<span class="identifier">R</span> <span class="identifier">tuple_cat_</span><span class="special">(</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">Is</span><span class="special">...>,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">Ks</span><span class="special">...>,</span> <span class="identifier">Tp</span> <span class="identifier">tp</span> <span class="special">)</span>
|
||||
<span class="special">{</span>
|
||||
<span class="keyword">return</span> <span class="identifier">R</span><span class="special">{</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Ks</span><span class="special">::</span><span class="identifier">value</span><span class="special">>(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Is</span><span class="special">::</span><span class="identifier">value</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">tp</span><span class="special">)))...</span> <span class="special">};</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></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"><</span>
|
||||
<span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">remove_reference</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span><span class="special">>::</span><span class="identifier">type</span><span class="special">;</span>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</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">></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"><</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">>;</span>
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></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"><</span><span class="identifier">tuple_element</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">T</span><span class="special">>,</span> <span class="identifier">mp_iota</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple_size</span><span class="special"><</span><span class="identifier">T</span><span class="special">>>>;</span>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">...</span> <span class="identifier">Tp</span><span class="special">,</span>
|
||||
<span class="keyword">class</span> <span class="identifier">R</span> <span class="special">=</span> <span class="identifier">mp_append</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><>,</span> <span class="identifier">from_tuple_like</span><span class="special"><</span><span class="identifier">remove_cv_ref</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">>>...>></span>
|
||||
<span class="identifier">R</span> <span class="identifier">tuple_cat</span><span class="special">(</span> <span class="identifier">Tp</span> <span class="special">&&...</span> <span class="identifier">tp</span> <span class="special">)</span>
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="keyword">const</span> <span class="identifier">N</span> <span class="special">=</span> <span class="keyword">sizeof</span><span class="special">...(</span><span class="identifier">Tp</span><span class="special">);</span>
|
||||
|
||||
<span class="comment">// inner</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">list1</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="identifier">from_tuple_like</span><span class="special"><</span><span class="identifier">remove_cv_ref</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">>>...>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">list2</span> <span class="special">=</span> <span class="identifier">mp_iota_c</span><span class="special"><</span><span class="identifier">N</span><span class="special">>;</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">list3</span> <span class="special">=</span> <span class="identifier">mp_transform</span><span class="special"><</span><span class="identifier">mp_fill</span><span class="special">,</span> <span class="identifier">list1</span><span class="special">,</span> <span class="identifier">list2</span><span class="special">>;</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">inner</span> <span class="special">=</span> <span class="identifier">mp_apply</span><span class="special"><</span><span class="identifier">mp_append</span><span class="special">,</span> <span class="identifier">list3</span><span class="special">>;</span>
|
||||
|
||||
<span class="comment">// outer</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">list4</span> <span class="special">=</span> <span class="identifier">mp_transform</span><span class="special"><</span><span class="identifier">F</span><span class="special">,</span> <span class="identifier">list1</span><span class="special">>;</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">outer</span> <span class="special">=</span> <span class="identifier">mp_apply</span><span class="special"><</span><span class="identifier">mp_append</span><span class="special">,</span> <span class="identifier">list4</span><span class="special">>;</span>
|
||||
|
||||
<span class="comment">//</span>
|
||||
|
||||
<span class="keyword">return</span> <span class="identifier">tuple_cat_</span><span class="special"><</span><span class="identifier">R</span><span class="special">>(</span> <span class="identifier">inner</span><span class="special">(),</span> <span class="identifier">outer</span><span class="special">(),</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">forward_as_tuple</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special"><</span><span class="identifier">Tp</span><span class="special">>(</span><span class="identifier">tp</span><span class="special">)...</span> <span class="special">)</span> <span class="special">);</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
@@ -611,6 +864,15 @@
|
||||
words, <code class="computeroutput"><span class="identifier">mp_size</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">T</span><span class="special">...>></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">mp_size_t</span><span class="special"><</span><span class="keyword">sizeof</span><span class="special">...(</span><span class="identifier">T</span><span class="special">)></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_size</span><span class="special"><</span><span class="identifier">L1</span><span class="special">>;</span> <span class="comment">// mp_size_t<0></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">int</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_size</span><span class="special"><</span><span class="identifier">L2</span><span class="special">>;</span> <span class="comment">// mp_size_t<2></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L3</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R3</span> <span class="special">=</span> <span class="identifier">mp_size</span><span class="special"><</span><span class="identifier">L3</span><span class="special">>;</span> <span class="comment">// mp_size_t<1></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -637,6 +899,15 @@
|
||||
That is, <code class="computeroutput"><span class="identifier">mp_front</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T</span><span class="special">...>></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">T1</span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">float</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_front</span><span class="special"><</span><span class="identifier">L1</span><span class="special">>;</span> <span class="comment">// int</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_front</span><span class="special"><</span><span class="identifier">L2</span><span class="special">>;</span> <span class="comment">// float</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L3</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">3</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">4</span><span class="special">]>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R3</span> <span class="special">=</span> <span class="identifier">mp_front</span><span class="special"><</span><span class="identifier">L3</span><span class="special">>;</span> <span class="comment">// char[1]</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -650,6 +921,12 @@
|
||||
That is, <code class="computeroutput"><span class="identifier">mp_pop_front</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T</span><span class="special">...>></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">L</span><span class="special"><</span><span class="identifier">T</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_pop_front</span><span class="special"><</span><span class="identifier">L1</span><span class="special">>;</span> <span class="comment">// std::tuple<double, long double></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">void</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_pop_front</span><span class="special"><</span><span class="identifier">L2</span><span class="special">>;</span> <span class="comment">// mp_list<></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -685,6 +962,15 @@
|
||||
That is, <code class="computeroutput"><span class="identifier">mp_second</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="identifier">T</span><span class="special">...>></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">T2</span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">float</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_second</span><span class="special"><</span><span class="identifier">L1</span><span class="special">>;</span> <span class="comment">// float</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_second</span><span class="special"><</span><span class="identifier">L2</span><span class="special">>;</span> <span class="comment">// double</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L3</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">3</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">4</span><span class="special">]>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R3</span> <span class="special">=</span> <span class="identifier">mp_second</span><span class="special"><</span><span class="identifier">L3</span><span class="special">>;</span> <span class="comment">// char[2]</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -698,6 +984,12 @@
|
||||
That is, <code class="computeroutput"><span class="identifier">mp_third</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="identifier">T3</span><span class="special">,</span> <span class="identifier">T</span><span class="special">...>></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">T3</span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_third</span><span class="special"><</span><span class="identifier">L1</span><span class="special">>;</span> <span class="comment">// long double</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">3</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">4</span><span class="special">]>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_third</span><span class="special"><</span><span class="identifier">L2</span><span class="special">>;</span> <span class="comment">// char[3]</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -710,6 +1002,12 @@
|
||||
at the front of the list <code class="computeroutput"><span class="identifier">L</span></code>.
|
||||
That is, <code class="computeroutput"><span class="identifier">mp_push_front</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">U</span><span class="special">...>,</span> <span class="identifier">T</span><span class="special">...></span></code> is an alias for <code class="computeroutput"><span class="identifier">L</span><span class="special"><</span><span class="identifier">T</span><span class="special">...,</span> <span class="identifier">U</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_push_front</span><span class="special"><</span><span class="identifier">L1</span><span class="special">,</span> <span class="keyword">float</span><span class="special">>;</span> <span class="comment">// std::tuple<float, double, long double></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">void</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_push_front</span><span class="special"><</span><span class="identifier">L2</span><span class="special">,</span> <span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">]>;</span> <span class="comment">// mp_list<char[1], char[2], void></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -723,6 +1021,12 @@
|
||||
That is, <code class="computeroutput"><span class="identifier">mp_push_back</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">U</span><span class="special">...>,</span> <span class="identifier">T</span><span class="special">...></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">L</span><span class="special"><</span><span class="identifier">U</span><span class="special">...,</span> <span class="identifier">T</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_push_back</span><span class="special"><</span><span class="identifier">L1</span><span class="special">,</span> <span class="keyword">float</span><span class="special">>;</span> <span class="comment">// std::tuple<double, long double, float></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">void</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_push_back</span><span class="special"><</span><span class="identifier">L2</span><span class="special">,</span> <span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">]>;</span> <span class="comment">// mp_list<void, char[1], char[2]></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -736,6 +1040,12 @@
|
||||
That is, <code class="computeroutput"><span class="identifier">mp_rename</span><span class="special"><</span><span class="identifier">L</span><span class="special"><</span><span class="identifier">T</span><span class="special">...>,</span> <span class="identifier">Y</span><span class="special">></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">Y</span><span class="special"><</span><span class="identifier">T</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_rename</span><span class="special"><</span><span class="identifier">L1</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">>;</span> <span class="comment">// std::tuple<double, long double></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">void</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_rename</span><span class="special"><</span><span class="identifier">L2</span><span class="special">,</span> <span class="identifier">mp_list</span><span class="special">>;</span> <span class="comment">// mp_list<void></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -751,6 +1061,9 @@
|
||||
<code class="computeroutput"><span class="identifier">mp_rename</span></code> with the arguments
|
||||
reversed.)
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_apply</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">is_same</span><span class="special">,</span> <span class="identifier">L1</span><span class="special">>;</span> <span class="comment">// std::is_same<double, long double></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -763,6 +1076,10 @@
|
||||
Same as <code class="computeroutput"><span class="identifier">mp_apply</span></code>, but takes
|
||||
a quoted metafunction.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">long</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_apply_q</span><span class="special"><</span><span class="identifier">mp_bind_front</span><span class="special"><</span><span class="identifier">mp_push_back</span><span class="special">,</span> <span class="identifier">L1</span><span class="special">>,</span> <span class="identifier">L2</span><span class="special">>;</span> <span class="comment">// std::tuple<double, long double, int, long></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -777,6 +1094,13 @@
|
||||
<span class="identifier">Ln</span><span class="special"><</span><span class="identifier">Tn</span><span class="special">...>></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">L1</span><span class="special"><</span><span class="identifier">T1</span><span class="special">...,</span> <span class="identifier">T2</span><span class="special">...,</span> <span class="special">...,</span> <span class="identifier">Tn</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">int</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">L3</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">short</span><span class="special">,</span> <span class="keyword">long</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">L4</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><>;</span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_append</span><span class="special"><</span><span class="identifier">L1</span><span class="special">,</span> <span class="identifier">L2</span><span class="special">,</span> <span class="identifier">L3</span><span class="special">,</span> <span class="identifier">L4</span><span class="special">>;</span> <span class="comment">// std::tuple<double, long double, int, short, long></span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -791,6 +1115,15 @@
|
||||
<span class="identifier">T</span><span class="special">></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">L</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">U</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">float</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_replace_front</span><span class="special"><</span><span class="identifier">L1</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// std::pair<void, float></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_replace_front</span><span class="special"><</span><span class="identifier">L2</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// std::tuple<void, double, long double></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L3</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">3</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">4</span><span class="special">]>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R3</span> <span class="special">=</span> <span class="identifier">mp_replace_front</span><span class="special"><</span><span class="identifier">L3</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// mp_list<void, char[2], char[3], char[4]>;</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -815,6 +1148,15 @@
|
||||
<span class="identifier">T</span><span class="special">></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">L</span><span class="special"><</span><span class="identifier">U1</span><span class="special">,</span> <span class="identifier">T</span><span class="special">,</span> <span class="identifier">U</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">float</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_replace_second</span><span class="special"><</span><span class="identifier">L1</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// std::pair<int, void></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_replace_second</span><span class="special"><</span><span class="identifier">L2</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// std::tuple<float, void, long double></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L3</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">3</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">4</span><span class="special">]>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R3</span> <span class="special">=</span> <span class="identifier">mp_replace_second</span><span class="special"><</span><span class="identifier">L3</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// mp_list<char[1], void, char[3], char[4]>;</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section">
|
||||
<div class="titlepage"><div><div><h4 class="title">
|
||||
@@ -829,6 +1171,12 @@
|
||||
<span class="identifier">T</span><span class="special">></span></code>
|
||||
is an alias for <code class="computeroutput"><span class="identifier">L</span><span class="special"><</span><span class="identifier">U1</span><span class="special">,</span> <span class="identifier">U2</span><span class="special">,</span> <span class="identifier">T</span><span class="special">,</span> <span class="identifier">U</span><span class="special">...></span></code>.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">L1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span><span class="special">>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R1</span> <span class="special">=</span> <span class="identifier">mp_replace_third</span><span class="special"><</span><span class="identifier">L1</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// std::tuple<float, double, void></span>
|
||||
|
||||
<span class="keyword">using</span> <span class="identifier">L2</span> <span class="special">=</span> <span class="identifier">mp_list</span><span class="special"><</span><span class="keyword">char</span><span class="special">[</span><span class="number">1</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">2</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">3</span><span class="special">],</span> <span class="keyword">char</span><span class="special">[</span><span class="number">4</span><span class="special">]>;</span>
|
||||
<span class="keyword">using</span> <span class="identifier">R2</span> <span class="special">=</span> <span class="identifier">mp_replace_third</span><span class="special"><</span><span class="identifier">L2</span><span class="special">,</span> <span class="keyword">void</span><span class="special">>;</span> <span class="comment">// mp_list<char[1], char[2], void, char[4]>;</span>
|
||||
</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="section">
|
||||
@@ -1951,7 +2299,7 @@
|
||||
</div>
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"><p><small>Last revised: May 13, 2017 at 18:21:04 GMT</small></p></td>
|
||||
<td align="left"><p><small>Last revised: May 17, 2017 at 17:44:23 GMT</small></p></td>
|
||||
<td align="right"><div class="copyright-footer"></div></td>
|
||||
</tr></table>
|
||||
<hr>
|
||||
|
||||
Reference in New Issue
Block a user