Merge [51862], [53211], [53212], and [53218] from the trunk

[SVN r53872]
This commit is contained in:
Steven Watanabe
2009-06-13 18:30:31 +00:00
parent 700d64acc8
commit 41ebb2ee6c
8 changed files with 191 additions and 129 deletions

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@ -15,39 +15,39 @@ The advanced features described in this document are all under namespace <code>:
<h2>Metafunctions for tuple types</h2>
<p>
Suppose <code>T</code> is a tuple type, and <code>N</code> is a constant integral expression.
Suppose <code>T</code> is a tuple type, and <code>N</code> is a constant integral expression.</p>
<code><pre>element&lt;N, T&gt;::type</pre></code>
<pre><code>element&lt;N, T&gt;::type</code></pre>
gives the type of the <code>N</code>th element in the tuple type <code>T</code>. If <code>T</code> is const, the resulting type is const qualified as well.
<p>gives the type of the <code>N</code>th element in the tuple type <code>T</code>. If <code>T</code> is const, the resulting type is const qualified as well.
Note that the constness of <code>T</code> does not affect reference type
elements.
</p>
<code><pre>length&lt;T&gt;::value</pre></code>
<pre><code>length&lt;T&gt;::value</code></pre>
gives the length of the tuple type <code>T</code>.
<p>gives the length of the tuple type <code>T</code>.
</p>
<h2>Cons lists</h2>
<p>
Tuples are internally represented as <i>cons lists</i>.
For example, the tuple
For example, the tuple </p>
<code><pre>tuple&lt;A, B, C, D&gt;</pre></code>
<pre><code>tuple&lt;A, B, C, D&gt;</code></pre>
inherits from the type
<code><pre>cons&lt;A, cons&lt;B, cons&lt;C, cons&lt;D, null_type&gt; &gt; &gt; &gt;
</pre></code>
<p>inherits from the type</p>
<pre><code>cons&lt;A, cons&lt;B, cons&lt;C, cons&lt;D, null_type&gt; &gt; &gt; &gt;
</code></pre>
The tuple template provides the typedef <code>inherited</code> to access the cons list representation. E.g.:
<p>The tuple template provides the typedef <code>inherited</code> to access the cons list representation. E.g.:
<code>tuple&lt;A&gt;::inherited</code> is the type <code>cons&lt;A, null_type&gt;</code>.
</p>
<h4>Empty tuple</h4>
<p>
The internal representation of the empty tuple <code>tuple&lt;&gt</code> is <code>null_type</code>.
The internal representation of the empty tuple <code>tuple&lt;&gt;</code> is <code>null_type</code>.
</p>
<h4>Head and tail</h4>
@ -83,11 +83,11 @@ inline void set_to_zero(cons&lt;H, T&gt;&amp; x) { x.get_head() = 0; set_to_zero
A cons list can be default constructed provided that all its elements can be default constructed.
</p>
<p>
A cons list can be constructed from its head and tail. The prototype of the constructor is:
A cons list can be constructed from its head and tail. The prototype of the constructor is:</p>
<pre><code>cons(typename access_traits&lt;head_type&gt;::parameter_type h,
const tail_type&amp; t)
</code></pre>
The traits template for the head parameter selects correct parameter types for different kinds of element types (for reference elements the parameter type equals the element type, for non-reference types the parameter type is a reference to const non-volatile element type).
<p>The traits template for the head parameter selects correct parameter types for different kinds of element types (for reference elements the parameter type equals the element type, for non-reference types the parameter type is a reference to const non-volatile element type).
</p>
<p>
For a one-element cons list the tail argument (<code>null_type</code>) can be omitted.
@ -98,16 +98,16 @@ For a one-element cons list the tail argument (<code>null_type</code>) can be om
<h4><code>access_traits</code></h4>
<p>
The template <code>access_traits</code> defines three type functions. Let <code>T</code> be a type of an element in a tuple:
The template <code>access_traits</code> defines three type functions. Let <code>T</code> be a type of an element in a tuple:</p>
<ol>
<li><code>access_traits&lt;T&gt;::non_const_type</code> maps <code>T</code> to the return type of the non-const access functions (nonmeber and member <code>get</code> functions, and the <code>get_head</code> function).</li>
<li><code>access_traits&lt;T&gt;::non_const_type</code> maps <code>T</code> to the return type of the non-const access functions (nonmember and member <code>get</code> functions, and the <code>get_head</code> function).</li>
<li><code>access_traits&lt;T&gt;::const_type</code> maps <code>T</code> to the return type of the const access functions.</li>
<li><code>access_traits&lt;T&gt;::parameter_type</code> maps <code>T</code> to the parameter type of the tuple constructor.</li>
</ol>
<h4><code>make_tuple_traits</code></h4>
The element types of the tuples that are created with the <code>make_tuple</code> functions are computed with the type function <code>make_tuple_traits</code>.
The type function call <code>make_tuple_traits&lt;T&gt;::type</code> implements the following type mapping:
<p>The element types of the tuples that are created with the <code>make_tuple</code> functions are computed with the type function <code>make_tuple_traits</code>.
The type function call <code>make_tuple_traits&lt;T&gt;::type</code> implements the following type mapping:</p>
<ul>
<li><i>any reference type</i> -&gt; <i>compile time error</i>
</li>
@ -119,7 +119,7 @@ The type function call <code>make_tuple_traits&lt;T&gt;::type</code> implements
</li>
</ul>
Objects of type <code>reference_wrapper</code> are created with the <code>ref</code> and <code>cref</code> functions (see <A href="tuple_users_guide.html#make_tuple">The <code>make_tuple</code> function</A>.)
<p>Objects of type <code>reference_wrapper</code> are created with the <code>ref</code> and <code>cref</code> functions (see <A href="tuple_users_guide.html#make_tuple">The <code>make_tuple</code> function</A>.)
</p>
<p>Reference wrappers were originally part of the tuple library, but they are now a general utility of boost.