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<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE header PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
"http://www.boost.org/tools/boostbook/dtd/boostbook.dtd">
<header name="boost/variant/recursive_wrapper.hpp">
<namespace name="boost">
<class name="recursive_wrapper">
<purpose>Solves circular dependencies, enabling recursive types.</purpose>
<template>
<template-type-parameter name="T"/>
</template>
<description>
<simpara>The <code>recursive_wrapper</code> class template has an
interface similar to a simple value container, but its content is
allocated dynamically. This allows <code>recursive_wrapper</code> to
hold types <code>T</code> whose member data leads to a circular
dependency (e.g., a data member of <code>T</code> has a data member
of type <code>T</code>).</simpara>
<simpara>The application of <code>recursive_wrapper</code> is easiest
understood in context. See
<xref linkend="variant.tutorial.recursive.recursive-wrapper"/> for a
demonstration of a common use of the class template.</simpara>
<simpara><emphasis role="bold">Notes</emphasis>:</simpara>
<itemizedlist>
<listitem>Any type specified as the template argument to
<code>recursive_wrapper</code> must be capable of construction via
<code>operator new</code>. Thus, for instance, references are not
supported.</listitem>
</itemizedlist>
</description>
<typedef name="type">
<type>T</type>
</typedef>
<destructor>
<purpose>Destructor.</purpose>
<description>
<simpara>Deletes the content of <code>*this</code>.</simpara>
</description>
<throws>Will not throw.</throws>
</destructor>
<constructor>
<purpose>Default constructor.</purpose>
<description>
<simpara>Initializes <code>*this</code> by default construction of
<code>T</code>.</simpara>
</description>
<requires>
<simpara><code>T</code> must fulfill the requirements of the
<emphasis>DefaultConstructible</emphasis> [20.1.4]
concept.</simpara>
</requires>
<throws>
<simpara>May fail with any exceptions arising from the default
constructor of <code>T</code> or, in the event of
insufficient memory, with <code>std::bad_alloc</code>.</simpara>
</throws>
</constructor>
<constructor>
<parameter name="other">
<paramtype>const recursive_wrapper &</paramtype>
</parameter>
<purpose>Copy constructor.</purpose>
<description>
<simpara>Copies the content of <code>other</code> into
<code>*this</code>.</simpara>
</description>
<throws>
<simpara>May fail with any exceptions arising from the
copy constructor of <code>T</code> or, in the event of
insufficient memory, with <code>std::bad_alloc</code>.</simpara>
</throws>
</constructor>
<constructor>
<parameter name="operand">
<paramtype>const T &</paramtype>
</parameter>
<purpose>Value constructor.</purpose>
<description>
<simpara>Copies <code>operand</code> into
<code>*this</code>.</simpara>
</description>
<throws>
<simpara>May fail with any exceptions arising from the
copy constructor of <code>T</code> or, in the event of
insufficient memory, with <code>std::bad_alloc</code>.</simpara>
</throws>
</constructor>
<method-group name="modifiers">
<method name="swap">
<type>void</type>
<parameter name="other">
<paramtype>recursive_wrapper &</paramtype>
</parameter>
<description>
<simpara>Exchanges contents of <code>*this</code> and
<code>other</code>.</simpara>
</description>
<throws>Will not throw.</throws>
</method>
<method name="operator=">
<type>recursive_wrapper &</type>
<parameter name="rhs">
<paramtype>const recursive_wrapper &</paramtype>
</parameter>
<purpose>Copy assignment operator.</purpose>
<description>
<simpara>Assigns the content of <code>rhs</code> to the content of
<code>*this</code>.</simpara>
</description>
<requires>
<simpara><code>T</code> must fulfill the requirements of
the <conceptname>Assignable</conceptname>
concept.</simpara>
</requires>
<throws>
<simpara>May fail with any exceptions arising from the assignment
operator of <code>T</code>.</simpara>
</throws>
</method>
<method name="operator=">
<type>recursive_wrapper &</type>
<parameter name="rhs">
<paramtype>const T &</paramtype>
</parameter>
<purpose>Value assignment operator.</purpose>
<description>
<simpara>Assigns <code>rhs</code> into the content of
<code>*this</code>.</simpara>
</description>
<requires>
<simpara><code>T</code> must fulfill the requirements of the
<conceptname>Assignable</conceptname>
concept.</simpara>
</requires>
<throws>
<simpara>May fail with any exceptions arising from the assignment
operator of <code>T</code>.</simpara>
</throws>
</method>
</method-group>
<method-group name="queries">
<overloaded-method name="get">
<signature>
<type>T &</type>
</signature>
<signature cv="const">
<type>const T &</type>
</signature>
<description>
<simpara>Returns a reference to the content of
<code>*this</code>.</simpara>
</description>
<throws>Will not throw.</throws>
</overloaded-method>
<overloaded-method name="get_pointer">
<signature>
<type>T *</type>
</signature>
<signature cv="const">
<type>const T *</type>
</signature>
<description>
<simpara>Returns a pointer to the content of
<code>*this</code>.</simpara>
</description>
<throws>Will not throw.</throws>
</overloaded-method>
</method-group>
</class>
<class name="is_recursive_wrapper">
<purpose>
<simpara>Determines whether the specified type is a specialization of
<code>recursive_wrapper</code>.</simpara>
</purpose>
<template>
<template-type-parameter name="T"/>
</template>
<description>
<simpara>Value is true iff <code>T</code> is a specialization of
<code><classname>recursive_wrapper</classname></code>.</simpara>
<simpara><emphasis role="bold">Note</emphasis>:
<code>is_recursive_wrapper</code> is a model of
<libraryname>MPL</libraryname>'s
<emphasis>IntegralConstant</emphasis> concept.</simpara>
</description>
<typedef name="type">
<type><emphasis>unspecified</emphasis></type>
</typedef>
<static-constant name="value">
<type>bool</type>
<default><emphasis>unspecified</emphasis></default>
</static-constant>
</class>
<class name="unwrap_recursive_wrapper">
<purpose>
<simpara>Unwraps the specified argument if given a specialization of
<code><classname>recursive_wrapper</classname></code>.</simpara>
</purpose>
<template>
<template-type-parameter name="T"/>
</template>
<description>
<simpara><code>type</code> is equivalent to <code>T::type</code> if
<code>T</code> is a specialization of
<code><classname>recursive_wrapper</classname></code>. Otherwise,
<code>type</code> is equivalent to <code>T</code>.</simpara>
</description>
<typedef name="type">
<type><emphasis>unspecified</emphasis></type>
</typedef>
</class>
</namespace>
</header>
|
