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some progress on transform_iterator

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[SVN r21612]
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Jeremy Siek 2004-01-12 01:51:27 +00:00
parent 45b6a92f61
commit fbfcf97e18
4 changed files with 132 additions and 29 deletions
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2
doc/filter_iterator_ref.rst
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@ -151,4 +151,4 @@ operations.
:Effects: Increments ``*this`` and then continues to
increment ``*this`` until either ``this->base() == this->end()``
or ``f(**this) == true``.
:Returns: ``*this``

115
doc/transform_iterator.html
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@ -49,8 +49,9 @@ then returns the result.</p>
<p class="topic-title"><a name="table-of-contents">Table of Contents</a></p>
<ul class="simple">
<li><a class="reference" href="#transform-iterator-requirements" id="id1" name="id1"><tt class="literal"><span class="pre">transform_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#transform-iterator-public-operations" id="id2" name="id2"><tt class="literal"><span class="pre">transform_iterator</span></tt> public operations</a></li>
<li><a class="reference" href="#transform-iterator-private-operations" id="id3" name="id3"><tt class="literal"><span class="pre">transform_iterator</span></tt> private operations</a></li>
<li><a class="reference" href="#transform-iterator-models" id="id2" name="id2"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></li>
<li><a class="reference" href="#transform-iterator-operations" id="id3" name="id3"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#example" id="id4" name="id4">Example</a></li>
</ul>
</div>
<!-- Version 1.3 of this document was accepted for TR1 -->
@ -60,9 +61,7 @@ template &lt;class UnaryFunction,
class Reference = use_default,
class Value = use_default&gt;
class transform_iterator
: public iterator_adaptor&lt;/* see discussion */&gt;
{
friend class iterator_core_access;
public:
transform_iterator();
transform_iterator(Iterator const&amp; x, UnaryFunction f);
@ -74,10 +73,13 @@ public:
, typename enable_if_convertible&lt;F2, UnaryFunction&gt;::type* = 0 // exposition
);
reference operator*() const;
transform_iterator&amp; operator++();
Iterator base() const;
UnaryFunction functor() const;
private:
typename transform_iterator::value_type dereference() const;
UnaryFunction m_f;
Iterator m_iterator; // exposition
UnaryFunction m_f; // exposition
};
</pre>
<div class="section" id="transform-iterator-requirements">
@ -87,8 +89,11 @@ the expression <tt class="literal"><span class="pre">f(*i)</span></tt> must be v
type <tt class="literal"><span class="pre">UnaryFunction</span></tt>, <tt class="literal"><span class="pre">i</span></tt> is an object of type <tt class="literal"><span class="pre">Iterator</span></tt>, and
where the type of <tt class="literal"><span class="pre">f(*i)</span></tt> must be
<tt class="literal"><span class="pre">result_of&lt;UnaryFunction(iterator_traits&lt;Iterator&gt;::reference)&gt;::type</span></tt>.</p>
<p>The type <tt class="literal"><span class="pre">Iterator</span></tt> must at least model Readable Iterator. The
resulting <tt class="literal"><span class="pre">transform_iterator</span></tt> models the most refined of the
<p>The type <tt class="literal"><span class="pre">Iterator</span></tt> must at least model Readable Iterator.</p>
</div>
<div class="section" id="transform-iterator-models">
<h1><a class="toc-backref" href="#id2" name="transform-iterator-models"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></h1>
<p>The resulting <tt class="literal"><span class="pre">transform_iterator</span></tt> models the most refined of the
following options that is also modeled by <tt class="literal"><span class="pre">Iterator</span></tt>.</p>
<blockquote>
<ul class="simple">
@ -104,8 +109,8 @@ concept that is modeled by <tt class="literal"><span class="pre">Iterator</span>
<tt class="literal"><span class="pre">result_of&lt;UnaryFunction(iterator_traits&lt;Iterator&gt;::reference)&gt;::type</span></tt>.
The <tt class="literal"><span class="pre">value_type</span></tt> is <tt class="literal"><span class="pre">remove_cv&lt;remove_reference&lt;reference&gt;</span> <span class="pre">&gt;::type</span></tt>.</p>
</div>
<div class="section" id="transform-iterator-public-operations">
<h1><a class="toc-backref" href="#id2" name="transform-iterator-public-operations"><tt class="literal"><span class="pre">transform_iterator</span></tt> public operations</a></h1>
<div class="section" id="transform-iterator-operations">
<h1><a class="toc-backref" href="#id3" name="transform-iterator-operations"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></h1>
<p><tt class="literal"><span class="pre">transform_iterator();</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
@ -143,6 +148,15 @@ transform_iterator(
</tr>
</tbody>
</table>
<p><tt class="literal"><span class="pre">Iterator</span> <span class="pre">base()</span> <span class="pre">const;</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="literal"><span class="pre">m_iterator</span></tt></td>
</tr>
</tbody>
</table>
<p><tt class="literal"><span class="pre">UnaryFunction</span> <span class="pre">functor()</span> <span class="pre">const;</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
@ -152,19 +166,90 @@ transform_iterator(
</tr>
</tbody>
</table>
</div>
<div class="section" id="transform-iterator-private-operations">
<h1><a class="toc-backref" href="#id3" name="transform-iterator-private-operations"><tt class="literal"><span class="pre">transform_iterator</span></tt> private operations</a></h1>
<p><tt class="literal"><span class="pre">typename</span> <span class="pre">transform_iterator::value_type</span> <span class="pre">dereference()</span> <span class="pre">const;</span></tt></p>
<p><tt class="literal"><span class="pre">reference</span> <span class="pre">operator*()</span> <span class="pre">const;</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="literal"><span class="pre">m_f(transform_iterator::dereference());</span></tt></td>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="literal"><span class="pre">m_f(*m_iterator)</span></tt></td>
</tr>
</tbody>
</table>
<p><tt class="literal"><span class="pre">transform_iterator&amp;</span> <span class="pre">operator++();</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Effects:</th><td class="field-body"><tt class="literal"><span class="pre">++m_iterator</span></tt></td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="literal"><span class="pre">*this</span></tt></td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class UnaryFunction, class Iterator&gt;
transform_iterator&lt;UnaryFunction, Iterator&gt;
make_transform_iterator(Iterator it, UnaryFunction fun);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">transform_iterator&lt;UnaryFunction,</span> <span class="pre">Iterator&gt;</span></tt> with <tt class="literal"><span class="pre">m_f</span></tt>
initialized to <tt class="literal"><span class="pre">f</span></tt> and <tt class="literal"><span class="pre">m_iterator</span></tt> initialized to <tt class="literal"><span class="pre">x</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class UnaryFunction, class Iterator&gt;
transform_iterator&lt;UnaryFunction, Iterator&gt;
make_transform_iterator(Iterator it);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">transform_iterator</span></tt> with <tt class="literal"><span class="pre">m_f</span></tt>
default constructed and <tt class="literal"><span class="pre">m_iterator</span></tt> initialized to <tt class="literal"><span class="pre">x</span></tt>.</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="example">
<h1><a class="toc-backref" href="#id4" name="example">Example</a></h1>
<p>This is a simple example of using the transform_iterators class to
generate iterators that multiply (or add to) the value returned by
dereferencing the iterator. It would be cooler to use lambda library
in this example.</p>
<pre class="literal-block">
int x[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
const int N = sizeof(x)/sizeof(int);
typedef boost::binder1st&lt; std::multiplies&lt;int&gt; &gt; Function;
typedef boost::transform_iterator&lt;Function, int*&gt; doubling_iterator;
doubling_iterator i(x, boost::bind1st(std::multiplies&lt;int&gt;(), 2)),
i_end(x + N, boost::bind1st(std::multiplies&lt;int&gt;(), 2));
std::cout &lt;&lt; &quot;multiplying the array by 2:&quot; &lt;&lt; std::endl;
while (i != i_end)
std::cout &lt;&lt; *i++ &lt;&lt; &quot; &quot;;
std::cout &lt;&lt; std::endl;
std::cout &lt;&lt; &quot;adding 4 to each element in the array:&quot; &lt;&lt; std::endl;
std::copy(boost::make_transform_iterator(x, boost::bind1st(std::plus&lt;int&gt;(), 4)),
boost::make_transform_iterator(x + N, boost::bind1st(std::plus&lt;int&gt;(), 4)),
std::ostream_iterator&lt;int&gt;(std::cout, &quot; &quot;));
std::cout &lt;&lt; std::endl;
</pre>
<p>The output is:</p>
<pre class="literal-block">
multiplying the array by 2:
2 4 6 8 10 12 14 16
adding 4 to each element in the array:
5 6 7 8 9 10 11 12
</pre>
</div>
</div>
</body>
</html>

2
doc/transform_iterator.rst
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@ -21,3 +21,5 @@
.. contents:: Table of Contents
.. include:: transform_iterator_ref.rst
.. include:: make_transform_iterator.rst
.. include:: transform_iterator_eg.rst

42
doc/transform_iterator_ref.rst
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@ -7,9 +7,7 @@
class Reference = use_default,
class Value = use_default>
class transform_iterator
: public iterator_adaptor</* see discussion */>
{
friend class iterator_core_access;
public:
transform_iterator();
transform_iterator(Iterator const& x, UnaryFunction f);
@ -21,15 +19,18 @@
, typename enable_if_convertible<F2, UnaryFunction>::type* = 0 // exposition
);
reference operator*() const;
transform_iterator& operator++();
Iterator base() const;
UnaryFunction functor() const;
private:
typename transform_iterator::value_type dereference() const;
UnaryFunction m_f;
Iterator m_iterator; // exposition
UnaryFunction m_f; // exposition
};
``transform_iterator`` requirements
...................................
-----------------------------------
The type ``UnaryFunction`` must be Assignable, Copy Constructible, and
the expression ``f(*i)`` must be valid where ``f`` is an object of
@ -37,8 +38,13 @@ type ``UnaryFunction``, ``i`` is an object of type ``Iterator``, and
where the type of ``f(*i)`` must be
``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type``.
The type ``Iterator`` must at least model Readable Iterator. The
resulting ``transform_iterator`` models the most refined of the
The type ``Iterator`` must at least model Readable Iterator.
``transform_iterator`` models
-----------------------------
The resulting ``transform_iterator`` models the most refined of the
following options that is also modeled by ``Iterator``.
* Writable Lvalue Iterator if ``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type`` is a non-const reference.
@ -56,9 +62,9 @@ The ``reference`` type of ``transform_iterator`` is
``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type``.
The ``value_type`` is ``remove_cv<remove_reference<reference> >::type``.
``transform_iterator`` public operations
........................................
``transform_iterator`` operations
---------------------------------
``transform_iterator();``
@ -83,14 +89,24 @@ The ``value_type`` is ``remove_cv<remove_reference<reference> >::type``.
:Returns: An instance of ``transform_iterator`` that is a copy of ``t``.
:Requires: ``OtherIterator`` is implicitly convertible to ``Iterator``.
``Iterator base() const;``
:Returns: ``m_iterator``
``UnaryFunction functor() const;``
:Returns: ``m_f``
``transform_iterator`` private operations
.........................................
``typename transform_iterator::value_type dereference() const;``
``reference operator*() const;``
:Returns: ``m_f(transform_iterator::dereference());``
:Returns: ``m_f(*m_iterator)``
``transform_iterator& operator++();``
:Effects: ``++m_iterator``
:Returns: ``*this``