1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
|
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="generator" content="Docutils 0.3.6: http://docutils.sourceforge.net/" />
<title>Permutation Iterator</title>
<meta name="author" content="Toon Knapen, David Abrahams, Roland Richter, Jeremy Siek" />
<meta name="organization" content="Boost Consulting, Indiana University Open Systems Lab" />
<meta name="date" content="2004-11-01" />
<meta name="copyright" content="Copyright Toon Knapen, David Abrahams, Roland Richter, and Jeremy Siek 2003." />
<link rel="stylesheet" href="default.css" type="text/css" />
</head>
<body>
<h1 class="title">Permutation Iterator</h1>
<table class="docinfo" frame="void" rules="none">
<col class="docinfo-name" />
<col class="docinfo-content" />
<tbody valign="top">
<tr><th class="docinfo-name">Author:</th>
<td>Toon Knapen, David Abrahams, Roland Richter, Jeremy Siek</td></tr>
<tr><th class="docinfo-name">Contact:</th>
<td><a class="first reference" href="mailto:dave@boost-consulting.com">dave@boost-consulting.com</a>, <a class="last reference" href="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</a></td></tr>
<tr><th class="docinfo-name">Organization:</th>
<td><a class="first reference" href="http://www.boost-consulting.com">Boost Consulting</a>, Indiana University <a class="last reference" href="http://www.osl.iu.edu">Open Systems
Lab</a></td></tr>
<tr><th class="docinfo-name">Date:</th>
<td>2004-11-01</td></tr>
<tr><th class="docinfo-name">Copyright:</th>
<td>Copyright Toon Knapen, David Abrahams, Roland Richter, and Jeremy Siek 2003.</td></tr>
</tbody>
</table>
<div class="document" id="permutation-iterator">
<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">abstract:</th><td class="field-body">The permutation iterator adaptor provides a permuted view of a given
range. That is, the view includes every element of the given range but
in a potentially different order.</td>
</tr>
</tbody>
</table>
<div class="contents topic" id="table-of-contents">
<p class="topic-title first"><a name="table-of-contents">Table of Contents</a></p>
<ul class="simple">
<li><a class="reference" href="#introduction" id="id2" name="id2">Introduction</a></li>
<li><a class="reference" href="#reference" id="id3" name="id3">Reference</a><ul>
<li><a class="reference" href="#permutation-iterator-requirements" id="id4" name="id4"><tt class="literal"><span class="pre">permutation_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#permutation-iterator-models" id="id5" name="id5"><tt class="literal"><span class="pre">permutation_iterator</span></tt> models</a></li>
<li><a class="reference" href="#permutation-iterator-operations" id="id6" name="id6"><tt class="literal"><span class="pre">permutation_iterator</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#example" id="id7" name="id7">Example</a></li>
</ul>
</div>
<div class="section" id="introduction">
<h1><a class="toc-backref" href="#id2" name="introduction">Introduction</a></h1>
<p>The adaptor takes two arguments:</p>
<blockquote>
<ul class="simple">
<li>an iterator to the range V on which the permutation
will be applied</li>
<li>the reindexing scheme that defines how the
elements of V will be permuted.</li>
</ul>
</blockquote>
<p>Note that the permutation iterator is not limited to strict
permutations of the given range V. The distance between begin and end
of the reindexing iterators is allowed to be smaller compared to the
size of the range V, in which case the permutation iterator only
provides a permutation of a subrange of V. The indexes neither need
to be unique. In this same context, it must be noted that the past the
end permutation iterator is completely defined by means of the
past-the-end iterator to the indices.</p>
</div>
<div class="section" id="reference">
<h1><a class="toc-backref" href="#id3" name="reference">Reference</a></h1>
<pre class="literal-block">
template< class ElementIterator
, class IndexIterator
, class ValueT = use_default
, class CategoryT = use_default
, class ReferenceT = use_default
, class DifferenceT = use_default >
class permutation_iterator
{
public:
permutation_iterator();
explicit permutation_iterator(ElementIterator x, IndexIterator y);
template< class OEIter, class OIIter, class V, class C, class R, class D >
permutation_iterator(
permutation_iterator<OEIter, OIIter, V, C, R, D> const& r
, typename enable_if_convertible<OEIter, ElementIterator>::type* = 0
, typename enable_if_convertible<OIIter, IndexIterator>::type* = 0
);
reference operator*() const;
permutation_iterator& operator++();
ElementIterator const& base() const;
private:
ElementIterator m_elt; // exposition only
IndexIterator m_order; // exposition only
};
template <class ElementIterator, class IndexIterator>
permutation_iterator<ElementIterator, IndexIterator>
make_permutation_iterator( ElementIterator e, IndexIterator i);
</pre>
<div class="section" id="permutation-iterator-requirements">
<h2><a class="toc-backref" href="#id4" name="permutation-iterator-requirements"><tt class="literal"><span class="pre">permutation_iterator</span></tt> requirements</a></h2>
<p><tt class="literal"><span class="pre">ElementIterator</span></tt> shall model Random Access Traversal Iterator.
<tt class="literal"><span class="pre">IndexIterator</span></tt> shall model Readable Iterator. The value type of
the <tt class="literal"><span class="pre">IndexIterator</span></tt> must be convertible to the difference type of
<tt class="literal"><span class="pre">ElementIterator</span></tt>.</p>
</div>
<div class="section" id="permutation-iterator-models">
<h2><a class="toc-backref" href="#id5" name="permutation-iterator-models"><tt class="literal"><span class="pre">permutation_iterator</span></tt> models</a></h2>
<p><tt class="literal"><span class="pre">permutation_iterator</span></tt> models the same iterator traversal concepts
as <tt class="literal"><span class="pre">IndexIterator</span></tt> and the same iterator access concepts as
<tt class="literal"><span class="pre">ElementIterator</span></tt>.</p>
<p>If <tt class="literal"><span class="pre">IndexIterator</span></tt> models Single Pass Iterator and
<tt class="literal"><span class="pre">ElementIterator</span></tt> models Readable Iterator then
<tt class="literal"><span class="pre">permutation_iterator</span></tt> models Input Iterator.</p>
<p>If <tt class="literal"><span class="pre">IndexIterator</span></tt> models Forward Traversal Iterator and
<tt class="literal"><span class="pre">ElementIterator</span></tt> models Readable Lvalue Iterator then
<tt class="literal"><span class="pre">permutation_iterator</span></tt> models Forward Iterator.</p>
<p>If <tt class="literal"><span class="pre">IndexIterator</span></tt> models Bidirectional Traversal Iterator and
<tt class="literal"><span class="pre">ElementIterator</span></tt> models Readable Lvalue Iterator then
<tt class="literal"><span class="pre">permutation_iterator</span></tt> models Bidirectional Iterator.</p>
<p>If <tt class="literal"><span class="pre">IndexIterator</span></tt> models Random Access Traversal Iterator and
<tt class="literal"><span class="pre">ElementIterator</span></tt> models Readable Lvalue Iterator then
<tt class="literal"><span class="pre">permutation_iterator</span></tt> models Random Access Iterator.</p>
<p><tt class="literal"><span class="pre">permutation_iterator<E1,</span> <span class="pre">X,</span> <span class="pre">V1,</span> <span class="pre">C2,</span> <span class="pre">R1,</span> <span class="pre">D1></span></tt> is interoperable
with <tt class="literal"><span class="pre">permutation_iterator<E2,</span> <span class="pre">Y,</span> <span class="pre">V2,</span> <span class="pre">C2,</span> <span class="pre">R2,</span> <span class="pre">D2></span></tt> if and only if
<tt class="literal"><span class="pre">X</span></tt> is interoperable with <tt class="literal"><span class="pre">Y</span></tt> and <tt class="literal"><span class="pre">E1</span></tt> is convertible
to <tt class="literal"><span class="pre">E2</span></tt>.</p>
</div>
<div class="section" id="permutation-iterator-operations">
<h2><a class="toc-backref" href="#id6" name="permutation-iterator-operations"><tt class="literal"><span class="pre">permutation_iterator</span></tt> operations</a></h2>
<p>In addition to those operations required by the concepts that
<tt class="literal"><span class="pre">permutation_iterator</span></tt> models, <tt class="literal"><span class="pre">permutation_iterator</span></tt> provides the
following operations.</p>
<p><tt class="literal"><span class="pre">permutation_iterator();</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">Default constructs <tt class="literal"><span class="pre">m_elt</span></tt> and <tt class="literal"><span class="pre">m_order</span></tt>.</td>
</tr>
</tbody>
</table>
<p><tt class="literal"><span class="pre">explicit</span> <span class="pre">permutation_iterator(ElementIterator</span> <span class="pre">x,</span> <span class="pre">IndexIterator</span> <span class="pre">y);</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">Constructs <tt class="literal"><span class="pre">m_elt</span></tt> from <tt class="literal"><span class="pre">x</span></tt> and <tt class="literal"><span class="pre">m_order</span></tt> from <tt class="literal"><span class="pre">y</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template< class OEIter, class OIIter, class V, class C, class R, class D >
permutation_iterator(
permutation_iterator<OEIter, OIIter, V, C, R, D> const& r
, typename enable_if_convertible<OEIter, ElementIterator>::type* = 0
, typename enable_if_convertible<OIIter, IndexIterator>::type* = 0
);
</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">Effects:</th><td class="field-body">Constructs <tt class="literal"><span class="pre">m_elt</span></tt> from <tt class="literal"><span class="pre">r.m_elt</span></tt> and
<tt class="literal"><span class="pre">m_order</span></tt> from <tt class="literal"><span class="pre">y.m_order</span></tt>.</td>
</tr>
</tbody>
</table>
<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_elt</span> <span class="pre">+</span> <span class="pre">*m_order)</span></tt></td>
</tr>
</tbody>
</table>
<p><tt class="literal"><span class="pre">permutation_iterator&</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_order</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>
<p><tt class="literal"><span class="pre">ElementIterator</span> <span class="pre">const&</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_order</span></tt></td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template <class ElementIterator, class IndexIterator>
permutation_iterator<ElementIterator, IndexIterator>
make_permutation_iterator(ElementIterator e, IndexIterator i);
</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"><tt class="literal"><span class="pre">permutation_iterator<ElementIterator,</span> <span class="pre">IndexIterator>(e,</span> <span class="pre">i)</span></tt></td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="section" id="example">
<h1><a class="toc-backref" href="#id7" name="example">Example</a></h1>
<pre class="literal-block">
using namespace boost;
int i = 0;
typedef std::vector< int > element_range_type;
typedef std::list< int > index_type;
static const int element_range_size = 10;
static const int index_size = 4;
element_range_type elements( element_range_size );
for(element_range_type::iterator el_it = elements.begin() ; el_it != elements.end() ; ++el_it)
*el_it = std::distance(elements.begin(), el_it);
index_type indices( index_size );
for(index_type::iterator i_it = indices.begin() ; i_it != indices.end() ; ++i_it )
*i_it = element_range_size - index_size + std::distance(indices.begin(), i_it);
std::reverse( indices.begin(), indices.end() );
typedef permutation_iterator< element_range_type::iterator, index_type::iterator > permutation_type;
permutation_type begin = make_permutation_iterator( elements.begin(), indices.begin() );
permutation_type it = begin;
permutation_type end = make_permutation_iterator( elements.begin(), indices.end() );
std::cout << "The original range is : ";
std::copy( elements.begin(), elements.end(), std::ostream_iterator< int >( std::cout, " " ) );
std::cout << "\n";
std::cout << "The reindexing scheme is : ";
std::copy( indices.begin(), indices.end(), std::ostream_iterator< int >( std::cout, " " ) );
std::cout << "\n";
std::cout << "The permutated range is : ";
std::copy( begin, end, std::ostream_iterator< int >( std::cout, " " ) );
std::cout << "\n";
std::cout << "Elements at even indices in the permutation : ";
it = begin;
for(i = 0; i < index_size / 2 ; ++i, it+=2 ) std::cout << *it << " ";
std::cout << "\n";
std::cout << "Permutation backwards : ";
it = begin + (index_size);
assert( it != begin );
for( ; it-- != begin ; ) std::cout << *it << " ";
std::cout << "\n";
std::cout << "Iterate backward with stride 2 : ";
it = begin + (index_size - 1);
for(i = 0 ; i < index_size / 2 ; ++i, it-=2 ) std::cout << *it << " ";
std::cout << "\n";
</pre>
<p>The output is:</p>
<pre class="literal-block">
The original range is : 0 1 2 3 4 5 6 7 8 9
The reindexing scheme is : 9 8 7 6
The permutated range is : 9 8 7 6
Elements at even indices in the permutation : 9 7
Permutation backwards : 6 7 8 9
Iterate backward with stride 2 : 6 8
</pre>
<p>The source code for this example can be found <a class="reference" href="../example/permutation_iter_example.cpp">here</a>.</p>
</div>
</div>
<hr class="footer" />
<div class="footer">
<a class="reference" href="permutation_iterator.rst">View document source</a>.
Generated by <a class="reference" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source.
</div>
</body>
</html>
|
