[ceph.git] / ceph / src / boost / libs / iterator / doc / RandomAccessTraversal.html

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<h1 class="title">Random Access Traversal Concept</h1>

<!-- Copyright David Abrahams 2006. Distributed under the Boost -->
<!-- Software License, Version 1.0. (See accompanying -->
<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
<p>A class or built-in type <tt class="docutils literal"><span class="pre">X</span></tt> models the <em>Random Access Traversal</em>
concept if the following expressions are valid and respect the stated
semantics.  In the table below, <tt class="docutils literal"><span class="pre">Distance</span></tt> is
<tt class="docutils literal"><span class="pre">iterator_traits&lt;X&gt;::difference_type</span></tt> and <tt class="docutils literal"><span class="pre">n</span></tt> represents a
constant object of type <tt class="docutils literal"><span class="pre">Distance</span></tt>.</p>
<table border="1" class="docutils">
<colgroup>
<col width="28%" />
<col width="30%" />
<col width="23%" />
<col width="20%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head" colspan="4">Random Access Traversal Iterator Requirements (in addition to Bidirectional Traversal)</th>
</tr>
<tr><th class="head">Expression</th>
<th class="head">Return Type</th>
<th class="head">Operational Semantics</th>
<th class="head">Assertion/
Precondition</th>
</tr>
</thead>
<tbody valign="top">
<tr><td><tt class="docutils literal"><span class="pre">r</span> <span class="pre">+=</span> <span class="pre">n</span></tt></td>
<td><tt class="docutils literal"><span class="pre">X&amp;</span></tt></td>
<td><pre class="first last literal-block">
{
  Distance m = n;
  if (m &gt;= 0)
    while (m--)
      ++r;
  else
    while (m++)
      --r;
  return r;
}
</pre>
</td>
<td>&nbsp;</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">+</span> <span class="pre">n</span></tt>, <tt class="docutils literal"><span class="pre">n</span> <span class="pre">+</span> <span class="pre">a</span></tt></td>
<td><tt class="docutils literal"><span class="pre">X</span></tt></td>
<td><tt class="docutils literal"><span class="pre">{</span> <span class="pre">X</span> <span class="pre">tmp</span> <span class="pre">=</span> <span class="pre">a;</span> <span class="pre">return</span> <span class="pre">tmp</span>
<span class="pre">+=</span> <span class="pre">n;</span> <span class="pre">}</span></tt></td>
<td>&nbsp;</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">r</span> <span class="pre">-=</span> <span class="pre">n</span></tt></td>
<td><tt class="docutils literal"><span class="pre">X&amp;</span></tt></td>
<td><tt class="docutils literal"><span class="pre">return</span> <span class="pre">r</span> <span class="pre">+=</span> <span class="pre">-n</span></tt></td>
<td>&nbsp;</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">-</span> <span class="pre">n</span></tt></td>
<td><tt class="docutils literal"><span class="pre">X</span></tt></td>
<td><tt class="docutils literal"><span class="pre">{</span> <span class="pre">X</span> <span class="pre">tmp</span> <span class="pre">=</span> <span class="pre">a;</span> <span class="pre">return</span> <span class="pre">tmp</span>
<span class="pre">-=</span> <span class="pre">n;</span> <span class="pre">}</span></tt></td>
<td>&nbsp;</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">b</span> <span class="pre">-</span> <span class="pre">a</span></tt></td>
<td><tt class="docutils literal"><span class="pre">Distance</span></tt></td>
<td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">&lt;</span> <span class="pre">b</span> <span class="pre">?</span>&nbsp; <span class="pre">distance(a,b)</span>
<span class="pre">:</span> <span class="pre">-distance(b,a)</span></tt></td>
<td>pre: there exists a
value <tt class="docutils literal"><span class="pre">n</span></tt> of
<tt class="docutils literal"><span class="pre">Distance</span></tt> such that
<tt class="docutils literal"><span class="pre">a</span> <span class="pre">+</span> <span class="pre">n</span> <span class="pre">==</span> <span class="pre">b</span></tt>.  <tt class="docutils literal"><span class="pre">b</span>
<span class="pre">==</span> <span class="pre">a</span> <span class="pre">+</span> <span class="pre">(b</span> <span class="pre">-</span> <span class="pre">a)</span></tt>.</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a[n]</span></tt></td>
<td>convertible to T</td>
<td><tt class="docutils literal"><span class="pre">*(a</span> <span class="pre">+</span> <span class="pre">n)</span></tt></td>
<td>pre: a is a <em>Readable
Iterator</em></td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a[n]</span> <span class="pre">=</span> <span class="pre">v</span></tt></td>
<td>convertible to T</td>
<td><tt class="docutils literal"><span class="pre">*(a</span> <span class="pre">+</span> <span class="pre">n)</span> <span class="pre">=</span> <span class="pre">v</span></tt></td>
<td>pre: a is a <em>Writable
iterator</em></td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">&lt;</span> <span class="pre">b</span></tt></td>
<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td><tt class="docutils literal"><span class="pre">b</span> <span class="pre">-</span> <span class="pre">a</span> <span class="pre">&gt;</span> <span class="pre">0</span></tt></td>
<td><tt class="docutils literal"><span class="pre">&lt;</span></tt> is a total
ordering relation</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">&gt;</span> <span class="pre">b</span></tt></td>
<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td><tt class="docutils literal"><span class="pre">b</span> <span class="pre">&lt;</span> <span class="pre">a</span></tt></td>
<td><tt class="docutils literal"><span class="pre">&gt;</span></tt> is a total
ordering relation</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">&gt;=</span> <span class="pre">b</span></tt></td>
<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td><tt class="docutils literal"><span class="pre">!(a</span> <span class="pre">&lt;</span> <span class="pre">b)</span></tt></td>
<td>&nbsp;</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">&lt;=</span> <span class="pre">b</span></tt></td>
<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td><tt class="docutils literal"><span class="pre">!(a</span> <span class="pre">&gt;</span> <span class="pre">b)</span></tt></td>
<td>&nbsp;</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">iterator_traversal&lt;X&gt;::type</span></tt></td>
<td>Convertible to
<tt class="docutils literal"><span class="pre">random_access_traversal_tag</span></tt></td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
</div>
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<a class="reference external" href="RandomAccessTraversal.rst">View document source</a>.
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Commit	Line	Data
7c673cae FG	1	<?xml version="1.0" encoding="utf-8" ?>
	2	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
	3	<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
	4	<head>
	5	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	6	<meta name="generator" content="Docutils 0.5: http://docutils.sourceforge.net/" />
	7	<title>Random Access Traversal Concept</title>
	8	<link rel="stylesheet" href="../../../rst.css" type="text/css" />
	9	</head>
	10	<body>
	11	<div class="document" id="random-access-traversal-concept">
	12	<h1 class="title">Random Access Traversal Concept</h1>
	13
	14	<!-- Copyright David Abrahams 2006. Distributed under the Boost -->
	15	<!-- Software License, Version 1.0. (See accompanying -->
	16	<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
	17	<p>A class or built-in type <tt class="docutils literal"><span class="pre">X</span></tt> models the <em>Random Access Traversal</em>
	18	concept if the following expressions are valid and respect the stated
	19	semantics. In the table below, <tt class="docutils literal"><span class="pre">Distance</span></tt> is
	20	<tt class="docutils literal"><span class="pre">iterator_traits<X>::difference_type</span></tt> and <tt class="docutils literal"><span class="pre">n</span></tt> represents a
	21	constant object of type <tt class="docutils literal"><span class="pre">Distance</span></tt>.</p>
	22	<table border="1" class="docutils">
	23	<colgroup>
	24	<col width="28%" />
	25	<col width="30%" />
	26	<col width="23%" />
	27	<col width="20%" />
	28	</colgroup>
	29	<thead valign="bottom">
	30	<tr><th class="head" colspan="4">Random Access Traversal Iterator Requirements (in addition to Bidirectional Traversal)</th>
	31	</tr>
	32	<tr><th class="head">Expression</th>
	33	<th class="head">Return Type</th>
	34	<th class="head">Operational Semantics</th>
	35	<th class="head">Assertion/
	36	Precondition</th>
	37	</tr>
	38	</thead>
	39	<tbody valign="top">
	40	<tr><td><tt class="docutils literal"><span class="pre">r</span> <span class="pre">+=</span> <span class="pre">n</span></tt></td>
	41	<td><tt class="docutils literal"><span class="pre">X&</span></tt></td>
	42	<td><pre class="first last literal-block">
	43	{
	44	Distance m = n;
	45	if (m >= 0)
	46	while (m--)
	47	++r;
	48	else
	49	while (m++)
	50	--r;
	51	return r;
	52	}
	53	</pre>
	54	</td>
	55	<td> </td>
	56	</tr>
	57	<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">+</span> <span class="pre">n</span></tt>, <tt class="docutils literal"><span class="pre">n</span> <span class="pre">+</span> <span class="pre">a</span></tt></td>
	58	<td><tt class="docutils literal"><span class="pre">X</span></tt></td>
	59	<td><tt class="docutils literal"><span class="pre">{</span> <span class="pre">X</span> <span class="pre">tmp</span> <span class="pre">=</span> <span class="pre">a;</span> <span class="pre">return</span> <span class="pre">tmp</span>
	60	<span class="pre">+=</span> <span class="pre">n;</span> <span class="pre">}</span></tt></td>
	61	<td> </td>
	62	</tr>
	63	<tr><td><tt class="docutils literal"><span class="pre">r</span> <span class="pre">-=</span> <span class="pre">n</span></tt></td>
	64	<td><tt class="docutils literal"><span class="pre">X&</span></tt></td>
65	<td><tt class="docutils literal"><span class="pre">return</span> <span class="pre">r</span> <span class="pre">+=</span> <span class="pre">-n</span></tt></td>
66	<td> </td>
67	</tr>
68	<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">-</span> <span class="pre">n</span></tt></td>
69	<td><tt class="docutils literal"><span class="pre">X</span></tt></td>
70	<td><tt class="docutils literal"><span class="pre">{</span> <span class="pre">X</span> <span class="pre">tmp</span> <span class="pre">=</span> <span class="pre">a;</span> <span class="pre">return</span> <span class="pre">tmp</span>
71	<span class="pre">-=</span> <span class="pre">n;</span> <span class="pre">}</span></tt></td>
72	<td> </td>
73	</tr>
74	<tr><td><tt class="docutils literal"><span class="pre">b</span> <span class="pre">-</span> <span class="pre">a</span></tt></td>
75	<td><tt class="docutils literal"><span class="pre">Distance</span></tt></td>
76	<td><tt class="docutils literal"><span class="pre">a</span> <span class="pre"><</span> <span class="pre">b</span> <span class="pre">?</span>  <span class="pre">distance(a,b)</span>
77	<span class="pre">:</span> <span class="pre">-distance(b,a)</span></tt></td>
78	<td>pre: there exists a
79	value <tt class="docutils literal"><span class="pre">n</span></tt> of
80	<tt class="docutils literal"><span class="pre">Distance</span></tt> such that
81	<tt class="docutils literal"><span class="pre">a</span> <span class="pre">+</span> <span class="pre">n</span> <span class="pre">==</span> <span class="pre">b</span></tt>. <tt class="docutils literal"><span class="pre">b</span>
82	<span class="pre">==</span> <span class="pre">a</span> <span class="pre">+</span> <span class="pre">(b</span> <span class="pre">-</span> <span class="pre">a)</span></tt>.</td>
83	</tr>
84	<tr><td><tt class="docutils literal"><span class="pre">a[n]</span></tt></td>
85	<td>convertible to T</td>
86	<td><tt class="docutils literal"><span class="pre">*(a</span> <span class="pre">+</span> <span class="pre">n)</span></tt></td>
87	<td>pre: a is a <em>Readable
88	Iterator</em></td>
89	</tr>
90	<tr><td><tt class="docutils literal"><span class="pre">a[n]</span> <span class="pre">=</span> <span class="pre">v</span></tt></td>
91	<td>convertible to T</td>
92	<td><tt class="docutils literal"><span class="pre">*(a</span> <span class="pre">+</span> <span class="pre">n)</span> <span class="pre">=</span> <span class="pre">v</span></tt></td>
93	<td>pre: a is a <em>Writable
94	iterator</em></td>
95	</tr>
96	<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre"><</span> <span class="pre">b</span></tt></td>
97	<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
98	<td><tt class="docutils literal"><span class="pre">b</span> <span class="pre">-</span> <span class="pre">a</span> <span class="pre">></span> <span class="pre">0</span></tt></td>
99	<td><tt class="docutils literal"><span class="pre"><</span></tt> is a total
100	ordering relation</td>
101	</tr>
102	<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">></span> <span class="pre">b</span></tt></td>
103	<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
104	<td><tt class="docutils literal"><span class="pre">b</span> <span class="pre"><</span> <span class="pre">a</span></tt></td>
105	<td><tt class="docutils literal"><span class="pre">></span></tt> is a total
106	ordering relation</td>
107	</tr>
108	<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre">>=</span> <span class="pre">b</span></tt></td>
109	<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
110	<td><tt class="docutils literal"><span class="pre">!(a</span> <span class="pre"><</span> <span class="pre">b)</span></tt></td>
111	<td> </td>
112	</tr>
113	<tr><td><tt class="docutils literal"><span class="pre">a</span> <span class="pre"><=</span> <span class="pre">b</span></tt></td>
114	<td>convertible to <tt class="docutils literal"><span class="pre">bool</span></tt></td>
115	<td><tt class="docutils literal"><span class="pre">!(a</span> <span class="pre">></span> <span class="pre">b)</span></tt></td>
116	<td> </td>
117	</tr>
118	<tr><td><tt class="docutils literal"><span class="pre">iterator_traversal<X>::type</span></tt></td>
119	<td>Convertible to
120	<tt class="docutils literal"><span class="pre">random_access_traversal_tag</span></tt></td>
121	<td> </td>
122	<td> </td>
123	</tr>
124	</tbody>
125	</table>
126	</div>
127	<div class="footer">
128	<hr class="footer" />
129	<a class="reference external" href="RandomAccessTraversal.rst">View document source</a>.
130	Generated by <a class="reference external" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference external" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source.
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