boostorg/preprocessor
1
0
Fork 1
mirror of https://github.com/boostorg/preprocessor.git synced 2025-07-29 03:37:15 +02:00
Code Issues Packages Projects Releases Wiki Activity

lib cleanup

Browse Source 
[SVN r15693]
This commit is contained in:
Paul Mensonides
2002-10-03 22:13:37 +00:00
parent ae584c68b2
commit 4bb690a819
263 changed files with 14965 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

68
doc/ref/list_fold_right.html Normal file
View File

@ -0,0 +1,68 @@
<html>
<head>
<title>BOOST_PP_LIST_FOLD_RIGHT</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<div style="margin-left: 0px;">
The <b>BOOST_PP_LIST_FOLD_RIGHT</b> macro folds (or accumulates) the elements of a <i>list</i> right-to-left.
</div>
<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_LIST_FOLD_RIGHT</b>(<i>op</i>, <i>state</i>, <i>list</i>)
</div>
<h4>Arguments</h4>
<dl>
<dt>op</dt>
<dd>
A ternary operation of the form <i>op</i>(<i>d</i>, <i>state</i>, <i>elem</i>).&nbsp;
This macro is called for each element in <i>list</i>--each time returning a new <i>state</i>.&nbsp;
This operation is expanded by <b>BOOST_PP_LIST_FOLD_RIGHT</b> with the next available <b>BOOST_PP_WHILE</b> iteration,
the current <i>state</i>, and the current element.
</dd>
<dt>state</dt>
<dd>
The initial state of the fold.
</dd>
<dt>list</dt>
<dd>
The <i>list</i> to be folded.
</dd>
</dl>
<h4>Remarks</h4>
<div>
This macro does not have the same signature as it previously did.&nbsp;
The arguments have been swapped to provide a uniform interface with <b>BOOST_PP_LIST_FOLD_LEFT</b>.
</div>
<div>
For the <i>list</i>, (<i>0</i>, (<i>1</i>, (<i>2</i>, <b>BOOST_PP_NIL</b>))), this macro expands to:
<div>
<i>op</i>(<i>d</i>, <i>op</i>(<i>d</i>, <i>op</i>(<i>d</i>, <i>state</i>, <i>2</i>), <i>1</i>), <i>0</i>)
</div>
</div>
<div>
Previously, this macro could not be used inside <b>BOOST_PP_WHILE</b>.&nbsp;
There is no longer any such restriction.&nbsp;
It is more efficient, however, to use <b>BOOST_PP_LIST_FOLD_RIGHT_<i>d</i></b> in such a situation.
</div>
<h4>See Also</h4>
<ul>
<li><a href="list_fold_right_d.html">BOOST_PP_LIST_FOLD_RIGHT_<i>d</i></a></li>
</ul>
<h4>Requirements</h4>
<div>
<b>Header:</b> &nbsp;<a href="../headers/list/fold_right.hpp.html">&lt;boost/preprocessor/list/fold_right.hpp&gt;</a>
</div>
<h4>Sample Code</h4>
<div><pre>
#include &lt;<a href="../headers/cat.hpp.html">boost/preprocessor/cat.hpp</a>&gt;
#include &lt;<a href="../headers/list/fold_right.html">boost/preprocessor/list/fold_right.hpp</a>&gt;
#define LIST (a, (b, (c, <a href="nil.html">BOOST_PP_NIL</a>)))
#define OP(d, state, x) <a href="cat.html">BOOST_PP_CAT</a>(state, x)
<a href="list_fold_right.html">BOOST_PP_LIST_FOLD_RIGHT</a>(OP, _, LIST) // expands to _cba
</pre></div>
</body>
</html>