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+<html>
+  <head>
+    <meta content="text/html; charset=windows-1252" http-equiv="content-type">
+    <title>BOOST_PP_FOR_r</title>
+    <link rel="stylesheet" type="text/css" href="../styles.css">
+  </head>
+  <body>
+    <div style="margin-left:  0px;"> The <b>BOOST_PP_FOR_<i>r</i></b> macro
+      represents a reentry into the <b>BOOST_PP_FOR</b> repetition construct. </div>
+    <h4>Usage</h4>
+    <div class="code"> <b>BOOST_PP_FOR_</b> ## <i>r</i>(<i>state</i>, <i>pred</i>,
+      <i>op</i>, <i>macro</i>) </div>
+    <h4>Arguments</h4>
+    <dl>
+      <dt>r</dt>
+      <dd> The next available <b>BOOST_PP_FOR</b> repetition. </dd>
+      <dt>state</dt>
+      <dd> The initial state. </dd>
+      <dt>pred</dt>
+      <dd> A binary predicate of the form <i>pred</i>(<i>r</i>, <i>state</i>).&nbsp;
+        This macro must expand to an integer in the range of <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.&nbsp;
+        <b>BOOST_PP_FOR</b> repeatedly expands <i>macro</i> while this
+        predicate returns non-zero.&nbsp; This macro is called with the next
+        available <b>BOOST_PP_FOR</b> repetition and the current <i>state</i>.
+      </dd>
+      <dt>op</dt>
+      <dd> A binary operation of the form <i>op</i>(<i>r</i>, <i>state</i>).&nbsp;
+        This operation is expanded by <b>BOOST_PP_FOR</b> with the next
+        available <b>BOOST_PP_FOR</b> repetition and the current <i>state</i>.&nbsp;
+        This macro is repeatedly applied to the <i>state</i>, each time
+        producing a new <i>state</i>, until <i>pred</i> returns <i>0</i>. </dd>
+      <dt>macro</dt>
+      <dd> A binary macro of the form <i>macro</i>(<i>r</i>, <i>state</i>).&nbsp;
+        This macro is expanded by <b>BOOST_PP_FOR</b> with the next available <b>BOOST_PP_FOR</b>
+        repetition and the current <i>state</i>.&nbsp; This macro is is
+        repeated by <b>BOOST_PP_FOR</b> until <i>pred</i> returns <i>0</i>. </dd>
+    </dl>
+    <h4>Remarks</h4>
+    <div> This macro expands to the sequence:
+      <div> <i>macro</i>(<i>r</i>, <i>state</i>) <i>macro</i>(<i>r</i>, <i>op</i>(<i>r</i>,
+        <i>state</i>)) ... <i>macro</i>(<i>r</i>, <i>op</i>(<i>r</i>, ... <i>op</i>(<i>r</i>,
+        <i>state</i>) ... )) </div>
+    </div>
+    <div> At certain times, it may be necessary to perform the concatenation
+      with <b>BOOST_PP_CAT</b> rather than the preprocessor token-pasting
+      operator.&nbsp; This happens when the <i>r</i> value is a macro
+      invocation itself.&nbsp; It needs a delay to allow it to expand.&nbsp; The
+      syntax in such a scenario becomes:
+      <div> <b>BOOST_PP_CAT</b>(<b>BOOST_PP_FOR_</b>, <i>r</i>)(<i>state</i>,
+        <i>pred</i>, <i>op</i>, <i>macro</i>) </div>
+    </div>
+    <h4>See Also</h4>
+    <ul>
+      <li><a href="cat.html">BOOST_PP_CAT</a></li>
+      <li><a href="for.html">BOOST_PP_FOR</a></li>
+      <li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
+      <li><a href="for_r_macros.html"><span style="color: gray;">Macros with R
+            re-entrancy forms</span></a></li>
+    </ul>
+    <h4>Requirements</h4>
+    <div> <b>Header:</b> &nbsp;<a href="../headers/repetition/for.html">&lt;boost/preprocessor/repetition/for.hpp&gt;</a>
+    </div>
+    <h4>Sample Code</h4>
+    <div>
+      <pre>#include &lt;<a href="../headers/arithmetic/dec.html">boost/preprocessor/arithmetic/dec.hpp</a>&gt;
+#include &lt;<a href="../headers/arithmetic/inc.html">boost/preprocessor/arithmetic/inc.hpp</a>&gt;
+#include &lt;<a href="../headers/comparison/not_equal.html">boost/preprocessor/comparison/not_equal.hpp</a>&gt;
+#include &lt;<a href="../headers/punctuation/comma_if.html">boost/preprocessor/punctuation/comma_if.hpp</a>&gt;
+#include &lt;<a href="../headers/repetition/for.html">boost/preprocessor/repetition/for.hpp</a>&gt;
+#include &lt;<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>&gt;
+
+#define PRED(r, state) \
+   <a href="not_equal.html">BOOST_PP_NOT_EQUAL</a>( \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, state), \
+      <a href="inc.html">BOOST_PP_INC</a>( \
+         <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 1, state) \
+      ) \
+   ) \
+   /**/
+
+#define OP(r, state) \
+   ( \
+      <a href="inc.html">BOOST_PP_INC</a>( \
+         <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, state) \
+      ), \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 1, state), \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 2, state), \
+      <a href="inc.html">BOOST_PP_INC</a>( \
+         <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 3, state) \
+      ) \
+   ) \
+   /**/
+
+#define MACRO(r, state) \
+   <a href="comma_if.html">BOOST_PP_COMMA_IF</a>( \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 3, state) \
+   ) template&lt; \
+      <a href="for_r.html">BOOST_PP_FOR_</a> ## r( \
+         (0, <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, state), _, 0), \
+         PRED_2, OP, MACRO_2 \
+      ) \
+   &gt; class <a href="cat.html">BOOST_PP_CAT</a>( \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 2, state), \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, state) \
+   ) \
+   /**/
+
+#define PRED_2(r, state) \
+   <a href="not_equal.html">BOOST_PP_NOT_EQUAL</a>( \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, state), \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 1, state) \
+   ) \
+   /**/
+
+#define MACRO_2(r, state) \
+   <a href="comma_if.html">BOOST_PP_COMMA_IF</a>( \
+      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, state) \
+   ) class \
+   /**/
+
+#define TEMPLATE_TEMPLATE(low, high, name) \
+   <a href="for.html">BOOST_PP_FOR</a>( \
+      (low, high, name, 0), \
+      PRED, OP, MACRO \
+   ) \
+   /**/
+
+TEMPLATE_TEMPLATE(2, 4, T)
+/*
+   expands to...
+   template&lt;class, class&gt; class T2,
+   template&lt;class, class, class&gt; class T3,
+   template&lt;class, class, class, class&gt; class T4
+*/
+</pre></div>
+    <hr size="1">
+    <div style="margin-left: 0px;"> <i>© Copyright <a href="http://www.housemarque.com"
+          target="_top">Housemarque Oy</a> 2002</i> <br>
+      <i>© Copyright Paul Mensonides 2002<br>
+      </i><i>© Copyright Edward Diener 2014</i><br>
+    </div>
+    <div style="margin-left: 0px;">
+      <p><small>Distributed under the Boost Software License, Version 1.0. (See
+          accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
+          or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+    </div>
+  </body>
+</html>