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<title>Simple Segregated Storage Implementation</title>
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<img src="../../../../boost.png" width="276" height="86" alt="C++ Boost">
<h1 align="center">Simple Segregated Storage Implementation</h1>
<h2>Dependencies</h2>
<p>Includes the system headers <span class="code"><cstddef></span>
and <span class="code"><functional></span>.</p>
<h2>Protected Interface</h2>
<h3>Synopsis</h3>
<pre class="code">
template <typename SizeType = std::size_t>
class simple_segregated_storage
{
... // Public interface
protected:
void * first;
static void * & nextof(void * const ptr);
void * find_prev(void * ptr);
};
</pre>
<h3 class="code">void * first;</h3>
<p>This data member is the free list. It points to the first chunk in the
free list, or is equal to 0 if the free list is empty.</p>
<h3 class="code">static void * & nextof(void * const ptr);</h3>
<p>This is a convenience function. It helps clean up code dealing with the
free list by making it more readable. The return value is just <span class=
"code">*ptr</span> cast to the appropriate type. <span class=
"code">ptr</span> must not be 0.</p>
<p>As an example, let us assume that we want to truncate the free list
after the first chunk. That is, we want to set <span class=
"code">*first</span> to 0; this will result in a free list with only one
entry. The normal way to do this is to first cast <span class=
"code">first</span> to a pointer to a pointer to void, and then dereference
and assign (<span class="code">*static_cast<void **>(first) =
0;</span>). This can be done more easily through the use of this
convenience function (<span class="code">nextof(first) = 0;</span>).</p>
<h3 class="code">void * find_prev(void * ptr);</h3>
<p>Traverses the free list referred to by <span class="code">first</span>,
and returns the pointer previous to where <span class="code">ptr</span>
would go if it was in the free list. Returns 0 if <span class=
"code">ptr</span> would go at the beginning of the free list (i.e., before
<span class="code">first</span>).</p>
<p>Note that this function finds the location previous to where
<span class="code">ptr</span> <strong>would</strong> go <strong>if it
was</strong> in the free list. It does <strong>not</strong> find the entry
in the free list before <span class="code">ptr</span> (unless <span class=
"code">ptr</span> is already in the free list). Specifically, <span class=
"code">find_prev(0)</span> will return 0, <strong>not</strong> the last
entry in the free list.</p>
<h2><a href="../interfaces/simple_segregated_storage.html">Interface
Description</a></h2>
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<p>Revised
<!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B, %Y" startspan -->05
December, 2006<!--webbot bot="Timestamp" endspan i-checksum="38516" --></p>
<p><i>Copyright © 2000, 2001 Stephen Cleary (scleary AT jerviswebb DOT
com)</i></p>
<p><i>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">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
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