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<TITLE>Simple Segregated Storage Implementation</TITLE>
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<H1 ALIGN=CENTER>Simple Segregated Storage Implementation</H1>
<P>
<H2>Dependencies</H2>
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Includes the system headers <SPAN CLASS="code"><cstddef></SPAN> and <SPAN CLASS="code"><functional></SPAN>.
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<H2>Protected Interface</H2>
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<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>
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<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.
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<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.
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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>).
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<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>
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.
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<H2><A HREF="../interfaces/simple_segregated_storage.html">Interface Description</A></H2>
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<HR>
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Copyright © 2000, 2001 Stephen Cleary (<A HREF="mailto:shammah@voyager.net">shammah@voyager.net</A>)
<P>
This file can be redistributed and/or modified under the terms found in <A HREF="../copyright.html">copyright.html</A>
<P>
This software and its documentation is provided "as is" without express or implied warranty, and with no claim as to its suitability for any purpose.
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