<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML> <HEAD> <TITLE>Simple Segregated Storage Implementation</TITLE> <LINK HREF="../pool.css" REL="stylesheet" TYPE="text/css"> </HEAD> <BODY> <IMG SRC="../../../../c++boost.gif" WIDTH=276 HEIGHT=86 ALT="C++ Boost"> <H1 ALIGN=CENTER>Simple Segregated Storage Implementation</H1> <P> <H2>Dependencies</H2> <P> Includes the system headers <SPAN CLASS="code"><cstddef></SPAN> and <SPAN CLASS="code"><functional></SPAN>. <P> <H2>Protected Interface</H2> <P> <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> <P> <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> 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> 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> <P> <HR> <P> Copyright © 2000, 2001 Stephen Cleary (scleary AT jerviswebb DOT com) <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. </BODY> </HTML>