Adwaith-Rajesh/gperf
1
0
Fork 0
mirror of https://git.savannah.gnu.org/git/gperf.git synced 2025-12-02 13:09:22 +00:00
Code Activity

regenerated

Browse Source
This commit is contained in:
Brendan Kehoe
2009-02-01 12:23:37 +00:00
parent c9bd4009aa
commit cfbb6bdc79
16 changed files with 7636 additions and 5495 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
doc/gperf_4.html
View File

@@ -1,22 +1,23 @@
<HTML>
<HEAD>
<!-- This HTML file has been created by texi2html 1.51
from gperf.texi on 31 March 2007 -->
<!-- This HTML file has been created by texi2html 1.52b
from gperf.texi on 1 February 2009 -->
<TITLE>Perfect Hash Function Generator - 2 Static search structures and GNU gperf</TITLE>
<META HTTP-EQUIV="content-type" CONTENT="text/html; charset=UTF-8">
<TITLE>Perfect Hash Function Generator - 3 Static search structures and GNU gperf</TITLE>
</HEAD>
<BODY>
Go to the <A HREF="gperf_1.html">first</A>, <A HREF="gperf_3.html">previous</A>, <A HREF="gperf_5.html">next</A>, <A HREF="gperf_10.html">last</A> section, <A HREF="gperf_toc.html">table of contents</A>.
<P><HR><P>
<H1><A NAME="SEC6" HREF="gperf_toc.html#TOC6">2 Static search structures and GNU <CODE>gperf</CODE></A></H1>
<H1><A NAME="SEC4" HREF="gperf_toc.html#TOC4">3 Static search structures and GNU <CODE>gperf</CODE></A></H1>
<P>
<A NAME="IDX2"></A>
</P>
<P>
A <STRONG>static search structure</STRONG> is an Abstract Data Type with certain
A <EM>static search structure</EM> is an Abstract Data Type with certain
fundamental operations, e.g., <EM>initialize</EM>, <EM>insert</EM>,
and <EM>retrieve</EM>. Conceptually, all insertions occur before any
retrievals. In practice, <CODE>gperf</CODE> generates a <EM>static</EM> array
@@ -26,7 +27,7 @@ insertions. It is a useful data structure for representing <EM>static
search sets</EM>. Static search sets occur frequently in software system
applications. Typical static search sets include compiler reserved
words, assembler instruction opcodes, and built-in shell interpreter
commands. Search set members, called <STRONG>keywords</STRONG>, are inserted into
commands. Search set members, called <EM>keywords</EM>, are inserted into
the structure only once, usually during program initialization, and are
not generally modified at run-time.
@@ -55,13 +56,13 @@ function is defined by two properties:
<LI>
It allows keyword recognition in a static search set using at most
<EM>one</EM> probe into the hash table. This represents the "perfect"
<EM>one</EM> probe into the hash table. This represents the “perfect”
property.
<LI>
The actual memory allocated to store the keywords is precisely large
enough for the keyword set, and <EM>no larger</EM>. This is the
"minimal" property.
“minimal” property.
</UL>
<P>
@@ -69,7 +70,7 @@ For most applications it is far easier to generate <EM>perfect</EM> hash
functions than <EM>minimal perfect</EM> hash functions. Moreover,
non-minimal perfect hash functions frequently execute faster than
minimal ones in practice. This phenomena occurs since searching a
sparse keyword table increases the probability of locating a "null"
sparse keyword table increases the probability of locating a “null”
entry, thereby reducing string comparisons. <CODE>gperf</CODE>'s default
behavior generates <EM>near-minimal</EM> perfect hash functions for
keyword sets. However, <CODE>gperf</CODE> provides many options that permit