While teaching a data structures course at University of California,
Irvine, I developed a program called GPERF that generates perfect hash
functions for sets of key words.  A perfect hash function is simply:
 
          A hash function and a data structure that allows
          recognition of a key word in a set of words using
          exactly 1 probe into the data structure.
 
The gperf.texinfo file explains how the program works, the form of the
input, what options are available, and hints on choosing the best
options for particular key word sets.  The texinfo file is readable
both via the GNU emacs `info' command, and is also suitable for
typesetting with TeX.  The texinfo.tex macros needed to run 
gperf.texinfo through TeX are available in the GNU GCC release.  If 
you don't have access to these please email me and I'll send them to
you (about 75k).
 
The enclosed Makefile creates the executable program ``gperf'' and
also runs some tests.
 
Output from the GPERF program is used to recognize reserved words in
the GNU C, GNU C++, and GNU Pascal compilers, as well as with the GNU
indent program.
 
Happy hacking!
 
Douglas C. Schmidt
schmidt@ics.uci.edu
