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.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.022.
.TH GPERF "1" "September 2000" "GNU gperf 2.7.2" FSF
.SH NAME
gperf \- generate a perfect hash function from a key set
.SH SYNOPSIS
.B gperf
[\fIOPTION\fR]... [\fIINPUT-FILE\fR]
.SH DESCRIPTION
GNU `gperf' generates perfect hash functions.
.PP
If a long option shows an argument as mandatory, then it is mandatory
for the equivalent short option also.
.SS "Input file interpretation:"
.TP
\fB\-e\fR, \fB\-\-delimiters\fR=\fIDELIMITER\-LIST\fR
Allow user to provide a string containing delimiters
used to separate keywords from their attributes.
Default is ",\en".
.TP
\fB\-t\fR, \fB\-\-struct\-type\fR
Allows the user to include a structured type
declaration for generated code. Any text before %%
is considered part of the type declaration. Key
words and additional fields may follow this, one
group of fields per line.
.SS "Language for the output code:"
.TP
\fB\-L\fR, \fB\-\-language\fR=\fILANGUAGE\-NAME\fR
Generates code in the specified language. Languages
handled are currently C++, ANSI-C, C, and KR-C. The
default is C.
.SS "Details in the output code:"
.TP
\fB\-K\fR, \fB\-\-slot\-name\fR=\fINAME\fR
Select name of the keyword component in the keyword
structure.
.TP
\fB\-F\fR, \fB\-\-initializer\-suffix\fR=\fIINITIALIZERS\fR
Initializers for additional components in the keyword
structure.
.TP
\fB\-H\fR, \fB\-\-hash\-fn\-name\fR=\fINAME\fR
Specify name of generated hash function. Default is
`hash'.
.TP
\fB\-N\fR, \fB\-\-lookup\-fn\-name\fR=\fINAME\fR
Specify name of generated lookup function. Default
name is `in_word_set'.
.TP
\fB\-Z\fR, \fB\-\-class\-name\fR=\fINAME\fR
Specify name of generated C++ class. Default name is
`Perfect_Hash'.
.TP
\fB\-7\fR, \fB\-\-seven\-bit\fR
Assume 7-bit characters.
.TP
\fB\-c\fR, \fB\-\-compare\-strncmp\fR
Generate comparison code using strncmp rather than
strcmp.
.TP
\fB\-C\fR, \fB\-\-readonly\-tables\fR
Make the contents of generated lookup tables
constant, i.e., readonly.
.TP
\fB\-E\fR, \fB\-\-enum\fR
Define constant values using an enum local to the
lookup function rather than with defines.
.TP
\fB\-I\fR, \fB\-\-includes\fR
Include the necessary system include file <string.h>
at the beginning of the code.
.TP
\fB\-G\fR, \fB\-\-global\fR
Generate the static table of keywords as a static
global variable, rather than hiding it inside of the
lookup function (which is the default behavior).
.TP
\fB\-W\fR, \fB\-\-word\-array\-name\fR=\fINAME\fR
Specify name of word list array. Default name is
`wordlist'.
.TP
\fB\-S\fR, \fB\-\-switch\fR=\fICOUNT\fR
Causes the generated C code to use a switch
statement scheme, rather than an array lookup table.
This can lead to a reduction in both time and space
requirements for some keyfiles. The COUNT argument
determines how many switch statements are generated.
A value of 1 generates 1 switch containing all the
elements, a value of 2 generates 2 tables with 1/2
the elements in each table, etc. If COUNT is very
large, say 1000000, the generated C code does a
binary search.
.TP
\fB\-T\fR, \fB\-\-omit\-struct\-type\fR
Prevents the transfer of the type declaration to the
output file. Use this option if the type is already
defined elsewhere.
.SS "Algorithm employed by gperf:"
.TP
\fB\-k\fR, \fB\-\-key\-positions\fR=\fIKEYS\fR
Select the key positions used in the hash function.
The allowable choices range between 1-126, inclusive.
The positions are separated by commas, ranges may be
used, and key positions may occur in any order.
Also, the meta-character '*' causes the generated
hash function to consider ALL key positions, and $
indicates the ``final character'' of a key, e.g.,
$,1,2,4,6-10.
.TP
\fB\-l\fR, \fB\-\-compare\-strlen\fR
Compare key lengths before trying a string
comparison. This helps cut down on the number of
string comparisons made during the lookup.
.TP
\fB\-D\fR, \fB\-\-duplicates\fR
Handle keywords that hash to duplicate values. This
is useful for certain highly redundant keyword sets.
.TP
\fB\-f\fR, \fB\-\-fast\fR=\fIITERATIONS\fR
Generate the gen-perf.hash function ``fast''. This
decreases gperf's running time at the cost of
minimizing generated table size. The numeric
argument represents the number of times to iterate
when resolving a collision. `0' means ``iterate by
the number of keywords''.
.TP
\fB\-i\fR, \fB\-\-initial\-asso\fR=\fIN\fR
Provide an initial value for the associate values
array. Default is 0. Setting this value larger helps
inflate the size of the final table.
.TP
\fB\-j\fR, \fB\-\-jump\fR=\fIJUMP\-VALUE\fR
Affects the ``jump value'', i.e., how far to advance
the associated character value upon collisions. Must
be an odd number, default is 5.
.TP
\fB\-n\fR, \fB\-\-no\-strlen\fR
Do not include the length of the keyword when
computing the hash function.
.TP
\fB\-o\fR, \fB\-\-occurrence\-sort\fR
Reorders input keys by frequency of occurrence of
the key sets. This should decrease the search time
dramatically.
.TP
\fB\-r\fR, \fB\-\-random\fR
Utilizes randomness to initialize the associated
values table.
.TP
\fB\-s\fR, \fB\-\-size\-multiple\fR=\fIN\fR
Affects the size of the generated hash table. The
numeric argument N indicates ``how many times larger
or smaller'' the associated value range should be,
in relationship to the number of keys, e.g. a value
of 3 means ``allow the maximum associated value to
be about 3 times larger than the number of input
keys.'' Conversely, a value of \fB\-3\fR means ``make the
maximum associated value about 3 times smaller than
the number of input keys. A larger table should
decrease the time required for an unsuccessful
search, at the expense of extra table space. Default
value is 1.
.SS "Informative output:"
.TP
\fB\-h\fR, \fB\-\-help\fR
Print this message.
.TP
\fB\-v\fR, \fB\-\-version\fR
Print the gperf version number.
.TP
\fB\-d\fR, \fB\-\-debug\fR
Enables the debugging option (produces verbose
output to the standard error).
.SH "REPORTING BUGS"
Report bugs to <bug-gnu-utils@gnu.org>.
.SH "SEE ALSO"
The full documentation for
.B gperf
is maintained as a Texinfo manual.  If the
.B info
and
.B gperf
programs are properly installed at your site, the command
.IP
.B info gperf
.PP
should give you access to the complete manual.