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OpenDarwin 7.2.1 - man page for gperf (opendarwin section 1)

GPERF(1)				       FSF					 GPERF(1)

NAME
       gperf - generate a perfect hash function from a key set

SYNOPSIS
       gperf [OPTION]... [INPUT-FILE]

DESCRIPTION
       GNU `gperf' generates perfect hash functions.

       If  a  long option shows an argument as mandatory, then it is mandatory for the equivalent
       short option also.

   Input file interpretation:
       -e, --delimiters=DELIMITER-LIST
	      Allow user to provide a string containing delimiters used to separate keywords from
	      their attributes.  Default is ",\n".

       -t, --struct-type
	      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.

   Language for the output code:
       -L, --language=LANGUAGE-NAME
	      Generates  code  in  the	specified  language. Languages handled are currently C++,
	      ANSI-C, C, and KR-C. The default is C.

   Details in the output code:
       -K, --slot-name=NAME
	      Select name of the keyword component in the keyword structure.

       -F, --initializer-suffix=INITIALIZERS
	      Initializers for additional components in the keyword structure.

       -H, --hash-fn-name=NAME
	      Specify name of generated hash function. Default is `hash'.

       -N, --lookup-fn-name=NAME
	      Specify name of generated lookup function. Default name is `in_word_set'.

       -Z, --class-name=NAME
	      Specify name of generated C++ class. Default name is `Perfect_Hash'.

       -7, --seven-bit
	      Assume 7-bit characters.

       -c, --compare-strncmp
	      Generate comparison code using strncmp rather than strcmp.

       -C, --readonly-tables
	      Make the contents of generated lookup tables constant, i.e., readonly.

       -E, --enum
	      Define constant values using an enum local to the lookup function rather than  with
	      defines.

       -I, --includes
	      Include the necessary system include file <string.h> at the beginning of the code.

       -G, --global
	      Generate the static table of keywords as a static global variable, rather than hid-
	      ing it inside of the lookup function (which is the default behavior).

       -W, --word-array-name=NAME
	      Specify name of word list array. Default name is `wordlist'.

       -S, --switch=COUNT
	      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  gener-
	      ated.   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.

       -T, --omit-struct-type
	      Prevents	the  transfer of the type declaration to the output file. Use this option
	      if the type is already defined elsewhere.

   Algorithm employed by gperf:
       -k, --key-positions=KEYS
	      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.

       -l, --compare-strlen
	      Compare key lengths before trying a string comparison. This helps cut down  on  the
	      number of string comparisons made during the lookup.

       -D, --duplicates
	      Handle  keywords	that  hash to duplicate values. This is useful for certain highly
	      redundant keyword sets.

       -f, --fast=ITERATIONS
	      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''.

       -i, --initial-asso=N
	      Provide an initial value for the associate values array. Default is 0. Setting this
	      value larger helps inflate the size of the final table.

       -j, --jump=JUMP-VALUE
	      Affects the ``jump value'', i.e., how far to advance the associated character value
	      upon collisions. Must be an odd number, default is 5.

       -n, --no-strlen
	      Do not include the length of the keyword when computing the hash function.

       -o, --occurrence-sort
	      Reorders	input  keys  by  frequency  of	occurrence  of	the key sets. This should
	      decrease the search time dramatically.

       -r, --random
	      Utilizes randomness to initialize the associated values table.

       -s, --size-multiple=N
	      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 rela-
	      tionship to the number of keys, e.g. a value of 3 means ``allow the maximum associ-
	      ated  value to be about 3 times larger than the number of input keys.'' Conversely,
	      a value of -3 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.

   Informative output:
       -h, --help
	      Print this message.

       -v, --version
	      Print the gperf version number.

       -d, --debug
	      Enables the debugging option (produces verbose output to the standard error).

REPORTING BUGS
       Report bugs to <bug-gnu-utils@gnu.org>.

SEE ALSO
       The full documentation for gperf is maintained as a Texinfo manual.  If the info and gperf
       programs are properly installed at your site, the command

	      info gperf

       should give you access to the complete manual.

GNU gperf 2.7.2 			  September 2000				 GPERF(1)


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