gperf man page on FreeBSD

Man page or keyword search:  
man Server   9747 pages
apropos Keyword Search (all sections)
Output format
FreeBSD logo
[printable version]

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	 `Per‐
	      fect_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	 func‐
	      tion 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	 vari‐
	      able, rather than hiding 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 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 ta‐
	      ble, 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	allow‐
	      able  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 associ‐
	      ated  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	 argu‐
	      ment  N indicates ``how many times larger or smaller'' the asso‐
	      ciated 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 -3 means ``make the maximum asso‐
	      ciated 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)
[top]

List of man pages available for FreeBSD

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
...................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net