/usr/bin/gperf

GNU 'gperf' generates perfect hash functions.

Usage: /usr/bin/gperf [OPTION]... [INPUT-FILE]

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

Output file location:
      --output-file=FILE Write output to specified file.
The results are written to standard output if no output file is specified
or if it is -.

Input file interpretation:
  -e, --delimiters=DELIMITER-LIST
                         Allow user to provide a string containing delimiters
                         used to separate keywords from their attributes.
                         Default is ",".
  -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.
      --ignore-case      Consider upper and lower case ASCII characters as
                         equivalent. Note that locale dependent case mappings
                         are ignored.

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 ANSI-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-function-name=NAME
                         Specify name of generated hash function. Default is
                         'hash'.
  -N, --lookup-function-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.
  -l, --compare-lengths  Compare key lengths before trying a string
                         comparison. This is necessary if the keywords
                         contain NUL bytes. It also helps cut down on the
                         number of string comparisons made during the lookup.
  -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-table     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).
  -P, --pic              Optimize the generated table for inclusion in shared
                         libraries.  This reduces the startup time of programs
                         using a shared library containing the generated code.
  -Q, --string-pool-name=NAME
                         Specify name of string pool generated by option --pic.
                         Default name is 'stringpool'.
      --null-strings     Use NULL strings instead of empty strings for empty
                         keyword table entries.
      --constants-prefix=PREFIX
                         Specify prefix for the constants like TOTAL_KEYWORDS.
  -W, --word-array-name=NAME
                         Specify name of word list array. Default name is
                         'wordlist'.
      --length-table-name=NAME
                         Specify name of length table array. Default name is
                         'lengthtable'.
  -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 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 1-255, 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.
  -D, --duplicates       Handle keywords that hash to duplicate values. This
                         is useful for certain highly redundant keyword sets.
  -m, --multiple-iterations=ITERATIONS
                         Perform multiple choices of the -i and -j values,
                         and choose the best results. This increases the
                         running time by a factor of ITERATIONS but does a
                         good job minimizing the generated table size.
  -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.
  -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 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 1/3 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).

Report bugs to <bug-gperf@gnu.org>.