Manual Pages for UNIX Darwin command on man gperf

GPERF(1) FSF GPERF(1)

NAME

gperf - generate a perfect hash function from a key set

SYNOPSIS

ggppeerrff [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. OOuuttppuutt ffiillee llooccaattiioonn::

--oouuttppuutt-ffiillee=FILE Write output to specified file.

The results are written to standard output if no output file is speci-

fied or if it is -.

IInnppuutt ffiillee iinntteerrpprreettaattiioonn::

-ee, --ddeelliimmiitteerrss=DELIMITER-LIST

Allow user to provide a string containing delimiters used to separate keywords from their attributes. Default is ",".

-tt, --ssttrruucctt-ttyyppee

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.

--iiggnnoorree-ccaassee

Consider upper and lower case ASCII characters as equivalent. Note that locale dependent case mappings are ignored. LLaanngguuaaggee ffoorr tthhee oouuttppuutt ccooddee::

-LL, --llaanngguuaaggee=LANGUAGE-NAME

Generates code in the specified language. Languages handled are

currently C++, ANSI-C, C, and KR-C. The default is C.

DDeettaaiillss iinn tthhee oouuttppuutt ccooddee::

-KK, --sslloott-nnaammee=NAME

Select name of the keyword component in the keyword structure.

-FF, --iinniittiiaalliizzeerr-ssuuffffiixx=INITIALIZERS

Initializers for additional components in the keyword structure.

-HH, --hhaasshh-ffuunnccttiioonn-nnaammee=NAME

Specify name of generated hash function. Default is 'hash'.

-NN, --llooookkuupp-ffuunnccttiioonn-nnaammee=NAME

Specify name of generated lookup function. Default name is 'inwordset'.

-ZZ, --ccllaassss-nnaammee=NAME

Specify name of generated C++ class. Default name is 'Per-

fectHash'.

-77, --sseevveenn-bbiitt

Assume 7-bit characters.

-ll, --ccoommppaarree-lleennggtthhss

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.

-cc, --ccoommppaarree-ssttrrnnccmmpp

Generate comparison code using strncmp rather than strcmp.

-CC, --rreeaaddoonnllyy-ttaabblleess

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

-EE, --eennuumm

Define constant values using an enum local to the lookup func-

tion rather than with defines.

-II, --iinncclluuddeess

Include the necessary system include file at the beginning of the code.

-GG, --gglloobbaall-ttaabbllee

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).

-PP, --ppiicc

Optimize the generated table for inclusion in shared libraries. This reduces the startup time of programs using a shared library containing the generated code.

-QQ, --ssttrriinngg-ppooooll-nnaammee=NAME

Specify name of string pool generated by option --ppiicc. Default

name is 'stringpool'.

--nnuullll-ssttrriinnggss

Use NULL strings instead of empty strings for empty keyword ta-

ble entries.

-WW, --wwoorrdd-aarrrraayy-nnaammee=NAME

Specify name of word list array. Default name is 'wordlist'.

-SS, --sswwiittcchh=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.

-TT, --oommiitt-ssttrruucctt-ttyyppee

Prevents the transfer of the type declaration to the output file. Use this option if the type is already defined elsewhere. AAllggoorriitthhmm eemmppllooyyeedd bbyy ggppeerrff::

-kk, --kkeeyy-ppoossiittiioonnss=KEYS

Select the key positions used in the hash function. The allow-

able 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.

-DD, --dduupplliiccaatteess

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

-mm, --mmuullttiippllee-iitteerraattiioonnss=ITERATIONS

Perform multiple choices of the -ii and -jj 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.

-ii, --iinniittiiaall-aassssoo=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.

-jj, --jjuummpp=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.

-nn, --nnoo-ssttrrlleenn

Do not include the length of the keyword when computing the hash function.

-rr, --rraannddoomm

Utilizes randomness to initialize the associated values table.

-ss, --ssiizzee-mmuullttiippllee=N

Affects the size of the generated hash table. The numeric argu-

ment N indicates "how many times larger or smaller" the associ-

ated 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 unsuccess-

ful search, at the expense of extra table space. Default value is 1. IInnffoorrmmaattiivvee oouuttppuutt::

-hh, --hheellpp

Print this message.

-vv, --vveerrssiioonn

Print the gperf version number.

-dd, --ddeebbuugg

Enables the debugging option (produces verbose output to the standard error). AUTHOR Written by Douglas C. Schmidt and Bruno Haible.

REPORTING BUGS

Report bugs to .

This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.