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diff --git a/doc/gperf.info b/doc/gperf.info index 4f9946f..31bb1c6 100644 --- a/doc/gperf.info +++ b/doc/gperf.info @@ -1,14 +1,14 @@ -This is Info file gperf.info, produced by Makeinfo version 1.68 from -the input file gperf.texi. +This is gperf.info, produced by makeinfo version 4.0 from gperf.texi. +INFO-DIR-SECTION Programming Tools START-INFO-DIR-ENTRY * Gperf: (gperf). Perfect Hash Function Generator. END-INFO-DIR-ENTRY This file documents the features of the GNU Perfect Hash Function -Generator +Generator 2.7.2. - Copyright (C) 1989-1998 Free Software Foundation, Inc. + Copyright (C) 1989-2000 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are @@ -23,10 +23,9 @@ identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified -versions, except that the section entitled "GNU `gperf' General Public -License" and this permission notice may be included in translations -approved by the Free Software Foundation instead of in the original -English. +versions, except that the section entitled "GNU General Public License" +and this permission notice may be included in translations approved by +the Free Software Foundation instead of in the original English. File: gperf.info, Node: Top, Next: Copying, Prev: (dir), Up: (dir) @@ -40,38 +39,40 @@ bugs. * Menu: -* Copying:: GNU `gperf' General Public License says +* Copying:: GNU `gperf' General Public License says how you can copy and share `gperf'. -* Contributors:: People who have contributed to `gperf'. -* Motivation:: Static search structures and GNU GPERF. -* Search Structures:: Static search structures and GNU `gperf' -* Description:: High-level discussion of how GPERF functions. -* Options:: A description of options to the program. -* Bugs:: Known bugs and limitations with GPERF. -* Projects:: Things still left to do. -* Implementation:: Implementation Details for GNU GPERF. -* Bibliography:: Material Referenced in this Report. - - -- The Detailed Node Listing -- +* Contributors:: People who have contributed to `gperf'. +* Motivation:: Static search structures and GNU GPERF. +* Search Structures:: Static search structures and GNU `gperf' +* Description:: High-level discussion of how GPERF functions. +* Options:: A description of options to the program. +* Bugs:: Known bugs and limitations with GPERF. +* Projects:: Things still left to do. +* Implementation:: Implementation Details for GNU GPERF. +* Bibliography:: Material Referenced in this Report. + +* Concept Index:: + High-Level Description of GNU `gperf' -* Input Format:: Input Format to `gperf' -* Output Format:: Output Format for Generated C Code with `gperf' +* Input Format:: Input Format to `gperf' +* Output Format:: Output Format for Generated C Code with `gperf' +* Binary Strings:: Use of NUL characters Input Format to `gperf' -* Declarations:: `struct' Declarations and C Code Inclusion. -* Keywords:: Format for Keyword Entries. -* Functions:: Including Additional C Functions. +* Declarations:: `struct' Declarations and C Code Inclusion. +* Keywords:: Format for Keyword Entries. +* Functions:: Including Additional C Functions. -Options to the `gperf' Utility +Invoking `gperf' -* Input Details:: Options that affect Interpretation of the Input File -* Output Language:: Specifying the Language for the Output Code -* Output Details:: Fine tuning Details in the Output Code -* Algorithmic Details:: Changing the Algorithms employed by `gperf' -* Verbosity:: Informative Output +* Input Details:: Options that affect Interpretation of the Input File +* Output Language:: Specifying the Language for the Output Code +* Output Details:: Fine tuning Details in the Output Code +* Algorithmic Details:: Changing the Algorithms employed by `gperf' +* Verbosity:: Informative Output File: gperf.info, Node: Copying, Next: Contributors, Prev: Top, Up: Top @@ -79,10 +80,10 @@ File: gperf.info, Node: Copying, Next: Contributors, Prev: Top, Up: Top GNU GENERAL PUBLIC LICENSE ************************** - Version 1, February 1989 + Version 2, June 1991 - Copyright (C) 1989 Free Software Foundation, Inc. - 675 Mass Ave, Cambridge, MA 02139, USA + Copyright (C) 1989, 1991 Free Software Foundation, Inc., + 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. @@ -90,30 +91,33 @@ GNU GENERAL PUBLIC LICENSE Preamble ======== - The license agreements of most software companies try to keep users -at the mercy of those companies. By contrast, our General Public + The licenses for most software are designed to take away your +freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free -software--to make sure the software is free for all its users. The -General Public License applies to the Free Software Foundation's -software and to any other program whose authors commit to using it. -You can use it for your programs, too. +software--to make sure the software is free for all its users. This +General Public License applies to most of the Free Software +Foundation's software and to any other program whose authors commit to +using it. (Some other Free Software Foundation software is covered by +the GNU Library General Public License instead.) You can apply it to +your programs, too. When we speak of free software, we are referring to freedom, not -price. Specifically, the General Public License is designed to make -sure that you have the freedom to give away or sell copies of free -software, that you receive source code or can get it if you want it, -that you can change the software or use pieces of it in new free -programs; and that you know you can do these things. +price. Our General Public Licenses are designed to make sure that you +have the freedom to distribute copies of free software (and charge for +this service if you wish), that you receive source code or can get it +if you want it, that you can change the software or use pieces of it in +new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. - For example, if you distribute copies of a such a program, whether + For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the -source code. And you must tell them their rights. +source code. And you must show them these terms so they know their +rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, @@ -126,124 +130,214 @@ want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. + Finally, any free program is threatened constantly by software +patents. We wish to avoid the danger that redistributors of a free +program will individually obtain patent licenses, in effect making the +program proprietary. To prevent this, we have made it clear that any +patent must be licensed for everyone's free use or not licensed at all. + The precise terms and conditions for copying, distribution and modification follow. - TERMS AND CONDITIONS - - 1. This License Agreement applies to any program or other work which - contains a notice placed by the copyright holder saying it may be - distributed under the terms of this General Public License. The - "Program", below, refers to any such program or work, and a "work - based on the Program" means either the Program or any work - containing the Program or a portion of it, either verbatim or with - modifications. Each licensee is addressed as "you". - - 2. You may copy and distribute verbatim copies of the Program's source - code as you receive it, in any medium, provided that you - conspicuously and appropriately publish on each copy an - appropriate copyright notice and disclaimer of warranty; keep - intact all the notices that refer to this General Public License - and to the absence of any warranty; and give any other recipients - of the Program a copy of this General Public License along with - the Program. You may charge a fee for the physical act of - transferring a copy. - - 3. You may modify your copy or copies of the Program or any portion of - it, and copy and distribute such modifications under the terms of - Paragraph 1 above, provided that you also do the following: - - * cause the modified files to carry prominent notices stating - that you changed the files and the date of any change; and - - * cause the whole of any work that you distribute or publish, - that in whole or in part contains the Program or any part - thereof, either with or without modifications, to be licensed - at no charge to all third parties under the terms of this - General Public License (except that you may choose to grant - warranty protection to some or all third parties, at your - option). - - * If the modified program normally reads commands interactively + TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION + + 0. This License applies to any program or other work which contains a + notice placed by the copyright holder saying it may be distributed + under the terms of this General Public License. The "Program", + below, refers to any such program or work, and a "work based on + the Program" means either the Program or any derivative work under + copyright law: that is to say, a work containing the Program or a + portion of it, either verbatim or with modifications and/or + translated into another language. (Hereinafter, translation is + included without limitation in the term "modification".) Each + licensee is addressed as "you". + + Activities other than copying, distribution and modification are + not covered by this License; they are outside its scope. The act + of running the Program is not restricted, and the output from the + Program is covered only if its contents constitute a work based on + the Program (independent of having been made by running the + Program). 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You may copy and distribute the Program (or a portion or - derivative of it, under Paragraph 2) in object code or executable - form under the terms of Paragraphs 1 and 2 above provided that you - also do one of the following: - - * accompany it with the complete corresponding machine-readable + interactive use in the most ordinary way, to print or display + an announcement including an appropriate copyright notice and + a notice that there is no warranty (or else, saying that you + provide a warranty) and that users may redistribute the + program under these conditions, and telling the user how to + view a copy of this License. (Exception: if the Program + itself is interactive but does not normally print such an + announcement, your work based on the Program is not required + to print an announcement.) + + These requirements apply to the modified work as a whole. If + identifiable sections of that work are not derived from the + Program, and can be reasonably considered independent and separate + works in themselves, then this License, and its terms, do not + apply to those sections when you distribute them as separate + works. But when you distribute the same sections as part of a + whole which is a work based on the Program, the distribution of + the whole must be on the terms of this License, whose permissions + for other licensees extend to the entire whole, and thus to each + and every part regardless of who wrote it. + + Thus, it is not the intent of this section to claim rights or + contest your rights to work written entirely by you; rather, the + intent is to exercise the right to control the distribution of + derivative or collective works based on the Program. + + In addition, mere aggregation of another work not based on the + Program with the Program (or with a work based on the Program) on + a volume of a storage or distribution medium does not bring the + other work under the scope of this License. + + 3. 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You may not copy, modify, sublicense, or distribute the Program + except as expressly provided under this License. Any attempt + otherwise to copy, modify, sublicense or distribute the Program is + void, and will automatically terminate your rights under this + License. However, parties who have received copies, or rights, + from you under this License will not have their licenses + terminated so long as such parties remain in full compliance. + + 5. You are not required to accept this License, since you have not + signed it. However, nothing else grants you permission to modify + or distribute the Program or its derivative works. These actions + are prohibited by law if you do not accept this License. + Therefore, by modifying or distributing the Program (or any work + based on the Program), you indicate your acceptance of this + License to do so, and all its terms and conditions for copying, + distributing or modifying the Program or works based on it. + + 6. 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If you cannot distribute so as to satisfy simultaneously + your obligations under this License and any other pertinent + obligations, then as a consequence you may not distribute the + Program at all. For example, if a patent license would not permit + royalty-free redistribution of the Program by all those who + receive copies directly or indirectly through you, then the only + way you could satisfy both it and this License would be to refrain + entirely from distribution of the Program. + + If any portion of this section is held invalid or unenforceable + under any particular circumstance, the balance of the section is + intended to apply and the section as a whole is intended to apply + in other circumstances. + + It is not the purpose of this section to induce you to infringe any + patents or other property right claims or to contest validity of + any such claims; this section has the sole purpose of protecting + the integrity of the free software distribution system, which is + implemented by public license practices. Many people have made + generous contributions to the wide range of software distributed + through that system in reliance on consistent application of that + system; it is up to the author/donor to decide if he or she is + willing to distribute software through any other system and a + licensee cannot impose that choice. + + This section is intended to make thoroughly clear what is believed + to be a consequence of the rest of this License. + + 8. If the distribution and/or use of the Program is restricted in + certain countries either by patents or by copyrighted interfaces, + the original copyright holder who places the Program under this + License may add an explicit geographical distribution limitation + excluding those countries, so that distribution is permitted only + in or among countries not thus excluded. In such case, this + License incorporates the limitation as if written in the body of + this License. + + 9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the - Program specifies a version number of the license which applies to - it and "any later version", you have the option of following the - terms and conditions either of that version or of any later + Program specifies a version number of this License which applies + to it and "any later version", you have the option of following + the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program - does not specify a version number of the license, you may choose + does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. - 9. If you wish to incorporate parts of the Program into other free + 10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software @@ -254,7 +348,7 @@ modification follow. NO WARRANTY - 10. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO + 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT @@ -265,7 +359,7 @@ modification follow. PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. - 11. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN + 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, @@ -278,26 +372,26 @@ modification follow. END OF TERMS AND CONDITIONS -Appendix: How to Apply These Terms to Your New Programs -======================================================= +How to Apply These Terms to Your New Programs +============================================= If you develop a new program, and you want it to be of the greatest -possible use to humanity, the best way to achieve this is to make it +possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively -convey the exclusion of warranty; and each file should have at least the -"copyright" line and a pointer to where the full notice is found. +convey the exclusion of warranty; and each file should have at least +the "copyright" line and a pointer to where the full notice is found. - ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES. - Copyright (C) 19YY NAME OF AUTHOR + ONE LINE TO GIVE THE PROGRAM'S NAME AND AN IDEA OF WHAT IT DOES. + Copyright (C) YEAR NAME OF AUTHOR - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 1, or (at your option) - any later version. + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License + as published by the Free Software Foundation; either version 2 + of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of @@ -306,7 +400,7 @@ convey the exclusion of warranty; and each file should have at least the You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software - Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. Also add information on how to contact you by electronic and paper mail. @@ -314,10 +408,11 @@ mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: - Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR - Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. - This is free software, and you are welcome to redistribute it - under certain conditions; type `show c' for details. + Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR + Gnomovision comes with ABSOLUTELY NO WARRANTY; for details + type `show w'. This is free software, and you are welcome + to redistribute it under certain conditions; type `show c' + for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the @@ -327,16 +422,21 @@ program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, -if necessary. Here a sample; alter the names: +if necessary. Here is a sample; alter the names: - Yoyodyne, Inc., hereby disclaims all copyright interest in the - program `Gnomovision' (a program to direct compilers to make passes - at assemblers) written by James Hacker. + Yoyodyne, Inc., hereby disclaims all copyright + interest in the program `Gnomovision' + (which makes passes at compilers) written + by James Hacker. SIGNATURE OF TY COON, 1 April 1989 Ty Coon, President of Vice - That's all there is to it! + This General Public License does not permit incorporating your +program into proprietary programs. If your program is a subroutine +library, you may consider it more useful to permit linking proprietary +applications with the library. If this is what you want to do, use the +GNU Library General Public License instead of this License. File: gperf.info, Node: Contributors, Next: Motivation, Prev: Copying, Up: Top @@ -353,7 +453,7 @@ Contributors to GNU `gperf' Utility modified, enhanced, and extended implementation of Keith's basic idea, created at the University of California, Irvine. Bugs, patches, and suggestions should be reported to - `<bug-gnu-utils@gnu.org>' and `<schmidt@ics.uci.edu>'. + `<bug-gnu-utils@gnu.org>'. * Special thanks is extended to Michael Tiemann and Doug Lea, for providing a useful compiler, and for giving me a forum to exhibit @@ -363,6 +463,9 @@ Contributors to GNU `gperf' Utility insights that greatly helped improve the quality and functionality of `gperf'. + * A testsuite was added by Bruno Haible. He also rewrote the output + routines for better reliability. + File: gperf.info, Node: Motivation, Next: Search Structures, Prev: Contributors, Up: Top @@ -372,7 +475,7 @@ Introduction `gperf' is a perfect hash function generator written in C++. It transforms an N element user-specified keyword set W into a perfect hash function F. F uniquely maps keywords in W onto the range 0..K, -where K >= N. If K = N then F is a *minimal* perfect hash function. +where K >= N. If K = N then F is a _minimal_ perfect hash function. `gperf' generates a 0..K element static lookup table and a pair of C functions. These functions determine whether a given character string S occurs in W, using at most one probe into the lookup table. @@ -381,13 +484,9 @@ S occurs in W, using at most one probe into the lookup table. lexical analyzers in several production and research compilers and language processing tools, including GNU C, GNU C++, GNU Pascal, GNU Modula 3, and GNU indent. Complete C++ source code for `gperf' is -available via anonymous ftp from `ics.uci.edu' and `ftp.santafe.edu'. -`gperf' was also distributed along with the GNU libg++ library for -several years. A highly portable, functionally equivalent K&R C -version of `gperf' is archived in comp.sources.unix, volume 20. -Finally, a paper describing `gperf''s design and implementation in -greater detail is available in the Second USENIX C++ Conference -proceedings. +available via anonymous ftp from `ftp://ftp.gnu.org/pub/gnu/gperf/'. A +paper describing `gperf''s design and implementation in greater detail +is available in the Second USENIX C++ Conference proceedings. File: gperf.info, Node: Search Structures, Next: Description, Prev: Motivation, Up: Top @@ -396,12 +495,12 @@ Static search structures and GNU `gperf' **************************************** A "static search structure" is an Abstract Data Type with certain -fundamental operations, e.g., *initialize*, *insert*, and *retrieve*. +fundamental operations, e.g., _initialize_, _insert_, and _retrieve_. Conceptually, all insertions occur before any retrievals. In practice, `gperf' generates a `static' array containing search set keywords and any associated attributes specified by the user. Thus, there is essentially no execution-time cost for the insertions. It is a useful -data structure for representing *static search sets*. Static search +data structure for representing _static search sets_. Static search sets occur frequently in software system applications. Typical static search sets include compiler reserved words, assembler instruction opcodes, and built-in shell interpreter commands. Search set members, @@ -419,32 +518,32 @@ to log N. Conversely, hash table implementations often locate a table entry in constant time, but typically impose additional memory overhead and exhibit poor worst case performance. - *Minimal perfect hash functions* provide an optimal solution for a + _Minimal perfect hash functions_ provide an optimal solution for a particular class of static search sets. A minimal perfect hash function is defined by two properties: * It allows keyword recognition in a static search set using at most - *one* probe into the hash table. This represents the "perfect" + _one_ probe into the hash table. This represents the "perfect" property. * The actual memory allocated to store the keywords is precisely - large enough for the keyword set, and *no larger*. This is the + large enough for the keyword set, and _no larger_. This is the "minimal" property. - For most applications it is far easier to generate *perfect* hash -functions than *minimal perfect* hash functions. Moreover, non-minimal + For most applications it is far easier to generate _perfect_ hash +functions than _minimal perfect_ hash functions. Moreover, non-minimal perfect hash functions frequently execute faster than minimal ones in practice. This phenomena occurs since searching a sparse keyword table increases the probability of locating a "null" entry, thereby reducing string comparisons. `gperf''s default behavior generates -*near-minimal* perfect hash functions for keyword sets. However, +_near-minimal_ perfect hash functions for keyword sets. However, `gperf' provides many options that permit user control over the degree of minimality and perfection. Static search sets often exhibit relative stability over time. For example, Ada's 63 reserved words have remained constant for nearly a decade. It is therefore frequently worthwhile to expend concerted -effort building an optimal search structure *once*, if it subsequently +effort building an optimal search structure _once_, if it subsequently receives heavy use multiple times. `gperf' removes the drudgery associated with constructing time- and space-efficient search structures by hand. It has proven a useful and practical tool for @@ -463,8 +562,9 @@ High-Level Description of GNU `gperf' * Menu: -* Input Format:: Input Format to `gperf' -* Output Format:: Output Format for Generated C Code with `gperf' +* Input Format:: Input Format to `gperf' +* Output Format:: Output Format for Generated C Code with `gperf' +* Binary Strings:: Use of NUL characters The perfect hash function generator `gperf' reads a set of "keywords" from a "keyfile" (or from the standard input by default). @@ -509,15 +609,15 @@ utilities `lex' and `yacc'). Here's an outline of the general format: %% functions - *Unlike* `flex' or `bison', all sections of `gperf''s input are + _Unlike_ `flex' or `bison', all sections of `gperf''s input are optional. The following sections describe the input format for each section. * Menu: -* Declarations:: `struct' Declarations and C Code Inclusion. -* Keywords:: Format for Keyword Entries. -* Functions:: Including Additional C Functions. +* Declarations:: `struct' Declarations and C Code Inclusion. +* Keywords:: Format for Keyword Entries. +* Functions:: Including Additional C Functions. File: gperf.info, Node: Declarations, Next: Keywords, Prev: Input Format, Up: Input Format @@ -527,14 +627,14 @@ File: gperf.info, Node: Declarations, Next: Keywords, Prev: Input Format, Up The keyword input file optionally contains a section for including arbitrary C declarations and definitions, as well as provisions for -providing a user-supplied `struct'. If the `-t' option *is* enabled, -you *must* provide a C `struct' as the last component in the +providing a user-supplied `struct'. If the `-t' option _is_ enabled, +you _must_ provide a C `struct' as the last component in the declaration section from the keyfile file. The first field in this -struct must be a `char *' identifier called `name', although it is -possible to modify this field's name with the `-K' option described -below. +struct must be a `char *' or `const char *' identifier called `name', +although it is possible to modify this field's name with the `-K' +option described below. - Here is simple example, using months of the year and their + Here is a simple example, using months of the year and their attributes as input: struct months { char *name; int number; int days; int leap_days; }; @@ -552,7 +652,7 @@ attributes as input: november, 11, 30, 30 december, 12, 31, 31 - Separating the `struct' declaration from the list of key words and + Separating the `struct' declaration from the list of keywords and other fields are a pair of consecutive percent signs, `%%', appearing left justified in the first column, as in the UNIX utility `lex'. @@ -595,13 +695,15 @@ the first column is considered a comment. Everything following the `#' is ignored, up to and including the following newline. The first field of each non-comment line is always the key itself. -It should be given as a simple name, i.e., without surrounding string -quotation marks, and be left-justified flush against the first column. -In this context, a "field" is considered to extend up to, but not -include, the first blank, comma, or newline. Here is a simple example -taken from a partial list of C reserved words: - - # These are a few C reserved words, see the c.`gperf' file +It can be given in two ways: as a simple name, i.e., without surrounding +string quotation marks, or as a string enclosed in double-quotes, in C +syntax, possibly with backslash escapes like `\"' or `\234' or `\xa8'. +In either case, it must start right at the beginning of the line, +without leading whitespace. In this context, a "field" is considered +to extend up to, but not include, the first blank, comma, or newline. +Here is a simple example taken from a partial list of C reserved words: + + # These are a few C reserved words, see the c.gperf file # for a complete list of ANSI C reserved words. unsigned sizeof @@ -620,7 +722,7 @@ elided if the declaration section is empty. should be separated by commas, and terminate at the end of line. What these fields mean is entirely up to you; they are used to initialize the elements of the user-defined `struct' provided by you in the -declaration section. If the `-t' option is *not* enabled these fields +declaration section. If the `-t' option is _not_ enabled these fields are simply ignored. All previous examples except the last one contain keyword attributes. @@ -638,47 +740,52 @@ responsibility to ensure that the code contained in this section is valid C. -File: gperf.info, Node: Output Format, Prev: Input Format, Up: Description +File: gperf.info, Node: Output Format, Next: Binary Strings, Prev: Input Format, Up: Description Output Format for Generated C Code with `gperf' =============================================== Several options control how the generated C code appears on the standard output. Two C function are generated. They are called `hash' -and `in_word_set', although you may modify the name for `in_word_set' -with a command-line option. Both functions require two arguments, a -string, `char *' STR, and a length parameter, `int' LEN. Their default +and `in_word_set', although you may modify their names with a +command-line option. Both functions require two arguments, a string, +`char *' STR, and a length parameter, `int' LEN. Their default function prototypes are as follows: - static int hash (char *str, int len); - int in_word_set (char *str, int len); - - By default, the generated `hash' function returns an integer value -created by adding LEN to several user-specified STR key positions -indexed into an "associated values" table stored in a local static -array. The associated values table is constructed internally by -`gperf' and later output as a static local C array called HASH_TABLE; -its meaning and properties are described below. *Note -Implementation::. The relevant key positions are specified via the `-k' -option when running `gperf', as detailed in the *Options* section -below. *Note Options::. - - Two options, `-g' (assume you are compiling with GNU C and its -`inline' feature) and `-a' (assume ANSI C-style function prototypes), -alter the content of both the generated `hash' and `in_word_set' -routines. However, function `in_word_set' may be modified more -extensively, in response to your option settings. The options that -affect the `in_word_set' structure are: - - `-t' - Make use of the user-defined `struct'. - - `-S TOTAL SWITCH STATEMENTS' - Generate 1 or more C `switch' statement rather than use a - large, (and potentially sparse) static array. Although the - exact time and space savings of this approach vary according - to your C compiler's degree of optimization, this method - often results in smaller and faster code. + - Function: unsigned int hash (const char * STR, unsigned int LEN) + By default, the generated `hash' function returns an integer value + created by adding LEN to several user-specified STR key positions + indexed into an "associated values" table stored in a local static + array. The associated values table is constructed internally by + `gperf' and later output as a static local C array called + `hash_table'; its meaning and properties are described below + (*note Implementation::). The relevant key positions are specified + via the `-k' option when running `gperf', as detailed in the + _Options_ section below(*note Options::). + + - Function: in_word_set (const char * STR, unsigned int LEN) + If STR is in the keyword set, returns a pointer to that keyword. + More exactly, if the option `-t' was given, it returns a pointer + to the matching keyword's structure. Otherwise it returns `NULL'. + + If the option `-c' is not used, STR must be a NUL terminated string +of exactly length LEN. If `-c' is used, STR must simply be an array of +LEN characters and does not need to be NUL terminated. + + The code generated for these two functions is affected by the +following options: + +`-t' +`--struct-type' + Make use of the user-defined `struct'. + +`-S TOTAL-SWITCH-STATEMENTS' +`--switch=TOTAL-SWITCH-STATEMENTS' + Generate 1 or more C `switch' statement rather than use a large, + (and potentially sparse) static array. Although the exact time and + space savings of this approach vary according to your C compiler's + degree of optimization, this method often results in smaller and + faster code. If the `-t' and `-S' options are omitted, the default action is to generate a `char *' array containing the keys, together with additional @@ -688,23 +795,46 @@ can determine the best option choices for different keyword set characteristics. -File: gperf.info, Node: Options, Next: Input Details, Prev: Description, Up: Top +File: gperf.info, Node: Binary Strings, Prev: Output Format, Up: Description + +Use of NUL characters +===================== + + By default, the code generated by `gperf' operates on zero +terminated strings, the usual representation of strings in C. This means +that the keywords in the input file must not contain NUL characters, +and the STR argument passed to `hash' or `in_word_set' must be NUL +terminated and have exactly length LEN. + + If option `-c' is used, then the STR argument does not need to be +NUL terminated. The code generated by `gperf' will only access the +first LEN, not LEN+1, bytes starting at STR. However, the keywords in +the input file still must not contain NUL characters. -Options to the `gperf' Utility -****************************** + If option `-l' is used, then the hash table performs binary +comparison. The keywords in the input file may contain NUL characters, +written in string syntax as `\000' or `\x00', and the code generated by +`gperf' will treat NUL like any other character. Also, in this case +the `-c' option is ignored. - There are *many* options to `gperf'. They were added to make the + +File: gperf.info, Node: Options, Next: Bugs, Prev: Description, Up: Top + +Invoking `gperf' +**************** + + There are _many_ options to `gperf'. They were added to make the program more convenient for use with real applications. "On-line" help is readily available via the `-h' option. Here is the complete list of options. * Menu: -* Input Details:: Options that affect Interpretation of the Input File -* Output Language:: Specifying the Language for the Output Code -* Output Details:: Fine tuning Details in the Output Code -* Algorithmic Details:: Changing the Algorithms employed by `gperf' -* Verbosity:: Informative Output +* Input Details:: Options that affect Interpretation of the Input File +* Output Language:: Specifying the Language for the Output Code +* Output Details:: Fine tuning Details in the Output Code +* Algorithmic Details:: Changing the Algorithms employed by `gperf' +* Verbosity:: Informative Output File: gperf.info, Node: Input Details, Next: Output Language, Prev: Options, Up: Options @@ -712,22 +842,23 @@ File: gperf.info, Node: Input Details, Next: Output Language, Prev: Options, Options that affect Interpretation of the Input File ==================================================== - `-e KEYWORD DELIMITER LIST' - Allows the user to provide a string containing delimiters - used to separate keywords from their attributes. The default - is ",\n". This option is essential if you want to use - keywords that have embedded commas or newlines. One useful - trick is to use -e'TAB', where TAB is the literal tab - character. - - `-t' - Allows you to include a `struct' type declaration for - generated code. Any text before a pair of consecutive %% is - consider part of the type declaration. Key words and - additional fields may follow this, one group of fields per - line. A set of examples for generating perfect hash tables - and functions for Ada, C, and G++, Pascal, and Modula 2 and 3 - reserved words are distributed with this release. +`-e KEYWORD-DELIMITER-LIST' +`--delimiters=KEYWORD-DELIMITER-LIST' + Allows the user to provide a string containing delimiters used to + separate keywords from their attributes. The default is ",\n". + This option is essential if you want to use keywords that have + embedded commas or newlines. One useful trick is to use -e'TAB', + where TAB is the literal tab character. + +`-t' +`--struct-type' + Allows you to include a `struct' type declaration for generated + code. Any text before a pair of consecutive `%%' is considered + part of the type declaration. Keywords and additional fields may + follow this, one group of fields per line. A set of examples for + generating perfect hash tables and functions for Ada, C, C++, + Pascal, Modula 2, Modula 3 and JavaScript reserved words are + distributed with this release. File: gperf.info, Node: Output Language, Next: Output Details, Prev: Input Details, Up: Options @@ -735,38 +866,38 @@ File: gperf.info, Node: Output Language, Next: Output Details, Prev: Input De Options to specify the Language for the Output Code =================================================== - `-L GENERATED LANGUAGE NAME' - Instructs `gperf' to generate code in the language specified - by the option's argument. Languages handled are currently: +`-L GENERATED-LANGUAGE-NAME' +`--language=GENERATED-LANGUAGE-NAME' + Instructs `gperf' to generate code in the language specified by the + option's argument. Languages handled are currently: - `KR-C' - Old-style K&R C. This language is understood by - old-style C compilers and ANSI C compilers, but - ANSI C compilers may flag warnings (or even errors) - because of lacking `const'. + `KR-C' + Old-style K&R C. This language is understood by old-style C + compilers and ANSI C compilers, but ANSI C compilers may flag + warnings (or even errors) because of lacking `const'. - `C' - Common C. This language is understood by ANSI C - compilers, and also by old-style C compilers, - provided that you `#define const' to empty for - compilers which don't know about this keyword. + `C' + Common C. This language is understood by ANSI C compilers, + and also by old-style C compilers, provided that you `#define + const' to empty for compilers which don't know about this + keyword. - `ANSI-C' - ANSI C. This language is understood by ANSI C - compilers and C++ compilers. + `ANSI-C' + ANSI C. This language is understood by ANSI C compilers and + C++ compilers. - `C++' - C++. This language is understood by C++ compilers. + `C++' + C++. This language is understood by C++ compilers. - The default is C. + The default is C. - `-a' - This option is supported for compatibility with previous - releases of `gperf'. It does not do anything. +`-a' + This option is supported for compatibility with previous releases + of `gperf'. It does not do anything. - `-g' - This option is supported for compatibility with previous - releases of `gperf'. It does not do anything. +`-g' + This option is supported for compatibility with previous releases + of `gperf'. It does not do anything. File: gperf.info, Node: Output Details, Next: Algorithmic Details, Prev: Output Language, Up: Options @@ -774,94 +905,110 @@ File: gperf.info, Node: Output Details, Next: Algorithmic Details, Prev: Outp Options for fine tuning Details in the Output Code ================================================== - `-K KEY NAME' - This option is only useful when option `-t' has been given. - By default, the program assumes the structure component - identifier for the keyword is `name'. This option allows an - arbitrary choice of identifier for this component, although - it still must occur as the first field in your supplied - `struct'. - - `-H HASH FUNCTION NAME' - Allows you to specify the name for the generated hash - function. Default name is `hash'. This option permits the - use of two hash tables in the same file. - - `-N LOOKUP FUNCTION NAME' - Allows you to specify the name for the generated lookup - function. Default name is `in_word_set'. This option - permits completely automatic generation of perfect hash - functions, especially when multiple generated hash functions - are used in the same application. - - `-Z CLASS NAME' - This option is only useful when option `-L C++' has been - given. It allows you to specify the name of generated C++ - class. Default name is `Perfect_Hash'. - - `-7' - This option specifies that all strings that will be passed as - arguments to the generated hash function and the generated - lookup function will solely consist of 7-bit ASCII characters - (characters in the range 0..127). (Note that the ANSI C - functions `isalnum' and `isgraph' do *not* guarantee that a - character is in this range. Only an explicit test like `c >= - 'A' && c <= 'Z'' guarantees this.) This was the default in - earlier versions of `gperf'; now the default is to assume - 8-bit characters. - - `-c' - Generates C code that uses the `strncmp' function to perform - string comparisons. The default action is to use `strcmp'. - - `-C' - Makes the contents of all generated lookup tables constant, - i.e., "readonly". Many compilers can generate more efficient - code for this by putting the tables in readonly memory. - - `-E' - Define constant values using an enum local to the lookup - function rather than with #defines. This also means that - different lookup functions can reside in the same file. - Thanks to James Clark `<jjc@ai.mit.edu>'. - - `-I' - Include the necessary system include file, `<string.h>', at - the beginning of the code. By default, this is not done; the - user must include this header file himself to allow - compilation of the code. - - `-G' - 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). - - `-W HASH TABLE ARRAY NAME' - Allows you to specify the name for the generated array - containing the hash table. Default name is `wordlist'. This - option permits the use of two hash tables in the same file, - even when the option `-G' is given. - - `-S TOTAL SWITCH STATEMENTS' - 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 argument to this option 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 `switch', etc. This - is useful since many C compilers cannot correctly generate - code for large `switch' statements. This option was inspired - in part by Keith Bostic's original C program. - - `-T' - Prevents the transfer of the type declaration to the output - file. Use this option if the type is already defined - elsewhere. - - `-p' - This option is supported for compatibility with previous - releases of `gperf'. It does not do anything. +`-K KEY-NAME' +`--slot-name=KEY-NAME' + This option is only useful when option `-t' has been given. By + default, the program assumes the structure component identifier for + the keyword is `name'. This option allows an arbitrary choice of + identifier for this component, although it still must occur as the + first field in your supplied `struct'. + +`-F INITIALIZERS' +`--initializer-suffix=INITIALIZERS' + This option is only useful when option `-t' has been given. It + permits to specify initializers for the structure members following + KEY NAME in empty hash table entries. The list of initializers + should start with a comma. By default, the emitted code will + zero-initialize structure members following KEY NAME. + +`-H HASH-FUNCTION-NAME' +`--hash-fn-name=HASH-FUNCTION-NAME' + Allows you to specify the name for the generated hash function. + Default name is `hash'. This option permits the use of two hash + tables in the same file. + +`-N LOOKUP-FUNCTION-NAME' +`--lookup-fn-name=LOOKUP-FUNCTION-NAME' + Allows you to specify the name for the generated lookup function. + Default name is `in_word_set'. This option permits completely + automatic generation of perfect hash functions, especially when + multiple generated hash functions are used in the same application. + +`-Z CLASS-NAME' +`--class-name=CLASS-NAME' + This option is only useful when option `-L C++' has been given. It + allows you to specify the name of generated C++ class. Default + name is `Perfect_Hash'. + +`-7' +`--seven-bit' + This option specifies that all strings that will be passed as + arguments to the generated hash function and the generated lookup + function will solely consist of 7-bit ASCII characters (characters + in the range 0..127). (Note that the ANSI C functions `isalnum' + and `isgraph' do _not_ guarantee that a character is in this + range. Only an explicit test like `c >= 'A' && c <= 'Z'' + guarantees this.) This was the default in versions of `gperf' + earlier than 2.7; now the default is to assume 8-bit characters. + +`-c' +`--compare-strncmp' + Generates C code that uses the `strncmp' function to perform + string comparisons. The default action is to use `strcmp'. + +`-C' +`--readonly-tables' + Makes the contents of all generated lookup tables constant, i.e., + "readonly". Many compilers can generate more efficient code for + this by putting the tables in readonly memory. + +`-E' +`--enum' + Define constant values using an enum local to the lookup function + rather than with #defines. This also means that different lookup + functions can reside in the same file. Thanks to James Clark + `<jjc@ai.mit.edu>'. + +`-I' +`--includes' + Include the necessary system include file, `<string.h>', at the + beginning of the code. By default, this is not done; the user must + include this header file himself to allow compilation of the code. + +`-G' +`--global' + 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). + +`-W HASH-TABLE-ARRAY-NAME' +`--word-array-name=HASH-TABLE-ARRAY-NAME' + Allows you to specify the name for the generated array containing + the hash table. Default name is `wordlist'. This option permits + the use of two hash tables in the same file, even when the option + `-G' is given. + +`-S TOTAL-SWITCH-STATEMENTS' +`--switch=TOTAL-SWITCH-STATEMENTS' + 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 + argument to this option 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 `switch', etc. This is useful since many C + compilers cannot correctly generate code for large `switch' + statements. This option was inspired in part by Keith Bostic's + original C program. + +`-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. + +`-p' + This option is supported for compatibility with previous releases + of `gperf'. It does not do anything. File: gperf.info, Node: Algorithmic Details, Next: Verbosity, Prev: Output Details, Up: Options @@ -869,169 +1016,175 @@ File: gperf.info, Node: Algorithmic Details, Next: Verbosity, Prev: Output De Options for changing the Algorithms employed by `gperf' ======================================================= - `-k KEYS' - Allows selection of the character key positions used in the - keywords' hash function. The allowable choices range between - 1-126, inclusive. The positions are separated by commas, - e.g., `-k 9,4,13,14'; ranges may be used, e.g., `-k 2-7'; and - positions may occur in any order. Furthermore, the - meta-character '*' causes the generated hash function to - consider *all* character positions in each key, whereas '$' - instructs the hash function to use the "final character" of a - key (this is the only way to use a character position greater - than 126, incidentally). - - For instance, the option `-k 1,2,4,6-10,'$'' generates a hash - function that considers positions 1,2,4,6,7,8,9,10, plus the - last character in each key (which may differ for each key, - obviously). Keys with length less than the indicated key - positions work properly, since selected key positions - exceeding the key length are simply not referenced in the - hash function. - - `-l' - Compare key lengths before trying a string comparison. This - might cut down on the number of string comparisons made - during the lookup, since keys with different lengths are - never compared via `strcmp'. However, using `-l' might - greatly increase the size of the generated C code if the - lookup table range is large (which implies that the switch - option `-S' is not enabled), since the length table contains - as many elements as there are entries in the lookup table. - - `-D' - Handle keywords whose key position sets hash to duplicate - values. Duplicate hash values occur for two reasons: - - * Since `gperf' does not backtrack it is possible for it - to process all your input keywords without finding a - unique mapping for each word. However, frequently only - a very small number of duplicates occur, and the - majority of keys still require one probe into the table. - - * Sometimes a set of keys may have the same names, but - possess different attributes. With the -D option - `gperf' treats all these keys as part of an equivalence - class and generates a perfect hash function with multiple - comparisons for duplicate keys. It is up to you to - completely disambiguate the keywords by modifying the - generated C code. However, `gperf' helps you out by - organizing the output. - - Option `-D' is extremely useful for certain large or highly - redundant keyword sets, e.g., assembler instruction opcodes. - Using this option usually means that the generated hash - function is no longer perfect. On the other hand, it permits - `gperf' to work on keyword sets that it otherwise could not - handle. - - `-f ITERATION AMOUNT' - Generate the perfect hash function "fast". This decreases - `gperf''s running time at the cost of minimizing generated - table-size. The iteration amount represents the number of - times to iterate when resolving a collision. `0' means - iterate by the number of keywords. This option is probably - most useful when used in conjunction with options `-D' and/or - `-S' for *large* keyword sets. - - `-i INITIAL VALUE' - Provides an initial VALUE for the associate values array. - Default is 0. Increasing the initial value helps inflate the - final table size, possibly leading to more time efficient - keyword lookups. Note that this option is not particularly - useful when `-S' is used. Also, `-i' is overriden when the - `-r' option is used. - - `-j JUMP VALUE' - Affects the "jump value", i.e., how far to advance the - associated character value upon collisions. JUMP VALUE is - rounded up to an odd number, the default is 5. If the JUMP - VALUE is 0 `gperf' jumps by random amounts. - - `-n' - Instructs the generator not to include the length of a - keyword when computing its hash value. This may save a few - assembly instructions in the generated lookup table. - - `-o' - Reorders the keywords by sorting the keywords so that - frequently occuring key position set components appear first. - A second reordering pass follows so that keys with "already - determined values" are placed towards the front of the - keylist. This may decrease the time required to generate a - perfect hash function for many keyword sets, and also produce - more minimal perfect hash functions. The reason for this is - that the reordering helps prune the search time by handling - inevitable collisions early in the search process. On the - other hand, if the number of keywords is *very* large using - `-o' may *increase* `gperf''s execution time, since - collisions will begin earlier and continue throughout the - remainder of keyword processing. See Cichelli's paper from - the January 1980 Communications of the ACM for details. - - `-r' - Utilizes randomness to initialize the associated values - table. This frequently generates solutions faster than using - deterministic initialization (which starts all associated - values at 0). Furthermore, using the randomization option - generally increases the size of the table. If `gperf' has - difficultly with a certain keyword set try using `-r' or `-D'. - - `-s SIZE-MULTIPLE' - Affects the size of the generated hash table. The numeric - argument for this option indicates "how many times larger or - smaller" the maximum associated value range should be, in - relationship to the number of keys. If the SIZE-MULTIPLE is - negative the maximum associated value is calculated by - *dividing* it into the total number of keys. For example, 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 "allow the maximum associated - value to be about 3 times smaller than the number of input - keys". Negative values are useful for limiting the overall - size of the generated hash table, though this usually - increases the number of duplicate hash values. - - If `generate switch' option `-S' is *not* enabled, the maximum - associated value influences the static array table size, and - a larger table should decrease the time required for an - unsuccessful search, at the expense of extra table space. - - The default value is 1, thus the default maximum associated - value about the same size as the number of keys (for - efficiency, the maximum associated value is always rounded up - to a power of 2). The actual table size may vary somewhat, - since this technique is essentially a heuristic. In - particular, setting this value too high slows down `gperf''s - runtime, since it must search through a much larger range of - values. Judicious use of the `-f' option helps alleviate this - overhead, however. +`-k KEYS' +`--key-positions=KEYS' + Allows selection of the character key positions used in the + keywords' hash function. The allowable choices range between + 1-126, inclusive. The positions are separated by commas, e.g., + `-k 9,4,13,14'; ranges may be used, e.g., `-k 2-7'; and positions + may occur in any order. Furthermore, the meta-character '*' + causes the generated hash function to consider *all* character + positions in each key, whereas '$' instructs the hash function to + use the "final character" of a key (this is the only way to use a + character position greater than 126, incidentally). + + For instance, the option `-k 1,2,4,6-10,'$'' generates a hash + function that considers positions 1,2,4,6,7,8,9,10, plus the last + character in each key (which may differ for each key, obviously). + Keys with length less than the indicated key positions work + properly, since selected key positions exceeding the key length + are simply not referenced in the hash function. + +`-l' +`--compare-strlen' + Compare key lengths before trying a string comparison. This might + cut down on the number of string comparisons made during the + lookup, since keys with different lengths are never compared via + `strcmp'. However, using `-l' might greatly increase the size of + the generated C code if the lookup table range is large (which + implies that the switch option `-S' is not enabled), since the + length table contains as many elements as there are entries in the + lookup table. This option is mandatory for binary comparisons + (*note Binary Strings::). + +`-D' +`--duplicates' + Handle keywords whose key position sets hash to duplicate values. + Duplicate hash values occur for two reasons: + + * Since `gperf' does not backtrack it is possible for it to + process all your input keywords without finding a unique + mapping for each word. However, frequently only a very small + number of duplicates occur, and the majority of keys still + require one probe into the table. + + * Sometimes a set of keys may have the same names, but possess + different attributes. With the -D option `gperf' treats all + these keys as part of an equivalence class and generates a + perfect hash function with multiple comparisons for duplicate + keys. It is up to you to completely disambiguate the + keywords by modifying the generated C code. However, `gperf' + helps you out by organizing the output. + + Option `-D' is extremely useful for certain large or highly + redundant keyword sets, e.g., assembler instruction opcodes. + Using this option usually means that the generated hash function + is no longer perfect. On the other hand, it permits `gperf' to + work on keyword sets that it otherwise could not handle. + +`-f ITERATION-AMOUNT' +`--fast=ITERATION-AMOUNT' + Generate the perfect hash function "fast". This decreases + `gperf''s running time at the cost of minimizing generated + table-size. The iteration amount represents the number of times to + iterate when resolving a collision. `0' means iterate by the + number of keywords. This option is probably most useful when used + in conjunction with options `-D' and/or `-S' for _large_ keyword + sets. + +`-i INITIAL-VALUE' +`--initial-asso=INITIAL-VALUE' + Provides an initial VALUE for the associate values array. Default + is 0. Increasing the initial value helps inflate the final table + size, possibly leading to more time efficient keyword lookups. + Note that this option is not particularly useful when `-S' is + used. Also, `-i' is overridden when the `-r' option is used. + +`-j JUMP-VALUE' +`--jump=JUMP-VALUE' + Affects the "jump value", i.e., how far to advance the associated + character value upon collisions. JUMP-VALUE is rounded up to an + odd number, the default is 5. If the JUMP-VALUE is 0 `gperf' + jumps by random amounts. + +`-n' +`--no-strlen' + Instructs the generator not to include the length of a keyword when + computing its hash value. This may save a few assembly + instructions in the generated lookup table. + +`-o' +`--occurrence-sort' + Reorders the keywords by sorting the keywords so that frequently + occuring key position set components appear first. A second + reordering pass follows so that keys with "already determined + values" are placed towards the front of the keylist. This may + decrease the time required to generate a perfect hash function for + many keyword sets, and also produce more minimal perfect hash + functions. The reason for this is that the reordering helps prune + the search time by handling inevitable collisions early in the + search process. On the other hand, if the number of keywords is + _very_ large using `-o' may _increase_ `gperf''s execution time, + since collisions will begin earlier and continue throughout the + remainder of keyword processing. See Cichelli's paper from the + January 1980 Communications of the ACM for details. + +`-r' +`--random' + Utilizes randomness to initialize the associated values table. + This frequently generates solutions faster than using deterministic + initialization (which starts all associated values at 0). + Furthermore, using the randomization option generally increases + the size of the table. If `gperf' has difficultly with a certain + keyword set try using `-r' or `-D'. + +`-s SIZE-MULTIPLE' +`--size-multiple=SIZE-MULTIPLE' + Affects the size of the generated hash table. The numeric + argument for this option indicates "how many times larger or + smaller" the maximum associated value range should be, in + relationship to the number of keys. If the SIZE-MULTIPLE is + negative the maximum associated value is calculated by _dividing_ + it into the total number of keys. For example, 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 "allow the maximum associated + value to be about 3 times smaller than the number of input keys". + Negative values are useful for limiting the overall size of the + generated hash table, though this usually increases the number of + duplicate hash values. + + If `generate switch' option `-S' is _not_ enabled, the maximum + associated value influences the static array table size, and a + larger table should decrease the time required for an unsuccessful + search, at the expense of extra table space. + + The default value is 1, thus the default maximum associated value + about the same size as the number of keys (for efficiency, the + maximum associated value is always rounded up to a power of 2). + The actual table size may vary somewhat, since this technique is + essentially a heuristic. In particular, setting this value too + high slows down `gperf''s runtime, since it must search through a + much larger range of values. Judicious use of the `-f' option + helps alleviate this overhead, however. -File: gperf.info, Node: Verbosity, Next: Bugs, Prev: Algorithmic Details, Up: Options +File: gperf.info, Node: Verbosity, Prev: Algorithmic Details, Up: Options Informative Output ================== - `-h' - Prints a short summary on the meaning of each program option. - Aborts further program execution. +`-h' +`--help' + Prints a short summary on the meaning of each program option. + Aborts further program execution. - `-v' - Prints out the current version number. +`-v' +`--version' + Prints out the current version number. - `-d' - Enables the debugging option. This produces verbose - diagnostics to "standard error" when `gperf' is executing. - It is useful both for maintaining the program and for - determining whether a given set of options is actually - speeding up the search for a solution. Some useful - information is dumped at the end of the program when the `-d' - option is enabled. +`-d' +`--debug' + Enables the debugging option. This produces verbose diagnostics to + "standard error" when `gperf' is executing. It is useful both for + maintaining the program and for determining whether a given set of + options is actually speeding up the search for a solution. Some + useful information is dumped at the end of the program when the + `-d' option is enabled. -File: gperf.info, Node: Bugs, Next: Projects, Prev: Verbosity, Up: Top +File: gperf.info, Node: Bugs, Next: Projects, Prev: Options, Up: Top Known Bugs and Limitations with `gperf' *************************************** @@ -1051,17 +1204,17 @@ Known Bugs and Limitations with `gperf' occurs on every run. On the other hand, it is usually easy to obtain a solution by varying the option parameters. In particular, try the `-r' option, and also try changing the default - arguments to the `-s' and `-j' options. To *guarantee* a + arguments to the `-s' and `-j' options. To _guarantee_ a solution, use the `-D' and `-S' options, although the final - results are not likely to be a *perfect* hash function anymore! + results are not likely to be a _perfect_ hash function anymore! Finally, use the `-f' option if you want `gperf' to generate the - perfect hash function *fast*, with less emphasis on making it + perfect hash function _fast_, with less emphasis on making it minimal. - * The size of the generate static keyword array can get *extremely* + * The size of the generate static keyword array can get _extremely_ large if the input keyword file is large or if the keywords are quite similar. This tends to slow down the compilation of the - generated C code, and *greatly* inflates the object code size. If + generated C code, and _greatly_ inflates the object code size. If this situation occurs, consider using the `-S' option to reduce data size, potentially increasing keyword recognition time a negligible amount. Since many C compilers cannot correctly @@ -1123,7 +1276,7 @@ file, and a provably optimal algorithm for simultaneously determining both the minimum and maximum elements in a list. -File: gperf.info, Node: Bibliography, Prev: Implementation, Up: Top +File: gperf.info, Node: Bibliography, Next: Concept Index, Prev: Implementation, Up: Top Bibliography ************ @@ -1174,29 +1327,63 @@ Addison-Wesley, 1986. [14] Tiemann, Michael D. User's Guide to GNU C++ Free Software Foundation, 1989. + +File: gperf.info, Node: Concept Index, Prev: Bibliography, Up: Top + +Concept Index +************* + +* Menu: + +* %%: Declarations. +* %{: Declarations. +* %}: Declarations. +* Array name: Output Details. +* Bugs: Contributors. +* Class name: Output Details. +* Declaration section: Input Format. +* Delimiters: Input Details. +* Duplicates: Algorithmic Details. +* Format: Input Format. +* Functions section: Input Format. +* hash: Output Format. +* hash table: Output Format. +* in_word_set: Output Format. +* Initializers: Output Details. +* Jump value: Algorithmic Details. +* Keywords section: Input Format. +* Minimal perfect hash functions: Search Structures. +* NUL: Binary Strings. +* Slot name: Output Details. +* Static search structure: Search Structures. +* switch <1>: Output Details. +* switch: Output Format. + Tag Table: -Node: Top1228 -Node: Copying2845 -Node: Contributors16148 -Node: Motivation17279 -Node: Search Structures18560 -Node: Description22105 -Node: Input Format23925 -Node: Declarations24720 -Node: Keywords27025 -Node: Functions28614 -Node: Output Format29108 -Node: Options31474 -Node: Input Details32192 -Node: Output Language33268 -Node: Output Details34742 -Node: Algorithmic Details39066 -Node: Verbosity46861 -Node: Bugs47612 -Node: Projects49842 -Node: Implementation51419 -Node: Bibliography52136 +Node: Top1236 +Node: Copying3130 +Node: Contributors22321 +Node: Motivation23534 +Node: Search Structures24610 +Node: Description28155 +Node: Input Format30056 +Node: Declarations30898 +Node: Keywords33222 +Node: Functions34977 +Node: Output Format35471 +Node: Binary Strings38067 +Node: Options39073 +Node: Input Details39779 +Node: Output Language40844 +Node: Output Details42148 +Node: Algorithmic Details46796 +Node: Verbosity54238 +Node: Bugs54941 +Node: Projects57169 +Node: Implementation58746 +Node: Bibliography59463 +Node: Concept Index61406 End Tag Table |