# # $Id: README,v 1.3 1999/09/21 15:47:43 mleisher Exp $ # # Copyright 1997, 1998, 1999 Computing Research Labs, # New Mexico State University # # Permission is hereby granted, free of charge, to any person obtaining a # copy of this software and associated documentation files (the "Software"), # to deal in the Software without restriction, including without limitation # the rights to use, copy, modify, merge, publish, distribute, sublicense, # and/or sell copies of the Software, and to permit persons to whom the # Software is furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in # all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL # THE COMPUTING RESEARCH LAB OR NEW MEXICO STATE UNIVERSITY BE LIABLE FOR ANY # CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT # OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR # THE USE OR OTHER DEALINGS IN THE SOFTWARE. # Unicode and Regular Expressions Version 0.5 This is a simple regular expression package for matching against Unicode text in UCS2 form. The implementation of this URE package is a variation on the RE->DFA algorithm done by Mark Hopkins (markh@csd4.csd.uwm.edu). Mark Hopkins' algorithm had the virtue of being very simple, so it was used as a model. --------------------------------------------------------------------------- Assumptions: o Regular expression and text already normalized. o Conversion to lower case assumes a 1-1 mapping. Definitions: Separator - any one of U+2028, U+2029, '\n', '\r'. Operators: . - match any character. * - match zero or more of the last subexpression. + - match one or more of the last subexpression. ? - match zero or one of the last subexpression. () - subexpression grouping. Notes: o The "." operator normally does not match separators, but a flag is available for the ure_exec() function that will allow this operator to match a separator. Literals and Constants: c - literal UCS2 character. \x.... - hexadecimal number of up to 4 digits. \X.... - hexadecimal number of up to 4 digits. \u.... - hexadecimal number of up to 4 digits. \U.... - hexadecimal number of up to 4 digits. Character classes: [...] - Character class. [^...] - Negated character class. \pN1,N2,...,Nn - Character properties class. \PN1,N2,...,Nn - Negated character properties class. POSIX character classes recognized: :alnum: :alpha: :cntrl: :digit: :graph: :lower: :print: :punct: :space: :upper: :xdigit: Notes: o Character property classes are \p or \P followed by a comma separated list of integers between 1 and 32. These integers are references to the following character properties: N Character Property -------------------------- 1 _URE_NONSPACING 2 _URE_COMBINING 3 _URE_NUMDIGIT 4 _URE_NUMOTHER 5 _URE_SPACESEP 6 _URE_LINESEP 7 _URE_PARASEP 8 _URE_CNTRL 9 _URE_PUA 10 _URE_UPPER 11 _URE_LOWER 12 _URE_TITLE 13 _URE_MODIFIER 14 _URE_OTHERLETTER 15 _URE_DASHPUNCT 16 _URE_OPENPUNCT 17 _URE_CLOSEPUNCT 18 _URE_OTHERPUNCT 19 _URE_MATHSYM 20 _URE_CURRENCYSYM 21 _URE_OTHERSYM 22 _URE_LTR 23 _URE_RTL 24 _URE_EURONUM 25 _URE_EURONUMSEP 26 _URE_EURONUMTERM 27 _URE_ARABNUM 28 _URE_COMMONSEP 29 _URE_BLOCKSEP 30 _URE_SEGMENTSEP 31 _URE_WHITESPACE 32 _URE_OTHERNEUT o Character classes can contain literals, constants, and character property classes. Example: [abc\U10A\p1,3,4] --------------------------------------------------------------------------- Before using URE ---------------- Before URE is used, two functions need to be created. One to check if a character matches a set of URE character properties, and one to convert a character to lower case. Stubs for these function are located in the urestubs.c file. Using URE --------- Sample pseudo-code fragment. ure_buffer_t rebuf; ure_dfa_t dfa; ucs2_t *re, *text; unsigned long relen, textlen; unsigned long match_start, match_end; /* * Allocate the dynamic storage needed to compile regular expressions. */ rebuf = ure_buffer_create(); for each regular expression in a list { re = next regular expression; relen = length(re); /* * Compile the regular expression with the case insensitive flag * turned on. */ dfa = ure_compile(re, relen, 1, rebuf); /* * Look for the first match in some text. The matching will be done * in a case insensitive manner because the expression was compiled * with the case insensitive flag on. */ if (ure_exec(dfa, 0, text, textlen, &match_start, &match_end)) printf("MATCH: %ld %ld\n", match_start, match_end); /* * Look for the first match in some text, ignoring non-spacing * characters. */ if (ure_exec(dfa, URE_IGNORE_NONSPACING, text, textlen, &match_start, &match_end)) printf("MATCH: %ld %ld\n", match_start, match_end); /* * Free the DFA. */ ure_free_dfa(dfa); } /* * Free the dynamic storage used for compiling the expressions. */ ure_free_buffer(rebuf); --------------------------------------------------------------------------- Mark Leisher 29 March 1997 =========================================================================== CHANGES ------- Version: 0.5 Date : 21 September 1999 ========================== 1. Added copyright stuff and put in CVS.