openldap/libraries/liblunicode/utbm/README

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# $Id: README,v 1.1 1999/09/21 15:45:17 mleisher Exp $
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                       Unicode and Boyer-Moore Searching
                                 Version 0.2

UTBM (Unicode Tuned Boyer-Moore) is a simple package that provides tuned
Boyer-Moore searches on Unicode UCS2 text (handles high and low surrogates).

---------------------------------------------------------------------------

Assumptions:

  o  Search pattern and text already normalized in some fasion.

  o  Upper, lower, and title case conversions are one-to-one.

  o  For conversions between upper, lower, and title case, UCS2 characters
     always convert to other UCS2 characters, and UTF-16 characters always
     convert to other UTF-16 characters.

Flags:

  UTBM provides three processing flags:

  o  UTBM_CASEFOLD          - search in a case-insensitive manner.

  o  UTBM_IGNORE_NONSPACING - ignore non-spacing characters in the pattern and
                              the text.

  o  UTBM_SPACE_COMPRESS    - view as a *single space*, sequential groups of
                              U+2028, U+2029, '\n', '\r', '\t', and any
                              character identified as a space by the Unicode
                              support on the platform.

                              This flag also causes all characters identified
                              as control by the Unicode support on the
                              platform to be ignored (except for '\n', '\r',
                              and '\t').

---------------------------------------------------------------------------

Before using UTBM
-----------------
Before UTBM is used, some functions need to be created.  The "utbmstub.c" file
contains stubs that need to be rewritten so they work with the Unicode support
on the platform on which this package is being used.

Using UTBM
----------

Sample pseudo-code fragment.

  utbm_pattern_t pat;
  ucs2_t *pattern, *text;
  unsigned long patternlen, textlen;
  unsigned long flags, match_start, match_end;

  /*
   * Allocate the dynamic storage needed for a search pattern.
   */
  pat = utbm_create_pattern();

  /*
   * Set the search flags desired.
   */
  flags = UTBM_CASEFOLD|UTBM_IGNORE_NONSPACING;

  /*
   * Compile the search pattern.
   */
  utbm_compile(pattern, patternlen, flags, pat);

  /*
   * Find the first occurance of the search pattern in the text.
   */
  if (utbm_exec(pat, text, textlen, &match_start, &match_end))
    printf("MATCH: %ld %ld\n", match_start, match_end);

  /*
   * Free the dynamic storage used for the search pattern.
   */
  ure_free_pattern(pat);

---------------------------------------------------------------------------

Mark Leisher <mleisher@crl.nmsu.edu>
2 May 1997

===========================================================================

CHANGES
-------

Version: 0.2
Date   : 21 September 1999
==========================
  1. Added copyright stuff and put in CVS.