comparison src/casetab.c @ 4407:4ee73bbe4f8e

Always use boyer_moore in ASCII or Latin-1 buffers with ASCII search strings. 2007-12-26 Aidan Kehoe <kehoea@parhasard.net> * casetab.c: Extend and correct some case table documentation. * search.c (search_buffer): Correct a bug where only the first entry for a character in the case equivalence table was examined in determining if the Boyer-Moore search algorithm is appropriate. If there are case mappings outside of the charset and row of the characters specified in the search string, those case mappings can be safely ignored (and Boyer-Moore search can be used) if we know from the buffer statistics that the corresponding characters cannot occur. * search.c (boyer_moore): Assert that we haven't been passed a string with varying characters sets or rows within character sets. That's what simple_search is for. In the very rare event that a character in the search string has a canonical case mapping that is not in the same character set and row, don't try to search for the canonical character, search for some other character that is in the the desired character set and row. Assert that the case table isn't corrupt. Do not search for any character case mappings that cannot possibly occur in the buffer, given the buffer metadata about its contents.
author Aidan Kehoe <kehoea@parhasard.net>
date Wed, 26 Dec 2007 17:30:16 +0100
parents 1e7cc382eb16
children a98ca4640147 e0db3c197671
comparison
equal deleted inserted replaced
4356:cc293ef846d2 4407:4ee73bbe4f8e
46 (3) `canon' maps each character to a "canonical" lowercase, such that if 46 (3) `canon' maps each character to a "canonical" lowercase, such that if
47 two different uppercase characters map to the same lowercase character, 47 two different uppercase characters map to the same lowercase character,
48 or vice versa, both characters will have the same entry in the canon 48 or vice versa, both characters will have the same entry in the canon
49 table. 49 table.
50 50
51 (4) `equiv' lists the "equivalence classes" defined by `canon'. Imagine 51 (4) `eqv' lists the "equivalence classes" defined by `canon'. Imagine
52 that all characters are divided into groups having the same `canon' 52 that all characters are divided into groups having the same `canon'
53 entry; these groups are called "equivalence classes" and `equiv' lists 53 entry; these groups are called "equivalence classes" and `eqv' lists them
54 them by linking the characters in each equivalence class together in a 54 by linking the characters in each equivalence class together in a
55 circular list. 55 circular list. That is, to find out all all the members of a given char's
56 56 equivalence classe, you need something like the following code:
57 `canon' is used when doing case-insensitive comparisons. `equiv' is 57
58 (let* ((char ?i)
59 (original-char char)
60 (standard-case-eqv (case-table-eqv (standard-case-table))))
61 (loop
62 with res = (list char)
63 until (eq (setq char (get-char-table char standard-case-eqv))
64 original-char)
65 do (push char res)
66 finally return res))
67
68 (Where #'case-table-eqv doesn't yet exist, and probably never will, given
69 that the C code needs to keep it in a consistent state so Lisp can't mess
70 around with it.)
71
72 `canon' is used when doing case-insensitive comparisons. `eqv' is
58 used in the Boyer-Moore search code. 73 used in the Boyer-Moore search code.
59 */ 74 */
60 75
61 #include <config.h> 76 #include <config.h>
62 #include "lisp.h" 77 #include "lisp.h"