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Re: PATCH: ordering of hash table scans
- X-seq: zsh-workers 23153
- From: Peter Stephenson <pws@xxxxxxx>
- To: zsh-workers@xxxxxxxxxx (Zsh hackers list)
- Subject: Re: PATCH: ordering of hash table scans
- Date: Wed, 7 Feb 2007 10:10:47 +0000
- In-reply-to: <200702062142.l16LgOoa007853@xxxxxxxxxxxxxxxxx>
- Mailing-list: contact zsh-workers-help@xxxxxxxxxx; run by ezmlm
- Organization: Cambridge Silicon Radio
- References: <200702062142.l16LgOoa007853@xxxxxxxxxxxxxxxxx>
Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx> wrote:
> This started off as an attempt to make ztrcmp() handle multibyte
> characters when MULTIBYTE is turned on, which I've done. ztrcmp() is
> only used when sorting the names of hash nodes for use when scanning
> through hash tables, usually in order to print them out: this is used
> for commands of various sort, parameters, and a few other miscellaneous
> bist and pieces.
>
> I have a vague memory that it's deliberate that we don't use strcoll()
> here, which would make the sorting locale dependent and in particular
> possibly case-insensitive.
This gave me a sleepless night. If we're not using strcoll(), it seems
overkill to convert every single multibyte character to a wide character on
every comparison between two strings when sorting. So I've put that bit
back and stuck a note at the top.
Index: Src/utils.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/utils.c,v
retrieving revision 1.153
diff -u -r1.153 utils.c
--- Src/utils.c 6 Feb 2007 21:47:55 -0000 1.153
+++ Src/utils.c 7 Feb 2007 10:06:38 -0000
@@ -3693,61 +3693,46 @@
return fn;
}
-/* Unmetafy and compare two strings, comparing unsigned character values.
- * "a\0" sorts after "a". */
+/*
+ * Unmetafy and compare two strings, comparing unsigned character values.
+ * "a\0" sorts after "a".
+ *
+ * Currently this is only used in hash table sorting, where the
+ * keys are names of hash nodes and where we don't use strcoll();
+ * it's not clear if that's right but it does guarantee the ordering
+ * of shell structures on output.
+ *
+ * As we don't use strcoll(), it seems overkill to convert multibyte
+ * characters to wide characters for comparison every time. In the case
+ * of UTF-8, Unicode ordering is preserved when sorted raw, and for
+ * other character sets we rely on an extension of ASCII so the result,
+ * while it may not be correct, is at least rational.
+ */
/**/
int
ztrcmp(char const *s1, char const *s2)
{
- convchar_t c1 = 0, c2;
-
-#ifdef MULTIBYTE_SUPPORT
- if (isset(MULTIBYTE)) {
- mb_metacharinit();
- while (*s1) {
- int clen = mb_metacharlenconv(s1, &c1);
-
- if (strncmp(s1, s2, clen))
- break;
- s1 += clen;
- s2 += clen;
- }
- } else
-#endif
- while (*s1 && *s1 == *s2) {
- s1++;
- s2++;
- }
+ int c1, c2;
- if (!*s1) {
- if (!*s2)
- return 0;
- return -1;
- }
- if (!*s2)
- return 1;
-#ifdef MULTIBYTE_SUPPORT
- if (isset(MULTIBYTE)) {
- /* TODO: shift state for s2 might be wrong? */
- mb_metacharinit();
- (void)mb_metacharlenconv(s2, &c2);
- if (c1 == WEOF)
- c1 = STOUC(*s1 == Meta ? s1[1] ^ 32 : *s1);
- if (c2 == WEOF)
- c2 = STOUC(*s2 == Meta ? s2[1] ^ 32 : *s2);
- }
- else
-#endif
- {
- c1 = STOUC(*s1 == Meta ? s1[1] ^ 32 : *s1);
- c2 = STOUC(*s2 == Meta ? s2[1] ^ 32 : *s2);
- }
+ while(*s1 && *s1 == *s2) {
+ s1++;
+ s2++;
+ }
+
+ if(!(c1 = *s1))
+ c1 = -1;
+ else if(c1 == STOUC(Meta))
+ c1 = *++s1 ^ 32;
+ if(!(c2 = *s2))
+ c2 = -1;
+ else if(c2 == STOUC(Meta))
+ c2 = *++s2 ^ 32;
- if (c1 < c2)
- return -1;
- else if (c1 == c2)
+ if(c1 == c2)
return 0;
+ else if(c1 < c2)
+ return -1;
else
return 1;
}
--
Peter Stephenson <pws@xxxxxxx> Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK Tel: +44 (0)1223 692070
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