PATCH: fix tests for combining and base characters

[Peter Stephenson <pws@csr.com>]

This is a nice, easy patch to fix tests for combining characters along
the lines already discussed.

If the test for combining characters needs to be made safer when we use
an imported wcwidth(), our options are fairly limited; adding a test for
!iswcntrl() is about the best I can think of.

Index: Src/utils.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/utils.c,v
retrieving revision 1.186
diff -u -r1.186 utils.c
--- Src/utils.c	20 Apr 2008 21:17:29 -0000	1.186
+++ Src/utils.c	21 Apr 2008 11:44:44 -0000
@@ -3088,7 +3088,7 @@
 	     * logically they are still part of the word, even if they
 	     * don't get displayed properly, so always do this.
 	     */
-	    if (iswpunct(c) && wcwidth(c) == 0)
+	    if (IS_COMBINING(c))
 		return 1;
 	    return !!wmemchr(wordchars_wide.chars, c, wordchars_wide.len);
 
Index: Src/zsh.h
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/zsh.h,v
retrieving revision 1.123
diff -u -r1.123 zsh.h
--- Src/zsh.h	20 Apr 2008 21:17:29 -0000	1.123
+++ Src/zsh.h	21 Apr 2008 11:44:45 -0000
@@ -2281,7 +2281,34 @@
 #define ZWC(c)	L ## c
 #define ZWS(s)	L ## s
 
-#else
+/*
+ * Test for a combining character.
+ *
+ * wc is assumed to be a wchar_t (i.e. we don't need zwcwidth).
+ *
+ * This may need to be more careful if we import a wcwidth() for
+ * compatibility to try to avoid clashes with the system library.
+ *
+ * Pedantic note: in Unicode, a combining character need not be
+ * zero length.  However, we are concerned here about display;
+ * we simply need to know whether the character will be displayed
+ * on top of another one.  We use "combining character" in this
+ * sense throughout the shell.  I am not aware of a way of
+ * detecting the Unicode trait in standard libraries.
+ */
+#define IS_COMBINING(wc)	(wcwidth(wc) == 0)
+/*
+ * Test for the base of a combining character.
+ *
+ * We assume a combining character can be successfully displayed with
+ * any non-space printable character, which is what a graphic character
+ * is, as long as it has non-zero width.  We need to avoid all forms of
+ * space because the shell will split words on any whitespace.
+ */
+#define IS_BASECHAR(wc)		(iswgraph(wc) && wcwidth(wc) > 0)
+
+#else /* not MULTIBYTE_SUPPORT */
+
 #define MB_METACHARINIT()
 typedef int convchar_t;
 #define MB_METACHARLENCONV(str, cp)	metacharlenconv((str), (cp))
@@ -2296,4 +2323,4 @@
 #define ZWC(c)	c
 #define ZWS(s)	s
 
-#endif
+#endif /* MULTIBYTE_SUPPORT */
Index: Src/Zle/zle_move.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/zle_move.c,v
retrieving revision 1.15
diff -u -r1.15 zle_move.c
--- Src/Zle/zle_move.c	21 Apr 2008 09:06:10 -0000	1.15
+++ Src/Zle/zle_move.c	21 Apr 2008 11:44:45 -0000
@@ -54,22 +54,20 @@
     if (!isset(COMBININGCHARS) || loccs == zlell || loccs == 0)
 	return 0;
 
-    /* need to be on zero-width punctuation character */
-    if (!iswpunct(zleline[loccs]) || wcwidth(zleline[loccs]) != 0)
+    /* need to be on combining character */
+    if (!IS_COMBINING(zleline[loccs]))
 	 return 0;
 
     /* yes, go left */
     loccs--;
 
     for (;;) {
-	/* second test here is paranoia */
-	if (iswalnum(zleline[loccs]) && wcwidth(zleline[loccs]) > 0) {
+	if (IS_BASECHAR(zleline[loccs])) {
 	    /* found start position */
 	    if (setpos)
 		*pos = loccs;
 	    return 1;
-	} else if (!iswpunct(zleline[loccs]) ||
-		   wcwidth(zleline[loccs]) != 0) {
+	} else if (!IS_COMBINING(zleline[loccs])) {
 	    /* no go */
 	    return 0;
 	}
@@ -103,7 +101,7 @@
 
     while (loccs < zlell) {
 	/* Anything other than a combining char will do here */
-	if (!iswpunct(zleline[loccs]) || wcwidth(zleline[loccs]) != 0) {
+	if (!IS_COMBINING(zleline[loccs])) {
 	    if (setpos)
 		*pos = loccs;
 	    return 1;
@@ -221,16 +219,14 @@
 		    *retchr = wc;
 		return ptr;
 	    }
- 	    /* HERE: test for combining char, fix when test changes */
-	    if (!iswpunct(wc) || wcwidth(wc) != 0) {
+	    if (!IS_COMBINING(wc)) {
 		/* not a combining character... */
 		if (last) {
 		    /*
 		     * ... but we were looking for a suitable base character,
 		     * test it.
 		     */
-		    /* HERE this test will change too */
-		    if (iwsalnum(wc) && wcwidth(wc) > 0) {
+		    if (IS_BASECHAR(wc)) {
 			/*
 			 * Yes, this will do.
 			 */
Index: Src/Zle/zle_refresh.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/zle_refresh.c,v
retrieving revision 1.59
diff -u -r1.59 zle_refresh.c
--- Src/Zle/zle_refresh.c	20 Apr 2008 21:17:30 -0000	1.59
+++ Src/Zle/zle_refresh.c	21 Apr 2008 11:44:46 -0000
@@ -1245,13 +1245,12 @@
 		    rpms.nvcs = rpms.s - nbuf[rpms.nvln = rpms.ln];
 		}
 	    }
-	    if (isset(COMBININGCHARS) && iswalnum(*t)) {
+	    if (isset(COMBININGCHARS) && IS_BASECHAR(*t)) {
 		/*
-		 * Look for combining characters:  trailing punctuation
-		 * characters with printing width zero.
+		 * Look for combining characters.
 		 */
 		for (ichars = 1; tmppos + ichars < tmpll; ichars++) {
-		    if (!iswpunct(t[ichars]) || wcwidth(t[ichars]) != 0)
+		    if (!IS_COMBINING(t[ichars]))
 			break;
 		}
 	    } else
@@ -2267,9 +2266,8 @@
 #ifdef MULTIBYTE_SUPPORT
 	else if (iswprint(tmpline[t0]) && (width = wcwidth(tmpline[t0]) > 0)) {
 	    vsiz += width;
-	    if (isset(COMBININGCHARS) && iswalnum(tmpline[t0])) {
-		while (t0 < tmpll-1 && iswpunct(tmpline[t0+1]) &&
-		       wcwidth(tmpline[t0+1]) == 0)
+	    if (isset(COMBININGCHARS) && IS_BASECHAR(tmpline[t0])) {
+		while (t0 < tmpll-1 && IS_COMBINING(tmpline[t0+1]))
 		    t0++;
 	    }
 	}
@@ -2344,14 +2342,12 @@
 	} else if (iswprint(tmpline[t0]) &&
 		   (width = wcwidth(tmpline[t0])) > 0) {
 	    int ichars;
-	    if (isset(COMBININGCHARS) && iswalnum(tmpline[t0])) {
+	    if (isset(COMBININGCHARS) && IS_BASECHAR(tmpline[t0])) {
 		/*
-		 * Look for combining characters:  trailing printable
-		 * characters with printing width zero.
+		 * Look for combining characters.
 		 */
 		for (ichars = 1; t0 + ichars < tmpll; ichars++) {
-		    if (!iswpunct(tmpline[t0+ichars]) ||
-			wcwidth(tmpline[t0+ichars]) != 0)
+		    if (!IS_COMBINING(tmpline[t0+ichars]))
 			break;
 		}
 	    } else

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070