PATCH: pws-25: prompt path segment rationalization.

[Peter Stephenson <pws@xxxxxxxxxxxxxxxxx>]

This is what I intended by my remarks on path segments a propos of %N.  By
separating the path stuff into a function, %/ and %~ can take integers like
%c and %C with no extra code.  Since you can do everything with %/ and %~
you can with %c and %C (the only difference is you need an explicit 1 for
one path segment as zero is the full path), and since it's much clearer and
less confusing with just the two, I've moved %c and %C down in the
documentation and marked them as decreprecated, though I have no intention
of removing them.

Now we can get %N to work on paths in a natural way:  the default is the
full path, but integers can specify trailing segments.  I've left %N in the
default PS4, however.

--- Doc/Zsh/prompt.yo.prdir	Sat Jul  3 15:06:37 1999
+++ Doc/Zsh/prompt.yo	Sat Jul  3 15:05:56 1999
@@ -42,21 +42,14 @@
 )
 xitem(tt(%d))
 item(tt(%/))(
-Present working directory (tt($PWD)).
+Present working directory (tt($PWD)).  If an integer follows the `tt(%)',
+it specifies a number of trailing components of tt($PWD) to show; zero
+means the whole path.
 )
 item(tt(%~))(
-tt($PWD).
-If it has a named directory as its prefix, that part is replaced
-by a `tt(~)' followed by the name of the directory.
-If it starts with tt($HOME), that part is
-replaced by a `tt(~)'.
-)
-xitem(tt(%c))
-xitem(tt(%.))
-item(tt(%C))(
-Trailing component of tt($PWD).
-An integer may follow the `tt(%)' to get more than one component.
-Unless `tt(%C)' is used, tilde contraction is performed first.
+As tt(%d) and tt(%/), but if tt($PWD) has a named directory as its prefix,
+that part is replaced by a `tt(~)' followed by the name of the directory.
+If it starts with tt($HOME), that part is replaced by a `tt(~)'.
 )
 xitem(tt(%h))
 item(tt(%!))(
@@ -98,7 +91,9 @@
 item(tt(%N))(
 The name of the script, sourced file, or shell function that zsh is
 currently executing, whichever was started most recently.  If there is
-none, this is equivalent to the parameter tt($0).
+none, this is equivalent to the parameter tt($0).  An integer may follow
+the `tt(%)' to specify a number of trailing path components to show; zero
+means the full path.
 )
 item(tt(%i))(
 The line number currently being executed in the script, sourced file, or
@@ -234,5 +229,15 @@
 current directory, followed by a `tt(%)' or `tt(#)', followed by a
 space.  Without the `tt(%<<)', those two characters would be included
 in the string to be truncated.
+)
+xitem(tt(%c))
+xitem(tt(%.))
+item(tt(%C))(
+Trailing component of tt($PWD).
+An integer may follow the `tt(%)' to get more than one component.
+Unless `tt(%C)' is used, tilde contraction is performed first.  These are
+deprecated as tt(%c) and tt(%C) are equivalent to tt(%1~) and tt(%1/),
+respectively, while explicit positive integers have the same effect as for
+the latter two sequences.
 )
 enditem()
--- Src/prompt.c.prdir	Mon Jun 28 10:21:14 1999
+++ Src/prompt.c	Sat Jul  3 14:59:16 1999
@@ -97,6 +97,38 @@
 
 static char *rstring, *Rstring;
 
+/*
+ * Expand path p; maximum is npath segments where 0 means the whole path.
+ * If tilde is 1, try and find a named directory to use.
+ */
+
+static void
+promptpath(char *p, int npath, int tilde)
+{
+    char *modp = p;
+    Nameddir nd;
+
+    if (tilde && ((nd = finddir(p))))
+	modp = tricat("~", nd->nam, p + strlen(nd->dir));
+
+    if (npath) {
+	char *sptr;
+	for (sptr = modp + strlen(modp); sptr > modp; sptr--) {
+	    if (*sptr == '/' && !--npath) {
+		sptr++;
+		break;
+	    }
+	}
+	if (*sptr == '/' && sptr[1] && sptr != modp)
+	    sptr++;
+	stradd(sptr);
+    } else
+	stradd(modp);
+
+    if (p != modp)
+	zsfree(modp);
+}
+
 /* Perform prompt expansion on a string, putting the result in a *
  * permanently-allocated string.  If ns is non-zero, this string *
  * may have embedded Inpar and Outpar, which indicate a toggling *
@@ -293,49 +325,21 @@
 		}
 	    switch (*fm) {
 	    case '~':
-		if ((nd = finddir(pwd))) {
-		    char *t = tricat("~", nd->nam, pwd + strlen(nd->dir));
-		    stradd(t);
-		    zsfree(t);
-		    break;
-		}
+		promptpath(pwd, arg, 1);
+		break;
 	    case 'd':
 	    case '/':
-		stradd(pwd);
+		promptpath(pwd, arg, 0);
 		break;
 	    case 'c':
 	    case '.':
-	        {
-		    char *t;
-
-		    if ((nd = finddir(pwd)))
-			t = tricat("~", nd->nam, pwd + strlen(nd->dir));
-		    else
-			t = ztrdup(pwd);
-		    if (!arg)
-			arg++;
-		    for (ss = t + strlen(t); ss > t; ss--)
-			if (*ss == '/' && !--arg) {
-			    ss++;
-			    break;
-			}
-		    if(*ss == '/' && ss[1] && ss != t)
-			ss++;
-		    stradd(ss);
-		    zsfree(t);
-		    break;
-		}
+		promptpath(pwd, arg ? arg : 1, 1);
+		break;
 	    case 'C':
-		if (!arg)
-		    arg++;
-		for (ss = pwd + strlen(pwd); ss > pwd; ss--)
-		    if (*ss == '/' && !--arg) {
-			ss++;
-			break;
-		    }
-		if (*ss == '/' && ss[1] && (ss != pwd))
-		    ss++;
-		stradd(ss);
+		promptpath(pwd, arg ? arg : 1, 0);
+		break;
+	    case 'N':
+		promptpath(scriptname ? scriptname : argzero, arg, 0);
 		break;
 	    case 'h':
 	    case '!':
@@ -535,9 +539,6 @@
 		addbufspc(DIGBUFSIZE);
 		sprintf(bp, "%ld", (long)lineno);
 		bp += strlen(bp);
-		break;
-	    case 'N':
-		stradd(scriptname ? scriptname : argzero);
 		break;
 	    case '\0':
 		return 0;

-- 
Peter Stephenson <pws@xxxxxxxxxxxxxxxxx>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy