Re: PATCH: CHR$(foo) => ${(#)foo}

[Peter Stephenson <pws@xxxxxxx>]

Peter Stephenson <pws@xxxxxxx> wrote:
> There are lots of ways of turning a number into a character, but few the
> other way round, none that I'm aware of convenient for use in general
> substitutions.  This adds the (#) expansion flag to do that.  I couldn't
> think of a better syntax, certainly none I was likely to remember.

After posting this, I realised that handling arrays element by element was
much more natural (consistent enough with other forms of array processing
that it doesn't need specially documenting).  You can do things like

  % foo=(0x41 0x42 0x43)
  % print ${(#j..)foo}
  ABC

which was what I was trying to do in the first place.

Index: Doc/Zsh/expn.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/expn.yo,v
retrieving revision 1.56
diff -u -r1.56 expn.yo
--- Doc/Zsh/expn.yo	23 Sep 2005 17:03:17 -0000	1.56
+++ Doc/Zsh/expn.yo	1 Nov 2005 14:49:12 -0000
@@ -632,6 +632,11 @@
 following flags are supported:
 
 startitem()
+item(tt(#))(
+Evaluate the parameter as a numeric expression and output the character
+corresponding to the resulting integer.  Note that this form is entirely
+distinct from use of the tt(#) without parentheses.
+)
 item(tt(%))(
 Expand all tt(%) escapes in the resulting words in the same way as in in
 prompts (see noderef(Prompt Expansion)). If this flag is given twice,
Index: Src/subst.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/subst.c,v
retrieving revision 1.42
diff -u -r1.42 subst.c
--- Src/subst.c	13 Oct 2005 16:30:14 -0000	1.42
+++ Src/subst.c	1 Nov 2005 14:49:15 -0000
@@ -915,6 +915,10 @@
      */
     int globsubst = isset(GLOBSUBST);
     /*
+     * Indicates ${(#)...}.
+     */
+    int evalchar = 0;
+    /*
      * Indicates ${#pm}, massaged by whichlen which is set by
      * the (c), (w), and (W) flags to indicate how we take the length.
      */
@@ -1320,6 +1324,11 @@
 		    unique = 1;
 		    break;
 
+		case '#':
+		case Pound:
+		    evalchar = 1;
+		    break;
+
 		default:
 		  flagerr:
 		    zerr("error in flags", NULL, 0);
@@ -2233,6 +2242,40 @@
     }
     if (errflag)
 	return NULL;
+    if (evalchar) {
+	/*
+	 * Evaluate the value numerically and output the result as
+	 * a character.
+	 *
+	 * Note this doesn't yet handle Unicode or multibyte characters:
+	 * that will need handling more generally probably by
+	 * an additional flag of some sort.
+	 */
+	zlong ires;
+
+	if (isarr) {
+	    char **aval2, **avptr, **av2ptr;
+
+	    aval2 = (char **)zhalloc((arrlen(aval)+1)*sizeof(char *));
+
+	    for (avptr = aval, av2ptr = aval2; *avptr; avptr++, av2ptr++)
+	    {
+		ires = mathevali(*avptr);
+		if (errflag)
+		    return NULL;
+		*av2ptr = zhalloc(2);
+		sprintf(*av2ptr, "%c", (int)ires);
+	    }
+	    *av2ptr = NULL;
+	    aval = aval2;
+	} else {
+	    ires = mathevali(val);
+	    if (errflag)
+		return NULL;
+	    val = zhalloc(2);
+	    sprintf(val, "%c", (int)ires);
+	}
+    }
     /*
      * This handles taking a length with ${#foo} and variations.
      * TODO: again. one might naively have thought this had the


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


This message has been scanned for viruses by BlackSpider MailControl - www.blackspider.com