PATCH: pws-24: prompt escapes for script/function and lineno

[Peter Stephenson <pws@ibmth.df.unipi.it>]

This implements the prompt escape %N for the nearest enclosing
script/sourced file/function, and %i for the corresponding line number
(sorry, %l, %L and %n were taken).  The main reason for having these is
that the PROMPT_SUBST option is set by emulation, so an `emulate zsh' will
turn it off, hence sticking $0 and $LINENO in PS4 is only partially
successful, and expecting functions to set it seems unfair.  Another reason
is that, because of FUNCTION_ARGZERO, it's not always possible to get the
name of whatever's being executed as the internal scriptname variable isn't
directly accessible.  I hope this seems reasonable.  People used to
complain when you added new % sequences, but with the size of the code
nowadays maybe they don't.

Maybe we should make '+%N:%i:%_> ' or something such the default PS4?

--- Doc/Zsh/params.yo.lns	Wed Jun 23 17:38:34 1999
+++ Doc/Zsh/params.yo	Mon Jun 28 10:57:32 1999
@@ -299,8 +299,11 @@
 )
 vindex(LINENO)
 item(tt(LINENO) <S>)(
-The line number of the current line within the current script
-being executed.
+The line number of the current line within the current script, sourced
+file, or shell function being executed, whichever was started most
+recently.  Note that in the case of shell functions the line
+number refers to the function as it appeared in the original definition,
+not necesarily as displayed by the tt(functions) builtin.
 )
 vindex(LOGNAME)
 item(tt(LOGNAME))(
--- Doc/Zsh/prompt.yo.lns	Mon Jun 28 10:26:15 1999
+++ Doc/Zsh/prompt.yo	Mon Jun 28 10:30:26 1999
@@ -95,6 +95,16 @@
 item(tt(%n))(
 tt($USERNAME).
 )
+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($0).
+)
+item(tt(%i))(
+The line number currently being executed in the script, sourced file, or
+shell function given by tt(%N).  This is most useful for debugging as part
+of tt($PS4).
+)
 item(tt(%w))(
 The date in var(day)tt(-)var(dd) format.
 )
--- Src/prompt.c.lns	Mon Apr 26 09:23:04 1999
+++ Src/prompt.c	Mon Jun 28 10:21:14 1999
@@ -531,6 +531,14 @@
 		if(Rstring)
 		    stradd(Rstring);
 		break;
+	    case 'i':
+		addbufspc(DIGBUFSIZE);
+		sprintf(bp, "%ld", (long)lineno);
+		bp += strlen(bp);
+		break;
+	    case 'N':
+		stradd(scriptname ? scriptname : argzero);
+		break;
 	    case '\0':
 		return 0;
 	    case Meta:

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