From 503a7e5169b4a18e2ad2569daeb9e13a99f21070 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Tue, 10 Dec 2019 01:21:43 +0000
Subject: [PATCH] Syntax: Introduce &. and friends

Incompatible change.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 README   | 18 ++++++++++++------
 generate | 12 ++++++++----
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/README b/README
index 006b57f..67ce6cc 100644
--- a/README
+++ b/README
@@ -218,27 +218,33 @@ empty string).
 	The assumption is that filenames are usually lowercase and
 	variables usually uppercase.  Otherwise, use another syntax:
 
+&/		=>	sub/dir/			or nothing
 &_		=>	sub_dir_			or TOP_
-&=_		=>	sub_dir				or TOP
+&.		=>	sub/dir				or .
+	(This implies that `&./' works roughly like `&/', although
+	it can produce a needless `./')
 
-&/		=>	sub/dir/			or nothing
-&=/		=>	sub/dir				or .
+&=		=>	sub_dir				or TOP
 
 &^lc		=>	$(top_srcdir)/sub/dir/lc
 &^/		=>	$(top_srcdir)/sub/dir/
+&^.		=>	$(top_srcdir)/sub/dir
 
 &~lc		=>	$(top_srcdir)/lc
 &~/		=>	$(top_srcdir)/
+&~.		=>	$(top_srcdir)
 
 In general:
-    =	return subdir without delimiter (not allowed with `^' `~')
     ^   pathname of this subdirectory in source tree
     ~   pathname of top level of source tree
-    /	terminates the escape (needed if next is not lwsp or space)
+    /	terminates the path escape } needed if next is
+    _   terminates the var escape  } not lwsp or space)
+    .   terminates path escape giving dir name (excluding /)
+    =	terminates var escape giving only prefix part (rarely needed)
   lwsp  starts multi-word processing (see below)
 
 So pathname syntax is a subset of:
-    '&' [ '^' | '~' ] [ lc | '/' ]
+    '&' [ '^' | '~' ] [ lc | '/' | '.' | '=' ]
 
 &&		=>	&&		for convenience in shell runes
 \&		=>	&		general escaping mechanism
diff --git a/generate b/generate
index ca54f94..ba66f86 100755
--- a/generate
+++ b/generate
@@ -137,11 +137,14 @@ sub process_input_mk ($$$$$$$$$) {
     }
     $input_files{$f}++;
 
+    my %srcdirmap = (
+		  '^' => "\$(top_srcdir)${dir_suffix}",
+		  '~' => "\$(top_srcdir)",
+		    );
     my %pfxmap = (
 		  ''  => $dir_prefix,
-		  '^' => "\$(top_srcdir)${dir_suffix}/",
-		  '~' => "\$(top_srcdir)/",
 		 );
+    $pfxmap{$_} = $srcdirmap{$_}.'/' foreach keys %srcdirmap;
 
     while (<$input>) {
 	if (s#^\s*$esc\:##) {
@@ -161,9 +164,10 @@ sub process_input_mk ($$$$$$$$$) {
 	    elsif (m{^(?=$caps_re)}) { o $var_prefix }
 	    elsif (s{^([~^]?)(?=$lc_re)}{}) { o $pfxmap{$1} }
 	    elsif (s{^_}{}) { o $var_prefix }
-	    elsif (s{^=_}{}) { o $var_prefix }
+	    elsif (s{^=}{}) { o $var_prefix_name }
 	    elsif (s{^([~^]?)/}{}) { o $pfxmap{$1} }
-	    elsif (s{^=/}{}) { o $dir_name }
+	    elsif (s{^\.}{}) { o $dir_name }
+	    elsif (s{^([~^])\.}{}) { o $srcdirmap{$1} }
 	    elsif (s{^([~^]?)(?=[ \t])}{}) {
 		my $prefix = $pfxmap{$1} // die;
 		my $after='';
-- 
2.30.2