matcher: back-reference Lisp variables.

* share/txr/stdlib/match.tl (struct var-list): New slot, menv.
(var-list exists): Method now falls back on lexical scope and
dynamic variables.
(get-var-list): New function.
(when-match, if-match, match-case, when-exprs-match): Capture
macro environment and use get-vars-list to convert to a vars
object which carries it as the menv slot. With this, the
compiler framework has access to the lexical environment.

* tests/011/patmatch.tl: Test cases of back-referencing with
Lisp lexicals.

* txr.1: Documented.

1 files changed, 21 insertions, 0 deletions

diff --git a/tests/011/patmatch.tl b/tests/011/patmatch.tl
index fe82d28c..870a3a0b 100644
--- a/tests/011/patmatch.tl
+++ b/tests/011/patmatch.tl
@@ -241,3 +241,24 @@
 
 (test (ack 1 1) 3)
 (test (ack 2 2) 7)
+
+(defun x-x-y (list x)
+  (when-match (@x @x @y) list y))
+
+(test (x-x-y '(1 1 2) 1) 2)
+(test (x-x-y '(1 2 3) 1) nil)
+(test (x-x-y '(1 1 2 r2) 1) nil)
+
+(test (let ((a 3) (x 0))
+        (match-case '(3 2 1)
+          ((@x 2 @b) ^(1 ,b))
+          ((@a 2 @b) ^(2 ,a))))
+      (2 3))
+
+(test
+  (let ((a 3) (x 0))
+    (labels ((local (:match)
+               ((@x 2 @b) ^(1 ,b))
+               ((@a 2 @b) ^(2 ,a))))
+      (local 3 2 1)))
+  (2 3))