matcher: rescind support for @(rcons ...) patterns.

There is no longer any way to write a @(rcons ...)
pattern using the range syntax, so there is no point in
supporting that operator. The silly syntax @@a..@b
which previously worked was actually due to a mistaken
requirement in the parser.

* share/txr/stdlib/match.tl (compile-range-match): Function
moved closer to compile-atom-match, below compile-vec-match.
The argument is now a range object containing patterns, so we
pull it apart with from and to.
(compile-atom-match): Pass range directly to
compile-range-match; no need to construct (rcons ...) syntax.

* tests/011/patmatch.tl: Add range tests from documentation
and a few others.

* txr.1: References to @(rcons ...) pattern scrubbed.
One wrong #R pattern example corrected.

3 files changed, 31 insertions, 41 deletions

diff --git a/share/txr/stdlib/match.tl b/share/txr/stdlib/match.tl
index 8161d57f..d1c45559 100644
--- a/share/txr/stdlib/match.tl
+++ b/share/txr/stdlib/match.tl
@@ -156,6 +156,24 @@
          vars (mappend .vars elem-matches)
          var-exprs (mappend .var-exprs elem-matches))))
 
+(defun compile-range-match (rcons-expr obj-var var-list)
+  (let ((from (from rcons-expr))
+        (to (to rcons-expr)))
+    (let* ((from-match (compile-match from (gensym "from") var-list))
+           (to-match (compile-match to (gensym "to") var-list))
+           (guard (new match-guard
+                       guard-expr ^(rangep ,obj-var)
+                       pure-vars (list from-match.obj-var to-match.obj-var)
+                       pure-var-exprs (list ^(from ,obj-var) ^(to ,obj-var)))))
+      (new compiled-match
+           pattern rcons-expr
+           obj-var obj-var
+           guard-chain (cons guard (append from-match.guard-chain
+                                           to-match.guard-chain))
+           test-expr ^(and ,from-match.test-expr ,to-match.test-expr)
+           vars (append from-match.vars to-match.vars)
+           var-exprs (append from-match.var-exprs to-match.var-exprs)))))
+
 (defun compile-atom-match (atom obj-var var-list)
   (flet ((compile-as-atom ()
            (new compiled-match
@@ -167,8 +185,7 @@
              (compile-vec-match atom obj-var var-list)
              (compile-as-atom)))
       (range (if (non-triv-pat-p atom)
-               (compile-range-match ^(rcons ,(from atom) ,(to atom))
-                                    obj-var var-list)
+               (compile-range-match atom obj-var var-list)
                (compile-as-atom)))
       (t (compile-as-atom)))))
 
@@ -388,23 +405,6 @@
            vars (mappend .vars hash-matches)
            var-exprs (mappend .var-exprs hash-matches)))))
 
-(defun compile-range-match (rcons-expr obj-var var-list)
-  (tree-bind (op from to) rcons-expr
-    (let* ((from-match (compile-match from (gensym "from") var-list))
-           (to-match (compile-match to (gensym "to") var-list))
-           (guard (new match-guard
-                       guard-expr ^(rangep ,obj-var)
-                       pure-vars (list from-match.obj-var to-match.obj-var)
-                       pure-var-exprs (list ^(from ,obj-var) ^(to ,obj-var)))))
-      (new compiled-match
-           pattern rcons-expr
-           obj-var obj-var
-           guard-chain (cons guard (append from-match.guard-chain
-                                           to-match.guard-chain))
-           test-expr ^(and ,from-match.test-expr ,to-match.test-expr)
-           vars (append from-match.vars to-match.vars)
-           var-exprs (append from-match.var-exprs to-match.var-exprs)))))
-
 (defun compile-match (pat : (obj-var (gensym)) (var-list (new var-list)))
   (cond
     ((consp pat)
diff --git a/tests/011/patmatch.tl b/tests/011/patmatch.tl
index d045c45b..ac474738 100644
--- a/tests/011/patmatch.tl
+++ b/tests/011/patmatch.tl
@@ -135,3 +135,12 @@
 
 (test (when-match @(hash (x @y) (@(symbolp y) @datum)) #H(() (x k) (k 42)) datum)
       (42))
+
+(test (if-match #R(10 20) 10..20 :yes :no) :yes)
+(test (if-match #R(10 20) #R(10 20) :yes :no) :yes)
+(test (if-match #R(10 20) #R(1 2) :yes :no) :no)
+(test (when-match #R(@a @b) 1..2 (list a b)) (1 2))
+(test (when-match #R(@a 2) 1..2 a) 1)
+(test (when-match #R(1 @a) 1..2 a) 2)
+(test (when-match #R(2 @a) 1..2 a) nil)
+(test (when-match #R(@a 1) 1..2 a) nil)
diff --git a/txr.1 b/txr.1
index b42cb75c..99e03045 100644
--- a/txr.1
+++ b/txr.1
@@ -39656,7 +39656,8 @@ binding
 .code a
 to
 .codn 3 .
-The notation supports lists, vectors and atoms. Atoms are compared using the
+The notation supports lists, vectors, ranges and atoms. Atoms are compared
+using the
 .code equal
 function. Thus, in the above pattern, the 1 and 2 in the pattern match the
 corresponding 1 and 2 atoms in the object using
@@ -39690,15 +39691,6 @@ can be significant. One sub-pattern may be expected to produce
 a match for a variable, which is then back-referenced in another
 sub-pattern.
 
-Ranges can be
-matched using the
-.code "@(rcons ...)"
-notation or its
-.code ..
-syntactic sugar, or using the
-.code #R
-printed representation.
-
 A pattern can contain multiple occurrences of the same variable.
 Except in the case when these variables occur in different branches
 of an
@@ -39886,21 +39878,10 @@ is matched against its
 .code to
 part.
 
-Note: ranges can also be matched using the
-.mono
-.meti >> @(rcons from-pattern << to-pattern )
-.onom
-operator, also expressible using its syntactic sugar
-.mono
-.meti >> @ from-pattern..to-pattern
-.onom
-described under Pattern operator
-.codn rcons .
-
 .TP* Examples:
 
 .verb
-  (if-match #R(10 20) 10..20 :yes :no) -> :no
+  (if-match #R(10 20) 10..20 :yes :no) -> :yes
   (if-match #R(10 20) #R(10 20) :yes :no) -> :yes
   (if-match #R(10 20) #R(1 2) :yes :no) -> :no