Check for the right number of bindings in pattern matching

[scheme.git] / ast.scm

diff --git a/ast.scm b/ast.scm
index 8a986173d675f43eb58cd0c5f7c6c7c679175d9f..b3f21bd07d6d07ba2b64017cff0a365cbf77abd4 100644 (file)
--- a/ast.scm
+++ b/ast.scm
@@ -83,27 +83,47 @@
                                        ;   v
                                        ; (let ([a (foo~0 (foo 123 345)]
                                         ;       [b (foo~1 (foo 123 345)]) a)
-(define (expand-pattern-matches x)  
+(define (expand-pattern-matches program)
+  (define (go x)
     (define (pattern-match binding)
       (let ([binding-name (car binding)]
            [body (cadr binding)])
        (if (eqv? (ast-type binding-name) 'var)
            (list (list binding-name body))
+           
            (let* ([sum-name (car binding-name)]
-                [destructor (lambda (i) (dtor-name sum-name i))])
+                  [destructor (lambda (i) (dtor-name sum-name i))]
+                  [products (cdr binding-name)]
+
+                  [data-layouts (program-data-layouts program)]
+
+                  [type (data-tor-type data-layouts sum-name)]
+
+                  [sum (assoc sum-name (cdr (assoc type data-layouts)))]
+                  
+                  [expected-number (length (cdr sum))])
+
+                                       ; assert that there is the correct number of bindings
+             (when (not (= (length products)
+                           expected-number))
+               (error #f (format "Got ~a bindings: expected ~a for ~a"
+                              (length products)
+                              expected-number
+                              binding)))
+             
              (flat-map (lambda (y i)
                          (pattern-match (list y `(,(destructor i) ,body))))
-                     (cdr binding-name)
-                     (range 0 (length (cdr binding-name))))))))
+                       products
+                       (range 0 (length products)))))))
     (case (ast-type x)
       ['let `(let ,(flat-map pattern-match (let-bindings x))
-                 ,@(map expand-pattern-matches (let-body x)))]
-      [else (ast-traverse expand-pattern-matches x)]))
+              ,@(map go (let-body x)))]
+      [else (ast-traverse go x)]))
+  (program-map-exprs go program))
 
 (define (lambda? x)
   (and (list? x) (eq? (car x) 'lambda)))
 
-
 (define (statement-type x)
   (cond
    [(and (list? x)
@@ -137,6 +157,11 @@
      ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
               program)))
 
+(define (data-tor-type data-layouts tor)
+  (let* ([tors (flat-map data-tors data-layouts)]
+        [info (cadr (assoc tor tors))])
+    (car info)))
+
                                        ; a data tor is either a constructor or destructor for an ADT
                                        ; data-tors returns constructors and destructors for a data-layout
                                        ; (data A (foo Int Bool)