X-Git-Url: https://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=ast.scm;h=4ca6eb1e1dc57100a344310ea1494ea2139236e0;hp=5064ca554bc8033bdbc0b483ac79249cd3312f73;hb=89ef32141732e6d0bbfc7484b465844b62d8d139;hpb=844dcd052c6f551d9936693c2b4c49cf920c7051

diff --git a/ast.scm b/ast.scm
index 5064ca5..4ca6eb1 100644
--- a/ast.scm
+++ b/ast.scm
@@ -46,6 +46,7 @@
 		     (inner (lambda-body x)))]
     ['if (append (f x)
 		 (flat-map inner (cdr x)))]
+    ['closure (flat-map inner (caddr x))]
     [else (f x)]))
 
 (define (ast-find p x)
@@ -71,15 +72,15 @@
     [else (p x)]))
 
 (define (let-bindings e)
-  (define (pattern-match x body)
-    (if (eqv? (ast-type x) 'var)
-	(list (cons x body))
-	(let* ([constructor (car x)]
+  (define (pattern-match binding body)
+    (if (eqv? (ast-type binding) 'var)
+	(list (cons binding body))
+	(let* ([constructor (car binding)]
 	       [destructor (lambda (i) (dtor-name constructor i))])
 	  (flat-map (lambda (y i)
-		      (pattern-match y (list (destructor i) body)))
-		    (cdr x)
-		    (range 0 (length (cdr x)))))))
+		      (pattern-match y `((,(destructor i) ,@body))))
+		    (cdr binding)
+		    (range 0 (length (cdr binding)))))))
   (flat-map (lambda (x) (pattern-match (car x) (cdr x))) (cadr e)))
 (define let-body cddr)
 
@@ -104,37 +105,44 @@
 	  program))
 
 (define (program-body program)
+  ; hack to have multi-expression bodies
   `(let ()
      ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
 	       program)))
 
+
+					; (A ((foo (Int Bool))
+					;     (bar (Bool)))
+
+(define data-layout cdr)
+
 					; gets both constructors and destructors
 					; (data A (foo Int Bool)
 					;         (bar Bool))
 					;        |
 					;        v
-					; (foo . (abs Int (abs Bool A)))
-					; (foo~0 . (abs A Int)
-					; (foo~1 . (abs A Bool)
-					; (bar . (abs Bool A)
-					; (bar~0 . (abs A Bool)
+					; (foo . (constructor . (abs Int (abs Bool A))))
+					; (foo~0 . (0 . (abs A Int)))
+					; (foo~1 . (1 . (abs A Bool)))
+					; (bar . (constructor . (abs Bool A)))
+					; (bar~0 . (0 . (abs A Bool)))
 
-(define (data-tors data-def)
+(define (data-tors data-layout)
   (define (constructor-type t products)
     (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
 
   (define (destructor ctor-name prod-type part-type index)
     (let ([name (dtor-name ctor-name index)])
-      (cons name `(abs ,prod-type ,part-type))))
+      (cons name (cons index `(abs ,prod-type ,part-type)))))
   
-  (let ([type-name (cadr data-def)]
-        [ctors (cddr data-def)])
+  (let ([type-name (car data-layout)]
+        [ctors (cdr data-layout)])
     (fold-right
      (lambda (ctor acc)       
        (let* ([ctor-name (car ctor)]
 	      [products (cdr ctor)]
 	      
-	      [maker (cons ctor-name (constructor-type type-name products))]
+	      [maker (cons ctor-name (cons 'constructor (constructor-type type-name products)))]
 	      
 	      [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
 			  products
@@ -142,7 +150,11 @@
 	 
 	 (cons maker (append dtors acc))))
      '()
-     ctrs)))
+     ctors)))
+
+					; creates a type environment for a given adt definition
+(define (data-tors-env data-layout)
+  (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
 
 (define (dtor-name ctor-name index)
   (string->symbol
@@ -156,7 +168,116 @@
 (define lambda-args cadr)
 (define lambda-body caddr)
 
+(define (references prog)
+  (ast-collect
+   (lambda (x)
+     (case (ast-type x)
+       ['var (list x)]
+       [else '()]))
+   prog))
+
+(define (graph bs)
+  (define (go bs orig-bs)
+    (if (null? bs)
+	'(() . ())
+	(let* [(bind (car bs))
+
+	       (vert (car bind))
+	       (refs (filter ; only count a reference if its a binding
+		      (lambda (x) (assoc x orig-bs))
+		      (references (cdr bind))))
+	       (edges (map (lambda (x) (cons vert x))
+			   refs))
+
+	       (rest (if (null? (cdr bs))
+			 (cons '() '())
+			 (go (cdr bs) orig-bs)))
+	       (total-verts (cons vert (car rest)))
+	       (total-edges (append edges (cdr rest)))]
+	  (cons total-verts total-edges))))
+  (go bs bs))
+
+(define (successors graph v)
+  (define (go v E)
+    (if (null? E)
+	'()
+	(if (eqv? v (caar E))
+	    (cons (cdar E) (go v (cdr E)))
+	    (go v (cdr E)))))
+  (go v (cdr graph)))
+
+					; takes in a graph (pair of vertices, edges)
+					; returns a list of strongly connected components
+
+					; ((x y w) . ((x . y) (x . w) (w . x))
+
+					; =>
+					; .->x->y
+					; |  |
+					; |  v
+					; .--w
+
+					; ((x w) (y))
+
+					; this uses tarjan's algorithm, to get reverse
+					; topological sorting for free
+(define (sccs graph)
+  
+  (let* ([indices (make-hash-table)]
+	 [lowlinks (make-hash-table)]
+	 [on-stack (make-hash-table)]
+	 [current 0]
+	 [stack '()]
+	 [result '()])
+
+    (define (index v)
+      (get-hash-table indices v #f))
+    (define (lowlink v)
+      (get-hash-table lowlinks v #f))
+
+    (letrec
+	([strong-connect
+	  (lambda (v)
+	    (begin
+	      (put-hash-table! indices v current)
+	      (put-hash-table! lowlinks v current)
+	      (set! current (+ current 1))
+	      (push! stack v)
+	      (put-hash-table! on-stack v #t)
+
+	      (for-each
+	       (lambda (w)
+		 (if (not (hashtable-contains? indices w))
+					; successor w has not been visited, recurse
+		     (begin
+		       (strong-connect w)
+		       (put-hash-table! lowlinks
+					v
+					(min (lowlink v) (lowlink w))))
+					; successor w has been visited
+		     (when (get-hash-table on-stack w #f)
+		       (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
+	       (successors graph v))
+
+	      (when (= (index v) (lowlink v))
+		(let ([scc
+		       (let new-scc ()
+			 (let ([w (pop! stack)])
+			   (put-hash-table! on-stack w #f)
+			   (if (eqv? w v)
+			       (list w)
+			       (cons w (new-scc)))))])
+		  (set! result (cons scc result))))))])
+      (for-each
+       (lambda (v)
+	 (when (not (hashtable-contains? indices v)) ; v.index == -1
+	   (strong-connect v)))
+       (car graph)))
+    result))
+
+
 					; utils
+
 (define (range s n)
   (if (= 0 n) '()
       (append (range s (- n 1))