X-Git-Url: http://git.lukelau.me/?a=blobdiff_plain;f=ast.scm;h=9af36531e7ef38bb1affc652eb09c5afa46a3dcc;hb=86531822ef58c5b29751976f5b41d1c631bdd459;hp=05716e40814287b15a67cfe7a87b1339734f13b0;hpb=64e7552f99ab98b7db77797cecfc3f34331296df;p=scheme.git

diff --git a/ast.scm b/ast.scm
index 05716e4..9af3653 100644
--- a/ast.scm
+++ b/ast.scm
@@ -1,23 +1,303 @@
-(define (app? x)
-  (and (list? x)
-       (>= (length x) 2)
-       (not (eq? (car x) 'let))
-       (not (eq? (car x) 'lambda))))
+(define (ast-type x)
+  (define (builtin? x)
+    (case x
+      ('+ #t)
+      ('- #t)
+      ('* #t)
+      ('! #t)
+      ('= #t)
+      ('bool->int #t)
+      ('print #t)
+      (else #f)))
+  (cond
+   ((list? x)
+    (case (car x)
+      ('if 'if)
+      ('let 'let)
+      ('lambda 'lambda)      
+      ('closure 'closure) ; only available in codegen
+      ('static-string 'static-string) ; only available in codegen
+      ('stack 'stack) ; only available in codegen (tag that value is passed via stack)
+      (else 'app)))
+   ((builtin? x) 'builtin)
+   ((symbol? x) 'var)
+   ((integer? x) 'int-literal)
+   ((boolean? x) 'bool-literal)
+   ((string? x) 'string-literal)))
 
-(define (let? x)
-  (and (list? x) (eq? (car x) 'let)))
+(define (ast-traverse f x)
+  (case (ast-type x)
+    ('let `(let ,(map (lambda (x) (list (car x) (f (cadr x))))
+		      (let-bindings x))
+	     ,@(map f (let-body x))))
+    ('app (map f x))
+    ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
+    ('if `(if ,@(map f (cdr x))))
+    ('stack `(stack ,(cadr x) ,(map f (caddr x))))
+    (else x)))
 
-(define let-bindings cadr)
+(define (ast-collect f x)
+  (define (inner y) (ast-collect f y))
+  (case (ast-type x)
+    ['let (append (f x)
+		  (flat-map inner (let-bindings x))
+		  (flat-map inner (let-body x)))]
+    ['app (append (f x)
+		  (flat-map inner x))]
+    ['lambda (append (f x)
+		     (inner (lambda-body x)))]
+    ['if (append (f x)
+		 (flat-map inner (cdr x)))]
+    ['stack (append (f x)
+		    (inner (caddr x)))]
+    [else (f x)]))
+
+(define (ast-find p x)
+  (define (inner y) (ast-find p y))
+  (define (any p x) (fold-left
+		     (lambda (acc y) (if acc #t (p y)))
+		     #f
+		     x))
+  (define (either . fs)
+    (if (null? fs) #f
+	(if (car fs) (car fs)
+	    (apply either (cdr fs)))))
+		     
+  (case (ast-type x)
+    ['let (either (p x)
+		  (any inner (let-bindings x))
+		  (any inner (let-body x)))]
+    ['app (either (p x)
+		  (any inner x))]
+    ['lambda (either (p x)
+		     (inner (lambda-body x)))]
+    ['if (either (p x) (any inner (cdr x)))]
+    ['stack (either (p x) (inner (caddr x)))]
+    [else (p x)]))
+
+(define (let-bindings e)
+  (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 `((,(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)
 
 (define (lambda? x)
   (and (list? x) (eq? (car x) 'lambda)))
 
+
+(define (statement-type x)
+  (cond
+   [(and (list? x)
+	 (eqv? (car x) 'data)) 'data]
+   [(and (list? x)
+	 (eqv? (car x) 'define)) 'define]
+   [else 'expr]))
+
+
+					; (A ((foo (Int Bool))
+					;     (bar (Bool)))
+(define (program-data-layouts program)
+  (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
+       (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
+			program))))
+
+(define (program-defines program)
+  (filter (lambda (x) (eqv? (statement-type x) 'defines))
+	  program))
+
+(define (program-body program)
+  ; hack to have multi-expression bodies
+  `(let ()
+     ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
+	       program)))
+
+					; 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)
+					;         (bar Bool))
+					;        |
+					;        v
+					; (foo   . ((A foo constructor) . (abs Int (abs Bool A))))
+					; (foo~0 . ((A foo 0)           . (abs A Int)))
+					; (foo~1 . ((A foo 1)           . (abs A Bool)))
+					; (bar   . ((A bar constructor) . (abs Bool A)))
+					; (bar~0 . ((A bar 0)           . (abs A Bool)))
+					;  ------+-------------------------------------
+					;  tor   | info                 | type
+
+(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 (cons (list prod-type ctor-name index) `(abs ,prod-type ,part-type)))))
+  
+  (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 (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
+	      
+	      [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
+			  products
+			  (range 0 (length products)))])
+	 (cons maker (append dtors acc))))
+     '()
+     ctors)))
+
+					; creates a type environment for a given adt definition
+(define (data-tors-type-env data-layout)
+  (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
+
+(define (dtor-name ctor-name index)
+  (string->symbol
+   (string-append (symbol->string ctor-name)
+		  "~"
+		  (number->string index))))
+
 ; for use in normalized form
 (define lambda-arg caadr)
 ; for use elsewhere
 (define lambda-args cadr)
 (define lambda-body caddr)
 
-(define (var? x)
-  (and (not (list? x)) (symbol? x)))
+(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))
+	      (list (+ s (- n 1))))))
+
+(define (flat-map f . xs) (fold-left append '() (apply map (cons f xs))))
+(define (repeat x n) (if (<= n 0) '()
+			 (cons x (repeat x (- n 1)))))
+
+
+(define-syntax push!
+  (syntax-rules ()
+    ((_ s x) (set! s (cons x s)))))
+
+(define-syntax pop!
+  (syntax-rules ()
+    ((_ s) (let ([x (car s)])
+	     (set! s (cdr s))
+	     x))))