X-Git-Url: https://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=ast.scm;h=1a4afe21f3258d829c4f305ea78fd2f804cca2ad;hp=a0899192e21a1d44b0fe3296e380604133a3f1d2;hb=25ef5a684dec5eedfc4e34a12b00a04e2d6b2b1b;hpb=94d1c48d51bfe32aa1e14d4fb012b283ec9352ef

diff --git a/ast.scm b/ast.scm
index a089919..1a4afe2 100644
--- a/ast.scm
+++ b/ast.scm
@@ -34,14 +34,103 @@
     ('if `(if ,@(map f (cdr 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)))]
+    [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)))]
+    [else (p x)]))
+
+(define (let-bindings e)
+  (define (pattern-match x body)
+    (if (eqv? (ast-type x) 'var)
+	(cons x body)
+	(let* ([constructor (car x)]
+	      [destructor (lambda (i) `(destruct ,i ,constructor))])
+	  (flat-map (lambda (y i)
+		      (pattern-match y (list (destructor i) body)))
+		    (cdr x)
+		    (range 0 (length (cdr x)))))))
+  (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]))
+
+(define (program-datas program)
+  (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)
+  `(let ()
+     ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
+	       program)))
+
 ; for use in normalized form
 (define lambda-arg caadr)
 ; for use elsewhere
 (define lambda-args cadr)
 (define lambda-body caddr)
+
+					; 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))))