98 lines
2.9 KiB
Plaintext
98 lines
2.9 KiB
Plaintext
; utilities for AST processing
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(define (symconcat s1 s2)
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(intern (string s1 s2)))
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(define (list-adjoin item lst)
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(if (member item lst)
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lst
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(cons item lst)))
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(define (index-of item lst start)
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(cond ((null lst) nil)
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((eq item (car lst)) start)
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(T (index-of item (cdr lst) (+ start 1)))))
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(define (each f l)
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(if (null l) l
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(progn (f (car l))
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(each f (cdr l)))))
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(define (maptree-pre f tr)
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(let ((new-t (f tr)))
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(if (consp new-t)
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(map (lambda (e) (maptree-pre f e)) new-t)
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new-t)))
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(define (maptree-post f tr)
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(if (not (consp tr))
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(f tr)
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(let ((new-t (map (lambda (e) (maptree-post f e)) tr)))
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(f new-t))))
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; collapse forms like (&& (&& (&& (&& a b) c) d) e) to (&& a b c d e)
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(define (flatten-left-op op e)
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(maptree-post (lambda (node)
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(if (and (consp node)
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(eq (car node) op)
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(consp (cdr node))
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(consp (cadr node))
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(eq (caadr node) op))
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(cons op
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(append (cdadr node) (cddr node)))
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node))
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e))
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; convert all local variable references to (lexref rib slot name)
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; where rib is the nesting level and slot is the stack slot#
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; name is just there for reference
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; this assumes lambda is the only remaining naming form
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(define (lookup-var v env lev)
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(if (null env) v
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(let ((i (index-of v (car env) 0)))
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(if i (list 'lexref lev i v)
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(lookup-var v (cdr env) (+ lev 1))))))
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(define (lvc- e env)
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(cond ((symbolp e) (lookup-var e env 0))
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((consp e)
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(if (eq (car e) 'quote)
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e
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(let* ((newvs (and (eq (car e) 'lambda) (cadr e)))
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(newenv (if newvs (cons newvs env) env)))
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(if newvs
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(cons 'lambda
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(cons (cadr e)
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(map (lambda (se) (lvc- se newenv))
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(cddr e))))
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(map (lambda (se) (lvc- se env)) e)))))
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(T e)))
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(define (lexical-var-conversion e)
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(lvc- e ()))
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; convert let to lambda
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(define (let-expand e)
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(maptree-post (lambda (n)
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(if (and (consp n) (eq (car n) 'let))
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`((lambda ,(map car (cadr n)) ,@(cddr n))
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,@(map cadr (cadr n)))
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n))
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e))
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; flatten op with any associativity
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(defmacro flatten-all-op (op e)
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`(pattern-expand
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(pattern-lambda (,op (-- l ...) (-- inner (,op ...)) (-- r ...))
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(cons ',op (append l (cdr inner) r)))
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,e))
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(defmacro pattern-lambda (pat body)
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(let* ((args (patargs pat))
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(expander `(lambda ,args ,body)))
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`(lambda (expr)
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(let ((m (match ',pat expr)))
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(if m
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; matches; perform expansion
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(apply ,expander (map (lambda (var) (cdr (or (assoc var m) '(0 . nil))))
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',args))
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nil)))))
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