98 lines
2.7 KiB
Scheme
98 lines
2.7 KiB
Scheme
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; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
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; Bindings: used to store bindings in packages.
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; Representation is #(type place operator-or-transform-or-#f [path]).
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; PLACE is a unique (to EQ?) value, usually a location.
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; Why aren't these records? Because they need to be written out in
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; the initial image?
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(define binding? vector?)
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(define (binding-type b) (vector-ref b 0))
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(define (binding-place b) (vector-ref b 1))
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(define (binding-static b) (vector-ref b 2))
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(define (binding-path binding)
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(if (= 4 (vector-length binding))
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(vector-ref binding 3)
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#f))
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(define (set-binding-place! binding place)
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(vector-set! binding 1 place))
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(define (make-binding type place static)
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(vector type place static))
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(define (add-path binding path)
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(vector (binding-type binding)
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(binding-place binding)
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(binding-static binding)
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path))
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; Used when updating a package binding.
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(define (clobber-binding! binding type place static)
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(vector-set! binding 0 type)
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(if place
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(vector-set! binding 1 place))
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(vector-set! binding 2 static))
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; Return a binding that's similar to the given one, but has its type
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; replaced with the given type.
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(define (impose-type type binding integrate?)
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(if (or (eq? type syntax-type)
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(not (binding? binding)))
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binding
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(make-binding (if (eq? type undeclared-type)
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(let ((type (binding-type binding)))
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(if (variable-type? type)
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(variable-value-type type)
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type))
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type)
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(binding-place binding)
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(if integrate?
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(binding-static binding)
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#f))))
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; Return a binding that's similar to the given one, but has any
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; procedure integration or other unnecesary static information
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; removed. But don't remove static information for macros (or
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; structures, interfaces, etc.)
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(define (forget-integration binding)
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(if (and (binding-static binding)
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(subtype? (binding-type binding) any-values-type))
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(make-binding (binding-type binding)
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(binding-place binding)
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#f)
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binding))
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; Do X and Y denote the same thing?
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(define (same-denotation? x y)
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(or (eq? x y) ; was EQUAL? because of names, now just for nodes
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(and (binding? x)
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(binding? y)
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(eq? (binding-place x)
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(binding-place y)))))
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; Special kludge for shadowing and package mutation.
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; Ignore this on first reading. See env/shadow.scm.
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(define (maybe-fix-place! binding)
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(let ((place (binding-place binding)))
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(if (and (location? place)
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(vector? (location-id place)))
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(set-binding-place! binding (follow-forwarding-pointers place))))
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binding)
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(define (follow-forwarding-pointers place)
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(let ((id (location-id place)))
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(if (vector? id)
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(follow-forwarding-pointers (vector-ref id 0))
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place)))
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