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|
; Part of Scheme 48 1.9. See file COPYING for notices and license.
; Authors: Mike Sperber
(define-record-type :record-type-data
(make-record-type-data uid sealed? opaque? field-specs immutable?)
record-type-data?
(uid record-type-data-uid) ; not to be confused with the generated uid
(sealed? record-type-data-sealed?)
(opaque? record-type-data-opaque?)
(field-specs record-type-data-field-specs)
(immutable? record-type-data-immutable?))
(define make-field-spec cons)
(define field-spec-mutable? car)
(define field-spec-name cdr)
(define (field-spec=? spec-1 spec-2)
(equal? spec-1 spec-2))
(define (record-type-uid rtd)
(record-type-data-uid (record-type-data rtd)))
(define (record-type-sealed? rtd)
(record-type-data-sealed? (record-type-data rtd)))
(define (record-type-opaque? rtd)
(record-type-data-opaque? (record-type-data rtd)))
(define (record-type-field-specs rtd)
(record-type-data-field-specs (record-type-data rtd)))
(define (record-type-immutable? rtd)
(record-type-data-immutable? (record-type-data rtd)))
(define (record-type-descriptor=? rtd-1 rtd-2)
(and (eq? (record-type-parent rtd-1) (record-type-parent rtd-2))
(eq? (record-type-uid rtd-1) (record-type-uid rtd-2))
(for-all field-spec=?
(record-type-field-specs rtd-1)
(record-type-field-specs rtd-2))))
(define nongenerative-record-types-table
(user-context-accessor 'nongenerative-record-types-table
(lambda () #f))) ; initializers don't work after the fact anyway
(define set-nongenerative-record-types-table!
(user-context-modifier 'nongenerative-record-types-table))
(define nongenerative-record-types-table-lock (make-lock))
(define (record-type-generative? rtd)
(not (record-type-uid rtd)))
(define (nongenerative-record-types)
(obtain-lock nongenerative-record-types-table-lock)
(let ((l
(table->entry-list (nongenerative-record-types-table))))
(release-lock nongenerative-record-types-table-lock)
l))
(define (delete-nongenerative-record-type thing)
(let ((name (cond
((symbol? thing)
thing)
((record-type? thing)
(record-type-uid thing))
(else
(assertion-violation 'delete-nongenerative-record-type "invalid argument" thing))))
(table
(nongenerative-record-types-table)))
(if (not (symbol? name))
(assertion-violation 'delete-nongenerative-record-type "generative record type" name))
(obtain-lock nongenerative-record-types-table-lock)
(cond
((table-ref table name)
(table-set! table name #f)
(release-lock nongenerative-record-types-table-lock)
#t)
(else
(release-lock nongenerative-record-types-table-lock)
#f))))
(define (make-record-type-descriptor name parent uid sealed? opaque? fields)
(check-parent-type 'make-record-type-descriptor name parent uid sealed? opaque? fields)
(let ((opaque? (if parent
(or (record-type-opaque? parent)
opaque?)
opaque?))
(field-specs (map parse-field-spec (vector->list fields))))
(let ((rtd (make-record-type name (map field-spec-name field-specs) parent))
(data (make-record-type-data uid sealed? opaque? field-specs
(not (exists field-spec-mutable? field-specs)))))
(record-record-type-data! rtd data)
rtd)))
(define (check-parent-type caller name parent uid sealed? opaque? fields)
(if (and parent
(record-type-sealed? parent))
(assertion-violation caller "can't extend a sealed parent class"
name parent uid sealed? opaque? fields))
(if (and parent
(not (record-type-uid parent)) ; parent generative
uid) ; ... but this one is non-generative
(assertion-violation caller
"a generative type can only be extended to give a generative type"
name parent uid sealed? opaque? fields)))
(define (record-record-type-data! rtd data)
(set-record-type-data! rtd data)
(cond
((record-type-data-uid data)
=> (lambda (uid)
(let ((table (nongenerative-record-types-table)))
(obtain-lock nongenerative-record-types-table-lock)
(cond
((table-ref table uid)
=> (lambda (old-rtd)
(release-lock nongenerative-record-types-table-lock)
(if (record-type-descriptor=? rtd old-rtd)
old-rtd
(assertion-violation "mismatched nongenerative record types with identical uids"
old-rtd rtd))))
(else
(table-set! table uid rtd)
(release-lock nongenerative-record-types-table-lock))))))))
; making non-R6RS record types into R6RS record types
(define (retrofit-record-type! rtd uid sealed? opaque? fields)
(let ((parent (record-type-parent rtd))
(name (record-type-name rtd)))
(if (and parent
(not (record-type-data? (record-type-data parent))))
(assertion-violation 'retrofit-record-type!
"parent type not an R6RS record type"
parent))
(check-parent-type 'retrofit-record-type! name parent uid sealed? opaque? fields)
(let ((opaque? (if parent
(or (record-type-opaque? parent)
opaque?)
opaque?))
(field-specs (map parse-field-spec (vector->list fields))))
(record-record-type-data! rtd
(make-record-type-data uid sealed? opaque? field-specs
(not (exists field-spec-mutable? field-specs)))))))
(define (record-type-descriptor? thing)
(and (record-type? thing)
(record-type-data? (record-type-data thing))))
(define (ensure-rtd who thing)
(if (not (record-type-descriptor? thing))
(assertion-violation who "not a record-type descriptor" thing)))
(define (parse-field-spec spec)
(apply (lambda (mutability name)
(make-field-spec
(case mutability
((mutable) #t)
((immutable) #f)
(else
(assertion-violation 'parse-field-spec
"field spec with invalid mutability specification" spec)))
name))
spec))
(define (record? thing)
(and (primitive:record? thing)
(let ((rtd (primitive:record-type thing)))
(and (record-type-descriptor? rtd)
(not (record-type-opaque? rtd))))))
(define (record-rtd rec)
(primitive:record-type rec))
; Constructing constructors
(define-record-type :record-constructor-descriptor
(really-make-record-constructor-descriptor rtd protocol custom-protocol? previous)
(rtd record-constructor-descriptor-rtd)
(protocol record-constructor-descriptor-protocol)
(custom-protocol? record-constructor-descriptor-custom-protocol?)
(previous record-constructor-descriptor-previous))
(define (make-record-constructor-descriptor rtd previous protocol)
(let ((parent (record-type-parent rtd)))
(if (and previous (not parent))
(assertion-violation 'make-record-constructor-descriptor
"mismatch between rtd and constructor descriptor" rtd previous))
(if (and previous
(not protocol)
(record-constructor-descriptor-custom-protocol? previous))
(assertion-violation 'make-record-constructor-descriptor
"default protocol requested when parent constructor descriptor has custom one"
protocol previous))
(let ((custom-protocol? (and protocol #t))
(protocol (or protocol (default-protocol rtd)))
(previous
(if (or previous
(not parent))
previous
(make-record-constructor-descriptor parent #f #f))))
(really-make-record-constructor-descriptor rtd protocol custom-protocol? previous))))
(define (default-protocol rtd)
(let ((parent (record-type-parent rtd)))
(if (not parent)
(lambda (p)
(lambda field-values
(apply p field-values)))
(let ((parent-field-count (record-type-size parent)))
(lambda (p)
(lambda all-field-values
(call-with-values
(lambda () (split-at all-field-values parent-field-count))
(lambda (parent-field-values this-field-values)
(apply (apply p parent-field-values) this-field-values)))))))))
; from SRFI 1
(define (split-at lis i)
(let loop ((i i)
(lis lis)
(rev '()))
(if (zero? i)
(values (reverse rev) lis)
(loop (- i 1) (cdr lis) (cons (car lis) rev)))))
; A "seeder" is the procedure passed to the protocol, used to seed the
; initial field values.
(define (make-make-seeder real-rtd for-desc)
(let recur ((for-desc for-desc))
(let* ((for-rtd (record-constructor-descriptor-rtd for-desc))
(for-rtd-field-count (length (record-type-field-specs for-rtd))))
(cond
((record-constructor-descriptor-previous for-desc)
=> (lambda (parent-desc)
(let ((parent-protocol (record-constructor-descriptor-protocol parent-desc))
(parent-make-seeder (recur parent-desc)))
(lambda extension-field-values
(lambda parent-protocol-args
(lambda for-rtd-field-values
(if (not (= (length for-rtd-field-values) for-rtd-field-count))
(assertion-violation 'record-constructor
"wrong number of arguments to record constructor"
for-rtd for-rtd-field-values))
(apply (parent-protocol
(apply parent-make-seeder
(append for-rtd-field-values extension-field-values)))
parent-protocol-args)))))))
(else
(let-syntax ((construct-with-wrap
(syntax-rules ()
((construct-with-wrap ?wrap)
(lambda extension-field-values
(lambda for-rtd-field-values
(if (not (= (length for-rtd-field-values) for-rtd-field-count))
(assertion-violation 'record-constructor
"wrong number of arguments to record constructor"
for-rtd for-rtd-field-values))
(?wrap
(apply record real-rtd
(append for-rtd-field-values extension-field-values)))))))))
(if (record-type-immutable? real-rtd)
(construct-with-wrap (lambda (r)
(make-immutable! r)
r))
(construct-with-wrap values))))))))
; needs optimization
(define (record rtd . field-vals)
(let ((r (primitive:make-record (+ 1 (length field-vals)) (unspecific))))
(primitive:record-set! r 0 rtd)
(let loop ((i 1)
(field-vals field-vals))
(if (null? field-vals)
r
(begin
(primitive:record-set! r i (car field-vals))
(loop (+ 1 i) (cdr field-vals)))))))
(define (record-constructor desc)
(let ((rtd (record-constructor-descriptor-rtd desc)))
(if (record-constructor-descriptor-custom-protocol? desc) ; +++
((record-constructor-descriptor-protocol desc)
((make-make-seeder rtd desc)))
(let ((construct (record-standard-constructor rtd)))
(if (record-type-immutable? rtd)
(lambda args
(let ((r (apply construct args)))
(make-immutable! r)
r))
construct)))))
(define (record-with-rtd? obj rtd)
(and (primitive:record? obj)
(record-type<=? (primitive:record-type obj) rtd)))
(define (record-accessor rtd field-id)
(let ((index (+ 1 (field-id-index rtd field-id))))
(lambda (thing)
(if (not (record-with-rtd? thing rtd))
(assertion-violation 'record-accessor "not a record of record type" thing rtd))
(primitive:record-ref thing index))))
(define (record-mutator rtd field-id)
(if (not (record-field-mutable? rtd field-id))
(assertion-violation 'record-mutator
"record-mutator called on immutable field" rtd field-id))
(let ((index (+ 1 (field-id-index rtd field-id))))
(lambda (thing val)
(if (not (record-with-rtd? thing rtd))
(assertion-violation 'record-mutator "not a record of record type" thing rtd))
(primitive:record-set! thing index val))))
; A FIELD-ID is an index, which refers to a field in RTD itself.
(define (field-id-index rtd field-id)
(+ (record-type-parent-size rtd)
field-id))
(define (record-field-mutable? rtd field-id)
(field-spec-mutable? (list-ref (record-type-field-specs rtd) field-id)))
(define (record-type-parent-size rt)
(cond
((record-type-parent rt)
=> record-type-size)
(else 0)))
; Initialization
(set-nongenerative-record-types-table! (make-symbol-table))
|
