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#| Copyright 2024 Peter McGoron
|
| Licensed under the Apache License, Version 2.0 (the "License");
| you may not use this file except in compliance with the License.
| You may obtain a copy of the License at
|
| http://www.apache.org/licenses/LICENSE-2.0
|
| Unless required by applicable law or agreed to in writing, software
| distributed under the License is distributed on an "AS IS" BASIS,
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
| See the License for the specific language governing permissions and
| limitations under the License.
|#
(define-record-type <iterator>
(make-iterator-container closure capabilities type)
iterator?
(closure iterator-closure)
(capabilities iterator-capabilities)
(type iterator-type))
(define (iterator-invoke itr field . args)
((iterator-closure itr) field args))
(define-syntax define-invocation
(syntax-rules ()
((define-invocation name args ...)
(define (name itr args ...)
(iterator-invoke itr (quote name) args ...)))))
(define-syntax define-iterator-implementation
(syntax-rules (else)
((_ (cstr cstr-args ...) self ((name . formal) body ...) ...)
(define (cstr cstr-args ...)
(letrec ((self
(make-iterator-container
(lambda (type args)
(case type
((name) (apply (lambda formal body ...) args))
...
(else (raise (not-implemented-exception self
type
args)))))
'(name ...)
(quote cstr))))
self)))))
(define-invocation iterator-at-start?)
(define-invocation iterator-at-end?)
(define-invocation iterator-advance spaces)
(define-invocation iterator-ref)
(define-invocation iterator-set! val)
(define-invocation iterator->index)
(define (iterator-next itr)
(iterator-advance itr 1))
(define (iterator-prev itr)
(iterator-advance itr -1))
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