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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 <not-a-stream-error>
(not-a-stream-error obj)
not-a-stream-error?
(obj not-a-stream-error:obj))
(define-record-type <malformed-reference-error>
(malformed-reference-error stream)
malformed-reference-error?
(stream malformed-reference-error:stream))
(define-record-type <stream-error>
(stream-error stream)
stream-error?
(stream stream-error:stream))
;;; Stream destructors.
(define (stream-pair=> stream)
(cond-values
(when-ct (stream-pair? stream)
(values (stream-car stream) (stream-cdr stream)))))
(define (stream-predicate=> stream predicate?)
(cond-values
(after ((let (stream-pair=> stream) => (head stream))
(when (predicate? head)))
(values head stream))))
(define-syntax with-stream-predicates
(syntax-rules ()
((_ stream ((predicate? name) ...) body ...)
(after ((let (stream-predicate=> stream predicate?) => (name stream))
...)
body ...))))
;;; Mapping destructors.
(define (mapping-ref=> mapping key)
(mapping-ref mapping key (lambda () (values))))
(define (mapping-new-field mapping key val)
(mapping-set mapping key (flexvector val)))
;;; Flexvector utils.
(define (flexvector-update-last! fv update)
(let ((len (flexvector-length fv)))
(flexvector-set! fv
(- len 1)
(update (flexvector-ref fv (- len 1))))))
;;; Parsing each line.
(define (prefix-char? ch)
(or (char-upper-case? ch) (char-numeric? ch)))
(define (end=> stream)
(cond-values
(when-ct (stream-null? stream)
stream)
(with-stream-predicates stream (((cut eqv? #\return <>) _)
((cut eqv? #\newline <>) _))
stream)
(with-stream-predicates stream (((cut eqv? #\newline <>) _))
stream)))
(define (read-rest stream)
(let ((fv (flexvector)))
(let read-rest ((stream stream))
(cond-thunk
(after ((let (end=> stream) => (stream)))
(values (flexvector->string fv) stream))
(after ((let (stream-predicate=> stream char?)
=> (x stream)))
(flexvector-add-back! fv x)
(read-rest stream))
(else (raise (stream-error stream)))))))
(define (prefix=> stream)
(let ((ws? (lambda (x)
(char=? x #\space))))
(cond-values
(with-stream-predicates stream ((prefix-char? char1)
(prefix-char? char2)
(ws? _)
(ws? _)
((cut char=? #\- <>) _)
(ws? _))
(let-values (((rest stream) (read-rest stream)))
(values (string char1 char2) rest stream))))))
;;; Parsing of references.
(define (read-reference stream mapping last-name)
(cond-thunk
(after ((let (prefix=> stream) => (name rest stream)))
(cond-thunk
(when-ct (equal? name "ER")
(values stream mapping))
(after ((let (mapping-ref=> mapping name) => (fv)))
(flexvector-add-back! fv rest)
(read-reference stream mapping name))
(else
(read-reference stream
(mapping-new-field mapping
name
rest)
name))))
(when-ct (stream-null? stream)
(values stream mapping))
(else
(let-values
(((fv) (mapping-ref mapping
last-name
(lambda () (error "internal error" stream))))
((rest stream) (read-rest stream)))
(flexvector-update-last! fv
(lambda (last)
(string-append last "\n" rest)))
(read-reference stream mapping last-name)))))
(define (read-new-reference stream mapping)
(cond-thunk
(when-ct (stream-null? stream)
mapping)
(after ((let (prefix=> stream) => (name rest stream))
(when (string=? name "TY")))
(let-values (((stream mapping)
(read-reference stream
(mapping-new-field mapping name rest)
name)))
(read-new-reference stream mapping)))
(else (raise (malformed-reference-error stream)))))
(define (ris->mapping port)
(read-new-reference (port->stream port)
(mapping (make-default-comparator))))
|
