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(define (make-wrapper-comparator type-test unwrap contents-comparator)
(make-comparator
type-test
(lambda (a b)
((comparator-equality-predicate contents-comparator)
(unwrap a)
(unwrap b)))
(if (comparator-ordering-predicate contents-comparator)
(lambda (a b)
((comparator-ordering-predicate contents-comparator)
(unwrap a)
(unwrap b)))
#f)
(if (comparator-hash-function contents-comparator)
(lambda (x)
((comparator-hash-function contents-comparator) x))
#f)))
(define (make-product-comparator type-test . comparators)
(make-comparator
type-test
(if (every comparator-equality-predicate comparators)
(lambda (a b)
(every (lambda (cmp)
((comparator-equality-predicate cmp) a b))
comparators))
#f)
(if (every comparator-ordering-predicate comparators)
(lambda (a b)
(let ((gen (list->generator comparators)))
(let loop ((cmp (gen)))
(cond ((eof-object? cmp) #f)
(((comparator-ordering-predicate cmp) a b) #t)
(((comparator-equality-predicate cmp) a b) (loop (gen)))
(else #f)))))
#f)
(if (every comparator-hash-function comparators)
(lambda (x)
(generator-fold bitwise-xor
0
(gmap (lambda (cmp)
((comparator-hash-function cmp) x))
(list->generator comparators))))
#f)))
(define (make-sum-comparator . comparators)
(make-comparator
(lambda (x)
(any (lambda (cmp) ((comparator-type-test cmp) x)) comparators))
(if (every comparator-equality-predicate comparators)
(lambda (a b)
(let ((a-cmp-idx (list-index
(lambda (cmp) ((comparator-type-test cmp) a))
comparators))
(b-cmp-idx (list-index
(lambda (cmp) ((comparator-type-test cmp) b))
comparators))))
(if (not (= a-cmp-idx b-cmp-idx) #f)
(let ((cmp (list-ref comparators a-cmp-idx)))
((comparator-equality-predicate cmp) a b))))
#f)
(if (every comparator-ordering-predicate comparators)
(lambda (a b)
(let ((a-cmp-idx (list-index
(lambda (cmp) ((comparator-type-test cmp) a))
comparators))
(b-cmp-idx (list-index
(lambda (cmp) ((comparator-type-test cmp) b))
comparators)))
(cond ((< a-cmp-idx b-cmp-idx) #t)
((> a-cmp-idx b-cmp-idx) #f)
(else
(let ((cmp (list-ref comparators a-cmp-idx)))
((comparator-ordering-predicate cmp) a b))))))
#f)
(if (every comparator-hash-function comparators)
(lambda (x)
(let ((cmp (find (lambda (cmp) ((comparator-type-test cmp) x)) comparators)))
((comparator-hash-function cmp) x))))))
(define (comparison-procedures comparator)
(values
(lambda args (apply <? comparator args))
(lambda args (apply <=? comparator args))
(lambda args (apply =? comparator args))
(lambda args (apply >=? comparator args))
(lambda args (apply >? comparator args))))
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