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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-composed-comparator type-test . comparators)
(make-comparator
type-test
(if (every comparator-equality-predicate comparators)
(lambda (a b)
(generator-every (lambda (cmp)
((comparator-equality-predicate cmp) a b))
(list->generator 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-syntax compose-comparator
(syntax-rules ()
((_ type-test (unwrap . more) ...)
(make-composed-comparator
type-test
(let ((cmp ((lambda x
(if (null? x) (make-default-comparator)
(car x))) . more)))
(make-wrapper-comparator
(comparator-type-test-predicate cmp)
unwrap
cmp)) ...))))
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