35 lines
1.3 KiB
Racket
35 lines
1.3 KiB
Racket
#lang racket/base
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(require racket/contract/base
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unstable/options)
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(provide lexer/c)
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(define lexer/c
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(option/c
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(or/c (->i ([in input-port?])
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(values [txt any/c]
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[type symbol?]
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[paren (or/c symbol? #f)]
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[start (or/c exact-positive-integer? #f)]
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[end (start)
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(if start
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(and/c exact-positive-integer?
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(>=/c start))
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#f)]))
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(->i ([in input-port?]
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[offset exact-nonnegative-integer?]
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[mode any/c])
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(values [txt any/c]
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[type symbol?]
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[paren (or/c symbol? #f)]
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[start (or/c exact-positive-integer? #f)]
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[end (start)
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(if start
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(and/c exact-positive-integer?
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(>=/c start))
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#f)]
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[backup exact-nonnegative-integer?]
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[new-mode any/c])))
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#:tester (λ (x) (and (procedure? x)
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(or (procedure-arity-includes? x 1)
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(procedure-arity-includes? x 3))))))
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