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104 lines
2.7 KiB
Racket
104 lines
2.7 KiB
Racket
#lang racket/base
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(require (for-syntax racket/base)
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br-parser-tools/lex)
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(provide (rename-out [sre-* *]
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[sre-+ +]
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[sre-= =]
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[sre->= >=]
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[sre-or or]
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[sre-- -]
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[sre-/ /])
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? ** : seq & ~ /-only-chars)
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(define-lex-trans (sre-* stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(repetition 0 +inf.0 (union RE ...))]))
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(define-lex-trans (sre-+ stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(repetition 1 +inf.0 (union RE ...))]))
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(define-lex-trans (? stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(repetition 0 1 (union RE ...))]))
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(define-lex-trans (sre-= stx)
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(syntax-case stx ()
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[(_ N RE ...)
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#'(repetition N N (union RE ...))]))
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(define-lex-trans (sre->= stx)
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(syntax-case stx ()
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[(_ N RE ...)
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#'(repetition N +inf.0 (union RE ...))]))
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(define-lex-trans (** stx)
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(syntax-case stx ()
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[(_ LOW #f RE ...)
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#'(** LOW +inf.0 RE ...)]
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[(_ LOW HIGH RE ...)
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#'(repetition LOW HIGH (union RE ...))]))
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(define-lex-trans (sre-or stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(union RE ...)]))
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(define-lex-trans (: stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(concatenation RE ...)]))
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(define-lex-trans (seq stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(concatenation RE ...)]))
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(define-lex-trans (& stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(intersection RE ...)]))
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(define-lex-trans (~ stx)
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(syntax-case stx ()
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[(_ RE ...)
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#'(char-complement (union RE ...))]))
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;; set difference
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(define-lex-trans (sre-- stx)
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(syntax-case stx ()
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[(_)
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(raise-syntax-error #f
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"must have at least one argument"
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stx)]
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[(_ BIG-RE RE ...)
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#'(& BIG-RE (complement (union RE ...)))]))
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(define-lex-trans (sre-/ stx)
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(syntax-case stx ()
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[(_ RANGE ...)
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(let ([chars
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(apply append (for/list ([r (in-list (syntax->list #'(RANGE ...)))])
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(let ([x (syntax-e r)])
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(cond
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[(char? x) (list x)]
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[(string? x) (string->list x)]
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[else
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(raise-syntax-error #f "not a char or string" stx r)]))))])
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(unless (even? (length chars))
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(raise-syntax-error #f "not given an even number of characters" stx))
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#`(/-only-chars #,@chars))]))
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(define-lex-trans (/-only-chars stx)
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(syntax-case stx ()
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[(_ C1 C2)
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#'(char-range C1 C2)]
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[(_ C1 C2 C ...)
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#'(union (char-range C1 C2) (/-only-chars C ...))]))
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