291 lines
12 KiB
Scheme
291 lines
12 KiB
Scheme
(module string "pre-base.ss"
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(provide real->decimal-string
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regexp-quote
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regexp-replace-quote
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regexp-match*
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regexp-match-positions*
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regexp-match-peek-positions*
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regexp-split
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regexp-match-exact?
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regexp-try-match)
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;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define (real->decimal-string n [digits 2])
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(let* ([e (expt 10 digits)]
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[num (round (abs (* e (inexact->exact n))))])
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(format "~a~a.~a"
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(if (negative? n) "-" "")
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(quotient num e)
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(let ([s (number->string (remainder num e))])
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(if (= (string-length s) digits)
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s
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(string-append (make-string (- digits (string-length s)) #\0)
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s))))))
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;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Regexp helpers
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(define (bstring-length s)
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(if (bytes? s) (bytes-length s) (string-length s)))
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(define (subbstring s st e)
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(if (bytes? s) (subbytes s st e) (substring s st e)))
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;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Regexp helpers
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(define regexp-quote-chars:s #rx"[][.*?+|(){}\\$^]")
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(define regexp-quote-chars:b #rx#"[][.*?+|(){}\\$^]")
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(define (regexp-quote s [case-sens? #t])
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(let* ([b? (cond [(bytes? s) #t]
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[(string? s) #f]
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[else (raise-type-error 'regexp-quote
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"string or byte string" s)])]
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[s (if b?
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(regexp-replace* regexp-quote-chars:b s #"\\\\&")
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(regexp-replace* regexp-quote-chars:s s "\\\\&"))])
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(cond [case-sens? s]
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[b? (bytes-append #"(?i:" s #")")]
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[else (string-append "(?i:" s ")")])))
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(define (regexp-replace-quote s)
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(let ([b? (cond [(bytes? s) #t]
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[(string? s) #f]
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[else (raise-type-error 'regexp-replace-quote
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"string or byte string" s)])])
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(if b?
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(regexp-replace* #rx#"[&\\]" s #"\\\\&")
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(regexp-replace* #rx"[&\\]" s "\\\\&"))))
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(define (regexp-try-match pattern input-port [start-k 0] [end-k #f] [out #f])
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(unless (input-port? input-port)
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(raise-type-error 'regexp-try-match
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"input port" input-port))
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(unless (or (not out) (output-port? out))
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(raise-type-error 'regexp-try-match
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"output port or #f" out))
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(let ([m (regexp-match-peek-positions pattern input-port start-k end-k)])
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(and m
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;; What happens if someone swipes our bytes before we can get them?
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(let ([drop (caar m)])
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;; drop prefix before match:
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(let ([s (read-bytes drop input-port)])
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(when out
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(display s out)))
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;; Get the matching part, and shift matching indicies
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(let ([s (read-bytes (- (cdar m) drop) input-port)])
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(cons s
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(map (lambda (p)
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(and p (subbytes s (- (car p) drop) (- (cdr p) drop))))
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(cdr m))))))))
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;; Helper function for the regexp functions below.
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(define (regexp-fn name success-k port-success-k failure-k port-failure-k
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need-leftover? peek?)
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(lambda (pattern string start end)
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(unless (or (string? pattern) (bytes? pattern)
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(regexp? pattern) (byte-regexp? pattern))
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(raise-type-error name "regexp, byte regexp, string, or byte string" pattern))
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(if peek?
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(unless (input-port? string)
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(raise-type-error name "input port" string))
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(unless (or (string? string)
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(bytes? string)
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(input-port? string))
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(raise-type-error name "string, byte string or input port" string)))
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(unless (and (number? start) (exact? start) (integer? start) (start . >= . 0))
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(raise-type-error name "non-negative exact integer" start))
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(unless (or (not end)
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(and (number? end) (exact? end) (integer? end) (end . >= . 0)))
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(raise-type-error name "non-negative exact integer or false" end))
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(unless (or (input-port? string)
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(and (string? string)
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(start . <= . (string-length string)))
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(and (bytes? string)
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(start . <= . (bytes-length string))))
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(raise-mismatch-error
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name
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(format "starting offset index out of range [0,~a]: "
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(if (string? string)
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(string-length string)
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(bytes-length string)))
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start))
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(unless (or (not end)
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(and (start . <= . end)
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(or (input-port? string)
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(and (string? string)
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(end . <= . (string-length string)))
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(and (bytes? string)
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(end . <= . (bytes-length string))))))
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(raise-mismatch-error
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name
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(format "ending offset index out of range [~a,~a]: "
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end
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(if (string? string)
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(string-length string)
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(bytes-length string)))
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start))
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(when (and (positive? start) (input-port? string) need-leftover?)
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;; Skip start chars:
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(let ([s (make-bytes 4096)])
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(let loop ([n 0])
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(unless (= n start)
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(let ([m (read-bytes-avail! s string 0 (min (- start n) 4096))])
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(unless (eof-object? m)
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(loop (+ n m))))))))
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(let ([expr (cond [(string? pattern) (regexp pattern)]
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[(bytes? pattern) (byte-regexp pattern)]
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[else pattern])])
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(if (and (input-port? string) port-success-k)
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;; Input port match, get string
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(let ([discarded 0]
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[leftover-port (and need-leftover? (open-output-bytes))])
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(let ([match
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(regexp-match
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expr string
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(if need-leftover? 0 start)
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(and end (if need-leftover? (- end start) end))
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(if need-leftover?
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leftover-port
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(make-output-port 'counter
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always-evt
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(lambda (s start end flush? breakable?)
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(let ([c (- end start)])
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(set! discarded (+ c discarded))
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c))
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void)))]
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[leftovers
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(and need-leftover?
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(if (and (regexp? pattern) (string? string))
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(get-output-string leftover-port)
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(get-output-bytes leftover-port)))])
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(if match
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(port-success-k expr string (car match)
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(and end (- end
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(if need-leftover?
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(+ (bstring-length leftovers) start)
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discarded)
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(bstring-length (car match))))
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leftovers)
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(port-failure-k leftovers))))
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;; String/port match, get positions
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(let ([match ((if peek?
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regexp-match-peek-positions
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regexp-match-positions)
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expr string start end)])
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(if match
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(let ([match-start (caar match)]
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[match-end (cdar match)])
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(when (= match-start match-end)
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(error name "pattern matched a zero-length substring"))
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(success-k expr string start end match-start match-end))
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(failure-k expr string start end)))))))
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;; Returns all the positions at which the pattern matched.
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(define -regexp-match-positions*
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(regexp-fn 'regexp-match-positions*
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;; success-k:
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(lambda (expr string start end match-start match-end)
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(cons (cons match-start match-end)
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(if (or (string? string) (bytes? string))
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(regexp-match-positions* expr string match-end end)
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;; Need to shift index of rest as reading:
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(map (lambda (p)
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(cons (+ match-end (car p))
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(+ match-end (cdr p))))
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(regexp-match-positions* expr string 0 (and end (- end match-end)))))))
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;; port-success-k --- use string case
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#f
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;; fail-k:
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(lambda (expr string start end) null)
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;; port-fail-k --- use string case
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#f
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#f
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#f))
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(define (regexp-match-positions* pattern string [start 0] [end #f])
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(-regexp-match-positions* pattern string start end))
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;; Returns all the positions at which the pattern matched.
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(define -regexp-match-peek-positions*
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(regexp-fn 'regexp-match-peek-positions*
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;; success-k:
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(lambda (expr string start end match-start match-end)
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(cons (cons match-start match-end)
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(regexp-match-peek-positions* expr string match-end end)))
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;; port-success-k --- use string case
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#f
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;; fail-k:
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(lambda (expr string start end) null)
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;; port-fail-k --- use string case
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#f
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#f
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#t))
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(define (regexp-match-peek-positions* pattern string [start 0] [end #f])
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(-regexp-match-peek-positions* pattern string start end))
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;; Splits a string into a list by removing any piece which matches
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;; the pattern.
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(define -regexp-split
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(regexp-fn 'regexp-split
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;; success-k
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(lambda (expr string start end match-start match-end)
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(let ([string (if (and (string? string)
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(or (bytes? expr) (byte-regexp? expr)))
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(string->bytes/utf-8 string (char->integer #\?))
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string)])
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(cons (subbstring string start match-start)
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(regexp-split expr string match-end end))))
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;; port-success-k:
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(lambda (expr string match-string new-end leftovers)
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(cons leftovers (regexp-split expr string 0 new-end)))
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;; failure-k:
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(lambda (expr string start end)
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(list (subbstring string start (or end (bstring-length string)))))
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;; port-fail-k
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(lambda (leftover) (list leftover))
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#t
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#f))
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(define (regexp-split pattern string [start 0] [end #f])
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(-regexp-split pattern string start end))
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;; Returns all the matches for the pattern in the string.
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(define -regexp-match*
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(regexp-fn 'regexp-match*
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;; success-k:
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(lambda (expr string start end match-start match-end)
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(let ([string (if (and (string? string)
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(or (bytes? expr) (byte-regexp? expr)))
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(string->bytes/utf-8 string (char->integer #\?))
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string)])
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(cons (subbstring string match-start match-end)
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(regexp-match* expr string match-end end))))
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;; port-success-k:
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(lambda (expr string match-string new-end leftovers)
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(cons match-string (regexp-match* expr string 0 new-end)))
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;; fail-k:
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(lambda (expr string start end) null)
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;; port-fail-k:
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(lambda (leftover) null)
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#f
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#f))
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(define (regexp-match* pattern string [start 0] [end #f])
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(-regexp-match* pattern string start end))
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(define (regexp-match-exact? p s)
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(let ([m (regexp-match-positions p s)])
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(and m
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(zero? (caar m))
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(if (or (byte-regexp? p) (bytes? p) (bytes? s))
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(= (cdar m) (if (bytes? s) (bytes-length s) (string-utf-8-length s)))
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(= (cdar m) (string-length s))))))
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)
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