racket/collects/mzlib/string.ss
2005-05-27 18:56:37 +00:00

406 lines
12 KiB
Scheme

(module string mzscheme
(provide string-lowercase!
string-uppercase!
eval-string
read-from-string
read-from-string-all
expr->string
regexp-quote
regexp-replace-quote
regexp-match*
regexp-match-positions*
regexp-match-peek-positions*
regexp-split
regexp-match-exact?
regexp-match/fail-without-reading)
(require (lib "etc.ss"))
(define make-string-do!
(lambda (translate)
(lambda (s)
(let loop ([n (sub1 (string-length s))])
(unless (negative? n)
(string-set! s n
(translate (string-ref s n)))
(loop (sub1 n)))))))
(define string-lowercase! (make-string-do! char-downcase))
(define string-uppercase! (make-string-do! char-upcase))
(define eval-string
(let ([do-eval
(lambda (str)
(let ([p (open-input-string str)])
(apply
values
(let loop ()
(let ([e (read p)])
(if (eof-object? e)
'()
(call-with-values
(lambda () (eval e))
(case-lambda
[() (loop)]
[(only) (cons only (loop))]
[multi
(append multi (loop))]))))))))])
(case-lambda
[(str) (eval-string str #f #f)]
[(str error-display) (eval-string str error-display #f)]
[(str error-display error-result)
(if (or error-display error-result)
(with-handlers ([void
(lambda (exn)
((or error-display (lambda (x)
((error-display-handler) x exn)))
(exn-message exn))
(if error-result
(error-result)
#f))])
(do-eval str))
(do-eval str))])))
(define read-from-string-one-or-all
(case-lambda
[(k all? str) (read-from-string-one-or-all k all? str #f #f)]
[(k all? str error-display) (read-from-string-one-or-all k all? str error-display #f)]
[(k all? str error-display error-result)
(let* ([p (open-input-string str)]
[go (lambda ()
(let loop ()
(let ([v (read p)])
(if (eof-object? v)
'()
(cons v
(if all?
(loop)
'()))))))])
(if error-display
(with-handlers ([void
(lambda (exn)
((or error-display (lambda (x)
((error-display-handler) x exn)))
(exn-message exn))
(k (if error-result
(error-result)
#f)))])
(go))
(go)))]))
(define read-from-string
(lambda args
(let/ec k
(let ([l (apply read-from-string-one-or-all k #f args)])
(if (null? l)
eof
(car l))))))
(define read-from-string-all
(lambda args
(let/ec k
(apply read-from-string-one-or-all k #t args))))
(define expr->string
(lambda (v)
(let ([port (open-output-string)])
(write v port)
(get-output-string port))))
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Regexp helpers
(define (bstring-length s)
(if (string? s)
(string-length s)
(bytes-length s)))
(define (subbstring s st e)
(if (string? s)
(substring s st e)
(subbytes s st e)))
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Regexp helpers
(define regexp-quote
(opt-lambda (s [case-sens? #t])
(unless (or (string? s)
(bytes? s))
(raise-type-error 'regexp-quote "string or byte string" s))
((if (bytes? s)
(lambda (l) (list->bytes (map char->integer l)))
list->string)
(apply
append
(map
(lambda (c)
(cond
[(memq c '(#\$ #\| #\\ #\[ #\] #\. #\* #\? #\+ #\( #\) #\^))
(list #\\ c)]
[(and (not case-sens?)
(not (char=? (char-upcase c) (char-downcase c))))
(list #\[ (char-upcase c) (char-downcase c) #\])]
[else (list c)]))
(if (bytes? s)
(map integer->char (bytes->list s))
(string->list s)))))))
(define (regexp-replace-quote s)
(unless (or (string? s)
(bytes? s))
(raise-type-error 'regexp-replace-quote "string or byte string" s))
(if (bytes? s)
(regexp-replace* #rx#"&" (regexp-replace* #rx#"\\\\" s #"\\\\\\\\") #"\\\\&")
(regexp-replace* #rx"&" (regexp-replace* #rx"\\\\" s "\\\\\\\\") "\\\\&")))
(define regexp-match/fail-without-reading
(opt-lambda (pattern input-port [start-k 0] [end-k #f] [out #f])
(unless (input-port? input-port)
(raise-type-error 'regexp-match/fail-without-reading "input port" input-port))
(unless (or (not out) (output-port? out))
(raise-type-error 'regexp-match/fail-without-reading "output port or #f" out))
(let ([m (regexp-match-peek-positions pattern input-port start-k end-k)])
(and m
;; What happens if someone swipes our bytes before we can get them?
(let ([drop (caar m)])
;; drop prefix before match:
(let ([s (read-bytes drop input-port)])
(when out
(display s out)))
;; Get the matching part, and shift matching indicies
(let ([s (read-bytes (- (cdar m) drop) input-port)])
(cons s
(map (lambda (p)
(and p (subbytes s (- (car p) drop) (- (cdr p) drop))))
(cdr m)))))))))
;; Helper function for the regexp functions below.
(define (regexp-fn name success-k port-success-k failure-k port-failure-k
need-leftover? peek?)
(lambda (pattern string start end)
(unless (or (string? pattern) (bytes? pattern)
(regexp? pattern) (byte-regexp? pattern))
(raise-type-error name "regexp, byte regexp, string, or byte string" pattern))
(if peek?
(unless (input-port? string)
(raise-type-error name "input port" string))
(unless (or (string? string)
(bytes? string)
(input-port? string))
(raise-type-error name "string, byte string or input port" string)))
(unless (and (number? start) (exact? start) (integer? start) (start . >= . 0))
(raise-type-error name "non-negative exact integer" start))
(unless (or (not end)
(and (number? end) (exact? end) (integer? end) (end . >= . 0)))
(raise-type-error name "non-negative exact integer or false" end))
(unless (or (input-port? string)
(and (string? string)
(start . <= . (string-length string)))
(and (bytes? string)
(start . <= . (bytes-length string))))
(raise-mismatch-error
name
(format "starting offset index out of range [0,~a]: "
(if (string? string)
(string-length string)
(bytes-length string)))
start))
(unless (or (not end)
(and (start . <= . end)
(or (input-port? string)
(and (string? string)
(end . <= . (string-length string)))
(and (bytes? string)
(end . <= . (bytes-length string))))))
(raise-mismatch-error
name
(format "ending offset index out of range [~a,~a]: "
end
(if (string? string)
(string-length string)
(bytes-length string)))
start))
(when (and (positive? start)
(input-port? string)
need-leftover?)
;; Skip start chars:
(let ([s (make-bytes 4096)])
(let loop ([n 0])
(unless (= n start)
(let ([m (read-bytes-avail! s string 0 (min (- start n) 4096))])
(unless (eof-object? m)
(loop (+ n m))))))))
(let ((expr (cond
[(string? pattern) (regexp pattern)]
[(bytes? pattern) (byte-regexp pattern)]
[else pattern])))
(if (and (input-port? string)
port-success-k)
;; Input port match, get string
(let ([discarded 0]
[leftover-port (and need-leftover?
(open-output-bytes))])
(let ([match (regexp-match expr string
(if need-leftover? 0 start)
(and end (if need-leftover? (- end start) end))
(if need-leftover?
leftover-port
(make-output-port
'counter
always-evt
(lambda (s start end flush? breakable?)
(let ([c (- end start)])
(set! discarded (+ c discarded))
c))
void)))]
[leftovers (and need-leftover?
(if (and (regexp? pattern)
(string? string))
(get-output-string leftover-port)
(get-output-bytes leftover-port)))])
(if match
(port-success-k expr string (car match)
(and end (- end
(if need-leftover?
(+ (bstring-length leftovers) start)
discarded)
(bstring-length (car match))))
leftovers)
(port-failure-k leftovers))))
;; String/port match, get positions
(let ([match ((if peek?
regexp-match-peek-positions
regexp-match-positions)
expr string start end)])
(if match
(let ((match-start (caar match))
(match-end (cdar match)))
(when (= match-start match-end)
(error name "pattern matched a zero-length substring"))
(success-k expr string start end match-start match-end))
(failure-k expr string start end)))))))
(define-syntax wrap
(syntax-rules ()
[(_ out orig)
(define out
(opt-lambda (pattern string [start 0] [end #f])
(orig pattern string start end)))]))
;; Returns all the positions at which the pattern matched.
(define -regexp-match-positions*
(regexp-fn 'regexp-match-positions*
;; success-k:
(lambda (expr string start end match-start match-end)
(cons (cons match-start match-end)
(if (or (string? string)
(bytes? string))
(regexp-match-positions* expr string match-end end)
;; Need to shift index of rest as reading:
(map (lambda (p)
(cons (+ match-end (car p))
(+ match-end (cdr p))))
(regexp-match-positions* expr string 0 (and end (- end match-end)))))))
;; port-success-k --- use string case
#f
;; fail-k:
(lambda (expr string start end)
null)
;; port-fail-k --- use string case
#f
#f
#f))
(wrap regexp-match-positions* -regexp-match-positions*)
;; Returns all the positions at which the pattern matched.
(define -regexp-match-peek-positions*
(regexp-fn 'regexp-match-peek-positions*
;; success-k:
(lambda (expr string start end match-start match-end)
(cons (cons match-start match-end)
(regexp-match-peek-positions* expr string match-end end)))
;; port-success-k --- use string case
#f
;; fail-k:
(lambda (expr string start end)
null)
;; port-fail-k --- use string case
#f
#f
#t))
(wrap regexp-match-peek-positions* -regexp-match-peek-positions*)
;; Splits a string into a list by removing any piece which matches
;; the pattern.
(define -regexp-split
(regexp-fn 'regexp-split
;; success-k
(lambda (expr string start end match-start match-end)
(let ([string (if (and (string? string)
(or (bytes? expr)
(byte-regexp? expr)))
(string->bytes/utf-8 string (char->integer #\?))
string)])
(cons
(subbstring string start match-start)
(regexp-split expr string match-end end))))
;; port-success-k:
(lambda (expr string match-string new-end leftovers)
(cons
leftovers
(regexp-split expr string 0 new-end)))
;; failure-k:
(lambda (expr string start end)
(list
(subbstring string start (or end (bstring-length string)))))
;; port-fail-k
(lambda (leftover)
(list leftover))
#t
#f))
(wrap regexp-split -regexp-split)
;; Returns all the matches for the pattern in the string.
(define -regexp-match*
(regexp-fn 'regexp-match*
;; success-k:
(lambda (expr string start end match-start match-end)
(let ([string (if (and (string? string)
(or (bytes? expr)
(byte-regexp? expr)))
(string->bytes/utf-8 string (char->integer #\?))
string)])
(cons
(subbstring string match-start match-end)
(regexp-match* expr string match-end end))))
;; port-success-k:
(lambda (expr string match-string new-end leftovers)
(cons
match-string
(regexp-match* expr string 0 new-end)))
;; fail-k:
(lambda (expr string start end)
null)
;; port-fail-k:
(lambda (leftover)
null)
#f
#f))
(wrap regexp-match* -regexp-match*)
(define regexp-match-exact?
(lambda (p s)
(let ([m (regexp-match-positions p s)])
(and m
(zero? (caar m))
(if (or (byte-regexp? p)
(bytes? p)
(bytes? s))
(= (cdar m) (if (bytes? s)
(bytes-length s)
(string-utf-8-length s)))
(= (cdar m) (string-length s))))))))