;;; -*-Scheme-*-
;;;
;;; Character Sets package
;;; - ported from MIT Scheme runtime
;;;   by Brian D. Carlstrom
;;; - Rehacked & extended by Olin Shivers 6/98.

;;; This is not great code. Char sets are represented as 256-char
;;; strings. If char i is ASCII 0, then it isn't in the set; if char i
;;; is ASCII 1, then it is in the set.
;;; - Should be rewritten to use bit strings, or at least byte vecs.
;;; - Is ASCII/Latin-1 specific. Would certainly have to be rewritten
;;;   for Unicode.
;;; - The standard character sets are not Latin-1 compliant, just ASCII.

;;; This code uses jar's DEFINE-RECORD-TYPE macro to define the char-set
;;; record type, because the scsh-standard DEFINE-RECORD form automatically
;;; defines a COPY-FOO function, which is not the one we want, being a shallow
;;; copy of the record fields.

;;; New dfns:
;;; (char-set=  cs1 cs2)
;;; (char-set<= cs1 cs2)
;;; (reduce-char-set kons knil cs)
;;; (set-char-set! cs char in?)
;;; (char-set-for-each f cs)
;;; (copy-char-set cs)
;;; (char-set-size cs)
;;; char-set:printing		(char-printing?  c)
;;; char-set:blank		(char-blank?     c)   
;;; char-set:control		(char-control?   c) 
;;; char-set:hex-digit		(char-hex-digit? c)
;;; char-set:ascii		(char-ascii?     c)   
;;; char-set:empty
;;; char-set:full

(define char:newline (ascii->char 13))
(define char:tab (ascii->char 9))
(define char:vtab (ascii->char 11))
(define char:page (ascii->char 12))
(define char:return (ascii->char 10))
(define char:space (ascii->char 32))

(define (string-fill-range! str lower upper ch)
  (do ((index lower (+ index 1)))
    ((>= index upper) str)
    (string-set! str index ch)))

(define (char-ascii? char)
  (let ((maybe-ascii (char->ascii char)))
    (and (<= 0 maybe-ascii 127) maybe-ascii)))

;;;; Character Sets

;(define-record char-set
;  s)	; 256-char string; each char is either ASCII 0 or ASCII 1.

;;; Use jar's record macro.
(define-record-type char-set :char-set
  (make-char-set s)
  char-set?
  (s char-set:s))

(define (copy-char-set cs) (make-char-set (string-copy (char-set:s cs))))

(define (char-set= cs1 cs2)
  (let ((s1 (char-set:s cs1))
	(s2 (char-set:s cs2)))
    (let lp ((i 255))
      (or (< i 0)
	  (and (char=? (string-ref s1 i) (string-ref s2 i))
	       (lp (- i 1)))))))

(define (char-set<= cs1 cs2)
  (let ((s1 (char-set:s cs1))
	(s2 (char-set:s cs2)))
    (let lp ((i 255))
      (or (< i 0)
	  (and (<= (char->ascii (string-ref s1 i))
		   (char->ascii (string-ref s2 i)))
	       (lp (- i 1)))))))


(define (char-set-size cs)
  (let ((s (char-set:s cs)))
    (let lp ((i 255) (size 0))
      (if (< i 0) size
	  (lp (- i 1)
	      (if (= 0 (char->ascii (string-ref s i))) size (+ size 1)))))))

(define (set-char-set! cs char in?)
  (string-set! (char-set:s cs)
	       (char->ascii char)
	       (ascii->char (if in? 1 0))))

(define (char-set-for-each f cs)
  (let ((s (char-set:s cs)))
    (let lp ((i 255))
      (cond ((>= i 0)
	     (if (not (= 0 (char->ascii (string-ref s i))))
		 (f (ascii->char i)))
	     (lp (- i 1)))))))

(define (reduce-char-set kons knil cs)
  (let ((s (char-set:s cs)))
    (let lp ((i 255) (ans knil))
      (if (< i 0) ans
	  (lp (- i 1)
	      (if (= 0 (char->ascii (string-ref s i)))
		  ans
		  (kons (ascii->char i) ans)))))))

(define (char-set . chars)
  (chars->char-set chars))

(define (chars->char-set chars)
  (let ((s (make-string 256 (ascii->char 0))))
    (for-each (lambda (char) 
		(string-set! s (char->ascii char) (ascii->char 1)))
	      chars)
    (make-char-set s)))

(define (string->char-set str)
  (let ((s (make-string 256 (ascii->char 0))))
    (do ((i (- (string-length str) 1) (- i 1)))
	((< i 0) (make-char-set s))
      (string-set! s (char->ascii (string-ref str i))
		   (ascii->char 1)))))

(define (ascii-range->char-set lower upper)
  (let ((s (make-string 256 (ascii->char 0))))
    (string-fill-range! s lower upper (ascii->char 1))
    (make-char-set s)))

(define (predicate->char-set predicate)
  (let ((s (make-string 256)))
    (let lp ((i 255))
      (if (>= i 0)
	  (begin (string-set! s i (if (predicate (ascii->char i)) 
				      (ascii->char 1)
				      (ascii->char 0)))
		 (lp (- i 1)))))
    (make-char-set s)))


;;; {string, char, char-set, char predicate} -> char-set

(define (->char-set x)
  (cond ((char-set? x) x)
	((string? x) (string->char-set x))
	((char? x) (char-set x))
	((procedure? x) (predicate->char-set x))
	(else (error "->char-set: Not a charset, string, char, or predicate."
		     x))))


;;;-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

(define (char-set-members cs)
  (let ((s (char-set:s cs)))
    (let lp ((i 255) (ans '()))
      (if (< i 0) ans
	  (lp (- i 1)
	      (if (zero? (char->ascii (string-ref s i))) ans
		  (cons (ascii->char i) ans)))))))

;;; De-releasing CHAR-SET-MEMBER?
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; No other way to do it. MIT Scheme defines it (c-s-m? cset char); scsh 0.3
;;; defined it (c-s-m? char cset). MIT Scheme's arg order is not consistent 
;;; with the MEMBER? procedure or common math notation, but they were here
;;; first, so I didn't want to just silently invert their arg order -- could
;;; break code. I ended up just choosing a new proc name that consistent with
;;; its arg order -- (CHAR-SET-CONTAINS? cset char).

(define (char-set-contains? cs char)
  (not (zero? (char->ascii (string-ref (char-set:s cs)
				       (char->ascii char))))))

;;; This actually isn't exported. Just CYA.
(define (char-set-member? . args)
  (error "CHAR-SET-MEMBER? is no longer provided. Use CHAR-SET-CONTAINS? instead."))

(define (char-set-invert cs)
  (predicate->char-set (lambda (char)
			 (not (char-set-contains? cs char)))))

;;; The union, intersection, and difference code is ugly, 
;;; because the ops are n-ary.

;;; Apply P to each index and it's char in S: (P I C).
;;; Used by the intersection & difference.
(define (string-iter s p)
  (let lp ((i (- (string-length s) 1)))
    (cond ((>= i 0)
	   (p i (string-ref s i))
	   (lp (- i 1))))))

(define (char-set-union . csets)
  (if (pair? csets)
      (let ((cset (copy-char-set (car csets))))
	(for-each (lambda (cs)
		    (char-set-for-each (lambda (c) (set-char-set! cset c #t))
				       cs))
		  (cdr csets))
	cset)
      char-set:empty))

(define (char-set-intersection . csets)
  (if (pair? csets)
      (let* ((cset (copy-char-set (car csets)))
	     (s (char-set:s cset)))
	(for-each (lambda (cs)
		    (string-iter (char-set:s cs)
				 (lambda (i c)
				   (if (= 0 (char->ascii c))
				       (string-set! s i (ascii->char 0))))))
		  (cdr csets))
	cset)
      char-set:full))

(define (char-set-difference cs1 . csets)
  (if (pair? csets)
      (let* ((cset (copy-char-set cs1))
	     (s (char-set:s cset)))
	(for-each (lambda (cs)
		    (string-iter (char-set:s cs)
				 (lambda (i c)
				   (if (= 1 (char->ascii c))
				       (string-set! s i (ascii->char 0))))))
		  csets)
	cset)
      cs1))

;;;; System Character Sets

(define char-set:lower-case (ascii-range->char-set #x61 #x7B))
(define char-set:upper-case (ascii-range->char-set #x41 #x5B))
(define char-set:alphabetic
  (char-set-union char-set:upper-case char-set:lower-case))
(define char-set:numeric (ascii-range->char-set #x30 #x3A))
(define char-set:alphanumeric
  (char-set-union char-set:alphabetic char-set:numeric))
(define char-set:graphic  (ascii-range->char-set #x21 #x7F))
(define char-set:printing (ascii-range->char-set #x20 #x7F))
(define char-set:whitespace (char-set char:tab  char:newline char:vtab
				      char:page char:return  char:space))
(define char-set:blank (char-set char:space char:tab))
(define char-set:control (char-set-union (ascii-range->char-set 0 32)
					 (char-set (ascii->char 127))))
(define char-set:punctuation
  (string->char-set "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~"))
(define char-set:hex-digit (string->char-set "0123456789abcdefABCDEF"))
(define char-set:ascii (ascii-range->char-set 0 128))
(define char-set:empty (char-set))
(define char-set:full (char-set-invert char-set:empty))


(define (char-set->pred cs) (lambda (c) (char-set-contains? cs c)))

(define char-lower-case?	(char-set->pred char-set:lower-case))
(define char-upper-case?	(char-set->pred char-set:upper-case))
(define char-alphabetic?	(char-set->pred char-set:alphabetic))
(define char-numeric?		(char-set->pred char-set:numeric))
(define char-alphanumeric?	(char-set->pred char-set:alphanumeric))
(define char-graphic?		(char-set->pred char-set:graphic))
(define char-printing?		(char-set->pred char-set:printing))
(define char-whitespace?	(char-set->pred char-set:whitespace))
(define char-blank?		(char-set->pred char-set:blank))
(define char-control?		(char-set->pred char-set:control))
(define char-punctuation?	(char-set->pred char-set:punctuation))
(define char-hex-digit?		(char-set->pred char-set:hex-digit))
(define char-ascii?		(char-set->pred char-set:ascii))