#| -*-Scheme-*-

$Id: sets.scm,v 4.6 2007/01/05 21:19:20 cph Exp $

Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007 Massachusetts Institute of Technology

This file is part of MIT/GNU Scheme.

MIT/GNU Scheme is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

MIT/GNU Scheme is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with MIT/GNU Scheme; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
USA.

|#

;;;; Simple Set Abstraction

(declare (usual-integrations))

(define (eq-set-adjoin element set)
  (if (memq element set)
      set
      (cons element set)))

(define (eqv-set-adjoin element set)
  (if (memv element set)
      set
      (cons element set)))

(define (eq-set-delete set item)
  (define (loop set)
    (cond ((null? set) '())
	  ((eq? (car set) item) (cdr set))
	  (else (cons (car set) (loop (cdr set))))))
  (loop set))

(define (eqv-set-delete set item)
  (define (loop set)
    (cond ((null? set) '())
	  ((eqv? (car set) item) (cdr set))
	  (else (cons (car set) (loop (cdr set))))))
  (loop set))

(define (eq-set-substitute set old new)
  (define (loop set)
    (cond ((null? set) '())
	  ((eq? (car set) old) (cons new (cdr set)))
	  (else (cons (car set) (loop (cdr set))))))
  (loop set))

(define (eqv-set-substitute set old new)
  (define (loop set)
    (cond ((null? set) '())
	  ((eqv? (car set) old) (cons new (cdr set)))
	  (else (cons (car set) (loop (cdr set))))))
  (loop set))

(define (set-search set procedure)
  (define (loop items)
    (and (not (null? items))
	 (or (procedure (car items))
	     (loop (cdr items)))))
  (loop set))

;;; The dataflow analyzer assumes that
;;; (eq? (list-tail (eq-set-union x y) n) y) for some n.

(define (eq-set-union x y)
  (if (null? y)
      x
      (let loop ((x x) (y y))
	(if (null? x)
	    y
	    (loop (cdr x)
		  (if (memq (car x) y)
		      y
		      (cons (car x) y)))))))

(define (eqv-set-union x y)
  (if (null? y)
      x
      (let loop ((x x) (y y))
	(if (null? x)
	    y
	    (loop (cdr x)
		  (if (memv (car x) y)
		      y
		      (cons (car x) y)))))))

(define (eq-set-difference x y)
  (define (loop x)
    (cond ((null? x) '())
	  ((memq (car x) y) (loop (cdr x)))
	  (else (cons (car x) (loop (cdr x))))))
  (loop x))

(define (eqv-set-difference x y)
  (define (loop x)
    (cond ((null? x) '())
	  ((memv (car x) y) (loop (cdr x)))
	  (else (cons (car x) (loop (cdr x))))))
  (loop x))

(define (eq-set-intersection x y)
  (define (loop x)
    (cond ((null? x) '())
	  ((memq (car x) y) (cons (car x) (loop (cdr x))))
	  (else (loop (cdr x)))))
  (loop x))

(define (eqv-set-intersection x y)
  (define (loop x)
    (cond ((null? x) '())
	  ((memv (car x) y) (cons (car x) (loop (cdr x))))
	  (else (loop (cdr x)))))
  (loop x))

(define (eq-set-disjoint? x y)
  (define (loop x)
    (cond ((null? x) true)
	  ((memq (car x) y) false)
	  (else (loop (cdr x)))))
  (loop x))

(define (eqv-set-disjoint? x y)
  (define (loop x)
    (cond ((null? x) true)
	  ((memv (car x) y) false)
	  (else (loop (cdr x)))))
  (loop x))

(define (eq-set-subset? x y)
  (define (loop x)
    (cond ((null? x) true)
	  ((memq (car x) y) (loop (cdr x)))
	  (else false)))
  (loop x))

(define (eqv-set-subset? x y)
  (define (loop x)
    (cond ((null? x) true)
	  ((memv (car x) y) (loop (cdr x)))
	  (else false)))
  (loop x))

(define (eq-set-same-set? x y)
  (and (eq-set-subset? x y)
       (eq-set-subset? y x)))

(define (eqv-set-same-set? x y)
  (and (eqv-set-subset? x y)
       (eqv-set-subset? y x)))

(define (list->eq-set elements)
  (if (null? elements)
      '()
      (eq-set-adjoin (car elements)
		     (list->eq-set (cdr elements)))))

(define (list->eqv-set elements)
  (if (null? elements)
      '()
      (eqv-set-adjoin (car elements)
		      (list->eqv-set (cdr elements)))))

(define (map->eq-set procedure items)
  (let loop ((items items))
    (if (null? items)
	'()
	(eq-set-adjoin (procedure (car items))
		       (loop (cdr items))))))

(define (map->eqv-set procedure items)
  (let loop ((items items))
    (if (null? items)
	'()
	(eqv-set-adjoin (procedure (car items))
			(loop (cdr items))))))