File size: 5,463 Bytes
3dcad1f |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 |
;;; enums.scm --- The R6RS enumerations library
;; Copyright (C) 2010 Free Software Foundation, Inc.
;;
;; This library is free software; you can redistribute it and/or
;; modify it under the terms of the GNU Lesser General Public
;; License as published by the Free Software Foundation; either
;; version 3 of the License, or (at your option) any later version.
;;
;; This library 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
;; Lesser General Public License for more details.
;;
;; You should have received a copy of the GNU Lesser General Public
;; License along with this library; if not, write to the Free Software
;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
(library (rnrs enums (6))
(export make-enumeration enum-set-universe enum-set-indexer
enum-set-constructor enum-set->list enum-set-member? enum-set-subset?
enum-set=? enum-set-union enum-set-intersection enum-set-difference
enum-set-complement enum-set-projection define-enumeration)
(import (only (guile) and=>)
(rnrs base (6))
(rnrs conditions (6))
(rnrs exceptions (6))
(rnrs records procedural (6))
(rnrs syntax-case (6))
(srfi :1))
(define enum-set-rtd (make-record-type-descriptor
'enum-set #f #f #f #f '#((mutable universe)
(immutable set))))
(define make-enum-set
(record-constructor
(make-record-constructor-descriptor enum-set-rtd #f #f)))
(define enum-set-universe-internal (record-accessor enum-set-rtd 0))
(define enum-set-universe-set! (record-mutator enum-set-rtd 0))
(define enum-set-set (record-accessor enum-set-rtd 1))
(define (make-enumeration symbol-list)
(let ((es (make-enum-set #f symbol-list)))
(enum-set-universe-set! es es)))
(define (enum-set-universe enum-set)
(or (enum-set-universe-internal enum-set)
enum-set))
(define (enum-set-indexer enum-set)
(let* ((symbols (enum-set->list (enum-set-universe enum-set)))
(cardinality (length symbols)))
(lambda (x)
(and=> (memq x symbols)
(lambda (probe) (- cardinality (length probe)))))))
(define (enum-set-constructor enum-set)
(lambda (symbol-list)
(make-enum-set (enum-set-universe enum-set)
(list-copy symbol-list))))
(define (enum-set->list enum-set)
(lset-intersection eq?
(enum-set-set (enum-set-universe enum-set))
(enum-set-set enum-set)))
(define (enum-set-member? symbol enum-set)
(and (memq symbol (enum-set-set enum-set)) #t))
(define (enum-set-subset? enum-set-1 enum-set-2)
(and (lset<= eq?
(enum-set-set (enum-set-universe enum-set-1))
(enum-set-set (enum-set-universe enum-set-2)))
(lset<= eq? (enum-set-set enum-set-1) (enum-set-set enum-set-2))))
(define (enum-set=? enum-set-1 enum-set-2)
(and (enum-set-subset? enum-set-1 enum-set-2)
(enum-set-subset? enum-set-2 enum-set-1)))
(define (enum-set-union enum-set-1 enum-set-2)
(if (equal? (enum-set-universe enum-set-1)
(enum-set-universe enum-set-2))
(make-enum-set (enum-set-universe enum-set-1)
(lset-union eq?
(enum-set-set enum-set-1)
(enum-set-set enum-set-2)))
(raise (make-assertion-violation))))
(define (enum-set-intersection enum-set-1 enum-set-2)
(if (equal? (enum-set-universe enum-set-1)
(enum-set-universe enum-set-2))
(make-enum-set (enum-set-universe enum-set-1)
(lset-intersection eq?
(enum-set-set enum-set-1)
(enum-set-set enum-set-2)))
(raise (make-assertion-violation))))
(define (enum-set-difference enum-set-1 enum-set-2)
(if (equal? (enum-set-universe enum-set-1)
(enum-set-universe enum-set-2))
(make-enum-set (enum-set-universe enum-set-1)
(lset-difference eq?
(enum-set-set enum-set-1)
(enum-set-set enum-set-2)))
(raise (make-assertion-violation))))
(define (enum-set-complement enum-set)
(let ((universe (enum-set-universe enum-set)))
(make-enum-set universe
(lset-difference
eq? (enum-set->list universe) (enum-set-set enum-set)))))
(define (enum-set-projection enum-set-1 enum-set-2)
(make-enum-set (enum-set-universe enum-set-2)
(lset-intersection eq?
(enum-set-set enum-set-1)
(enum-set->list
(enum-set-universe enum-set-2)))))
(define-syntax define-enumeration
(syntax-rules ()
((_ type-name (symbol ...) constructor-syntax)
(begin
(define-syntax type-name
(lambda (s)
(syntax-case s ()
((type-name sym)
(if (memq (syntax->datum #'sym) '(symbol ...))
#'(quote sym)
(syntax-violation (symbol->string 'type-name)
"not a member of the set"
#f))))))
(define-syntax constructor-syntax
(lambda (s)
(syntax-case s ()
((_ sym (... ...))
(let* ((universe '(symbol ...))
(syms (syntax->datum #'(sym (... ...))))
(quoted-universe
(datum->syntax s (list 'quote universe)))
(quoted-syms (datum->syntax s (list 'quote syms))))
(or (every (lambda (x) (memq x universe)) syms)
(syntax-violation (symbol->string 'constructor-syntax)
"not a subset of the universe"
#f))
#`((enum-set-constructor (make-enumeration #,quoted-universe))
#,quoted-syms))))))))))
)
|