blob: 778b089e156b4df2586d270ef4c0952d0d863517 (
plain) (
blame)
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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
;;; set.el --- Working with mathematical sets -*- lexical-binding: t -*-
;; Author: William Carroll <wpcarro@gmail.com>
;; Version: 0.0.1
;; Package-Requires: ((emacs "24.3"))
;;; Commentary:
;; The set data structure is a collection that deduplicates its elements.
;;; Code:
(require 'ht) ;; friendlier API for hash-tables
(require 'dotted)
(require 'struct)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Wish List
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; - TODO: Support enum protocol for set.
;; - TODO: Prefer a different hash-table library that doesn't rely on mutative
;; code.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Library
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(cl-defstruct set xs)
(defconst set-enable-testing? t
"Run tests when t.")
(defun set-from-list (xs)
"Create a new set from the list XS."
(make-set :xs (->> xs
(list-map #'dotted-new)
ht-from-alist)))
(defun set-new (&rest args)
"Create a new set from ARGS."
(set-from-list args))
(defun set-to-list (xs)
"Map set XS into a list."
(->> xs
set-xs
ht-keys))
(defun set-add (x xs)
"Add X to set XS."
(struct-update set
xs
(lambda (table)
(let ((table-copy (ht-copy table)))
(ht-set table-copy x nil)
table-copy))
xs))
;; TODO: Ensure all `*/reduce' functions share the same API.
(defun set-reduce (acc f xs)
"Return a new set by calling F on each element of XS and ACC."
(->> xs
set-to-list
(list-reduce acc f)))
(defun set-intersection (a b)
"Return the set intersection between A and B."
(set-reduce (set-new)
(lambda (x acc)
(if (set-contains? x b)
(set-add x acc)
acc))
a))
(defun set-count (xs)
"Return the number of elements in XS."
(->> xs
set-xs
ht-size))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Predicates
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defun set-empty? (xs)
"Return t if XS has no elements in it."
(= 0 (set-count xs)))
(defun set-contains? (x xs)
"Return t if set XS has X."
(ht-contains? (set-xs xs) x))
;; TODO: Prefer using `ht.el' functions for this.
(defun set-equal? (a b)
"Return t if A and B share the name members."
(ht-equal? (set-xs a)
(set-xs b)))
(defun set-distinct? (a b)
"Return t if A and B have no shared members."
(set-empty? (set-intersection a b)))
(defun set-superset? (a b)
"Return t if A has all of the members of B."
(->> b
set-to-list
(list-all? (lambda (x) (set-contains? x a)))))
(defun set-subset? (a b)
"Return t if each member of set A is present in set B."
(set-superset? b a))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Tests
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(when set-enable-testing?
;; set-distinct?
(prelude-assert
(set-distinct? (set-new 'one 'two 'three)
(set-new 'a 'b 'c)))
(prelude-refute
(set-distinct? (set-new 1 2 3)
(set-new 3 4 5)))
(prelude-refute
(set-distinct? (set-new 1 2 3)
(set-new 1 2 3)))
;; set-equal?
(prelude-refute
(set-equal? (set-new 'a 'b 'c)
(set-new 'x 'y 'z)))
(prelude-refute
(set-equal? (set-new 'a 'b 'c)
(set-new 'a 'b)))
(prelude-assert
(set-equal? (set-new 'a 'b 'c)
(set-new 'a 'b 'c)))
;; set-intersection
(prelude-assert
(set-equal? (set-new 2 3)
(set-intersection (set-new 1 2 3)
(set-new 2 3 4))))
;; set-{from,to}-list
(prelude-assert (equal '(1 2 3)
(->> '(1 1 2 2 3 3)
set-from-list
set-to-list)))
(let ((primary-colors (set-new "red" "green" "blue")))
;; set-subset?
(prelude-refute
(set-subset? (set-new "black" "grey")
primary-colors))
(prelude-assert
(set-subset? (set-new "red")
primary-colors))
;; set-superset?
(prelude-refute
(set-superset? primary-colors
(set-new "black" "grey")))
(prelude-assert
(set-superset? primary-colors
(set-new "red" "green" "blue")))
(prelude-assert
(set-superset? primary-colors
(set-new "red" "blue"))))
;; set-empty?
(prelude-assert (set-empty? (set-new)))
(prelude-refute (set-empty? (set-new 1 2 3)))
;; set-count
(prelude-assert (= 0 (set-count (set-new))))
(prelude-assert (= 2 (set-count (set-new 1 1 2 2)))))
(provide 'set)
;;; set.el ends here
|
