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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
module Hashery
# TODO: Should associations be singleton?
#
# TODO: Is it really wise to keep a table of all associations?
# Association is a general binary association that allows one
# object to be associated with another. It has a variety of uses,
# such as linked-lists, simple ordered maps and mixed collections,
# among them.
#
# NOTE: This class is still fairly experimental. And it is not
# loaded along with the other Hashery libraries when using
# `require 'hashery'`. It must be required independently.
#
# Associations can be used to draw simple relationships.
#
# :Apple >> :Fruit
# :Apple >> :Red
#
# :Apple.associations #=> [ :Fruit, :Red ]
#
# It can also be used for simple lists of ordered pairs.
#
# c = [ :a >> 1, :b >> 2 ]
# c.each { |k,v| puts "#{k} associated with #{v} }
#
# produces
#
# a associated with 1
# b associated with 2
#
# The method :>> is used to construct the association.
# It is a rarely used method so it is generally available.
# But you can't use it for any of the following classes
# becuase they use #>> for other things.
#
# Bignum
# Fixnum
# Date
# IPAddr
# Process::Status
#
class Association
include Comparable
class << self
#
# Store association references.
#
# Returns `Hash` of all associaitons.
#
def reference
@reference ||= Hash.new{ |h,k,v| h[k]=[] }
end
#
# Shortcut for #new.
#
# index - The "index key" of the association.
# value - The "value" of the association.
#
# Returns `Association`.
#
def [](index, value)
new(index, value)
end
#def new(index, value)
# lookup[[index, value]] ||= new(index, value)
#end
#def lookup
# @lookup ||= {}
#end
end
#
# The "index key" of the association.
#
attr_accessor :index
#
# The "value" of the association.
#
attr_accessor :value
#
# Initialize new Association.
#
# index - The "index key" of the association.
# value - The "value" of the association.
#
def initialize(index, value=nil)
@index = index
@value = value
unless index.associations.include?(value)
index.associations << value
end
end
#
# Compare the values of two associations.
#
# TODO: Comparions with non-associations?
#
# assoc - The other `Association`.
#
# Returns [Integer] `1`, `0`, or `-1`.
#
def <=>(assoc)
return -1 if self.value < assoc.value
return 1 if self.value > assoc.value
return 0 if self.value == assoc.value
end
#
# Invert association, making the index the value and vice-versa.
#
# Returns [Array] with two-elements reversed.
#
def invert!
temp = @index
@index = @value
@value = temp
end
#
# Produce a string representation.
#
# Returns [String].
#
def to_s
return "#{index} >> #{value}"
end
#
# Produce a literal code string for creating an association.
#
# Returns [String].
#
def inspect
"#{index.inspect} >> #{value.inspect}"
end
#
# Convert to two-element associative array.
#
# Returns [Array] Two-element Array of index and value pair.
#
def to_ary
[index, value]
end
#
# Object extensions.
#
module Kernel
#
# Define an association for +self+.
#
# to - The value of the association.
#
# Returns [Association].
#
def >>(to)
Association.new(self, to)
end
#
# List of associations for this object.
#
# Returns an `Array` of `Associations`.
#
def associations
Association.reference[self]
end
end
end
end
class Object #:nodoc:
include Hashery::Association::Kernel
end
#--
# Setup the >> method in classes that use it already.
#
# This is a bad idea b/c it can cause backward compability issues.
#
# class Bignum
# alias_method( :rshift, :>>) if method_defined?(:>>)
# remove_method :>>
# end
#
# class Fixnum
# alias_method( :rshift, :>>) if method_defined?(:>>)
# remove_method :>>
# end
#
# class Date
# alias_method( :months_later, :>>) if method_defined?(:>>)
# remove_method :>>
# end
#
# class IPAddr
# alias_method( :rshift, :>>) if method_defined?(:>>)
# remove_method :>>
# end
#
# class Process::Status
# alias_method( :rshift, :>>) if method_defined?(:>>)
# remove_method :>>
# end
#++
# Copyright (c) 2005 Rubyworks, Thomas Sawyer
|
