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
|
module Hamster
# @private
module Immutable
def self.included(klass)
klass.extend(ClassMethods)
klass.instance_eval do
include InstanceMethods
end
end
# @private
module ClassMethods
def new(*args)
super.__send__(:immutable!)
end
def memoize(*names)
include MemoizeMethods unless include?(MemoizeMethods)
names.each do |name|
original_method = "__hamster_immutable_#{name}__"
alias_method original_method, name
class_eval <<-METHOD, __FILE__, __LINE__
def #{name}
if @__hamster_immutable_memory__.instance_variable_defined?(:@#{name})
@__hamster_immutable_memory__.instance_variable_get(:@#{name})
else
@__hamster_immutable_memory__.instance_variable_set(:@#{name}, #{original_method})
end
end
METHOD
end
end
end
# @private
module MemoizeMethods
def immutable!
@__hamster_immutable_memory__ = Object.new
freeze
end
end
# @private
module InstanceMethods
def immutable!
freeze
end
def immutable?
frozen?
end
alias_method :__hamster_immutable_dup__, :dup
private :__hamster_immutable_dup__
def dup
self
end
def clone
self
end
protected
def transform_unless(condition, &block)
condition ? self : transform(&block)
end
def transform(&block)
__hamster_immutable_dup__.tap { |copy| copy.instance_eval(&block) }.immutable!
end
end
end
end
|
