Bill Kelly
9/18/2008 11:38:00 AM
From: "Me Me" <emanuelef@tiscali.it>
>
> I think this is not my case, I need a Hash as I explained
Here's an implementation for ruby 1.8 ... I apologize for the lack of tests.
class InsertOrderPreservingHash
include Enumerable
def initialize(*args, &block)
@h = Hash.new(*args, &block)
@ordered_keys = []
end
def []=(key, val)
@ordered_keys << key unless @h.has_key? key
@h[key] = val
end
def each
@ordered_keys.each {|k| yield(k, @h[k])}
end
alias :each_pair :each
def each_value
@ordered_keys.each {|k| yield(@h[k])}
end
def each_key
@ordered_keys.each {|k| yield k}
end
def keys
@ordered_keys
end
def values
@ordered_keys.map {|k| @h[k]}
end
def clear
@ordered_keys.clear
@h.clear
end
def delete(k, &block)
@ordered_keys.delete k
@h.delete(k, &block)
end
def reject!
del = []
each_pair {|k,v| del << k if yield k,v}
del.each {|k| delete k}
del.empty? ? nil : self
end
def delete_if(&block)
reject!(&block)
self
end
%w(merge!).each do |name|
define_method(name) do |*args|
raise NotImplementedError, "#{name} not implemented"
end
end
def method_missing(*args)
@h.send(*args)
end
end
# example:
h = InsertOrderPreservingHash.new
h[:aaa] = 0
h[:foo] = 123
h[:bar] = 456
h[:baz] = 789
h.delete :aaa
h[:aaa] = 1
h.each_pair {|k,v| p [k,v]}
# produces:
[:foo, 123]
[:bar, 456]
[:baz, 789]
[:aaa, 1]
Regards,
Bill