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|
require 'yaml'
YAML.add_builtin_type("omap") do |type, val|
ActiveSupport::OrderedHash[val.map(&:to_a).map(&:first)]
end
module ActiveSupport
# The order of iteration over hashes in Ruby 1.8 is undefined. For example, you do not know the
# order in which +keys+ will return keys, or +each+ yield pairs. <tt>ActiveSupport::OrderedHash</tt>
# implements a hash that preserves insertion order, as in Ruby 1.9:
#
# oh = ActiveSupport::OrderedHash.new
# oh[:a] = 1
# oh[:b] = 2
# oh.keys # => [:a, :b], this order is guaranteed
#
# <tt>ActiveSupport::OrderedHash</tt> is namespaced to prevent conflicts with other implementations.
class OrderedHash < ::Hash #:nodoc:
def to_yaml_type
"!tag:yaml.org,2002:omap"
end
def encode_with(coder)
coder.represent_seq '!omap', map { |k,v| { k => v } }
end
def to_yaml(opts = {})
if YAML.const_defined?(:ENGINE) && !YAML::ENGINE.syck?
return super
end
YAML.quick_emit(self, opts) do |out|
out.seq(taguri) do |seq|
each do |k, v|
seq.add(k => v)
end
end
end
end
# Hash is ordered in Ruby 1.9!
if RUBY_VERSION < '1.9'
# In MRI the Hash class is core and written in C. In particular, methods are
# programmed with explicit C function calls and polymorphism is not honored.
#
# For example, []= is crucial in this implementation to maintain the @keys
# array but hash.c invokes rb_hash_aset() originally. This prevents method
# reuse through inheritance and forces us to reimplement stuff.
#
# For instance, we cannot use the inherited #merge! because albeit the algorithm
# itself would work, our []= is not being called at all by the C code.
def initialize(*args, &block)
super
@keys = []
end
def self.[](*args)
ordered_hash = new
if (args.length == 1 && args.first.is_a?(Array))
args.first.each do |key_value_pair|
next unless (key_value_pair.is_a?(Array))
ordered_hash[key_value_pair[0]] = key_value_pair[1]
end
return ordered_hash
end
unless (args.size % 2 == 0)
raise ArgumentError.new("odd number of arguments for Hash")
end
args.each_with_index do |val, ind|
next if (ind % 2 != 0)
ordered_hash[val] = args[ind + 1]
end
ordered_hash
end
def initialize_copy(other)
super
# make a deep copy of keys
@keys = other.keys
end
def []=(key, value)
@keys << key unless has_key?(key)
super
end
def delete(key)
if has_key? key
index = @keys.index(key)
@keys.delete_at index
end
super
end
def delete_if
super
sync_keys!
self
end
def reject!
super
sync_keys!
self
end
def reject(&block)
dup.reject!(&block)
end
def keys
@keys.dup
end
def values
@keys.collect { |key| self[key] }
end
def to_hash
self
end
def to_a
@keys.map { |key| [ key, self[key] ] }
end
def each_key
@keys.each { |key| yield key }
end
def each_value
@keys.each { |key| yield self[key]}
end
def each
@keys.each {|key| yield [key, self[key]]}
end
alias_method :each_pair, :each
alias_method :select, :find_all
def clear
super
@keys.clear
self
end
def shift
k = @keys.first
v = delete(k)
[k, v]
end
def merge!(other_hash)
if block_given?
other_hash.each { |k, v| self[k] = key?(k) ? yield(k, self[k], v) : v }
else
other_hash.each { |k, v| self[k] = v }
end
self
end
alias_method :update, :merge!
def merge(other_hash, &block)
dup.merge!(other_hash, &block)
end
# When replacing with another hash, the initial order of our keys must come from the other hash -ordered or not.
def replace(other)
super
@keys = other.keys
self
end
def invert
OrderedHash[self.to_a.map!{|key_value_pair| key_value_pair.reverse}]
end
def inspect
"#<OrderedHash #{super}>"
end
private
def sync_keys!
@keys.delete_if {|k| !has_key?(k)}
end
end
end
end
|
