require 'hashie/hash'
module Hashie
# Mash allows you to create pseudo-objects that have method-like
# accessors for hash keys. This is useful for such implementations
# as an API-accessing library that wants to fake robust objects
# without the overhead of actually doing so. Think of it as OpenStruct
# with some additional goodies.
#
# A Mash will look at the methods you pass it and perform operations
# based on the following rules:
#
# * No punctuation: Returns the value of the hash for that key, or nil if none exists.
# * Assignment (<tt>=</tt>): Sets the attribute of the given method name.
# * Existence (<tt>?</tt>): Returns true or false depending on whether that key has been set.
# * Bang (<tt>!</tt>): Forces the existence of this key, used for deep Mashes. Think of it as "touch" for mashes.
# * Under Bang (<tt>_</tt>): Like Bang, but returns a new Mash rather than creating a key. Used to test existance in deep Mashes.
#
# == Basic Example
#
# mash = Mash.new
# mash.name? # => false
# mash.name = "Bob"
# mash.name # => "Bob"
# mash.name? # => true
#
# == Hash Conversion Example
#
# hash = {:a => {:b => 23, :d => {:e => "abc"}}, :f => [{:g => 44, :h => 29}, 12]}
# mash = Mash.new(hash)
# mash.a.b # => 23
# mash.a.d.e # => "abc"
# mash.f.first.g # => 44
# mash.f.last # => 12
#
# == Bang Example
#
# mash = Mash.new
# mash.author # => nil
# mash.author! # => <Mash>
#
# mash = Mash.new
# mash.author!.name = "Michael Bleigh"
# mash.author # => <Mash name="Michael Bleigh">
#
# == Under Bang Example
#
# mash = Mash.new
# mash.author # => nil
# mash.author_ # => <Mash>
# mash.author_.name # => nil
#
# mash = Mash.new
# mash.author_.name = "Michael Bleigh" (assigned to temp object)
# mash.author # => <Mash>
#
class Mash < Hash
include Hashie::PrettyInspect
alias_method :to_s, :inspect
# If you pass in an existing hash, it will
# convert it to a Mash including recursively
# descending into arrays and hashes, converting
# them as well.
def initialize(source_hash = nil, default = nil, &blk)
deep_update(source_hash) if source_hash
default ? super(default) : super(&blk)
end
class << self; alias [] new; end
def id #:nodoc:
self["id"]
end
def type #:nodoc:
self["type"]
end
alias_method :regular_reader, :[]
alias_method :regular_writer, :[]=
# Retrieves an attribute set in the Mash. Will convert
# any key passed in to a string before retrieving.
def custom_reader(key)
value = regular_reader(convert_key(key))
yield value if block_given?
value
end
# Sets an attribute in the Mash. Key will be converted to
# a string before it is set, and Hashes will be converted
# into Mashes for nesting purposes.
def custom_writer(key,value) #:nodoc:
regular_writer(convert_key(key), convert_value(value))
end
alias_method :[], :custom_reader
alias_method :[]=, :custom_writer
# This is the bang method reader, it will return a new Mash
# if there isn't a value already assigned to the key requested.
def initializing_reader(key)
ck = convert_key(key)
regular_writer(ck, self.class.new) unless key?(ck)
regular_reader(ck)
end
# This is the under bang method reader, it will return a temporary new Mash
# if there isn't a value already assigned to the key requested.
def underbang_reader(key)
ck = convert_key(key)
if key?(ck)
regular_reader(ck)
else
self.class.new
end
end
def fetch(key, *args)
super(convert_key(key), *args)
end
def delete(key)
super(convert_key(key))
end
alias_method :regular_dup, :dup
# Duplicates the current mash as a new mash.
def dup
self.class.new(self, self.default)
end
def key?(key)
super(convert_key(key))
end
alias_method :has_key?, :key?
alias_method :include?, :key?
alias_method :member?, :key?
# Performs a deep_update on a duplicate of the
# current mash.
def deep_merge(other_hash, &blk)
dup.deep_update(other_hash, &blk)
end
alias_method :merge, :deep_merge
# Recursively merges this mash with the passed
# in hash, merging each hash in the hierarchy.
def deep_update(other_hash, &blk)
other_hash.each_pair do |k,v|
key = convert_key(k)
if regular_reader(key).is_a?(Mash) and v.is_a?(::Hash)
custom_reader(key).deep_update(v, &blk)
else
value = convert_value(v, true)
value = blk.call(key, self[k], value) if blk
custom_writer(key, value)
end
end
self
end
alias_method :deep_merge!, :deep_update
alias_method :update, :deep_update
alias_method :merge!, :update
# Performs a shallow_update on a duplicate of the current mash
def shallow_merge(other_hash)
dup.shallow_update(other_hash)
end
# Merges (non-recursively) the hash from the argument,
# changing the receiving hash
def shallow_update(other_hash)
other_hash.each_pair do |k,v|
regular_writer(convert_key(k), convert_value(v, true))
end
self
end
def replace(other_hash)
(keys - other_hash.keys).each { |key| delete(key) }
other_hash.each { |key, value| self[key] = value }
self
end
# Will return true if the Mash has had a key
# set in addition to normal respond_to? functionality.
def respond_to?(method_name, include_private=false)
return true if key?(method_name) || method_name.to_s.slice(/[=?!_]\Z/)
super
end
def method_missing(method_name, *args, &blk)
return self.[](method_name, &blk) if key?(method_name)
match = method_name.to_s.match(/(.*?)([?=!_]?)$/)
case match[2]
when "="
self[match[1]] = args.first
when "?"
!!self[match[1]]
when "!"
initializing_reader(match[1])
when "_"
underbang_reader(match[1])
else
default(method_name, *args, &blk)
end
end
protected
def convert_key(key) #:nodoc:
key.to_s
end
def convert_value(val, duping=false) #:nodoc:
case val
when self.class
val.dup
when Hash
duping ? val.dup : val
when ::Hash
val = val.dup if duping
self.class.new(val)
when Array
val.collect{ |e| convert_value(e) }
else
val
end
end
end
end