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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.
  #
  # == 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">
  #
  class Mash < Hashie::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
      super default if default
      super &blk if blk
    end
    
    class << self; alias [] new; end

    def id #:nodoc:
      self["id"] ? self["id"] : super
    end
    
    # Borrowed from Merb's Mash object.
    #
    # ==== Parameters
    # key<Object>:: The default value for the mash. Defaults to nil.
    #
    # ==== Alternatives
    # If key is a Symbol and it is a key in the mash, then the default value will
    # be set to the value matching the key.
    def default(key = nil) 
      if key.is_a?(Symbol) && key?(key.to_s) 
        self[key] 
      else 
        key ? super : super()
      end 
    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 [](key)
      key = convert_key(key)
      regular_reader(key)
    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 []=(key,value) #:nodoc:
      key = convert_key(key)
      regular_writer(key, convert_value(value))
    end
    
    # 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)
      self[key] = Hashie::Mash.new unless key?(key)
      self[key]
    end
    
    alias_method :regular_dup, :dup  
    # Duplicates the current mash as a new mash.
    def dup
      Mash.new(self, self.default)
    end
    
    alias_method :picky_key?, :key?
    def key?(key)
      picky_key?(convert_key(key))
    end
    
    # Performs a deep_update on a duplicate of the
    # current mash.
    def deep_merge(other_hash)
      dup.deep_merge!(other_hash)
    end
    
    # Recursively merges this mash with the passed
    # in hash, merging each hash in the hierarchy.
    def deep_update(other_hash)
      other_hash = Hashie::Hash[other_hash].stringify_keys!
      
      other_hash.each_pair do |k,v|
        k = convert_key(k)
        self[k] = Hashie::Mash.new(self[k]).to_mash if self[k].is_a?(Hash) unless self[k].is_a?(Hashie::Mash)
        if self[k].is_a?(Hashie::Mash) && other_hash[k].is_a?(Hash)
          self[k] = self[k].deep_merge(other_hash[k])
        else
          self[k] = convert_value(other_hash[k],true)
        end
      end
      
      self
    end
    alias_method :deep_merge!, :deep_update
    
    # ==== Parameters
    # other_hash<Hash>::
    # A hash to update values in the mash with. Keys will be
    # stringified and Hashes will be converted to Mashes.
    #
    # ==== Returns
    # Mash:: The updated mash.
    def update(other_hash)
      other_hash.each_pair do |key, value|
        if respond_to?(convert_key(key) + "=")
          self.send(convert_key(key) + "=", convert_value(value))
        else
          regular_writer(convert_key(key), convert_value(value))
        end
      end
      self
    end
    alias_method :merge!, :update
    
    # Converts a mash back to a hash (with stringified keys)
    def to_hash
      Hash.new(default).merge(self)
    end
    
    def method_missing(method_name, *args) #:nodoc:
      if (match = method_name.to_s.match(/(.*)=$/)) && args.size == 1
        self[match[1]] = args.first
      elsif (match = method_name.to_s.match(/(.*)\?$/)) && args.size == 0
        key?(match[1])
      elsif (match = method_name.to_s.match(/(.*)!$/)) && args.size == 0
        initializing_reader(match[1])
      elsif key?(method_name)
        self[method_name]
      elsif match = method_name.to_s.match(/^([a-z][a-z0-9A-Z_]+)$/)
        default(method_name)
      else
        super
      end
    end
    
    protected
    
    def convert_key(key) #:nodoc:
      key.to_s
    end
    
    def convert_value(val, duping=false) #:nodoc:
      case val
        when ::Hash
          val = val.dup if duping
          Hashie::Mash.new(val)
        when Array
          val.collect{ |e| convert_value(e) }
        else
          val
      end
    end
  end
end