path: root/activesupport/lib/active_support/xml_mini.rb

# = XmlMini
# This is a derivitive work of XmlSimple 1.0.11
# Author::    Joseph Holsten <joseph@josephholsten.com>
# Copyright:: Copyright (c) 2008 Joseph Holsten
# Copyright:: Copyright (c) 2003-2006 Maik Schmidt <contact@maik-schmidt.de>
# License::   Distributes under the same terms as Ruby.
module XmlMini
  extend self

  CONTENT_KEY = '__content__'.freeze

  # Parse an XML Document string into a simple hash
  #
  # Same as XmlSimple::xml_in but doesn't shoot itself in the foot,
  # and uses the defaults from ActiveSupport
  #
  # string::
  #   XML Document string to parse
  def parse(string)
    require 'rexml/document' unless defined?(REXML::Document)
    doc = REXML::Document.new(string)
    merge_element!({}, doc.root)
  end

  private
    # Convert an XML element and merge into the hash
    #
    # hash::
    #   Hash to merge the converted element into.
    # element::
    #   XML element to merge into hash
    def merge_element!(hash, element)
      merge!(hash, element.name, collapse(element))
    end

    # Actually converts an XML document element into a data structure.
    #
    # element::
    #   The document element to be collapsed.
    def collapse(element)
      hash = get_attributes(element)

      if element.has_elements?
        element.each_element {|child| merge_element!(hash, child) }
        merge_texts!(hash, element) unless empty_content?(element)
        hash
      else
        merge_texts!(hash, element)
      end
    end

    # Merge all the texts of an element into the hash
    #
    # hash::
    #   Hash to add the converted emement to.
    # element::
    #   XML element whose texts are to me merged into the hash
    def merge_texts!(hash, element)
      unless element.has_text?
        hash
      else
        # must use value to prevent double-escaping
        merge!(hash, CONTENT_KEY, element.texts.sum(&:value))
      end
    end

    # Adds a new key/value pair to an existing Hash. If the key to be added
    # already exists and the existing value associated with key is not
    # an Array, it will be wrapped in an Array. Then the new value is
    # appended to that Array.
    #
    # hash::
    #   Hash to add key/value pair to.
    # key::
    #   Key to be added.
    # value::
    #   Value to be associated with key.
    def merge!(hash, key, value)
      if hash.has_key?(key)
        if hash[key].instance_of?(Array)
          hash[key] << value
        else
          hash[key] = [hash[key], value]
        end
      elsif value.instance_of?(Array)
        hash[key] = [value]
      else
        hash[key] = value
      end
      hash
    end

    # Converts the attributes array of an XML element into a hash.
    # Returns an empty Hash if node has no attributes.
    #
    # element::
    #   XML element to extract attributes from.
    def get_attributes(element)
      attributes = {}
      element.attributes.each { |n,v| attributes[n] = v }
      attributes
    end

    # Determines if a document element has text content
    #
    # element::
    #   XML element to be checked.
    def empty_content?(element)
      element.texts.join.blank?
    end
end