# PropertyList XML File Parser

# 2009, Otto Linnemann

require 'rexml/document'

include REXML

class PropertyParser

  private

  # Base Element with pointer to parent

  # element and dynamic content

  class PTreeBase

    attr_accessor :obj, :parent  

    def initialize( obj, parent = nil )

      @obj = obj

      @parent = parent  

    end  

  end

  # PList Dictionary object which is mapped to a Ruby hash

  class PTreeArray < PTreeBase

    def initialize( parent )   

      super( Array.new, parent )    

    end    

    def store_value( value )

      @obj << value

    end

  end

  # PList Dictionary object which is mapped to a Ruby hash

  class PTreeDict < PTreeBase

    def initialize( parent )   

      super( Hash.new, parent )

    end    

  end

  # PList KeyValue singleton object which is mapped to a Ruby hash

  # parent must be a PTreeDict object

  class PTreeKeyValue < PTreeBase

    def initialize( parent )   

      raise "wrong element eror" if ! parent.is_a?( PTreeDict )

      super( Hash.new, parent )

      @key    = nil

      @value  = nil    

    end    

    def store_key( string )

      raise "wrong element eror" if ! string.is_a?( String )

      @key = string

    end

    def store_value( value )

      @value = value

      @obj[@key] = value

      self.parent.obj[@key] = value

    end

  end

  def tabs

    tabstr = ""

    i=0; while( i < @level ) do tabstr << "\t"; i+=1; end

    tabstr

  end

  # logging function for debugging purposes

  def log( str )

    # puts str

  end

  public

  # intializes parse object

  def initialize()

    @root     = nil

    @top      = nil

    @tag      = ""    

    @state    = :idle

    @level    = 0  

  end

  def parse( xmldata )

      Document.parse_stream( xmldata, self )

      to_a

  end

  # delivers to level parsing result as array

  def to_a

    @root.obj

  end

  def tag_start( name, attributes )

    log tabs + "> tagstart(" + name + " attr: " + attributes.to_s + ")"

    @tag = name

    case @tag

      when "plist"

        # for the DOM root element a create new instance is created

        @root = PTreeArray.new( nil )

        @top  = @root

      when "dict"

        @top = PTreeDict.new( @top )

      when "array"

        @top = PTreeArray.new( @top )

      when "key"

        @top = PTreeKeyValue.new( @top )

    end   

    @state = :tag_start

    @level += 1

  end

  def text( str )

    if @state != :tag_start

      @state = :text

      return

    end

    text = if( str.length > 3 ) then str else "" end

    log tabs + "> text(" + text + ")"

    case @tag

      when "key"

        @top.store_key( str )

      when "string"

        @top.store_value( str ) 

      when "integer"

        @top.store_value( str.to_i )

      when "real"

        @top.store_value( str.to_f )

    end

  @state = :text

  end

  def tag_end( name )

    @tag = name

    case @tag

      when "plist"

        raise "parse error empty object"  if @top.obj.empty?

        @top = @top.parent

      when "dict", "array"

        raise "parse error empty object"  if @top.obj.empty?

        @top.parent.store_value( @top.obj )

        @top = @top.parent

        @top = @top.parent if( @top.is_a? PTreeKeyValue )

      when "string", "integer", "real"

        @top = @top.parent if( @top.is_a? PTreeKeyValue )

    end

    @level -= 1

    log tabs + "> tag_end(" + name + ")"

    @state = :tag_end

  end

  def xmldecl( version, encoding, options )

    log tabs + ">>>> xmldecl(" + version + ", " + encoding + ", " + options.to_s + ")"

  end

  def doctype( type, scope, manufacturer, options )

    log tabs + ">>>>> doctype(" + type.to_s + ", " + scope.to_s + ", " + manufacturer.to_s + ", " + options.to_s + ")"

  end

end

# Sample invocation

=begin

prop = PropertyParser.new

data = ""

File.open("Info.plist", "r" ) { |fp| data = fp.read }

Document.parse_stream( data, prop )

log prop.to_a

data = ""

File.open("Info.plist", "r" ) { |fp| data = fp.read }

collection  = PropertyParser.new.parse( data )

puts collection

=end

__END__