# Postscript wrapper class
class RGhost::PsObject
  # Creates new instance of PsObject. Example
  #   PsObject.new("/my_proc { 33 45 2 10 sub mul div} bind def")
  # Or by block code
  #   PsObject.new do
  #     set PsObject.new("(A test) show")
  #     raw "(Other Test in raw) show "
  #   end
  def initialize(body = "", &block)
    @body = if body.is_a? RGhost::PsObject
      body.ps
    else
      "#{body} "
    end

    instance_eval(&block) if block
  end

  # Alias for ps.
  def to_s
    ps
  end

  # Gets postscript code.
  def ps
    @body.to_s
  end

  # Pushes elements on the stack.
  def raw(*value)
    @body << "#{value.join(" ")} "
  end

  # Freezes graphic state
  def graphic_scope
    "beging #{self} endg "
  end

  # Sets PsObject into this object.
  def set(value)
    raise TypeError.new("can't convert #{value.class} into PsObject") unless value.is_a? RGhost::PsObject
    @body << "#{value.ps} "
    value
  end

  # Alias for set
  def <<(value)
    set value
  end

  # Call operator in the stack
  def call(name)
    set RGhost::PsObject.new(name)
  end
end