module REXML
	class ParseException < RuntimeError
		attr_accessor :source, :parser, :continued_exception

		def initialize( message, source=nil, parser=nil, exception=nil )
			super(message)
			@source = source
			@parser = parser
			@continued_exception = exception
		end

		def to_s
			# Quote the original exception, if there was one
			if @continued_exception
				err = @continued_exception.inspect
				err << "\n"
				err << @continued_exception.backtrace.join("\n")
				err << "\n...\n"
			else
				err = ""
			end

			# Get the stack trace and error message
			err << super

			# Add contextual information
			if @source
				err << "\nLine: #{line}\n"
				err << "Position: #{position}\n"
				err << "Last 80 unconsumed characters:\n"
				err << @source.buffer[0..80].gsub(/\n/, ' ')
			end
			
			err
		end

		def position
			@source.current_line[0] if @source and @source.current_line
		end

		def line
			@source.current_line[2] if @source and @source.current_line
		end

		def context
			@source.current_line
		end
	end	
end
