require 'nqxml/streamingparser'

module XML
  class ParserError < Exception; end

  class Parser
    DEFAULT = 0
    START_ELEM = 1
    END_ELEM = 2
    CDATA = 3
    PI = 4
    UNPARSED_ENTITY_DECL = 5
    NOTATION_DECL = 6
    EXTERNAL_ENTITY_REF = 7
    COMMENT = 8
    START_CDATA = 9
    END_CDATA = 10
    START_NAMESPACE_DECL = 11
    END_NAMESPACE_DECL = 12
    UNKNOWN_ENCODING = 13

    def initialize(*args)
      @inDocument = false
      @exception = nil
    end

    def parse(stream, *rest)
      @nqparser = NQXML::StreamingParser.new(stream)
      begin
        if block_given?
          @nqparser.each do |e|
            case e
            when NQXML::Tag
              if e.isTagStart
                @inDocument = e.name unless @inDocument
                yield(START_ELEM, e.name, e.attrs)
              else
                @inDocument = false if @inDocument == e.name
                yield(END_ELEM, e.name, nil)
              end
            when NQXML::Text
              next unless @inDocument
              yield(CDATA, nil, e.text)
            when NQXML::ProcessingInstruction
              data = e.source.sub(/<\?[^ \t\n\r]+[ \t\n\r]+(.*)\?>/m, '\1')
              yield(PI, e.name, data)
            when NQXML::Comment
              if respond_to?(:comment)
                data = e.source.sub(/<!--(.*)-->/m, '\1')
                yield(COMMENT, nil, data)
              end
            else
              ## ignore
            end
          end
        else
          @nqparser.each do |e|
            case e
            when NQXML::Tag
              if e.isTagStart
                @inDocument = e.name unless @inDocument
                startElement(e.name, e.attrs) if respond_to?(:startElement)
              else
                @inDocument = false if @inDocument == e.name
                endElement(e.name) if respond_to?(:endElement)
              end
            when NQXML::Text
              next unless @inDocument
              character(e.text) if respond_to?(:character)
            when NQXML::ProcessingInstruction
              next if e.name == 'xml' ## XML decraration is not a PI
              if respond_to?(:processingInstruction)
                data = e.source.sub(/<\?[^ \t\n\r]+[ \t\n\r]+(.*)\?>/m, '\1')
                processingInstruction(e.name, data)
              end
            when NQXML::Comment
              if respond_to?(:comment)
                data = e.source.sub(/<!--(.*)-->/m, '\1')
                comment(data)
              end
            else
              ## ignore
            end
          end ## each
        end ## if
      rescue NQXML::ParserError
        @exception = $!
        raise ParserError.new(@exception.message)
      end ## begin
    end ## parse

    def done; end

    def defaultCurrent; end

    def line
      return @exception.line if @exception
      0
    end

    def column
      return @exception.column if @exception
      0
    end

    def byteIndex
      return @exception.pos if @exception
      0
    end

    def setBase(baseURL); end

  end
end