655 lines
18 KiB
Ruby
Executable file
655 lines
18 KiB
Ruby
Executable file
require 'stringio'
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require 'html5/constants'
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module HTML5
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# Provides a unicode stream of characters to the HTMLTokenizer.
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# This class takes care of character encoding and removing or replacing
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# incorrect byte-sequences and also provides column and line tracking.
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class HTMLInputStream
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attr_accessor :queue, :char_encoding, :errors
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# Initialises the HTMLInputStream.
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#
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# HTMLInputStream(source, [encoding]) -> Normalized stream from source
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# for use by the HTML5Lib.
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#
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# source can be either a file-object, local filename or a string.
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#
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# The optional encoding parameter must be a string that indicates
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# the encoding. If specified, that encoding will be used,
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# regardless of any BOM or later declaration (such as in a meta
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# element)
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#
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# parseMeta - Look for a <meta> element containing encoding information
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def initialize(source, options = {})
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@encoding = nil
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@parse_meta = true
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@chardet = true
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options.each {|name, value| instance_variable_set("@#{name}", value) }
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# Raw Stream
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@raw_stream = open_stream(source)
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# Encoding Information
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#Number of bytes to use when looking for a meta element with
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#encoding information
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@NUM_BYTES_META = 512
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#Number of bytes to use when using detecting encoding using chardet
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@NUM_BYTES_CHARDET = 256
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#Number of bytes to use when reading content
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@NUM_BYTES_BUFFER = 1024
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#Encoding to use if no other information can be found
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@DEFAULT_ENCODING = 'windows-1252'
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#Detect encoding iff no explicit "transport level" encoding is supplied
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if @encoding.nil? or not HTML5.is_valid_encoding(@encoding)
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@char_encoding = detect_encoding
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else
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@char_encoding = @encoding
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end
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# Read bytes from stream decoding them into Unicode
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@buffer = @raw_stream.read(@NUM_BYTES_BUFFER) || ''
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if @char_encoding == 'windows-1252'
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@win1252 = true
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elsif @char_encoding != 'utf-8'
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begin
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require 'iconv'
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begin
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@buffer << @raw_stream.read unless @raw_stream.eof?
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@buffer = Iconv.iconv('utf-8', @char_encoding, @buffer).first
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rescue
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@win1252 = true
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end
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rescue LoadError
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@win1252 = true
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end
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end
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@queue = []
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@errors = []
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# Reset position in the list to read from
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@tell = 0
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@line = @col = 0
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@line_lengths = []
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end
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# Produces a file object from source.
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#
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# source can be either a file object, local filename or a string.
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def open_stream(source)
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# Already an IO like object
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if source.respond_to?(:read)
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@stream = source
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else
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# Treat source as a string and wrap in StringIO
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@stream = StringIO.new(source)
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end
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return @stream
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end
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def detect_encoding
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#First look for a BOM
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#This will also read past the BOM if present
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encoding = detect_bom
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#If there is no BOM need to look for meta elements with encoding
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#information
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if encoding.nil? and @parse_meta
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encoding = detect_encoding_meta
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end
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#Guess with chardet, if avaliable
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if encoding.nil? and @chardet
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begin
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require 'rubygems'
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require 'UniversalDetector' # gem install chardet
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buffers = []
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detector = UniversalDetector::Detector.instance
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detector.reset
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until @raw_stream.eof?
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buffer = @raw_stream.read(@NUM_BYTES_CHARDET)
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break if !buffer or buffer.empty?
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buffers << buffer
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detector.feed(buffer)
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break if detector.instance_eval {@done}
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detector.instance_eval {
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@_mLastChar = @_mLastChar.chr if Fixnum === @_mLastChar
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}
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end
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detector.close
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encoding = detector.result['encoding']
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seek(buffers*'', 0)
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rescue LoadError
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end
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end
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# If all else fails use the default encoding
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if encoding.nil?
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encoding = @DEFAULT_ENCODING
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end
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#Substitute for equivalent encodings
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encoding_sub = {'iso-8859-1' => 'windows-1252'}
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if encoding_sub.has_key?(encoding.downcase)
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encoding = encoding_sub[encoding.downcase]
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end
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return encoding
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end
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# Attempts to detect at BOM at the start of the stream. If
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# an encoding can be determined from the BOM return the name of the
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# encoding otherwise return nil
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def detect_bom
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bom_dict = {
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"\xef\xbb\xbf" => 'utf-8',
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"\xff\xfe" => 'utf-16le',
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"\xfe\xff" => 'utf-16be',
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"\xff\xfe\x00\x00" => 'utf-32le',
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"\x00\x00\xfe\xff" => 'utf-32be'
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}
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# Go to beginning of file and read in 4 bytes
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string = @raw_stream.read(4)
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return nil unless string
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# Try detecting the BOM using bytes from the string
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encoding = bom_dict[string[0...3]] # UTF-8
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seek = 3
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unless encoding
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# Need to detect UTF-32 before UTF-16
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encoding = bom_dict[string] # UTF-32
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seek = 4
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unless encoding
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encoding = bom_dict[string[0...2]] # UTF-16
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seek = 2
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end
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end
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# Set the read position past the BOM if one was found, otherwise
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# set it to the start of the stream
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seek(string, encoding ? seek : 0)
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return encoding
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end
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def seek(buffer, n)
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if @raw_stream.respond_to?(:unget)
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@raw_stream.unget(buffer[n..-1])
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return
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end
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if @raw_stream.respond_to?(:seek)
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begin
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@raw_stream.seek(n)
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return
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rescue Errno::ESPIPE
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end
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end
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#TODO: huh?
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require 'delegate'
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# @raw_stream = SimpleDelegator.new(@raw_stream)
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class << @raw_stream
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def read(chars=-1)
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if chars == -1 or chars > @data.length
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result = @data
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@data = ''
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return result if __getobj__.eof?
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return result + __getobj__.read if chars == -1
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return result + __getobj__.read(chars-result.length)
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elsif @data.empty?
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return __getobj__.read(chars)
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else
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result = @data[1...chars]
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@data = @data[chars..-1]
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return result
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end
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end
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def unget(data)
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if !@data or @data.empty?
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@data = data
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else
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@data += data
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end
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end
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end
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@raw_stream.unget(buffer[n .. -1])
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end
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# Report the encoding declared by the meta element
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def detect_encoding_meta
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buffer = @raw_stream.read(@NUM_BYTES_META)
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parser = EncodingParser.new(buffer)
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seek(buffer, 0)
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return parser.get_encoding
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end
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# Returns (line, col) of the current position in the stream.
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def position
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line, col = @line, @col
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@queue.reverse.each do |c|
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if c == "\n"
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line -= 1
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raise RuntimeError.new("col=#{col}") unless col == 0
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col = @line_lengths[line]
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else
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col -= 1
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end
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end
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return [line+1, col]
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end
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# Read one character from the stream or queue if available. Return
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# EOF when EOF is reached.
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def char
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unless @queue.empty?
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return @queue.shift
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else
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if @tell + 3 > @buffer.length and !@raw_stream.eof?
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# read next block
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@buffer = @buffer[@tell .. -1] + @raw_stream.read(@NUM_BYTES_BUFFER)
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@tell = 0
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end
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c = @buffer[@tell]
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@tell += 1
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case c
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when 0x01 .. 0x7F
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if c == 0x0D
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# normalize newlines
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@tell += 1 if @buffer[@tell] == 0x0A
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c = 0x0A
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end
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# update position in stream
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if c == 0x0a
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@line_lengths << @col
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@line += 1
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@col = 0
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else
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@col += 1
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end
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c.chr
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when 0x80 .. 0xBF
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if !@win1252
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[0xFFFD].pack('U') # invalid utf-8
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elsif c <= 0x9f
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[ENTITIES_WINDOWS1252[c-0x80]].pack('U')
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else
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"\xC2" + c.chr # convert to utf-8
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end
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when 0xC0 .. 0xFF
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if instance_variables.include?("@win1252") && @win1252
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"\xC3" + (c-64).chr # convert to utf-8
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elsif @buffer[@tell-1 .. @tell+3] =~ /^
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( [\xC2-\xDF][\x80-\xBF] # non-overlong 2-byte
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| \xE0[\xA0-\xBF][\x80-\xBF] # excluding overlongs
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| [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2} # straight 3-byte
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| \xED[\x80-\x9F][\x80-\xBF] # excluding surrogates
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| \xF0[\x90-\xBF][\x80-\xBF]{2} # planes 1-3
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| [\xF1-\xF3][\x80-\xBF]{3} # planes 4-15
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| \xF4[\x80-\x8F][\x80-\xBF]{2} # plane 16
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)/x
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@tell += $1.length - 1
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$1
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else
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[0xFFFD].pack('U') # invalid utf-8
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end
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when 0x00
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@errors.push("null-character")
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[0xFFFD].pack('U') # null characters are invalid
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else
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:EOF
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end
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end
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end
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# Returns a string of characters from the stream up to but not
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# including any character in characters or EOF. characters can be
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# any container that supports the in method being called on it.
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def chars_until(characters, opposite=false)
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char_stack = [char]
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while char_stack.last != :EOF
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break unless (characters.include?(char_stack.last)) == opposite
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char_stack.push(char)
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end
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# Put the character stopped on back to the front of the queue
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# from where it came.
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c = char_stack.pop
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@queue.insert(0, c) unless c == :EOF
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return char_stack.join('')
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end
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def unget(characters)
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@queue.unshift(*characters.to_a) unless characters == :EOF
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end
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end
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# String-like object with an assosiated position and various extra methods
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# If the position is ever greater than the string length then an exception is raised
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class EncodingBytes < String
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attr_accessor :position
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def initialize(value)
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super(value)
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@position = -1
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end
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def each
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while @position < length
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@position += 1
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yield self[@position]
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end
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rescue EOF
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end
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def current_byte
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raise EOF if @position >= length
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return self[@position].chr
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end
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# Skip past a list of characters
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def skip(chars=SPACE_CHARACTERS)
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while chars.include?(current_byte)
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@position += 1
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end
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end
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# Look for a sequence of bytes at the start of a string. If the bytes
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# are found return true and advance the position to the byte after the
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# match. Otherwise return false and leave the position alone
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def match_bytes(bytes, lower=false)
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data = self[position ... position+bytes.length]
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data.downcase! if lower
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rv = (data == bytes)
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@position += bytes.length if rv == true
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return rv
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end
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# Look for the next sequence of bytes matching a given sequence. If
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# a match is found advance the position to the last byte of the match
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def jump_to(bytes)
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new_position = self[position .. -1].index(bytes)
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if new_position
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@position += (new_position + bytes.length-1)
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return true
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else
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raise EOF
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end
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end
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# Move the pointer so it points to the next byte in a set of possible
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# bytes
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def find_next(byte_list)
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until byte_list.include?(current_byte)
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@position += 1
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end
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end
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end
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# Mini parser for detecting character encoding from meta elements
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class EncodingParser
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# string - the data to work on for encoding detection
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def initialize(data)
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@data = EncodingBytes.new(data.to_s)
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@encoding = nil
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end
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@@method_dispatch = [
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['<!--', :handle_comment],
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['<meta', :handle_meta],
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['</', :handle_possible_end_tag],
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['<!', :handle_other],
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['<?', :handle_other],
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['<', :handle_possible_start_tag]
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]
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def get_encoding
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@data.each do |byte|
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keep_parsing = true
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@@method_dispatch.each do |(key, method)|
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if @data.match_bytes(key, lower = true)
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keep_parsing = send(method)
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break
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end
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end
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break unless keep_parsing
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end
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@encoding = @encoding.strip unless @encoding.nil?
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return @encoding
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end
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# Skip over comments
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def handle_comment
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return @data.jump_to('-->')
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end
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def handle_meta
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# if we have <meta not followed by a space so just keep going
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return true unless SPACE_CHARACTERS.include?(@data.current_byte)
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#We have a valid meta element we want to search for attributes
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while true
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#Try to find the next attribute after the current position
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attr = get_attribute
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return true if attr.nil?
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if attr[0] == 'charset'
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tentative_encoding = attr[1]
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if HTML5.is_valid_encoding(tentative_encoding)
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@encoding = tentative_encoding
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return false
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end
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elsif attr[0] == 'content'
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content_parser = ContentAttrParser.new(EncodingBytes.new(attr[1]))
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tentative_encoding = content_parser.parse
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if HTML5.is_valid_encoding(tentative_encoding)
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@encoding = tentative_encoding
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return false
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end
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end
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end
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end
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def handle_possible_start_tag
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return handle_possible_tag(false)
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end
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def handle_possible_end_tag
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@data.position += 1
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return handle_possible_tag(true)
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end
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def handle_possible_tag(end_tag)
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unless ASCII_LETTERS.include?(@data.current_byte)
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#If the next byte is not an ascii letter either ignore this
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#fragment (possible start tag case) or treat it according to
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#handleOther
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if end_tag
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@data.position -= 1
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handle_other
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end
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return true
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end
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@data.find_next(SPACE_CHARACTERS + ['<', '>'])
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if @data.current_byte == '<'
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#return to the first step in the overall "two step" algorithm
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#reprocessing the < byte
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@data.position -= 1
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else
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#Read all attributes
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{} until get_attribute.nil?
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end
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return true
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end
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def handle_other
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return @data.jump_to('>')
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end
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# Return a name,value pair for the next attribute in the stream,
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# if one is found, or nil
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def get_attribute
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@data.skip(SPACE_CHARACTERS + ['/'])
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if @data.current_byte == '<'
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@data.position -= 1
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return nil
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elsif @data.current_byte == '>'
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return nil
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end
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attr_name = []
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attr_value = []
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space_found = false
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#Step 5 attribute name
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while true
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if @data.current_byte == '=' and attr_name
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break
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elsif SPACE_CHARACTERS.include?(@data.current_byte)
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space_found = true
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break
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elsif ['/', '<', '>'].include?(@data.current_byte)
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return [attr_name.join(''), '']
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elsif ASCII_UPPERCASE.include?(@data.current_byte)
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attr_name.push(@data.current_byte.downcase)
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else
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attr_name.push(@data.current_byte)
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end
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#Step 6
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@data.position += 1
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end
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#Step 7
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if space_found
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@data.skip
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#Step 8
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unless @data.current_byte == '='
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@data.position -= 1
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return [attr_name.join(''), '']
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end
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end
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#XXX need to advance position in both spaces and value case
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#Step 9
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@data.position += 1
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#Step 10
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@data.skip
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#Step 11
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if ["'", '"'].include?(@data.current_byte)
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#11.1
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quote_char = @data.current_byte
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while true
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@data.position+=1
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#11.3
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if @data.current_byte == quote_char
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@data.position += 1
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return [attr_name.join(''), attr_value.join('')]
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#11.4
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elsif ASCII_UPPERCASE.include?(@data.current_byte)
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attr_value.push(@data.current_byte.downcase)
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#11.5
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else
|
|
attr_value.push(@data.current_byte)
|
|
end
|
|
end
|
|
elsif ['>', '<'].include?(@data.current_byte)
|
|
return [attr_name.join(''), '']
|
|
elsif ASCII_UPPERCASE.include?(@data.current_byte)
|
|
attr_value.push(@data.current_byte.downcase)
|
|
else
|
|
attr_value.push(@data.current_byte)
|
|
end
|
|
while true
|
|
@data.position += 1
|
|
if (SPACE_CHARACTERS + ['>', '<']).include?(@data.current_byte)
|
|
return [attr_name.join(''), attr_value.join('')]
|
|
elsif ASCII_UPPERCASE.include?(@data.current_byte)
|
|
attr_value.push(@data.current_byte.downcase)
|
|
else
|
|
attr_value.push(@data.current_byte)
|
|
end
|
|
end
|
|
end
|
|
end
|
|
|
|
class ContentAttrParser
|
|
def initialize(data)
|
|
@data = data
|
|
end
|
|
|
|
def parse
|
|
begin
|
|
#Skip to the first ";"
|
|
@data.position = 0
|
|
@data.jump_to(';')
|
|
@data.position += 1
|
|
@data.skip
|
|
#Check if the attr name is charset
|
|
#otherwise return
|
|
@data.jump_to('charset')
|
|
@data.position += 1
|
|
@data.skip
|
|
unless @data.current_byte == '='
|
|
#If there is no = sign keep looking for attrs
|
|
return nil
|
|
end
|
|
@data.position += 1
|
|
@data.skip
|
|
#Look for an encoding between matching quote marks
|
|
if ['"', "'"].include?(@data.current_byte)
|
|
quote_mark = @data.current_byte
|
|
@data.position += 1
|
|
old_position = @data.position
|
|
@data.jump_to(quote_mark)
|
|
return @data[old_position ... @data.position]
|
|
else
|
|
#Unquoted value
|
|
old_position = @data.position
|
|
begin
|
|
@data.find_next(SPACE_CHARACTERS)
|
|
return @data[old_position ... @data.position]
|
|
rescue EOF
|
|
#Return the whole remaining value
|
|
return @data[old_position .. -1]
|
|
end
|
|
end
|
|
rescue EOF
|
|
return nil
|
|
end
|
|
end
|
|
end
|
|
|
|
# Determine if a string is a supported encoding
|
|
def self.is_valid_encoding(encoding)
|
|
(not encoding.nil? and encoding.kind_of?(String) and ENCODINGS.include?(encoding.downcase.strip))
|
|
end
|
|
|
|
end
|