Initial revision

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3925 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rexml/source.rb

@@ -0,0 +1,191 @@
+require 'rexml/encoding'
+
+module REXML
+	# Generates Source-s.  USE THIS CLASS.
+	class SourceFactory
+		# Generates a Source object
+		# @param arg Either a String, or an IO
+		# @return a Source, or nil if a bad argument was given
+		def SourceFactory::create_from arg#, slurp=true
+			if arg.kind_of? String
+				source = Source.new(arg)
+			elsif arg.kind_of? IO
+				source = IOSource.new(arg)
+			end
+			source
+		end
+	end
+
+	# A Source can be searched for patterns, and wraps buffers and other
+	# objects and provides consumption of text
+	class Source
+		include Encoding
+		# The current buffer (what we're going to read next)
+		attr_reader :buffer
+		# The line number of the last consumed text
+		attr_reader :line
+		attr_reader :encoding
+
+		# Constructor
+		# @param arg must be a String, and should be a valid XML document
+		def initialize arg
+			@orig = @buffer = arg
+			self.encoding = check_encoding( @buffer )
+			#@buffer = decode(@buffer) unless @encoding == UTF_8
+			@line = 0
+		end
+
+		# Inherited from Encoding
+		# Overridden to support optimized en/decoding
+		def encoding=(enc)
+			super
+			eval <<-EOL
+				alias :encode :to_#{encoding.tr('-', '_').downcase}
+				alias :decode :from_#{encoding.tr('-', '_').downcase}
+			EOL
+			@line_break = encode( '>' )
+			if enc != UTF_8
+				@buffer = decode(@buffer)
+				@to_utf = true
+			else
+				@to_utf = false
+			end
+		end
+
+		# Scans the source for a given pattern.  Note, that this is not your
+		# usual scan() method.  For one thing, the pattern argument has some
+		# requirements; for another, the source can be consumed.  You can easily
+		# confuse this method.  Originally, the patterns were easier
+		# to construct and this method more robust, because this method 
+		# generated search regexes on the fly; however, this was 
+		# computationally expensive and slowed down the entire REXML package 
+		# considerably, since this is by far the most commonly called method.
+		# @param pattern must be a Regexp, and must be in the form of
+		# /^\s*(#{your pattern, with no groups})(.*)/.  The first group
+		# will be returned; the second group is used if the consume flag is
+		# set.
+		# @param consume if true, the pattern returned will be consumed, leaving
+		# everything after it in the Source.
+		# @return the pattern, if found, or nil if the Source is empty or the
+		# pattern is not found.
+		def scan pattern, consume=false
+			return nil if @buffer.nil?
+			rv = @buffer.scan(pattern)
+			@buffer = $' if consume and rv.size>0
+			rv
+		end
+
+		def read
+		end
+
+		def match pattern, consume=false
+			md = pattern.match @buffer
+			@buffer = $' if consume and md
+			return md
+		end
+
+		# @return true if the Source is exhausted
+		def empty?
+			@buffer.nil? or @buffer.strip.nil?
+		end
+
+		# @return the current line in the source
+		def current_line
+			lines = @orig.split
+			res = lines.grep @buffer[0..30]
+			res = res[-1] if res.kind_of? Array
+			lines.index( res ) if res
+		end
+	end
+
+	# A Source that wraps an IO.  See the Source class for method
+	# documentation
+	class IOSource < Source
+		#attr_reader :block_size
+
+		def initialize arg, block_size=500
+			@er_source = @source = arg
+			@to_utf = false
+			# READLINE OPT
+			# The following was commented out when IOSource started using readline
+			# to pull the data from the stream.
+			#@block_size = block_size
+			#super @source.read(@block_size)
+			@line_break = '>'
+			super @source.readline( @line_break )
+		end
+
+		def scan pattern, consume=false
+			rv = super
+			# You'll notice that this next section is very similar to the same
+			# section in match(), but just a liiittle different.  This is
+			# because it is a touch faster to do it this way with scan()
+			# than the way match() does it; enough faster to warrent duplicating
+			# some code
+			if rv.size == 0
+				until @buffer =~ pattern or @source.nil?
+					begin
+						# READLINE OPT
+						#str = @source.read(@block_size)
+						str = @source.readline(@line_break)
+						str = decode(str) if @to_utf and str
+						@buffer << str
+					rescue
+						@source = nil
+					end
+				end
+				rv = super
+			end
+			rv.taint
+			rv
+		end
+
+		def read
+			begin
+				str = @source.readline('>')
+				str = decode(str) if @to_utf and str 
+				@buffer << str
+			rescue
+				@source = nil
+			end
+		end
+
+		def match pattern, consume=false
+			rv = pattern.match(@buffer)
+			@buffer = $' if consume and rv
+			while !rv and @source
+				begin
+					str = @source.readline('>')
+					str = decode(str) if @to_utf and str
+					@buffer << str
+					rv = pattern.match(@buffer)
+					@buffer = $' if consume and rv
+				rescue
+					@source = nil
+				end
+			end
+			rv.taint
+			rv
+		end
+		
+		def empty?
+			super and ( @source.nil? || @source.eof? )
+		end
+
+		# @return the current line in the source
+		def current_line
+			pos = @er_source.pos				# The byte position in the source
+			lineno = @er_source.lineno	# The XML < position in the source
+			@er_source.rewind
+			line = 0										# The \r\n position in the source
+			begin
+				while @er_source.pos < pos
+					@er_source.readline
+					line += 1
+				end
+			rescue
+			end
+			[pos, lineno, line]
+		end
+	end
+end