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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)
if arg.respond_to? :read and
arg.respond_to? :readline and
arg.respond_to? :nil? and
arg.respond_to? :eof?
IOSource.new(arg)
elsif arg.respond_to? :to_str
require 'stringio'
IOSource.new(StringIO.new(arg))
elsif arg.kind_of? Source
arg
else
raise "#{arg.class} is not a valid input stream. It must walk \n"+
"like either a String, an IO, or a Source."
end
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
# @param encoding if non-null, sets the encoding of the source to this
# value, overriding all encoding detection
def initialize(arg, encoding=nil)
@orig = @buffer = arg
if encoding
self.encoding = encoding
else
self.encoding = check_encoding( @buffer )
end
@line = 0
end
# Inherited from Encoding
# Overridden to support optimized en/decoding
def encoding=(enc)
return unless super
@line_break = encode( '>' )
if @encoding != 'UTF-8'
@buffer = decode(@buffer)
@to_utf = true
else
@to_utf = false
@buffer.force_encoding ::Encoding::UTF_8
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, cons=false)
return nil if @buffer.nil?
rv = @buffer.scan(pattern)
@buffer = $' if cons and rv.size>0
rv
end
def read
end
def consume( pattern )
@buffer = $' if pattern.match( @buffer )
end
def match_to( char, pattern )
return pattern.match(@buffer)
end
def match_to_consume( char, pattern )
md = pattern.match(@buffer)
@buffer = $'
return md
end
def match(pattern, cons=false)
md = pattern.match(@buffer)
@buffer = $' if cons and md
return md
end
# @return true if the Source is exhausted
def empty?
@buffer == ""
end
def position
@orig.index( @buffer )
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
# block_size has been deprecated
def initialize(arg, block_size=500, encoding=nil)
@er_source = @source = arg
@to_utf = false
# Determining the encoding is a deceptively difficult issue to resolve.
# First, we check the first two bytes for UTF-16. Then we
# assume that the encoding is at least ASCII enough for the '>', and
# we read until we get one of those. This gives us the XML declaration,
# if there is one. If there isn't one, the file MUST be UTF-8, as per
# the XML spec. If there is one, we can determine the encoding from
# it.
@buffer = ""
str = @source.read( 2 ) || ''
if encoding
self.encoding = encoding
elsif str[0,2] == "\xfe\xff"
@line_break = "\000>"
elsif str[0,2] == "\xff\xfe"
@line_break = ">\000"
elsif str[0,2] == "\xef\xbb"
str += @source.read(1)
str = '' if (str[2,1] == "\xBF")
@line_break = ">"
else
@line_break = ">"
end
super( @source.eof? ? str : str+@source.readline( @line_break ) )
if !@to_utf and
@buffer.respond_to?(:force_encoding) and
@source.respond_to?(:external_encoding) and
@source.external_encoding != ::Encoding::UTF_8
@force_utf8 = true
else
@force_utf8 = false
end
end
def scan(pattern, cons=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
@buffer << readline
rescue Iconv::IllegalSequence
raise
rescue
@source = nil
end
end
rv = super
end
rv.taint
rv
end
def read
begin
@buffer << readline
rescue Exception, NameError
@source = nil
end
end
def consume( pattern )
match( pattern, true )
end
def match( pattern, cons=false )
rv = pattern.match(@buffer)
@buffer = $' if cons and rv
while !rv and @source
begin
@buffer << readline
rv = pattern.match(@buffer)
@buffer = $' if cons and rv
rescue
@source = nil
end
end
rv.taint
rv
end
def empty?
super and ( @source.nil? || @source.eof? )
end
def position
@er_source.pos rescue 0
end
# @return the current line in the source
def current_line
begin
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
rescue IOError
pos = -1
line = -1
end
[pos, lineno, line]
end
private
def readline
str = @source.readline(@line_break)
return nil if str.nil?
if @to_utf
decode(str)
else
str.force_encoding(::Encoding::UTF_8) if @force_utf8
str
end
end
end
end