JezK
Edit File: sbcharsetprober.rb
######################## BEGIN LICENSE BLOCK ######################## # The Original Code is Mozilla Universal charset detector code. # # The Initial Developer of the Original Code is # Netscape Communications Corporation. # Portions created by the Initial Developer are Copyright (C) 2001 # the Initial Developer. All Rights Reserved. # # Contributor(s): # Jeff Hodges - port to Ruby # Mark Pilgrim - port to Python # Shy Shalom - original C code # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public # License as published by the Free Software Foundation; either # version 2.1 of the License, or (at your option) any later version. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA # 02110-1301 USA ######################### END LICENSE BLOCK ######################### module CharDet SAMPLE_SIZE = 64 SB_ENOUGH_REL_THRESHOLD = 1024 POSITIVE_SHORTCUT_THRESHOLD = 0.95 NEGATIVE_SHORTCUT_THRESHOLD = 0.05 SYMBOL_CAT_ORDER = 250 NUMBER_OF_SEQ_CAT = 4 POSITIVE_CAT = NUMBER_OF_SEQ_CAT - 1 #NEGATIVE_CAT = 0 class SingleByteCharSetProber < CharSetProber def initialize(model, reversed=false, nameProber=nil) super() @model = model @reversed = reversed # TRUE if we need to reverse every pair in the model lookup @nameProber = nameProber # Optional auxiliary prober for name decision reset() end def reset super() @lastOrder = 255 # char order of last character @seqCounters = [0] * NUMBER_OF_SEQ_CAT @totalSeqs = 0 @totalChar = 0 @freqChar = 0 # characters that fall in our sampling range end def get_charset_name if @nameProber return @nameProber.get_charset_name() else return @model['charsetName'] end end def feed(aBuf) if !@model['keepEnglishLetter'] aBuf = filter_without_english_letters(aBuf) end aLen = aBuf.length if aLen == 0 return get_state() end aBuf.each_byte do |b| c = b.chr order = @model['charToOrderMap'][c.bytes.first] if order < SYMBOL_CAT_ORDER @totalChar += 1 end if order < SAMPLE_SIZE @freqChar += 1 if @lastOrder < SAMPLE_SIZE @totalSeqs += 1 if !@reversed @seqCounters[@model['precedenceMatrix'][(@lastOrder * SAMPLE_SIZE) + order]] += 1 else # reverse the order of the letters in the lookup @seqCounters[@model['precedenceMatrix'][(order * SAMPLE_SIZE) + @lastOrder]] += 1 end end end @lastOrder = order end if get_state() == EDetecting if @totalSeqs > SB_ENOUGH_REL_THRESHOLD cf = get_confidence() if cf > POSITIVE_SHORTCUT_THRESHOLD $stderr << "#{@model['charsetName']} confidence = #{cf}, we have a winner\n" if $debug @state = EFoundIt elsif cf < NEGATIVE_SHORTCUT_THRESHOLD $stderr << "#{@model['charsetName']} confidence = #{cf}, below negative shortcut threshold #{NEGATIVE_SHORTCUT_THRESHOLD}\n" if $debug @state = ENotMe end end end return get_state() end def get_confidence r = 0.01 if @totalSeqs > 0 r = (1.0 * @seqCounters[POSITIVE_CAT]) / @totalSeqs / @model['mTypicalPositiveRatio'] r = r * @freqChar / @totalChar if r >= 1.0 r = 0.99 end end return r end end end