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180 lines
7.3 KiB
C#
180 lines
7.3 KiB
C#
/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Mozilla Universal charset detector code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2001
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Shy Shalom <shooshX@gmail.com>
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* Rudi Pettazzi <rudi.pettazzi@gmail.com> (C# port)
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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using System;
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namespace UniversalDetector.Core
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{
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// TODO: Using trigrams the detector should be able to discriminate between
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// latin-1 and iso8859-2
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public class Latin1Prober : CharsetProber
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{
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private const int FREQ_CAT_NUM = 4;
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private const int UDF = 0; // undefined
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private const int OTH = 1; // other
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private const int ASC = 2; // ascii capital letter
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private const int ASS = 3; // ascii small letter
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private const int ACV = 4; // accent capital vowel
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private const int ACO = 5; // accent capital other
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private const int ASV = 6; // accent small vowel
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private const int ASO = 7; // accent small other
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private const int CLASS_NUM = 8; // total classes
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private readonly static byte[] Latin1_CharToClass = {
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 00 - 07
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 08 - 0F
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 10 - 17
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 18 - 1F
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 20 - 27
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 28 - 2F
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 30 - 37
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 38 - 3F
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OTH, ASC, ASC, ASC, ASC, ASC, ASC, ASC, // 40 - 47
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ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC, // 48 - 4F
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ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC, // 50 - 57
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ASC, ASC, ASC, OTH, OTH, OTH, OTH, OTH, // 58 - 5F
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OTH, ASS, ASS, ASS, ASS, ASS, ASS, ASS, // 60 - 67
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ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS, // 68 - 6F
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ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS, // 70 - 77
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ASS, ASS, ASS, OTH, OTH, OTH, OTH, OTH, // 78 - 7F
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OTH, UDF, OTH, ASO, OTH, OTH, OTH, OTH, // 80 - 87
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OTH, OTH, ACO, OTH, ACO, UDF, ACO, UDF, // 88 - 8F
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UDF, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // 90 - 97
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OTH, OTH, ASO, OTH, ASO, UDF, ASO, ACO, // 98 - 9F
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // A0 - A7
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // A8 - AF
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // B0 - B7
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OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, // B8 - BF
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ACV, ACV, ACV, ACV, ACV, ACV, ACO, ACO, // C0 - C7
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ACV, ACV, ACV, ACV, ACV, ACV, ACV, ACV, // C8 - CF
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ACO, ACO, ACV, ACV, ACV, ACV, ACV, OTH, // D0 - D7
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ACV, ACV, ACV, ACV, ACV, ACO, ACO, ACO, // D8 - DF
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ASV, ASV, ASV, ASV, ASV, ASV, ASO, ASO, // E0 - E7
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ASV, ASV, ASV, ASV, ASV, ASV, ASV, ASV, // E8 - EF
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ASO, ASO, ASV, ASV, ASV, ASV, ASV, OTH, // F0 - F7
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ASV, ASV, ASV, ASV, ASV, ASO, ASO, ASO, // F8 - FF
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};
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/* 0 : illegal
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1 : very unlikely
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2 : normal
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3 : very likely
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*/
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private readonly static byte[] Latin1ClassModel = {
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/* UDF OTH ASC ASS ACV ACO ASV ASO */
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/*UDF*/ 0, 0, 0, 0, 0, 0, 0, 0,
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/*OTH*/ 0, 3, 3, 3, 3, 3, 3, 3,
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/*ASC*/ 0, 3, 3, 3, 3, 3, 3, 3,
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/*ASS*/ 0, 3, 3, 3, 1, 1, 3, 3,
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/*ACV*/ 0, 3, 3, 3, 1, 2, 1, 2,
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/*ACO*/ 0, 3, 3, 3, 3, 3, 3, 3,
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/*ASV*/ 0, 3, 1, 3, 1, 1, 1, 3,
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/*ASO*/ 0, 3, 1, 3, 1, 1, 3, 3,
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};
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private byte lastCharClass;
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private int[] freqCounter = new int[FREQ_CAT_NUM];
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public Latin1Prober()
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{
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Reset();
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}
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public override string GetCharsetName()
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{
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return "windows-1252";
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}
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public override void Reset()
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{
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state = ProbingState.Detecting;
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lastCharClass = OTH;
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for (int i = 0; i < FREQ_CAT_NUM; i++)
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freqCounter[i] = 0;
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}
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public override ProbingState HandleData(byte[] buf, int offset, int len)
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{
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byte[] newbuf = FilterWithEnglishLetters(buf, offset, len);
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byte charClass, freq;
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for (int i = 0; i < newbuf.Length; i++) {
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charClass = Latin1_CharToClass[newbuf[i]];
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freq = Latin1ClassModel[lastCharClass * CLASS_NUM + charClass];
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if (freq == 0) {
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state = ProbingState.NotMe;
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break;
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}
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freqCounter[freq]++;
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lastCharClass = charClass;
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}
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return state;
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}
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public override float GetConfidence()
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{
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if (state == ProbingState.NotMe)
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return 0.01f;
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float confidence = 0.0f;
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int total = 0;
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for (int i = 0; i < FREQ_CAT_NUM; i++) {
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total += freqCounter[i];
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}
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if (total <= 0) {
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confidence = 0.0f;
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} else {
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confidence = freqCounter[3] * 1.0f / total;
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confidence -= freqCounter[1] * 20.0f / total;
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}
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// lower the confidence of latin1 so that other more accurate detector
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// can take priority.
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return confidence < 0.0f ? 0.0f : confidence * 0.5f;
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}
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public override void DumpStatus()
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{
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//Console.WriteLine(" Latin1Prober: {0} [{1}]", GetConfidence(), GetCharsetName());
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}
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}
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}
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