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