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116 lines
4.6 KiB
C#
116 lines
4.6 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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namespace UniversalDetector.Core
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{
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/// <summary>
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/// for S-JIS encoding, observe characteristic:
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/// 1, kana character (or hankaku?) often have hight frequency of appereance
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/// 2, kana character often exist in group
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/// 3, certain combination of kana is never used in japanese language
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/// </summary>
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public class SJISProber : CharsetProber
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{
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private CodingStateMachine codingSM;
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private SJISContextAnalyser contextAnalyser;
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private SJISDistributionAnalyser distributionAnalyser;
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private byte[] lastChar = new byte[2];
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public SJISProber()
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{
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codingSM = new CodingStateMachine(new SJISSMModel());
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distributionAnalyser = new SJISDistributionAnalyser();
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contextAnalyser = new SJISContextAnalyser();
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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 "Shift-JIS";
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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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int codingState;
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int max = offset + len;
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for (int i = offset; i < max; i++) {
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codingState = codingSM.NextState(buf[i]);
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if (codingState == SMModel.ERROR) {
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state = ProbingState.NotMe;
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break;
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}
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if (codingState == SMModel.ITSME) {
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state = ProbingState.FoundIt;
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break;
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}
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if (codingState == SMModel.START) {
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int charLen = codingSM.CurrentCharLen;
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if (i == offset) {
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lastChar[1] = buf[offset];
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contextAnalyser.HandleOneChar(lastChar, 2-charLen, charLen);
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distributionAnalyser.HandleOneChar(lastChar, 0, charLen);
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} else {
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contextAnalyser.HandleOneChar(buf, i+1-charLen, charLen);
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distributionAnalyser.HandleOneChar(buf, i-1, charLen);
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}
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}
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}
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lastChar[0] = buf[max-1];
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if (state == ProbingState.Detecting)
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if (contextAnalyser.GotEnoughData() && GetConfidence() > SHORTCUT_THRESHOLD)
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state = ProbingState.FoundIt;
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return state;
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}
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public override void Reset()
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{
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codingSM.Reset();
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state = ProbingState.Detecting;
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contextAnalyser.Reset();
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distributionAnalyser.Reset();
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}
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public override float GetConfidence()
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{
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float contxtCf = contextAnalyser.GetConfidence();
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float distribCf = distributionAnalyser.GetConfidence();
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return (contxtCf > distribCf ? contxtCf : distribCf);
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}
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}
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}
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