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/* ***** 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 <shooshX@gmail.com>
* Rudi Pettazzi <rudi.pettazzi@gmail.com> (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());
}
}
}
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