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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 ***** */
namespace UniversalDetector.Core
{
public class UTF8Prober : CharsetProber
{
private static float ONE_CHAR_PROB = 0.50f;
private CodingStateMachine codingSM;
private int numOfMBChar;
public UTF8Prober()
{
numOfMBChar = 0;
codingSM = new CodingStateMachine(new UTF8SMModel());
Reset();
}
public override string GetCharsetName() {
return "UTF-8";
}
public override void Reset()
{
codingSM.Reset();
numOfMBChar = 0;
state = ProbingState.Detecting;
}
public override ProbingState HandleData(byte[] buf, int offset, int len)
{
int codingState = SMModel.START;
int max = offset + len;
for (int i = offset; i < max; i++) {
codingState = codingSM.NextState(buf[i]);
if (codingState == SMModel.ERROR) {
state = ProbingState.NotMe;
break;
}
if (codingState == SMModel.ITSME) {
state = ProbingState.FoundIt;
break;
}
if (codingState == SMModel.START) {
if (codingSM.CurrentCharLen >= 2)
numOfMBChar++;
}
}
if (state == ProbingState.Detecting)
if (GetConfidence() > SHORTCUT_THRESHOLD)
state = ProbingState.FoundIt;
return state;
}
public override float GetConfidence()
{
float unlike = 0.99f;
float confidence = 0.0f;
if (numOfMBChar < 6) {
for (int i = 0; i < numOfMBChar; i++)
unlike *= ONE_CHAR_PROB;
confidence = 1.0f - unlike;
} else {
confidence = 0.99f;
}
return confidence;
}
}
}
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