org.mozilla.universalchardet.prober.SingleByteCharsetProber Maven / Gradle / Ivy
/* ***** 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
* Kohei TAKETA (Java 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
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package org.mozilla.universalchardet.prober;
import org.mozilla.universalchardet.prober.sequence.SequenceModel;
public class SingleByteCharsetProber extends CharsetProber {
////////////////////////////////////////////////////////////////
// constants
////////////////////////////////////////////////////////////////
public static final int SAMPLE_SIZE = 64;
public static final int SB_ENOUGH_REL_THRESHOLD = 1024;
public static final float POSITIVE_SHORTCUT_THRESHOLD = 0.95f;
public static final float NEGATIVE_SHORTCUT_THRESHOLD = 0.05f;
public static final int SYMBOL_CAT_ORDER = 250;
public static final int NUMBER_OF_SEQ_CAT = 4;
public static final int POSITIVE_CAT = NUMBER_OF_SEQ_CAT-1;
public static final int NEGATIVE_CAT = 0;
////////////////////////////////////////////////////////////////
// fields
////////////////////////////////////////////////////////////////
private ProbingState state;
private SequenceModel model;
private boolean reversed;
private short lastOrder;
private int totalSeqs;
private int[] seqCounters;
private int totalChar;
private int freqChar;
private CharsetProber nameProber;
////////////////////////////////////////////////////////////////
// methods
////////////////////////////////////////////////////////////////
public SingleByteCharsetProber(SequenceModel model) {
super();
this.model = model;
this.reversed = false;
this.nameProber = null;
this.seqCounters = new int[NUMBER_OF_SEQ_CAT];
reset();
}
public SingleByteCharsetProber(
SequenceModel model,
boolean reversed,
CharsetProber nameProber)
{
super();
this.model = model;
this.reversed = reversed;
this.nameProber = nameProber;
this.seqCounters = new int[NUMBER_OF_SEQ_CAT];
reset();
}
boolean keepEnglishLetters() {
return this.model.getKeepEnglishLetter();
}
@Override
public String getCharSetName() {
if (this.nameProber == null) {
return this.model.getCharsetName();
} else {
return this.nameProber.getCharSetName();
}
}
@Override
public float getConfidence() {
if (this.totalSeqs > 0) {
float r = 1.0f * this.seqCounters[POSITIVE_CAT] / this.totalSeqs / this.model.getTypicalPositiveRatio();
r = r * this.freqChar / this.totalChar;
if (r >= 1.0f) {
r = 0.99f;
}
return r;
}
return 0.01f;
}
@Override
public ProbingState getState() {
return this.state;
}
@Override
public ProbingState handleData(byte[] buf, int offset, int length) {
short order;
int maxPos = offset + length;
for (int i=offset; i SB_ENOUGH_REL_THRESHOLD) {
float cf = getConfidence();
if (cf > POSITIVE_SHORTCUT_THRESHOLD) {
this.state = ProbingState.FOUND_IT;
} else if (cf < NEGATIVE_SHORTCUT_THRESHOLD){
this.state = ProbingState.NOT_ME;
}
}
}
return this.state;
}
@Override
public final void reset() {
this.state = ProbingState.DETECTING;
this.lastOrder = 255;
for (int i=0; i