org.mozilla.universalchardet.prober.CharsetProber 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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* decision by deleting the provisions above and replace them with the notice
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*
* ***** END LICENSE BLOCK ***** */
package org.mozilla.universalchardet.prober;
import java.nio.ByteBuffer;
public abstract class CharsetProber
{
////////////////////////////////////////////////////////////////
// constants
////////////////////////////////////////////////////////////////
public static final float SHORTCUT_THRESHOLD = 0.95f;
public static final int ASCII_A = 0x61; // 'a'
public static final int ASCII_Z = 0x7A; // 'z'
public static final int ASCII_A_CAPITAL = 0x41; // 'A'
public static final int ASCII_Z_CAPITAL = 0x5A; // 'Z'
public static final int ASCII_LT = 0x3C; // '<'
public static final int ASCII_GT = 0x3E; // '>'
public static final int ASCII_SP = 0x20; // ' '
private boolean active = true;
////////////////////////////////////////////////////////////////
// inner types
////////////////////////////////////////////////////////////////
public enum ProbingState
{
DETECTING,
FOUND_IT,
NOT_ME
}
////////////////////////////////////////////////////////////////
// methods
////////////////////////////////////////////////////////////////
public CharsetProber()
{}
public abstract String getCharSetName();
public abstract ProbingState handleData(final byte[] buf, int offset, int length);
public abstract ProbingState getState();
public abstract void reset();
public abstract float getConfidence();
public abstract void setOption();
// ByteBuffer.position() indicates number of bytes written.
public ByteBuffer filterWithoutEnglishLetters(final byte[] buf, int offset, int length)
{
ByteBuffer out = ByteBuffer.allocate(length);
boolean meetMSB = false;
byte c;
int prevPtr = offset;
int curPtr = offset;
int maxPtr = offset + length;
for (; curPtr prevPtr) {
// this segment contains more than single symbol,
// and it has upper ASCII, we need to keep it
out.put(buf, prevPtr, (curPtr-prevPtr));
out.put((byte)ASCII_SP);
prevPtr = curPtr + 1;
meetMSB = false;
} else {
// ignore current segment.
// (either because it is just a symbol or just an English word)
prevPtr = curPtr + 1;
}
}
}
if (meetMSB && curPtr > prevPtr) {
out.put(buf, prevPtr, (curPtr-prevPtr));
}
return out;
}
public ByteBuffer filterWithEnglishLetters(final byte[] buf, int offset, int length)
{
ByteBuffer out = ByteBuffer.allocate(length);
boolean isInTag = false;
byte c;
int prevPtr = offset;
int curPtr = offset;
int maxPtr = offset + length;
for (; curPtr < maxPtr; ++curPtr) {
c = buf[curPtr];
if (c == ASCII_GT) {
isInTag = false;
} else if (c == ASCII_LT) {
isInTag = true;
}
if (isAscii(c) && isAsciiSymbol(c)) {
if (curPtr > prevPtr && !isInTag) {
// Current segment contains more than just a symbol
// and it is not inside a tag, keep it.
out.put(buf, prevPtr, (curPtr-prevPtr));
out.put((byte)ASCII_SP);
prevPtr = curPtr + 1;
} else {
prevPtr = curPtr + 1;
}
}
}
// If the current segment contains more than just a symbol
// and it is not inside a tag then keep it.
if (!isInTag && curPtr > prevPtr) {
out.put(buf, prevPtr, (curPtr-prevPtr));
}
return out;
}
private boolean isAscii(byte b)
{
return ((b & 0x80) == 0);
}
// b must be in ASCII code range (MSB can't be 1).
private boolean isAsciiSymbol(byte b)
{
int c = b & 0xFF;
return ((c < ASCII_A_CAPITAL) ||
(c > ASCII_Z_CAPITAL && c < ASCII_A) ||
(c > ASCII_Z));
}
public boolean isActive() {
return active;
}
public void setActive(boolean active) {
this.active = active;
}
}