parent
554c0351dd
commit
6d5fefe060
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/**
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* ByteArray
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* Copyright 2007 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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* First published 30.03.2007 on http://yacy.net
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program in the file lgpl21.txt
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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package net.yacy.cora.util;
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import java.util.HashMap;
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import net.yacy.cora.document.UTF8;
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/**
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* this class is a experimental replacement of byte[].
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* It can be used if a byte[] shall be stored within a HashMap or HashSet
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* which is faster than TreeMap but is generally not possible because storing
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* a byte[] in a Hashtable does not work because the hash computation does not
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* work for byte[]. This class extends byte[] with a cached hashing function,
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* so it can be used in hashtables.
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* //FIXME: so does storing byte[] in HashMap help? as I'm moving use of Hashtable to
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* //FIXME: HashMap, if so, please remove this class- or notify me
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*/
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public class ByteArray {
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private final byte[] buffer;
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public ByteArray(final byte[] bb) {
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this.buffer = bb;
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}
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public byte[] asBytes() {
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return this.buffer;
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}
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public static boolean startsWith(final byte[] buffer, final byte[] pattern) {
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// compares two byte arrays: true, if pattern appears completely at offset position
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if (buffer == null && pattern == null) return true;
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if (buffer == null || pattern == null) return false;
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if (buffer.length < pattern.length) return false;
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for (int i = 0; i < pattern.length; i++) if (buffer[i] != pattern[i]) return false;
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return true;
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}
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private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
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@Override
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public int hashCode() {
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if (this.hashCache == Integer.MIN_VALUE) {
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this.hashCache = ByteArray.hashCode(this.buffer);
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}
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return this.hashCache;
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}
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/**
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* compute a hash code that is equal to the hash computation of String()
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* @param b
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* @return a hash number
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*/
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public static int hashCode(byte[] b) {
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int h = 0;
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for (byte c: b) h = 31 * h + (c & 0xFF);
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return h;
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}
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@Override
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public boolean equals(Object other) {
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ByteArray b = (ByteArray) other;
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if (this.buffer == null && b == null) return true;
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if (this.buffer == null || b == null) return false;
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if (this.buffer.length != b.buffer.length) return false;
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int l = this.buffer.length;
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while (--l >= 0) if (this.buffer[l] != b.buffer[l]) return false;
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return true;
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}
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public static long parseDecimal(final byte[] s) throws NumberFormatException {
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if (s == null) throw new NumberFormatException("null");
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long result = 0;
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boolean negative = false;
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int i = 0, max = s.length;
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long limit;
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long multmin;
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long digit;
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if (max <= 0) throw new NumberFormatException(UTF8.String(s));
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if (s[0] == '-') {
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negative = true;
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limit = Long.MIN_VALUE;
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i++;
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} else {
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limit = -Long.MAX_VALUE;
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}
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multmin = limit / 10;
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if (i < max) {
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digit = s[i++] - 48;
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if (digit < 0) throw new NumberFormatException(UTF8.String(s));
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result = -digit;
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}
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while (i < max) {
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// Accumulating negatively avoids surprises near MAX_VALUE
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digit = s[i++] - 48;
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if (digit < 0) throw new NumberFormatException(UTF8.String(s));
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if (result < multmin) throw new NumberFormatException(UTF8.String(s));
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result *= 10;
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if (result < limit + digit) throw new NumberFormatException(UTF8.String(s));
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result -= digit;
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}
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if (negative) {
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if (i > 1) return result;
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throw new NumberFormatException(UTF8.String(s));
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}
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return -result;
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}
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public static void main(String[] args) {
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ByteArray a0 = new ByteArray("abc".getBytes());
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ByteArray a1 = new ByteArray("abc".getBytes());
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ByteArray b = new ByteArray("bbb".getBytes());
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System.out.println("a0 " + ((a0.equals(a1)) ? "=" : "!=") + " a1");
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System.out.println("a0 " + ((a0.equals(b)) ? "=" : "!=") + " b");
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HashMap<ByteArray, Integer> map = new HashMap<ByteArray, Integer>();
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map.put(a0, 1);
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//map.put(a1, 1);
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map.put(b, 2);
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System.out.println("map.size() = " + map.size());
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System.out.println("hashCode(a0) = " + a0.hashCode());
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System.out.println("UTF8.String(a0).hashCode = " + (UTF8.String(a0.asBytes())).hashCode());
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System.out.println("hashCode(a1) = " + a1.hashCode());
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System.out.println("UTF8.String(a1).hashCode = " + (UTF8.String(a1.asBytes())).hashCode());
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System.out.println("hashCode(b) = " + b.hashCode());
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System.out.println("a0 " + ((map.containsKey(a0)) ? "in" : "not in") + " map");
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System.out.println("a1 " + ((map.containsKey(a1)) ? "in" : "not in") + " map");
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System.out.println("b " + ((map.containsKey(b)) ? "in" : "not in") + " map");
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System.out.println("parseIntDecimal " + parseDecimal("6543".getBytes()));
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}
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}
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@ -0,0 +1,288 @@
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/**
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* ByteBuffer
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* Copyright 2004 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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* First published 2004 on http://yacy.net
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program in the file lgpl21.txt
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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package net.yacy.cora.util;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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import net.yacy.cora.document.UTF8;
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public final class ByteBuffer extends OutputStream {
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private byte[] buffer;
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private int offset;
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private int length;
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public ByteBuffer() {
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this.buffer = new byte[10];
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this.length = 0;
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this.offset = 0;
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}
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public ByteBuffer(final int initLength) {
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this.buffer = new byte[initLength];
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this.length = 0;
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this.offset = 0;
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}
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public ByteBuffer(final byte[] bb) {
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this.buffer = bb;
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this.length = bb.length;
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this.offset = 0;
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}
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public ByteBuffer(final String s) {
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this.buffer = UTF8.getBytes(s);
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this.length = this.buffer.length;
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this.offset = 0;
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}
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public void clear() {
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// we keep the byte[] and just set the pointer to write positions to zero
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this.length = 0;
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this.offset = 0;
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}
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public int length() {
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return this.length;
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}
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public boolean isEmpty() {
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return this.length == 0;
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}
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private void grow() {
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int newsize = this.buffer.length * 2 + 1;
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if (newsize < 256) newsize = 256;
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final byte[] tmp = new byte[newsize];
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System.arraycopy(this.buffer, this.offset, tmp, 0, this.length);
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this.buffer = tmp;
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this.offset = 0;
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}
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@Override
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public void write(final int b) {
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write((byte) (b & 0xff));
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}
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public void write(final char b) {
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write((byte) b);
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}
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private void write(final byte b) {
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if (this.offset + this.length + 1 > this.buffer.length) grow();
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this.buffer[this.offset + this.length++] = b;
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}
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@Override
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public void write(final byte[] bb) {
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write(bb, 0, bb.length);
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}
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@Override
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public void write(final byte[] bb, final int of, final int le) {
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while (this.offset + this.length + le > this.buffer.length) grow();
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System.arraycopy(bb, of, this.buffer, this.offset + this.length, le);
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this.length += le;
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}
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public ByteBuffer append(final byte b) {
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write(b);
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return this;
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}
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public ByteBuffer append(final char b) {
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write(b);
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return this;
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}
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public ByteBuffer append(final int i) {
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write((byte) (i & 0xFF));
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return this;
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}
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public ByteBuffer append(final byte[] bb) {
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write(bb, 0, bb.length);
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return this;
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}
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public ByteBuffer append(final byte[] bb, final int of, final int le) {
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write(bb, of, le);
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return this;
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}
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public ByteBuffer append(final String s) {
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return append(UTF8.getBytes(s));
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}
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public byte byteAt(final int pos) {
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if (pos > this.length) return -1;
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return this.buffer[this.offset + pos];
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}
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public int indexOf(final byte[] bs, final int start) {
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if (start + bs.length > this.length) return -1;
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loop: for (int i = start; i <= this.length - bs.length; i++) {
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// first test only first byte
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if (this.buffer[this.offset + i] != bs[0]) continue loop;
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// then test all remaining bytes
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for (int j = 1; j < bs.length; j++) {
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if (this.buffer[this.offset + i + j] != bs[j]) continue loop;
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}
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// found hit
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return i;
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}
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return -1;
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}
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public boolean startsWith(final byte[] bs, final int start) {
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if (this.length - start < bs.length) return false;
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for (int i = 0; i < bs.length; i++) {
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if (this.buffer[this.offset + i + start] != bs[i]) return false;
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}
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return true;
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}
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public byte[] getBytes() {
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return getBytes(0);
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}
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private byte[] getBytes(final int start) {
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return getBytes(start, this.length);
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}
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public byte[] getBytes(final int start, final int len) {
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// start is inclusive, end is exclusive
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if (len > this.length) throw new IndexOutOfBoundsException("getBytes: len > length");
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if (start > this.length) throw new IndexOutOfBoundsException("getBytes: start > length");
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if ((start == 0) && (len == this.length) && (len == this.buffer.length)) return this.buffer;
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final byte[] tmp = new byte[len];
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System.arraycopy(this.buffer, this.offset + start, tmp, 0, len);
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return tmp;
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}
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public void copyTo(byte[] otherArray, int offset) {
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System.arraycopy(this.buffer, 0, otherArray, offset, this.length);
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}
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public ByteBuffer trim(final int start) {
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this.offset += start;
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this.length -= start;
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return this;
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}
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public ByteBuffer trim(final int start, final int len) {
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if (start + len > this.length) throw new IndexOutOfBoundsException("trim: start + len > length; this.offset = " + this.offset + ", this.length = " + this.length + ", start = " + start + ", len = " + len);
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this.offset = this.offset + start;
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this.length = len;
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return this;
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}
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@Override
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public String toString() {
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return UTF8.String(this.buffer, this.offset, this.length);
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}
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public String toString(final int left, final int length) {
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return UTF8.String(this.buffer, this.offset + left, length);
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}
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public StringBuilder toStringBuilder(final int left, final int length, final int sblength) {
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assert sblength >= length;
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final StringBuilder sb = new StringBuilder(sblength);
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int i = 0;
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sb.setLength(length);
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for (int j = left; j < left + length; j++) sb.setCharAt(i++, (char) this.buffer[this.offset + j]);
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return sb;
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}
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public static boolean equals(final byte[] buffer, final byte[] pattern) {
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// compares two byte arrays: true, if pattern appears completely at offset position
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if (buffer.length < pattern.length) return false;
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for (int i = 0; i < pattern.length; i++) if (buffer[i] != pattern[i]) return false;
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return true;
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}
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public static boolean equals(final byte[] b0, final int off0, final byte[] b1, final int off1, final int length) {
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if (b0.length - off0 < length || b1.length - off1 < length) return false;
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for (int i = 0; i < length; i++) if (b0[off0 + i] != b1[off1 + i]) return false;
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return true;
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}
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public void writeTo(final OutputStream dest) throws IOException {
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dest.write(this.buffer, this.offset, this.length);
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dest.flush();
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}
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public static boolean contains(final Collection<byte[]> collection, final byte[] key) {
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for (final byte[] v: collection) {
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if (equals(v, key)) return true;
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}
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return false;
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}
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public static int remove(final Collection<byte[]> collection, final byte[] key) {
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Iterator<byte[]> i = collection.iterator();
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byte[] v;
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int c = 0;
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while (i.hasNext()) {
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v = i.next();
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if (equals(v, key)) {
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i.remove();
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c++;
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}
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}
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return c;
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}
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public static List<byte[]> split(final byte[] b, final byte s) {
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final ArrayList<byte[]> a = new ArrayList<byte[]>();
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int c = 0;
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loop: while (c < b.length) {
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int i = c;
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search: while (i < b.length) {
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if (b[i] == s) break search;
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i++;
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}
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if (i >= b.length) {
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// nothing found; this is the end of the search
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final byte[] bb = new byte[b.length - c];
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System.arraycopy(b, c, bb, 0, bb.length);
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a.add(bb);
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break loop;
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}
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// found a separator
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final byte[] bb = new byte[i - c];
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System.arraycopy(b, c, bb, 0, bb.length);
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a.add(bb);
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c = i + 1;
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}
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return a;
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}
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}
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Loading…
Reference in new issue