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/*******************************************************************************
* Copyright (c) 2010, 2018 SAP AG
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Lazar Kirchev, SAP AG - initial API and implementation
*******************************************************************************/
package org.eclipse.equinox.console.common;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
/**
* A helper class, which implements history.
*/
public class HistoryHolder {
private static final int MAX = 100;
private final byte[][] history;
private int size;
private int pos;
public HistoryHolder() {
history = new byte[MAX][];
}
public synchronized void reset() {
size = 0;
pos = 0;
for (int i = 0; i < MAX; i++) {
history[i] = null;
}
}
public synchronized void add(byte[] data) {
data = new String(data, StandardCharsets.US_ASCII).trim().getBytes(StandardCharsets.US_ASCII);
if (data.length == 0) {
pos = size;
return;
}
for (int i = 0; i < size; i++) {
if (Arrays.equals(history[i], data)) {
System.arraycopy(history, i + 1, history, i, size - i - 1);
history[size - 1] = data;
pos = size;
return;
}
}
if (size >= MAX) {
System.arraycopy(history, 1, history, 0, size - 1);
size--;
}
history[size++] = data;
pos = size;
}
public synchronized byte[] next() {
if (pos >= size - 1) {
return null;
}
return history[++pos];
}
public synchronized byte[] last() {
if (size > 0) {
pos = size - 1;
return history[pos];
} else {
return null;
}
}
public synchronized byte[] first() {
if (size > 0) {
pos = 0;
return history[pos];
} else {
return null;
}
}
public synchronized byte[] prev() {
if (size == 0) {
return null;
}
if (pos == 0) {
return history[pos];
} else {
return history[--pos];
}
}
}
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