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/*******************************************************************************
* ============LICENSE_START====================================================
* * org.onap.aaf
* * ===========================================================================
* * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
* * ===========================================================================
* * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
* *
* * Unless required by applicable law or agreed to in writing, software
* * distributed under the License is distributed on an "AS IS" BASIS,
* * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* * See the License for the specific language governing permissions and
* * limitations under the License.
* * ============LICENSE_END====================================================
* *
* * ECOMP is a trademark and service mark of AT&T Intellectual Property.
* *
******************************************************************************/
package org.onap.aaf.rosetta;
/**
* A Ladder is a Stack like Storage Class, but where you can ascend and descend while
* the elements exists.
*
* Like an extension ladder, you can make taller as you go
*
*
*/
public class Ladder<T> {
public static final int DEFAULT_INIT_SIZE=8;
private final int init_size;
private int rung; // as in ladder
private Object[] struts;
public Ladder() {
rung=0;
init_size = DEFAULT_INIT_SIZE;
struts=new Object[init_size];
}
public Ladder(int initSize) {
rung=0;
init_size = initSize;
struts=new Object[init_size];
}
public void bottom() {
rung = 0;
}
public void top() {
rung = struts.length-1;
while(rung>0 && struts[rung]==null)--rung;
}
public int howHigh() {
return rung;
}
public void jumpTo(int rung) {
if(rung>=struts.length) {
Object[] temp = new Object[init_size*((rung/init_size)+1)];
System.arraycopy(struts, 0, temp, 0, struts.length);
struts = temp;
}
this.rung = rung;
}
public int height() {
return struts.length;
}
public void cutTo(int rungs) {
Object[] temp = new Object[rungs];
System.arraycopy(struts, 0, temp, 0, Math.min(rungs, struts.length));
struts = temp;
}
public void ascend() {
++rung;
if(rung>=struts.length) {
Object[] temp = new Object[struts.length+init_size];
System.arraycopy(struts, 0, temp, 0, struts.length);
struts = temp;
}
}
public void descend() {
--rung;
}
@SuppressWarnings("unchecked")
public T peek() {
return (T)struts[rung];
}
public void push(T t) {
struts[rung]=t;
}
@SuppressWarnings("unchecked")
public T pop() {
T t = (T)struts[rung];
struts[rung]=null;
return t;
}
}
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