*
*/
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 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() {
+ 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 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;
- }
+ 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;
+ }
}