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package bjc.utils.esodata;
import java.util.Deque;
import java.util.LinkedList;
/**
* A stack, with support for combinators.
*
* A FILO stack with support for forth/factor style combinators.
*
* @param T The datatype stored in the stack.
* @author Ben Culkin
*/
public class Stack<T> {
private Deque<T> backing;
/**
* Create a new empty stack.
*
*/
public Stack() {
backing = new LinkedList();
}
/**
* Push an element onto the stack.
*
* @param elm The element to insert.
*/
public void push(T elm) {
backing.push(elm);
}
/**
* Pop an element off of the stack.
*
* @return The element on top of the stack.
*/
public T pop(T elm) {
return backing.pop();
}
/**
* Get the top item of the stack without removing it.
*
* @return The element on top of the stack.
*/
public T top() {
return backing.peek();
}
/**
* Get the number of elements in the stack.
*
* @return the number of elements in the stack.
*/
public int size() {
return backing.size();
}
/** Check if the stack is empty.
*
* @return Whether or not the stack is empty
*/
public boolean empty() {
return backing.size() == 0;
}
/*
* Basic combinators
*/
/**
* Drop n items from the stack.
*
* @param n The number of items to drop.
*/
public void drop(int n) {
for(int i = 0; i < n; i++) {
backing.pop();
}
}
/**
* Drop one item from the stack.
*/
public void drop() {
drop(1);
}
/**
* Delete n items below the current one.
*
* @param n The number of items below the top to delete.
*/
public void nip(int n) {
T elm = backing.pop();
drop(n);
backing.push(elm);
}
/**
* Delete the second element in the stack.
*/
public void nip() {
nip(1);
}
/**
* Replicate the top n items of the stack m times.
*
* @param n The number of items to duplicate.
* @param m The number of times to duplicate items.
*/
public void multidup(int n, int m) {
LinkedList<T> lst = new LinkedList<>();
for(int i = 0; i < n; i++) {
lst.add(0, backing.pop());
}
for(int i = 0; i < m; i++) {
for(T elm : lst) {
backing.push(elm);
}
}
}
/**
* Duplicate the top n items of the stack.
*
* @param n The number of items to duplicate.
*/
public void dup(int n) {
multidup(n, 2);
}
/**
* Duplicate the top item on the stack.
*/
public void dup() {
dup(1);
}
/**
* Replicate the n elements below the top one m times.
*
* @param n The number of items to duplicate.
* @param m The number of times to duplicate items.
*/
public void multiover(int n, int m) {
LinkedList<T> lst = new LinkedList<>();
T elm = backing.pop();
for(int i = 0; i < n; i++) {
lst.add(0, backing.pop());
}
for(T nelm : lst) {
backing.push(nelm);
}
backing.push(elm);
for(int i = 1; i < m; i++) {
for(T nelm : lst) {
backing.push(nelm);
}
}
}
/**
* Duplicate the n elements below the top one.
*
* @param n The number of items to duplicate.
*/
public void over(int n) {
multiover(n, 2);
}
/**
* Duplicate the second item in the stack.
*/
public void over() {
over(1);
}
/**
* Duplicate the third item in the stack.
*/
public void pick() {
T z = backing.pop();
T y = backing.pop();
T x = backing.pop();
backing.push(x);
backing.push(y);
backing.push(z);
backing.push(x);
}
/**
* Swap the top two items on the stack.
*/
public void swap() {
T y = backing.pop();
T x = backing.pop();
backing.push(y);
backing.push(x);
}
/**
* Duplicate the second item below the first item.
*/
public void deepdup() {
T y = backing.pop();
T x = backing.pop();
backing.push(x);
backing.push(x);
backing.push(y);
}
/**
* Swap the second and third items in the stack.
*/
public void deepswap() {
T z = backing.pop();
T y = backing.pop();
T x = backing.pop();
backing.push(y);
backing.push(x);
backing.push(z);
}
/**
* Rotate the top three items on the stack
*/
public void rot() {
T z = backing.pop();
T y = backing.pop();
T x = backing.pop();
backing.push(y);
backing.push(z);
backing.push(x);
}
/**
* Inversely rotate the top three items on the stack
*/
public void invrot() {
T z = backing.pop();
T y = backing.pop();
T x = backing.pop();
backing.push(z);
backing.push(x);
backing.push(y);
}
}
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