77 lines
2.0 KiB
Java
77 lines
2.0 KiB
Java
import cs2030s.fp.Immutator;
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import cs2030s.fp.Combiner;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* A wrapper around an eagerly evaluated list that
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* can be generated with a lambda expression.
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*
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* @author Adi Yoga S. Prabawa
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* @version CS2030S AY 22/23 Sem 1
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*/
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class EagerList<T> {
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/** The wrapped java.util.List object */
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private List<T> list;
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/**
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* A private constructor to initialize the list to the given one.
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*
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* @param list The given java.util.List to wrap around.
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*/
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private EagerList(List<T> list) {
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this.list = list;
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}
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/**
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* Generate the content of the list. Given x and a lambda f,
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* generate the list of n elements as [x, f(x), f(f(x)), f(f(f(x))),
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* ... ]
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*
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* @param <T> The type of the elements in the list.
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* @param n The number of elements.
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* @param seed The first element.
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* @param f The immutator function on the elements.
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* @return The created list.
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*/
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public static <T> EagerList<T> generate(int n, T seed, Immutator<T, T> f) {
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EagerList<T> eagerList = new EagerList<>(new ArrayList<>());
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T curr = seed;
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for (int i = 0; i < n; i++ ) {
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eagerList.list.add(curr);
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curr = f.invoke(curr);
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}
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return eagerList;
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}
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/**
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* Return the element at index i of the list.
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*
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* @param i The index of the element to retrieved (0 for the 1st element).
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* @return The element at index i.
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*/
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public T get(int i) {
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return this.list.get(i);
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}
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/**
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* Find the index of a given element.
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*
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* @param v The value of the element to look for.
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* @return The index of the element in the list. -1 is element is not in the list.
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*/
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public int indexOf(T v) {
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return this.list.indexOf(v);
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}
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/**
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* Return the string representation of the list.
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*
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* @return The string representation of the list.
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*/
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@Override
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public String toString() {
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return this.list.toString();
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}
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}
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