feat: update structure

cs2030s/labs/Lab7/EagerList.java

@@ -0,0 +1,76 @@
+import cs2030s.fp.Immutator;
+import cs2030s.fp.Combiner;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A wrapper around an eagerly evaluated list that
+ * can be generated with a lambda expression.
+ *
+ * @author Adi Yoga S. Prabawa
+ * @version CS2030S AY 22/23 Sem 1
+ */
+class EagerList<T> {
+  /** The wrapped java.util.List object */
+  private List<T> list;
+
+  /** 
+   * A private constructor to initialize the list to the given one. 
+   *
+   * @param list The given java.util.List to wrap around.
+   */
+  private EagerList(List<T> list) {
+    this.list = list;
+  }
+
+  /** 
+   * Generate the content of the list.  Given x and a lambda f, 
+   * generate the list of n elements as [x, f(x), f(f(x)), f(f(f(x))), 
+   * ... ]
+   *
+   * @param <T> The type of the elements in the list.
+   * @param n The number of elements.
+   * @param seed The first element.
+   * @param f The immutator function on the elements.
+   * @return The created list.
+   */
+  public static <T> EagerList<T> generate(int n, T seed, Immutator<T, T> f) {
+    EagerList<T> eagerList = new EagerList<>(new ArrayList<>());
+    T curr = seed;
+    for (int i = 0; i < n; i++ ) {
+      eagerList.list.add(curr);
+      curr = f.invoke(curr);
+    }
+    return eagerList;
+  }
+
+  /** 
+   * Return the element at index i of the list.  
+   *
+   * @param i The index of the element to retrieved (0 for the 1st element).
+   * @return The element at index i.
+   */
+  public T get(int i) {
+    return this.list.get(i);
+  }
+
+  /** 
+   * Find the index of a given element.
+   *
+   * @param v The value of the element to look for.
+   * @return The index of the element in the list.  -1 is element is not in the list.
+   */
+  public int indexOf(T v) {
+    return this.list.indexOf(v);
+  }
+
+  /** 
+   * Return the string representation of the list.
+   *
+   * @return The string representation of the list.
+   */
+  @Override
+  public String toString() {
+    return this.list.toString();
+  }
+}