feat: update structure

cs2030s/labs/Lab6/Test3.java

@@ -0,0 +1,134 @@
+import cs2030s.fp.Constant;
+import cs2030s.fp.Immutator;
+import cs2030s.fp.Lazy;
+import cs2030s.fp.Memo;
+
+public class Test3 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    Constant<String> password = () -> "123456";
+    Lazy<String> lazy = Lazy.from(password);
+    
+    we.expect(
+      "lazy",
+      lazy.toString(),
+      "123456"
+    );
+    we.expect(
+      "lazy.transform(str -> str.substring(0, 1))",
+      lazy.transform(str -> str.substring(0, 1)).toString(),
+      "1"
+    );
+    
+    Memo<String> memo = Memo.from(password);
+    we.expect(
+      "memo",
+      memo.toString(),
+      "?"
+    );
+    we.expect(
+      "memo.transform(str -> str.substring(0, 1))",
+      memo.transform(str -> str.substring(0, 1)).toString(),
+      "?"
+    );
+    we.expect(
+      "memo.transform(str -> str.substring(0, 1)).get()",
+      memo.transform(str -> str.substring(0, 1)).get().toString(),
+      "1"
+    );
+    we.expect(
+      "memo",
+      memo.toString(),
+      "123456"
+    );
+    
+    Immutator<Integer, String> len = str -> {
+      System.out.println("length");
+      return str.length();
+    };
+    Lazy<Integer> lazyLen = lazy.transform(len);
+    we.expect(
+      "lazyLen // warning: we do not check print output",
+      lazyLen.toString(),
+      "6"
+    );
+    we.expect(
+      "lazyLen.get() // warning: we do not check print output",
+      lazyLen.get(),
+      6
+    );
+    we.expect(
+      "lazyLen.get() // warning: we do not check print output",
+      lazyLen.get(),
+      6
+    );
+    
+    Memo<Integer> memoLen = memo.transform(len);
+    we.expect(
+      "memoLen // warning: we do not check print output",
+      memoLen.toString(),
+      "?"
+    );
+    we.expect(
+      "memoLen.get() // warning: we do not check print output",
+      memoLen.get(),
+      6
+    );
+    we.expect(
+      "memoLen.get() // warning: we do not check print output",
+      memoLen.get(),
+      6
+    );
+    
+    Memo<Integer> step1 = Memo.from(1010);
+    Memo<Integer> step2 = step1.transform(i -> i * 2);
+    Memo<Integer> step3 = step2.next(i -> Memo.from(i + 10));
+    we.expect(
+      "step1",
+      step1.toString(),
+      "1010"
+    );
+    we.expect(
+      "step2",
+      step2.toString(),
+      "?"
+    );
+    we.expect(
+      "step3",
+      step3.toString(),
+      "?"
+    );
+    we.expect(
+      "step3.get()",
+      step3.get(),
+      2030
+    );
+    we.expect(
+      "step2",
+      step2.toString(),
+      "2020"
+    );
+    we.expect(
+      "step1",
+      step1.toString(),
+      "1010"
+    );
+    
+    Memo<Integer> noErr = Memo.from(0);
+    Memo<Integer> err = noErr.transform(x -> 1/x);
+    try {
+      we.expect(
+        "err.get()",
+        err.get(),
+        ""
+      );
+    } catch(ArithmeticException ae) {
+      we.expect(
+        "err.get()",
+        ae.getMessage(),
+        "/ by zero"
+      );
+    }
+  }
+}