feat: add Lab4

Lab1/test.sh

@@ -34,7 +34,7 @@ do
 		else
 			out=$(mktemp --suffix=$PROG)
 		fi
-		java $PROG < inputs/$PROG.$i.in | head -c 50MB > $out
+		java $PROG < inputs/$PROG.$i.in  > $out
 		status="$?"
 		if [ "$status" -ne "0" ]
 		then
@@ -72,5 +72,6 @@ then
 	echo "$PROG: passed everything 🎉"
 fi
 # Run style checker
-java -jar ~cs2030s/bin/checkstyle.jar -c ~cs2030s/bin/cs2030_checks.xml *.java 
+#java -jar ~cs2030s/bin/checkstyle.jar -c ~cs2030s/bin/cs2030_checks.xml *.java 
+java -jar ./checkstyle.jar -c ./cs2030_checks.xml *.java 
 # vim:noexpandtab:sw=4:ts=4

Lab4/Action.java

@@ -0,0 +1,11 @@
+/**
+ * The Action interface that can be called
+ * on an object of type T to act.
+ *
+ * Contains a single abstract method call.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/Actionable.java

@@ -0,0 +1,11 @@
+/**
+ * The Actionable interface that can
+ * act when given an action.
+ *
+ * Contains a single abstract method act.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/Applicable.java

@@ -0,0 +1,12 @@
+/**
+ * The Applicable interface that can probably
+ * transform if given something that is
+ * probably an Immutator.
+ *
+ * Contains a single abstract method apply.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/CS2030STest.java

@@ -0,0 +1,75 @@
+import java.net.URI;
+import java.util.List;
+import javax.tools.DiagnosticCollector;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.ToolProvider;
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+class CS2030STest {
+
+  private static final String ANSI_RESET = "\u001B[0m";
+  private static final String ANSI_RED = "\u001B[31m";
+  private static final String ANSI_GREEN = "\u001B[32m";
+
+  public void expect(String test, Object output, Object expect) {
+    System.out.print(test);
+    if ((expect == null && output == null) || output.equals(expect)) {
+      System.out.println(".. " + ANSI_GREEN + "ok" + ANSI_RESET);
+    } else {
+      System.out.println(".. " + ANSI_RED + "failed" + ANSI_RESET);
+      System.out.println("  expected: " + expect);
+      System.out.println("  got this: " + output);
+    }
+  }
+  
+  public static String clean(String txt) {
+    String res = "";
+    for (int i=0; i<txt.length(); i++) {
+      if (txt.charAt(i) != '\r' && txt.charAt(i) != '\n') {
+        res += txt.charAt(i);
+      }
+    }
+    return res;
+  }
+  public void expectPrint(String test, Object expect, ByteArrayOutputStream baos, PrintStream old) {
+    System.out.flush();
+    System.setOut(old);
+    expect(test, CS2030STest.clean(baos.toString()), expect);
+  }
+
+  public void expectCompile(String test, String statement, boolean success) {
+    System.out.print(test);
+
+    class JavaSourceFromString extends SimpleJavaFileObject {
+      final String code;
+
+      JavaSourceFromString(String code) {
+        super(URI.create("string:///TempClass.java"), Kind.SOURCE);
+        this.code = "class TempClass {void foo(){" +  code + ";}}";
+      }
+
+      @Override
+      public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+        return code;
+      }
+    }
+
+    boolean noError = ToolProvider
+        .getSystemJavaCompiler()
+        .getTask(null, null, new DiagnosticCollector<>(), null, null, 
+            List.of(new JavaSourceFromString(statement)))
+        .call();
+
+    if (noError != success) {
+      System.out.println(".. " + ANSI_RED + "failed" + ANSI_RESET);
+      if (!success) {
+        System.out.println("  expected compilation error but it compiles fine.");
+      } else {
+        System.out.println("  expected the statement to compile without errors but it does not.");
+      }
+    } else {
+      System.out.println(".. " + ANSI_GREEN + "ok" + ANSI_RESET);
+    }
+  }
+}

Lab4/Immutator.java

@@ -0,0 +1,11 @@
+/**
+ * The Immutator interface that can transform 
+ * to type T2, an object of type T1.
+ *
+ * Contains a single abstract method invoke.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/Immutatorable.java

@@ -0,0 +1,12 @@
+/**
+ * The Immutatorable interface that can
+ * transform when given something that is
+ * Immutator.
+ *
+ * Contains a single abstract method transform.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/Improbable.java

@@ -0,0 +1,9 @@
+/**
+ * A generic Immutator that takes in an object
+ * that is T and returns an object that is probably T.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/IsModEq.java

@@ -0,0 +1,12 @@
+/**
+ * A non-generic Immutator with parameter
+ * div and mod that takes in an integer val
+ * and return the boolean value by checking
+ * if the given value is equal to mod when
+ * divided by div.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/Lab4.java

@@ -0,0 +1,247 @@
+import java.util.Scanner;
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+/**
+ * The main class for CS2030S Lab 4.
+ *
+ * @author Wei Tsang
+   * @version CS2030S AY21/22 Semester 2
+ */
+class Lab4 {
+    
+  /**
+   * Inner class for testing.
+   */
+  static class Incr implements Immutator<Integer,Integer> {
+    public Integer invoke(Integer t1) {
+      return t1 + 1;
+    }
+  }
+  /**
+   * Inner class for testing.
+   */
+  static class Length implements Immutator<Integer,String> {
+    public Integer invoke(String t1) {
+      return t1.length();
+    }
+  }
+    
+  /**
+   * Helper method to clean a string from
+   * any newline.
+   *
+   * @param txt Input string.
+   * @return The cleaned string.
+   */
+  public static String clean(String txt) {
+    String res = "";
+    for (int i=0; i<txt.length(); i++) {
+      if (txt.charAt(i) != '\r' && txt.charAt(i) != '\n') {
+        res += txt.charAt(i);
+      }
+    }
+    return res;
+  }
+  
+  public static void main(String[] args) {
+    // Create a scanner to read from standard input.
+    Scanner sc = new Scanner(System.in);
+
+    // Read a single integer from the test file
+    // and then run the appropriate test case
+    switch (sc.nextInt()) {
+      case 1:
+        test1();
+        break;
+      case 2:
+        test2();
+        break;
+      case 3:
+        test3();
+        break;
+      case 4:
+        test4();
+        break;
+      case 5:
+        test5();
+        break;
+      case 6:
+        test6();
+        break;
+    }
+
+    // Clean up the scanner.
+    sc.close();
+  }
+  
+  /**
+   * Test #1.
+   */
+  public static void test1() {
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      new Print().call(17);
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      new Print().call("string");
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #2.
+   */
+  public static void test2() {
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      Probably.just(4).act(new Print());
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      Probably.just("string").act(new Print());
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+    
+    try {
+      baos = new ByteArrayOutputStream();
+      ps = new PrintStream(baos);
+      System.setOut(ps);
+      
+      Probably.none().act(new Print());
+      System.out.flush();
+      System.setOut(old);
+      
+      System.out.println(Lab4.clean(baos.toString()));
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #3.
+   */
+  public static void test3() {
+    try {
+      System.out.println(new Incr().invoke(4).toString());
+      System.out.println(new Incr().invoke(new Incr().invoke(4)).toString());
+      System.out.println(new Length().invoke("string").toString());
+      System.out.println(new Incr().invoke(new Length().invoke("string")).toString());
+      
+      System.out.println(new Improbable<Integer>().invoke(1).toString());
+      System.out.println(new Improbable<String>().invoke(null).toString());
+      System.out.println(new Improbable<Integer>().invoke(1).transform(new Incr()).toString());
+      System.out.println(new Improbable<>().invoke(new Improbable<Integer>().invoke(1)).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #4.
+   */
+  public static void test4() {
+    try {
+      System.out.println(Probably.just(4).transform(new Incr()).toString());
+      System.out.println(Probably.just(4).transform(new Incr()).transform(new Incr()).toString());
+      System.out.println(Probably.just("string").transform(new Length()).toString());
+      System.out.println(Probably.just("string").transform(new Length()).transform(new Incr()).toString());
+      
+      System.out.println(Probably.<Integer>none().transform(new Incr()).toString());
+      System.out.println(Probably.<String>none().transform(new Length()).toString());
+      System.out.println(Probably.<String>just(null).transform(new Length()).transform(new Incr()).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #5.
+   */
+  public static void test5() {
+    Probably<Immutator<Integer,Integer>> justIncr = Probably.just(new Incr());
+    Probably<Immutator<Integer,String>> justLength = Probably.just(new Length());
+    Probably<Immutator<Integer,Integer>> noIncr = Probably.none();
+    Probably<Immutator<Integer,String>> noLength = Probably.none();
+    
+    try {
+      System.out.println(Probably.just(17).check(new IsModEq(3,2)).toString());
+      System.out.println(Probably.just(18).check(new IsModEq(3,2)).toString());
+      
+      System.out.println(Probably.just(16).transform(new Incr()).check(new IsModEq(3,2)).toString());
+      System.out.println(Probably.just("string").transform(new Length()).transform(new Incr()).transform(new Incr()).check(new IsModEq(3,2)).toString());
+      System.out.println(Probably.<Integer>just(null).check(new IsModEq(0,2)).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+  
+  /**
+   * Test #6.
+   */
+  public static void test6() {
+    Probably<Immutator<Integer,Integer>> justIncr = Probably.just(new Incr());
+    Probably<Immutator<Integer,String>> justLength = Probably.just(new Length());
+    Probably<Immutator<Integer,Integer>> noIncr = Probably.none();
+    Probably<Immutator<Integer,String>> noLength = Probably.none();
+    
+    try {
+      System.out.println(Probably.just(17).apply(justIncr).toString());
+      System.out.println(Probably.<Integer>none().apply(justIncr).toString());
+      System.out.println(Probably.just(17).apply(noIncr).toString());
+      System.out.println(Probably.<Integer>none().apply(noIncr).toString());
+      
+      System.out.println(Probably.just("string").apply(justLength).toString());
+      System.out.println(Probably.<String>none().apply(justLength).toString());
+      System.out.println(Probably.just("string").apply(noLength).toString());
+      System.out.println(Probably.<String>none().apply(noLength).toString());
+    } catch(Exception e) {
+      System.out.println("Error occurred");
+    }
+  }
+}

Lab4/Print.java

@@ -0,0 +1,9 @@
+/**
+ * A non-generic Action to print the String
+ * representation of the object.
+ *
+ * CS2030S Lab 4
+ * AY22/23 Semester 1
+ *
+ * @author Put Your Name (Lab Group)
+ */

Lab4/Probably.java

@@ -0,0 +1,96 @@
+/**
+ * This class implements something that
+ * probably is just a value but may be nothing.
+ * We will never return null in this class, but
+ * we may return something that contains nothing
+ * where the nothing is a null.
+ *
+ * @author XXX
+ * @version CS2030S AY22/23 Semester 1
+ */
+class Probably<T> {
+  private final T value;
+
+  private static final Probably<?> NONE = new Probably<>(null);
+  
+  /**
+   * Private constructor, can only be invoked inside.
+   * This is called a factory method.  We can only
+   * create this using the two public static method.
+   *
+   * @return The shared NOTHING.
+   */
+  private Probably(T value) {
+    this.value = value;
+  }
+  
+  /**
+   * It is probably nothing, no value inside.
+   *
+   * @return The shared NOTHING.
+   */
+  public static <T> Probably<T> none() {
+    @SuppressWarnings("unchecked")
+    Probably<T> res = (Probably<T>) NONE;
+    return res;
+  }
+  
+  /**
+   * It is probably just the given value.
+   * Unless the value is null, then nothing is
+   * given again.
+   *
+   * @param value Probably this is the value
+   *              unless it is null then we say
+   *              that there is no 
+   * @return The given value or nothing but
+   *         never null.
+   */
+  public static <T> Probably<T> just(T value) {
+    if (value == null) {
+      return none();
+    }
+    return (Probably<T>) new Probably<>(value);
+  }
+  
+  /**
+   * Check for equality between something that
+   * is probably a value but maybe nothing.
+   *
+   * @param obj The other value to be compared.
+   * @return True if the two values are equal,
+   *         false otherwise.
+   */
+  @Override
+  public boolean equals(Object obj) {
+    if (obj == this) {
+      return true;
+    }
+    if (obj instanceof Probably<?>) {
+      Probably<?> some = (Probably<?>) obj;
+      if (this.value == some.value) {
+        return true;
+      }
+      if (this.value == null || some.value == null) {
+        return false;
+      }
+      return this.value.equals(some.value);
+    }
+    return false;
+  }
+  
+  /**
+   * String representation of something that
+   * is probably a value but maybe nothing.
+   *
+   * @return The string representation.
+   */
+  @Override
+  public String toString() {
+    if (this.value == null) {
+      return "<>";
+    } else {
+      return "<" + this.value.toString() + ">";
+    }
+  }
+}

Lab4/Test1.java

@@ -0,0 +1,35 @@
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+class Test1 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    new Print().call(17);
+    we.expectPrint("new Print().call(17)",
+                   "17",
+                   baos,
+                   old);
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    new Print().call("string");
+    we.expectPrint("new Print().call(\"string\")",
+                   "string",
+                   baos,
+                   old);
+
+    we.showStat();
+    we.print();
+  }
+}

Lab4/Test2.java

@@ -0,0 +1,45 @@
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+class Test2 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    Probably.just(4).act(new Print());
+    we.expectPrint("Probably.just(4).act(new Print())",
+                   "4",
+                   baos,
+                   old);
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    Probably.just("string").act(new Print());
+    we.expectPrint("Probably.just(\"string\").act(new Print())",
+                   "string",
+                   baos,
+                   old);
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    
+    Probably.none().act(new Print());
+    we.expectPrint("Probably.none().act(new Print())",
+                   "",
+                   baos,
+                   old);
+
+    we.showStat();
+    we.print();
+  }
+}

Lab4/Test3.java

@@ -0,0 +1,57 @@
+class Test3 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    class Incr implements Immutator<Integer,Integer> {
+      public Integer invoke(Integer t1) {
+        return t1 + 1;
+      }
+    }
+    class Length implements Immutator<Integer,String> {
+      public Integer invoke(String t1) {
+        return t1.length();
+      }
+    }
+    
+    we.prefix("jshell> class Incr implements Immutator<Integer,Integer> {");
+    we.prefix("   ...>   public Integer invoke(Integer t1) {");
+    we.prefix("   ...>     return t1 + 1;");
+    we.prefix("   ...>   }");
+    we.prefix("   ...> }");
+    
+    we.prefix("jshell> class Length implements Immutator<Integer,String> {");
+    we.prefix("   ...>   public Integer invoke(String t1) {");
+    we.prefix("   ...>     return t1.length();");
+    we.prefix("   ...>   }");
+    we.prefix("   ...> }");
+    
+    we.expect("new Incr().invoke(4)",
+              new Incr().invoke(4).toString(),
+              "5");
+    we.expect("new Incr().invoke(new Incr().invoke(4))",
+              new Incr().invoke(new Incr().invoke(4)).toString(),
+              "6");
+    we.expect("new Length().invoke(\"string\")",
+              new Length().invoke("string").toString(),
+              "6");
+    we.expect("new Incr().invoke(new Length().invoke(\"string\"))",
+              new Incr().invoke(new Length().invoke("string")).toString(),
+              "7");
+
+    we.expect("new Improbable<>().invoke(1)",
+              new Improbable<Integer>().invoke(1).toString(),
+              "<1>");
+    we.expect("new Improbable<String>().invoke(null)",
+              new Improbable<String>().invoke(null).toString(),
+              "<>");
+    we.expect("new Improbable<Integer>().invoke(1).transform(new Incr())",
+              new Improbable<Integer>().invoke(1).transform(new Incr()).toString(),
+              "<2>");
+    we.expect("new Improbable<>().invoke(new Improbable<>().invoke(1))",
+              new Improbable<>().invoke(new Improbable<Integer>().invoke(1)).toString(),
+              "<<1>>");
+
+    we.showStat();
+    we.print();
+  }
+}