feat(08, 09, 10, 14): homework

src/main/java/co/ivi/jus/error/review/songor/UseCase.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2021, songor. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.error.review.songor;
+
+import co.ivi.jus.error.union.Digest;
+import co.ivi.jus.error.union.Returned;
+
+public class UseCase {
+    public static void main(String[] args) {
+        Returned<Digest> rt = Digest.of("SHA-256");
+        if (rt instanceof Returned.ReturnValue rv && rv.returnValue() instanceof Digest d) {
+            d.digest("Hello, world!".getBytes());
+        } else if (rt instanceof Returned.ErrorCode ec) {
+            System.out.println("Failed to get instance of SHA-256");
+        } else {
+            // 不能使用 switch 模式匹配（穷举出所有的情景）而带来的不便之处
+            throw new UnsupportedOperationException("Invalid Returned instance");
+        }
+    }
+}

src/main/java/co/ivi/jus/flow/review/songor/UseCase.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, songor. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.flow.review.songor;
+
+import co.ivi.jus.flow.reactive.Destination;
+import co.ivi.jus.flow.reactive.Transform;
+
+import java.util.concurrent.SubmissionPublisher;
+import java.util.function.Function;
+
+public class UseCase {
+    public static void main(String[] args) throws InterruptedException {
+        transform(new Event(3, 4), UseCase::calculate);
+        Thread.sleep(200);
+    }
+
+    public static void transform(Event event, Function<Event, Integer> function) {
+        SubmissionPublisher<Event> publisher = new SubmissionPublisher<>();
+        Transform<Event, Integer> transform = new Transform<>(function);
+        Destination<Integer> subscriber = new Destination<>(System.out::println);
+        publisher.subscribe(transform);
+        transform.subscribe(subscriber);
+        publisher.submit(event);
+        publisher.close();
+    }
+
+    public static int calculate(Event event) {
+        return (event.start() + event.duration() - 1) % 7;
+    }
+
+    public static record Event(int start, int duration) {
+    }
+}

src/main/java/co/ivi/jus/nullp/review/songor/FullName.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2021, songor. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.nullp.review.songor;
+
+public final class FullName {
+    private final String firstName;
+    private final String middleName;
+    private final String lastName;
+
+    public FullName(String firstName, String middleName, String lastName) {
+        this.firstName = firstName;
+        this.middleName = middleName;
+        this.lastName = lastName;
+    }
+
+    public Returned firstName() {
+        if (firstName == null) {
+            return Returned.ErrorCode.UNDEFINED;
+        }
+        return new Returned.ReturnValue<>(firstName);
+    }
+
+    public Returned middleName() {
+        if (middleName == null) {
+            return Returned.ErrorCode.UNDEFINED;
+        }
+        return new Returned.ReturnValue<>(middleName);
+    }
+
+    public Returned lastName() {
+        if (lastName == null) {
+            return Returned.ErrorCode.UNDEFINED;
+        }
+        return new Returned.ReturnValue<>(lastName);
+    }
+}

src/main/java/co/ivi/jus/nullp/review/songor/Returned.java

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, songor. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.nullp.review.songor;
+
+public sealed interface Returned {
+    record ReturnValue<T>(T returnValue) implements Returned {
+    }
+
+    enum ErrorCode implements Returned {
+        UNDEFINED
+    }
+}

src/main/java/co/ivi/jus/nullp/review/songor/UseCase.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2021, Xuelei Fan. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.nullp.review.songor;
+
+public class UseCase {
+    public static void main(String[] args) {
+        FullName jack = new FullName("Jack", "", "Brown");
+        FullName rose = new FullName("Rose", null, "Brown");
+        FullName nova = new FullName("Nova", "Diane", "Brown");
+        System.out.println(
+                "Is Jack's middle name Diane? " +
+                        hasMiddleName(jack, "Diane"));
+        System.out.println(
+                "Is Rose's middle name Diane? " +
+                        hasMiddleName(rose, "Diane"));
+        System.out.println(
+                "Is Nova's middle name Diane? " +
+                        hasMiddleName(nova, "Diane"));
+    }
+
+    private static boolean hasMiddleName(FullName fullName, String middleName) {
+        return switch (fullName.middleName()) {
+            case Returned.ErrorCode ec -> switch (ec) {
+                case UNDEFINED -> false;
+            };
+            case Returned.ReturnValue rv -> {
+                String returnedMiddleName = (String) rv.returnValue();
+                yield returnedMiddleName.equals(middleName);
+            }
+        };
+    }
+}

src/main/java/co/ivi/jus/stack/review/songor/Digest.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2021, songor. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.stack.review.songor;
+
+public sealed abstract class Digest {
+    private static final class SHA256 extends Digest {
+        @Override
+        public byte[] digest(byte[] message) {
+            // snipped
+            return new byte[0];
+        }
+    }
+
+    private static final class SHA512 extends Digest {
+        @Override
+        public byte[] digest(byte[] message) {
+            // snipped
+            return new byte[0];
+        }
+    }
+
+    public static Returned of(String algorithm) {
+        return switch (algorithm) {
+            case "SHA-256" -> new Returned.ReturnValue<Digest>(new SHA256());
+            case "SHA-512" -> new Returned.ReturnValue<Digest>(new SHA512());
+            case null -> {
+                System.getLogger("co.ivi.jus.stack.review.songor")
+                        .log(System.Logger.Level.WARNING,
+                                "No algorithm is specified",
+                                new Throwable("the calling stack"));
+                yield Returned.ErrorCode.NO_SPECIFIED_ALGORITHM;
+            }
+            default -> {
+                System.getLogger("co.ivi.jus.stack.review.songor")
+                        .log(System.Logger.Level.INFO,
+                                "Unknown algorithm is specified " + algorithm,
+                                new Throwable("the calling stack"));
+                yield Returned.ErrorCode.UNKNOWN_SPECIFIED_ALGORITHM;
+            }
+        };
+    }
+
+    public abstract byte[] digest(byte[] message);
+}

src/main/java/co/ivi/jus/stack/review/songor/Returned.java

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, songor. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.stack.review.songor;
+
+public sealed interface Returned {
+    record ReturnValue<T>(T returnValue) implements Returned {
+    }
+
+    enum ErrorCode implements Returned {
+        NO_SPECIFIED_ALGORITHM, UNKNOWN_SPECIFIED_ALGORITHM
+    }
+}

src/main/java/co/ivi/jus/stack/review/songor/UseCase.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2021, songor. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ */
+
+package co.ivi.jus.stack.review.songor;
+
+public class UseCase {
+    public static void main(String[] args) {
+        Returned rt = Digest.of("SHA-128");
+        switch (rt) {
+            case Returned.ReturnValue rv -> {
+                Digest d = (Digest) rv.returnValue();
+                d.digest("Hello, world!".getBytes());
+            }
+            case Returned.ErrorCode ec -> {
+                switch (ec) {
+                    case NO_SPECIFIED_ALGORITHM -> System.getLogger("co.ivi.jus.stack.review.songor")
+                            .log(System.Logger.Level.INFO,
+                                    "Unlikely to happen");
+                    case UNKNOWN_SPECIFIED_ALGORITHM -> System.getLogger("co.ivi.jus.stack.review.songor")
+                            .log(System.Logger.Level.INFO,
+                                    "SHA-218 is not supported");
+                }
+            }
+        }
+    }
+}