/*

 * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * @test

 * @bug 8231827

 * @summary All example code from "Pattern Matching for Java" document, released April 2017, adjusted to current state (no switches, etc)

 * @compile --enable-preview -source ${jdk.version} ExamplesFromProposal.java

 * @run main/othervm --enable-preview ExamplesFromProposal

 */

interface Node {

}

class IntNode implements Node {

    int value;

    IntNode(int value) {

        this.value = value;

    }

}

class NegNode implements Node {

    Node node;

    NegNode(Node node) {

        this.node = node;

    }

}

class MulNode implements Node {

    Node left, right;

    MulNode(Node left, Node right) {

        this.left = left;

        this.right = right;

    }

}

class AddNode implements Node {

    Node left, right;

    AddNode(Node left, Node right) {

        this.left = left;

        this.right = right;

    }

}

public class ExamplesFromProposal {

    public static Object getSomething() {

        return new Long(42);

    }

    public static int eval(Node n) {

        if (n instanceof IntNode in) return in.value;

        else if (n instanceof NegNode nn) return -eval(nn.node);

        else if (n instanceof AddNode an) return eval(an.left) + eval(an.right);

        else if (n instanceof MulNode mn) return eval(mn.left) * eval(mn.right);

        else {

            // should never happen

            throw new AssertionError("broken");

        }

    }

    public static String toString(Node n) {

        if (n instanceof IntNode in) return String.valueOf(in.value);

        else if (n instanceof NegNode nn) return "-"+eval(nn.node);

        else if (n instanceof AddNode an) return eval(an.left) + " + " + eval(an.right);

        else if (n instanceof MulNode mn) return eval(mn.left) + " * " + eval(mn.right);

        else {

            // should never happen

            throw new AssertionError("broken");

        }

    }

    public static Node simplify(Node n) {

        if (n instanceof IntNode in) {

            return n;

        } else if (n instanceof NegNode nn) {

            return new NegNode(simplify(nn.node));

        } else if (n instanceof AddNode ad) {

            n = simplify(ad.left);

            if (n instanceof IntNode intn) {

                if (intn.value == 0)

                    return simplify(ad.right);

                else

                    return new AddNode(intn, simplify(ad.right));

            } else {

                return new AddNode(simplify(ad.left), simplify(ad.right));

            }

        } else if (n instanceof MulNode mn) {

            return new MulNode(simplify(mn.left), simplify(mn.right));

        } else {

            //should never happen

            throw new AssertionError("broken");

        }

    }

    public static void testNode(Node n, int expected) {

        if (eval(n) != expected)

            throw new AssertionError("broken");

    }

    public static void main(String[] args) {

        Object x = new Integer(42);

        if (x instanceof Integer i) {

            // can use i here

            System.out.println(i.intValue());

        }

        Object obj = getSomething();

        String formatted = "unknown";

        if (obj instanceof Integer i) {

            formatted = String.format("int %d", i);

        }

        else if (obj instanceof Byte b) {

            formatted = String.format("byte %d", b);

        }

        else if (obj instanceof Long l) {

            formatted = String.format("long %d", l);

        }

        else if (obj instanceof Double d) {

            formatted = String.format("double %f", d);

        }

        else if (obj instanceof String s) {

            formatted = String.format("String %s", s);

        }

        System.out.println(formatted);

        if (obj instanceof Integer i) formatted = String.format("int %d", i);

        else if (obj instanceof Byte b) formatted = String.format("byte %d", b);

        else if (obj instanceof Long l) formatted = String.format("long %d", l);

        else if (obj instanceof Double d) formatted = String.format("double %f", d);

        else if (obj instanceof String s) formatted = String.format("String %s", s);

        else formatted = String.format("Something else "+ obj.toString());

        System.out.println(formatted);

        Node zero = new IntNode(0);

        Node one = new IntNode(1);

        Node ft = new IntNode(42);

        Node temp = new AddNode(zero,ft);

        testNode(temp,42);

        if (toString(simplify(temp)).equals(toString(ft)))

            System.out.println("Simplify worked!");

        else

            throw new AssertionError("broken");

        if (toString(simplify(new AddNode(zero,temp))).equals(toString(ft)))

            System.out.println("Simplify worked!");

        else

            throw new AssertionError("broken");

        temp = new AddNode(zero,ft);

        temp = new AddNode(one,temp);

        temp = new AddNode(zero,temp);

        Node fortythree = new AddNode(one,ft);

        if (toString(simplify(temp)).equals(toString(fortythree)))

            System.out.println("Simplify worked!");

        else

            throw new AssertionError("broken");

        x = "Hello";

        if (x instanceof String s1) {

            System.out.println(s1);

        }

        if (x instanceof String s1 && s1.length() > 0) {

            System.out.println(s1);

        }

        if (x instanceof String s1) {

            System.out.println(s1 + " is a string");

        } else {

            System.out.println("not a string");

        }

        if (!(x instanceof String s1)) {

            System.out.println("not a string");

        } else {

            System.out.println(s1 + " is a string");

        }

    }

}