jdk-sandbox: comparison test/langtools/tools/javac/patterns/ExamplesFromProposal.java

equal deleted inserted replaced

-:88502b1cf76f
+:7799a51dbe30
+/*
+* 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");
+}
+}
+}