Mon, 02 Sep 2013 22:38:36 +0100
8016177: structural most specific and stuckness
Reviewed-by: jjg, vromero
Contributed-by: maurizio.cimadamore@oracle.com
duke@1 | 1 | /* |
ohair@554 | 2 | * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved. |
duke@1 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@1 | 4 | * |
duke@1 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@1 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@1 | 7 | * published by the Free Software Foundation. |
duke@1 | 8 | * |
duke@1 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@1 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@1 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@1 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@1 | 13 | * accompanied this code). |
duke@1 | 14 | * |
duke@1 | 15 | * You should have received a copy of the GNU General Public License version |
duke@1 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@1 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@1 | 18 | * |
ohair@554 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
ohair@554 | 20 | * or visit www.oracle.com if you need additional information or have any |
ohair@554 | 21 | * questions. |
duke@1 | 22 | */ |
duke@1 | 23 | |
duke@1 | 24 | package evalexpr; |
duke@1 | 25 | |
duke@1 | 26 | import java.lang.reflect.Method; |
duke@1 | 27 | import java.util.*; |
duke@1 | 28 | import javax.swing.JOptionPane; |
duke@1 | 29 | import javax.tools.*; |
duke@1 | 30 | import static javax.tools.StandardLocation.CLASS_OUTPUT; |
duke@1 | 31 | |
duke@1 | 32 | /** |
duke@1 | 33 | * JSR 199 Demo application: compile from a String. |
duke@1 | 34 | * |
jjg@581 | 35 | * <p><b>This is NOT part of any supported API. |
duke@1 | 36 | * If you write code that depends on this, you do so at your own |
duke@1 | 37 | * risk. This code and its internal interfaces are subject to change |
duke@1 | 38 | * or deletion without notice.</b></p> |
duke@1 | 39 | * |
duke@1 | 40 | * @author Peter von der Ahé |
duke@1 | 41 | */ |
duke@1 | 42 | public class CompileFromString { |
duke@1 | 43 | |
duke@1 | 44 | /** |
duke@1 | 45 | * The name of the class used to evaluate expressions. |
duke@1 | 46 | */ |
duke@1 | 47 | private final static String CLASS_NAME = "EvalExpression"; |
duke@1 | 48 | |
duke@1 | 49 | /** |
duke@1 | 50 | * Object used to signal errors from evalExpression. |
duke@1 | 51 | */ |
duke@1 | 52 | public final static Object ERROR = new Object() { |
duke@1 | 53 | public String toString() { return "error"; } |
duke@1 | 54 | }; |
duke@1 | 55 | |
duke@1 | 56 | /** |
duke@1 | 57 | * Compile and evaluate the specified expression using the |
duke@1 | 58 | * given compiler. |
duke@1 | 59 | * @param compiler a JSR 199 compiler tool used to compile the given expression |
duke@1 | 60 | * @param expression a Java Programming Language expression |
duke@1 | 61 | * @return the value of the expression; ERROR if any errors occured during compilation |
duke@1 | 62 | * @throws java.lang.Exception exceptions are ignored for brevity |
duke@1 | 63 | */ |
duke@1 | 64 | public static Object evalExpression(JavaCompiler compiler, |
duke@1 | 65 | DiagnosticListener<JavaFileObject> listener, |
duke@1 | 66 | List<String> flags, |
duke@1 | 67 | String expression) |
duke@1 | 68 | throws Exception |
duke@1 | 69 | { |
duke@1 | 70 | // Use a customized file manager |
duke@1 | 71 | MemoryFileManager mfm = |
duke@1 | 72 | new MemoryFileManager(compiler.getStandardFileManager(listener, null, null)); |
duke@1 | 73 | |
duke@1 | 74 | // Create a file object from a string |
duke@1 | 75 | JavaFileObject fileObject = mfm.makeSource(CLASS_NAME, |
duke@1 | 76 | "public class " + CLASS_NAME + " {\n" + |
duke@1 | 77 | " public static Object eval() throws Throwable {\n" + |
duke@1 | 78 | " return " + expression + ";\n" + |
duke@1 | 79 | " }\n}\n"); |
duke@1 | 80 | |
duke@1 | 81 | JavaCompiler.CompilationTask task = |
duke@1 | 82 | compiler.getTask(null, mfm, listener, flags, null, Arrays.asList(fileObject)); |
duke@1 | 83 | if (task.call()) { |
duke@1 | 84 | // Obtain a class loader for the compiled classes |
duke@1 | 85 | ClassLoader cl = mfm.getClassLoader(CLASS_OUTPUT); |
duke@1 | 86 | // Load the compiled class |
duke@1 | 87 | Class compiledClass = cl.loadClass(CLASS_NAME); |
duke@1 | 88 | // Find the eval method |
duke@1 | 89 | Method eval = compiledClass.getMethod("eval"); |
duke@1 | 90 | // Invoke it |
duke@1 | 91 | return eval.invoke(null); |
duke@1 | 92 | } else { |
duke@1 | 93 | // Report that an error occured |
duke@1 | 94 | return ERROR; |
duke@1 | 95 | } |
duke@1 | 96 | } |
duke@1 | 97 | |
duke@1 | 98 | /** |
duke@1 | 99 | * Main entry point for program; ask user for expressions, |
duke@1 | 100 | * compile, evaluate, and print them. |
duke@1 | 101 | * |
duke@1 | 102 | * @param args ignored |
duke@1 | 103 | * @throws java.lang.Exception exceptions are ignored for brevity |
duke@1 | 104 | */ |
duke@1 | 105 | public static void main(String... args) throws Exception { |
duke@1 | 106 | // Get a compiler tool |
duke@1 | 107 | final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); |
duke@1 | 108 | final List<String> compilerFlags = new ArrayList(); |
duke@1 | 109 | compilerFlags.add("-Xlint:all"); // report all warnings |
duke@1 | 110 | compilerFlags.add("-g:none"); // don't generate debug info |
duke@1 | 111 | String expression = "System.getProperty(\"java.vendor\")"; |
duke@1 | 112 | while (true) { |
duke@1 | 113 | expression = JOptionPane.showInputDialog("Please enter a Java expression", |
duke@1 | 114 | expression); |
duke@1 | 115 | if (expression == null) |
duke@1 | 116 | return; // end program on "cancel" |
duke@1 | 117 | long time = System.currentTimeMillis(); |
duke@1 | 118 | Object result = evalExpression(compiler, null, compilerFlags, expression); |
duke@1 | 119 | time = System.currentTimeMillis() - time; |
duke@1 | 120 | System.out.format("Elapsed time %dms %n", time); |
duke@1 | 121 | if (result == ERROR) |
duke@1 | 122 | System.out.format("Error compiling \"%s\"%n", expression); |
duke@1 | 123 | else |
duke@1 | 124 | System.out.format("%s => %s%n", expression, result); |
duke@1 | 125 | } |
duke@1 | 126 | } |
duke@1 | 127 | } |