Java example source code file (T6199075.java)

This example Java source code file (T6199075.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

argumentsarity, boolean, byte, error, errorchecker, exception, file, javasource, net, network, override, string, stringbuilder, test, typekind, util, varargsmethod

The T6199075.java Java example source code

/*
 * Copyright (c) 2010, 2011, 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 6199075
 *
 * @summary Unambiguous varargs method calls flagged as ambiguous
 * @author mcimadamore
 *
 */

import com.sun.source.util.JavacTask;
import com.sun.tools.classfile.Instruction;
import com.sun.tools.classfile.Attribute;
import com.sun.tools.classfile.ClassFile;
import com.sun.tools.classfile.Code_attribute;
import com.sun.tools.classfile.ConstantPool.*;
import com.sun.tools.classfile.Method;
import com.sun.tools.javac.api.JavacTool;
import com.sun.tools.javac.util.List;

import java.io.File;
import java.net.URI;
import java.util.Arrays;
import java.util.Locale;
import javax.tools.Diagnostic;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileObject;
import javax.tools.SimpleJavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;

public class T6199075 {

    int checkCount = 0;
    int bytecodeCheckCount = 0;

    enum TypeKind {
        BYTE("byte", "(byte)1", "[B", 0),
        CHAR("char", "'c'", "[C", 1),
        SHORT("short", "(short)1", "[S", 2),
        INT("int", "1", "[I", 3),
        LONG("long", "1L", "[J", 4),
        FLOAT("float", "1.0F", "[F", 5),
        DOUBLE("double", "1.0D", "[D", 6),
        BOOLEAN("boolean", "true", "[Z", -1);

        String typeString;
        String valueString;
        String bytecodeString;
        private int subtypeTag;

        TypeKind(String typeString, String valueString, String bytecodeString, int subtypeTag) {
            this.typeString = typeString;
            this.valueString = valueString;
            this.bytecodeString = bytecodeString;
            this.subtypeTag = subtypeTag;
        }

        boolean isSubtypeOf(TypeKind that) {
            switch (this) {
                case BOOLEAN:
                    return that == BOOLEAN;
                case BYTE:
                case CHAR:
                    return this.subtypeTag == that.subtypeTag ||
                            this.subtypeTag + 2 <= that.subtypeTag;
                default:
                    return this.subtypeTag <= that.subtypeTag;
            }
        }
    }

    enum ArgumentsArity {
        ZERO(0),
        ONE(1),
        TWO(2),
        THREE(3);

        int arity;

        ArgumentsArity(int arity) {
            this.arity = arity;
        }

        String asExpressionList(TypeKind type) {
            StringBuilder buf = new StringBuilder();
            String sep = "";
            for (int i = 0; i < arity; i++) {
                buf.append(sep);
                buf.append(type.valueString);
                sep = ",";
            }
            return buf.toString();
        }
    }

    static class VarargsMethod {
        TypeKind varargsElement;

        VarargsMethod(TypeKind varargsElement) {
            this.varargsElement = varargsElement;
        }

        @Override
        public String toString() {
            return "void m("+ varargsElement.typeString+ "... args) {}";
        }

        boolean isApplicable(TypeKind actual, ArgumentsArity argsArity) {
            return argsArity == ArgumentsArity.ZERO ||
                    actual.isSubtypeOf(varargsElement);
        }

        boolean isMoreSpecificThan(VarargsMethod that) {
            return varargsElement.isSubtypeOf(that.varargsElement);
        }
    }

    public static void main(String... args) throws Exception {
        new T6199075().test();
    }

    void test() throws Exception {
        for (TypeKind formal1 : TypeKind.values()) {
            VarargsMethod m1 = new VarargsMethod(formal1);
            for (TypeKind formal2 : TypeKind.values()) {
                VarargsMethod m2 = new VarargsMethod(formal2);
                for (TypeKind actual : TypeKind.values()) {
                    for (ArgumentsArity argsArity : ArgumentsArity.values()) {
                        compileAndCheck(m1, m2, actual, argsArity);
                    }
                }
            }
        }

        System.out.println("Total checks made: " + checkCount);
        System.out.println("Bytecode checks made: " + bytecodeCheckCount);
    }

    // Create a single file manager and reuse it for each compile to save time.
    StandardJavaFileManager fm = JavacTool.create().getStandardFileManager(null, null, null);

    void compileAndCheck(VarargsMethod m1, VarargsMethod m2, TypeKind actual, ArgumentsArity argsArity) throws Exception {
        final JavaCompiler tool = ToolProvider.getSystemJavaCompiler();
        JavaSource source = new JavaSource(m1, m2, actual, argsArity);
        ErrorChecker ec = new ErrorChecker();
        JavacTask ct = (JavacTask)tool.getTask(null, fm, ec,
                null, null, Arrays.asList(source));
        ct.generate();
        check(source, ec, m1, m2, actual, argsArity);
    }

    void check(JavaSource source, ErrorChecker ec, VarargsMethod m1, VarargsMethod m2, TypeKind actual, ArgumentsArity argsArity) {
        checkCount++;
        boolean resolutionError = false;
        VarargsMethod selectedMethod = null;

        boolean m1_applicable = m1.isApplicable(actual, argsArity);
        boolean m2_applicable = m2.isApplicable(actual, argsArity);

        if (!m1_applicable && !m2_applicable) {
            resolutionError = true;
        } else if (m1_applicable && m2_applicable) {
            //most specific
            boolean m1_moreSpecific = m1.isMoreSpecificThan(m2);
            boolean m2_moreSpecific = m2.isMoreSpecificThan(m1);
            resolutionError = m1_moreSpecific == m2_moreSpecific;
            selectedMethod = m1_moreSpecific ? m1 : m2;
        } else {
            selectedMethod = m1_applicable ?
                m1 : m2;
        }

        if (ec.errorFound != resolutionError) {
            throw new Error("invalid diagnostics for source:\n" +
                    source.getCharContent(true) +
                    "\nExpected resolution error: " + resolutionError +
                    "\nFound error: " + ec.errorFound +
                    "\nCompiler diagnostics:\n" + ec.printDiags());
        } else if (!resolutionError) {
            verifyBytecode(selectedMethod);
        }
    }

    void verifyBytecode(VarargsMethod selected) {
        bytecodeCheckCount++;
        File compiledTest = new File("Test.class");
        try {
            ClassFile cf = ClassFile.read(compiledTest);
            Method testMethod = null;
            for (Method m : cf.methods) {
                if (m.getName(cf.constant_pool).equals("test")) {
                    testMethod = m;
                    break;
                }
            }
            if (testMethod == null) {
                throw new Error("Test method not found");
            }
            Code_attribute ea = (Code_attribute)testMethod.attributes.get(Attribute.Code);
            if (testMethod == null) {
                throw new Error("Code attribute for test() method not found");
            }

            for (Instruction i : ea.getInstructions()) {
                if (i.getMnemonic().equals("invokevirtual")) {
                    int cp_entry = i.getUnsignedShort(1);
                    CONSTANT_Methodref_info methRef =
                            (CONSTANT_Methodref_info)cf.constant_pool.get(cp_entry);
                    String type = methRef.getNameAndTypeInfo().getType();
                    if (!type.contains(selected.varargsElement.bytecodeString)) {
                        throw new Error("Unexpected type method call: " + type);
                    }
                    break;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            throw new Error("error reading " + compiledTest +": " + e);
        }
    }

    static class JavaSource extends SimpleJavaFileObject {

        static final String source_template = "class Test {\n" +
                "   #V1\n" +
                "   #V2\n" +
                "   void test() { m(#E); }\n" +
                "}";

        String source;

        public JavaSource(VarargsMethod m1, VarargsMethod m2, TypeKind actual, ArgumentsArity argsArity) {
            super(URI.create("myfo:/Test.java"), JavaFileObject.Kind.SOURCE);
            source = source_template.replaceAll("#V1", m1.toString()).
                    replaceAll("#V2", m2.toString()).
                    replaceAll("#E", argsArity.asExpressionList(actual));
        }

        @Override
        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
            return source;
        }
    }

    static class ErrorChecker implements javax.tools.DiagnosticListener<JavaFileObject> {

        boolean errorFound;
        List<String> errDiags = List.nil();

        public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
            if (diagnostic.getKind() == Diagnostic.Kind.ERROR) {
                errDiags = errDiags.append(diagnostic.getMessage(Locale.getDefault()));
                errorFound = true;
            }
        }

        String printDiags() {
            StringBuilder buf = new StringBuilder();
            for (String s : errDiags) {
                buf.append(s);
                buf.append("\n");
            }
            return buf.toString();
        }
    }
}