src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/Target.java

/*
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 * 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.
 *
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package com.sun.tools.javac.jvm;

import java.util.*;

import com.sun.tools.javac.code.Flags;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.util.*;

import static com.sun.tools.javac.main.Option.TARGET;

/** The classfile version target.
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
public enum Target {
    JDK1_1("1.1", 45, 3),
    JDK1_2("1.2", 46, 0),
    JDK1_3("1.3", 47, 0),

    /** J2SE1.4 = Merlin. */
    JDK1_4("1.4", 48, 0),

    /** JDK 5, codename Tiger. */
    JDK1_5("1.5", 49, 0),

    /** JDK 6. */
    JDK1_6("1.6", 50, 0),

    /** JDK 7. */
    JDK1_7("1.7", 51, 0),

    /** JDK 8. */
    JDK1_8("1.8", 52, 0),

    /** JDK 9, initially an alias for 8. */
    JDK1_9("1.9", 52, 0);

    private static final Context.Key<Target> targetKey = new Context.Key<>();

    public static Target instance(Context context) {
        Target instance = context.get(targetKey);
        if (instance == null) {
            Options options = Options.instance(context);
            String targetString = options.get(TARGET);
            if (targetString != null) instance = lookup(targetString);
            if (instance == null) instance = DEFAULT;
            context.put(targetKey, instance);
        }
        return instance;
    }

    public static final Target MIN = Target.JDK1_6;

    private static final Target MAX = values()[values().length - 1];

    private static final Map<String,Target> tab = new HashMap<>();
    static {
        for (Target t : values()) {
            tab.put(t.name, t);
        }
        tab.put("5", JDK1_5);
        tab.put("6", JDK1_6);
        tab.put("7", JDK1_7);
        tab.put("8", JDK1_8);
        tab.put("9", JDK1_9);
    }

    public final String name;
    public final int majorVersion;
    public final int minorVersion;
    private Target(String name, int majorVersion, int minorVersion) {
        this.name = name;
        this.majorVersion = majorVersion;
        this.minorVersion = minorVersion;
    }

    public static final Target DEFAULT = JDK1_9;

    public static Target lookup(String name) {
        return tab.get(name);
    }

    /** Return the character to be used in constructing synthetic
     *  identifiers, where not specified by the JLS.
     */
    public char syntheticNameChar() {
        return '$';
    }

    /** Does the VM support an invokedynamic instruction?
     */
    public boolean hasInvokedynamic() {
        return compareTo(JDK1_7) >= 0;
    }

    /** Does the VM support polymorphic method handle invocation?
     *  Affects the linkage information output to the classfile.
     *  An alias for {@code hasInvokedynamic}, since all the JSR 292 features appear together.
     */
    public boolean hasMethodHandles() {
        return hasInvokedynamic();
    }

}