Java example source code file (TypeTag.java)

This example Java source code file (TypeTag.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

assertionerror, boolean, byte_superclasses, char, char_superclasses, double_class, float_class, float_superclasses, int_class, int_superclasses, long_class, short_class, short_superclasses, typetag

The TypeTag.java Java example source code

/*
 * Copyright (c) 1999, 2013, 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.  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.
 *
 * 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.
 */

package com.sun.tools.javac.code;

import com.sun.source.tree.Tree.Kind;

import javax.lang.model.type.TypeKind;

import static com.sun.tools.javac.code.TypeTag.NumericClasses.*;

/** An interface for type tag values, which distinguish between different
 *  sorts of types.
 *
 *  <p>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 TypeTag {
    /** The tag of the basic type `byte'.
     */
    BYTE(BYTE_CLASS, BYTE_SUPERCLASSES, true),

    /** The tag of the basic type `char'.
     */
    CHAR(CHAR_CLASS, CHAR_SUPERCLASSES, true),

    /** The tag of the basic type `short'.
     */
    SHORT(SHORT_CLASS, SHORT_SUPERCLASSES, true),

    /** The tag of the basic type `long'.
     */
    LONG(LONG_CLASS, LONG_SUPERCLASSES, true),

    /** The tag of the basic type `float'.
     */
    FLOAT(FLOAT_CLASS, FLOAT_SUPERCLASSES, true),
    /** The tag of the basic type `int'.
     */
    INT(INT_CLASS, INT_SUPERCLASSES, true),
    /** The tag of the basic type `double'.
     */
    DOUBLE(DOUBLE_CLASS, DOUBLE_CLASS, true),
    /** The tag of the basic type `boolean'.
     */
    BOOLEAN(0, 0, true),

    /** The tag of the type `void'.
     */
    VOID,

    /** The tag of all class and interface types.
     */
    CLASS,

    /** The tag of all array types.
     */
    ARRAY,

    /** The tag of all (monomorphic) method types.
     */
    METHOD,

    /** The tag of all package "types".
     */
    PACKAGE,

    /** The tag of all (source-level) type variables.
     */
    TYPEVAR,

    /** The tag of all type arguments.
     */
    WILDCARD,

    /** The tag of all polymorphic (method-) types.
     */
    FORALL,

    /** The tag of deferred expression types in method context
     */
    DEFERRED,

    /** The tag of the bottom type {@code <null>}.
     */
    BOT,

    /** The tag of a missing type.
     */
    NONE,

    /** The tag of the error type.
     */
    ERROR,

    /** The tag of an unknown type
     */
    UNKNOWN,

    /** The tag of all instantiatable type variables.
     */
    UNDETVAR,

    /** Pseudo-types, these are special tags
     */
    UNINITIALIZED_THIS,

    UNINITIALIZED_OBJECT;

    final int superClasses;
    final int numericClass;
    final boolean isPrimitive;

    private TypeTag() {
        this(0, 0, false);
    }

    private TypeTag(int numericClass, int superClasses, boolean isPrimitive) {
        this.superClasses = superClasses;
        this.numericClass = numericClass;
        this.isPrimitive = isPrimitive;
    }

    public static class NumericClasses {
        public static final int BYTE_CLASS = 1;
        public static final int CHAR_CLASS = 2;
        public static final int SHORT_CLASS = 4;
        public static final int INT_CLASS = 8;
        public static final int LONG_CLASS = 16;
        public static final int FLOAT_CLASS = 32;
        public static final int DOUBLE_CLASS = 64;

        static final int BYTE_SUPERCLASSES = BYTE_CLASS | SHORT_CLASS | INT_CLASS |
                LONG_CLASS | FLOAT_CLASS | DOUBLE_CLASS;

        static final int CHAR_SUPERCLASSES = CHAR_CLASS | INT_CLASS |
                LONG_CLASS | FLOAT_CLASS | DOUBLE_CLASS;

        static final int SHORT_SUPERCLASSES = SHORT_CLASS | INT_CLASS |
                LONG_CLASS | FLOAT_CLASS | DOUBLE_CLASS;

        static final int INT_SUPERCLASSES = INT_CLASS | LONG_CLASS | FLOAT_CLASS | DOUBLE_CLASS;

        static final int LONG_SUPERCLASSES = LONG_CLASS | FLOAT_CLASS | DOUBLE_CLASS;

        static final int FLOAT_SUPERCLASSES = FLOAT_CLASS | DOUBLE_CLASS;
    }

    public boolean isStrictSubRangeOf(TypeTag tag) {
        /*  Please don't change the implementation of this method to call method
         *  isSubRangeOf. Both methods are called from hotspot code, the current
         *  implementation is better performance-wise than the commented modification.
         */
        return (this.superClasses & tag.numericClass) != 0 && this != tag;
    }

    public boolean isSubRangeOf(TypeTag tag) {
        return (this.superClasses & tag.numericClass) != 0;
    }

    /** Returns the number of type tags.
     */
    public static int getTypeTagCount() {
        // last two tags are not included in the total as long as they are pseudo-types
        return (UNDETVAR.ordinal() + 1);
    }

    public Kind getKindLiteral() {
        switch (this) {
        case INT:
            return Kind.INT_LITERAL;
        case LONG:
            return Kind.LONG_LITERAL;
        case FLOAT:
            return Kind.FLOAT_LITERAL;
        case DOUBLE:
            return Kind.DOUBLE_LITERAL;
        case BOOLEAN:
            return Kind.BOOLEAN_LITERAL;
        case CHAR:
            return Kind.CHAR_LITERAL;
        case CLASS:
            return Kind.STRING_LITERAL;
        case BOT:
            return Kind.NULL_LITERAL;
        default:
            throw new AssertionError("unknown literal kind " + this);
        }
    }

    public TypeKind getPrimitiveTypeKind() {
        switch (this) {
        case BOOLEAN:
            return TypeKind.BOOLEAN;
        case BYTE:
            return TypeKind.BYTE;
        case SHORT:
            return TypeKind.SHORT;
        case INT:
            return TypeKind.INT;
        case LONG:
            return TypeKind.LONG;
        case CHAR:
            return TypeKind.CHAR;
        case FLOAT:
            return TypeKind.FLOAT;
        case DOUBLE:
            return TypeKind.DOUBLE;
        case VOID:
            return TypeKind.VOID;
        default:
            throw new AssertionError("unknown primitive type " + this);
        }
    }

}