flags.java

来自「是一款用JAVA 编写的编译器 具有很强的编译功能」· Java 代码 · 共 275 行

/*
 * Copyright 1999-2006 Sun Microsystems, Inc.  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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.tools.javac.code;

import java.util.Collections;
import java.util.Map;
import java.util.Set;
import javax.lang.model.element.Modifier;

/** Access flags and other modifiers for Java classes and members.
 *
 *  <p><b>This is NOT part of any API supported by Sun Microsystems.  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 class Flags {

    private Flags() {} // uninstantiable

    public static String toString(long flags) {
        StringBuffer buf = new StringBuffer();
        if ((flags&PUBLIC) != 0) buf.append("public ");
        if ((flags&PRIVATE) != 0) buf.append("private ");
        if ((flags&PROTECTED) != 0) buf.append("protected ");
        if ((flags&STATIC) != 0) buf.append("static ");
        if ((flags&FINAL) != 0) buf.append("final ");
        if ((flags&SYNCHRONIZED) != 0) buf.append("synchronized ");
        if ((flags&VOLATILE) != 0) buf.append("volatile ");
        if ((flags&TRANSIENT) != 0) buf.append("transient ");
        if ((flags&NATIVE) != 0) buf.append("native ");
        if ((flags&INTERFACE) != 0) buf.append("interface ");
        if ((flags&ABSTRACT) != 0) buf.append("abstract ");
        if ((flags&STRICTFP) != 0) buf.append("strictfp ");
        if ((flags&BRIDGE) != 0) buf.append("bridge ");
        if ((flags&SYNTHETIC) != 0) buf.append("synthetic ");
        if ((flags&DEPRECATED) != 0) buf.append("deprecated ");
        if ((flags&HASINIT) != 0) buf.append("hasinit ");
        if ((flags&ENUM) != 0) buf.append("enum ");
        if ((flags&IPROXY) != 0) buf.append("iproxy ");
        if ((flags&NOOUTERTHIS) != 0) buf.append("noouterthis ");
        if ((flags&EXISTS) != 0) buf.append("exists ");
        if ((flags&COMPOUND) != 0) buf.append("compound ");
        if ((flags&CLASS_SEEN) != 0) buf.append("class_seen ");
        if ((flags&SOURCE_SEEN) != 0) buf.append("source_seen ");
        if ((flags&LOCKED) != 0) buf.append("locked ");
        if ((flags&UNATTRIBUTED) != 0) buf.append("unattributed ");
        if ((flags&ANONCONSTR) != 0) buf.append("anonconstr ");
        if ((flags&ACYCLIC) != 0) buf.append("acyclic ");
        if ((flags&PARAMETER) != 0) buf.append("parameter ");
        if ((flags&VARARGS) != 0) buf.append("varargs ");
        return buf.toString();
    }

    /* Standard Java flags.
     */
    public static final int PUBLIC       = 1<<0;
    public static final int PRIVATE      = 1<<1;
    public static final int PROTECTED    = 1<<2;
    public static final int STATIC       = 1<<3;
    public static final int FINAL        = 1<<4;
    public static final int SYNCHRONIZED = 1<<5;
    public static final int VOLATILE     = 1<<6;
    public static final int TRANSIENT    = 1<<7;
    public static final int NATIVE       = 1<<8;
    public static final int INTERFACE    = 1<<9;
    public static final int ABSTRACT     = 1<<10;
    public static final int STRICTFP     = 1<<11;

    /* Flag that marks a symbol synthetic, added in classfile v49.0. */
    public static final int SYNTHETIC    = 1<<12;

    /** Flag that marks attribute interfaces, added in classfile v49.0. */
    public static final int ANNOTATION   = 1<<13;

    /** An enumeration type or an enumeration constant, added in
     *  classfile v49.0. */
    public static final int ENUM         = 1<<14;

    public static final int StandardFlags = 0x0fff;

    // Because the following access flags are overloaded with other
    // bit positions, we translate them when reading and writing class
    // files into unique bits positions: ACC_SYNTHETIC <-> SYNTHETIC,
    // for example.
    public static final int ACC_SUPER    = 0x0020;
    public static final int ACC_BRIDGE   = 0x0040;
    public static final int ACC_VARARGS  = 0x0080;

    /*****************************************
     * Internal compiler flags (no bits in the lower 16).
     *****************************************/

    /** Flag is set if symbol is deprecated.
     */
    public static final int DEPRECATED   = 1<<17;

    /** Flag is set for a variable symbol if the variable's definition
     *  has an initializer part.
     */
    public static final int HASINIT          = 1<<18;

    /** Flag is set for compiler-generated anonymous method symbols
     *  that `own' an initializer block.
     */
    public static final int BLOCK            = 1<<20;

    /** Flag is set for compiler-generated abstract methods that implement
     *  an interface method (Miranda methods).
     */
    public static final int IPROXY           = 1<<21;

    /** Flag is set for nested classes that do not access instance members
     *  or `this' of an outer class and therefore don't need to be passed
     *  a this$n reference.  This flag is currently set only for anonymous
     *  classes in superclass constructor calls and only for pre 1.4 targets.
     *  todo: use this flag for optimizing away this$n parameters in
     *  other cases.
     */
    public static final int NOOUTERTHIS  = 1<<22;

    /** Flag is set for package symbols if a package has a member or
     *  directory and therefore exists.
     */
    public static final int EXISTS           = 1<<23;

    /** Flag is set for compiler-generated compound classes
     *  representing multiple variable bounds
     */
    public static final int COMPOUND     = 1<<24;

    /** Flag is set for class symbols if a class file was found for this class.
     */
    public static final int CLASS_SEEN   = 1<<25;

    /** Flag is set for class symbols if a source file was found for this
     *  class.
     */
    public static final int SOURCE_SEEN  = 1<<26;

    /* State flags (are reset during compilation).
     */

    /** Flag for class symbols is set and later re-set as a lock in
     *  Enter to detect cycles in the superclass/superinterface
     *  relations.  Similarly for constructor call cycle detection in
     *  Attr.
     */
    public static final int LOCKED           = 1<<27;

    /** Flag for class symbols is set and later re-set to indicate that a class
     *  has been entered but has not yet been attributed.
     */
    public static final int UNATTRIBUTED = 1<<28;

    /** Flag for synthesized default constructors of anonymous classes.
     */
    public static final int ANONCONSTR   = 1<<29;

    /** Flag for class symbols to indicate it has been checked and found
     *  acyclic.
     */
    public static final int ACYCLIC          = 1<<30;

    /** Flag that marks bridge methods.
     */
    public static final long BRIDGE          = 1L<<31;

    /** Flag that marks formal parameters.
     */
    public static final long PARAMETER   = 1L<<33;

    /** Flag that marks varargs methods.
     */
    public static final long VARARGS   = 1L<<34;

    /** Flag for annotation type symbols to indicate it has been
     *  checked and found acyclic.
     */
    public static final long ACYCLIC_ANN      = 1L<<35;

    /** Flag that marks a generated default constructor.
     */
    public static final long GENERATEDCONSTR   = 1L<<36;

    /** Flag that marks a hypothetical method that need not really be
     *  generated in the binary, but is present in the symbol table to
     *  simplify checking for erasure clashes.
     */
    public static final long HYPOTHETICAL   = 1L<<37;

    /**
     * Flag that marks a Sun proprietary class.
     */
    public static final long PROPRIETARY = 1L<<38;

    /** Modifier masks.
     */
    public static final int
        AccessFlags           = PUBLIC | PROTECTED | PRIVATE,
        LocalClassFlags       = FINAL | ABSTRACT | STRICTFP | ENUM | SYNTHETIC,
        MemberClassFlags      = LocalClassFlags | INTERFACE | AccessFlags,
        ClassFlags            = LocalClassFlags | INTERFACE | PUBLIC | ANNOTATION,
        InterfaceVarFlags     = FINAL | STATIC | PUBLIC,
        VarFlags              = AccessFlags | FINAL | STATIC |
                                VOLATILE | TRANSIENT | ENUM,
        ConstructorFlags      = AccessFlags,
        InterfaceMethodFlags  = ABSTRACT | PUBLIC,
        MethodFlags           = AccessFlags | ABSTRACT | STATIC | NATIVE |
                                SYNCHRONIZED | FINAL | STRICTFP;
    public static final long
        LocalVarFlags         = FINAL | PARAMETER;

    public static Set<Modifier> asModifierSet(long flags) {
        Set<Modifier> modifiers = modifierSets.get(flags);
        if (modifiers == null) {
            modifiers = java.util.EnumSet.noneOf(Modifier.class);
            if (0 != (flags & PUBLIC))    modifiers.add(Modifier.PUBLIC);
            if (0 != (flags & PROTECTED)) modifiers.add(Modifier.PROTECTED);
            if (0 != (flags & PRIVATE))   modifiers.add(Modifier.PRIVATE);
            if (0 != (flags & ABSTRACT))  modifiers.add(Modifier.ABSTRACT);
            if (0 != (flags & STATIC))    modifiers.add(Modifier.STATIC);
            if (0 != (flags & FINAL))     modifiers.add(Modifier.FINAL);
            if (0 != (flags & TRANSIENT)) modifiers.add(Modifier.TRANSIENT);
            if (0 != (flags & VOLATILE))  modifiers.add(Modifier.VOLATILE);
            if (0 != (flags & SYNCHRONIZED))
                                          modifiers.add(Modifier.SYNCHRONIZED);
            if (0 != (flags & NATIVE))    modifiers.add(Modifier.NATIVE);
            if (0 != (flags & STRICTFP))  modifiers.add(Modifier.STRICTFP);
            modifiers = Collections.unmodifiableSet(modifiers);
            modifierSets.put(flags, modifiers);
        }
        return modifiers;
    }

    // Cache of modifier sets.
    private static Map<Long, Set<Modifier>> modifierSets =
        new java.util.concurrent.ConcurrentHashMap<Long, Set<Modifier>>(64);

    public static boolean isStatic(Symbol symbol) {
        return (symbol.flags() & STATIC) != 0;
    }

    public static boolean isEnum(Symbol symbol) {
        return (symbol.flags() & ENUM) != 0;
    }

    public static boolean isConstant(Symbol.VarSymbol symbol) {
        return symbol.getConstValue() != null;
    }
}