symbol.java

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/*
 * 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.ArrayList;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.Callable;
import javax.lang.model.element.*;
import javax.lang.model.type.ReferenceType;
import javax.lang.model.type.TypeMirror;
import javax.tools.JavaFileObject;

import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.Name;
import com.sun.tools.javac.code.Type.*;
import com.sun.tools.javac.comp.Attr;
import com.sun.tools.javac.comp.AttrContext;
import com.sun.tools.javac.comp.Env;
import com.sun.tools.javac.jvm.*;
import com.sun.tools.javac.model.*;
import com.sun.tools.javac.tree.JCTree;

import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Kinds.*;
import static com.sun.tools.javac.code.TypeTags.*;

/** Root class for Java symbols. It contains subclasses
 *  for specific sorts of symbols, such as variables, methods and operators,
 *  types, packages. Each subclass is represented as a static inner class
 *  inside Symbol.
 *
 *  <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 abstract class Symbol implements Element {
    // public Throwable debug = new Throwable();

    /** The kind of this symbol.
     *  @see Kinds
     */
    public int kind;

    /** The flags of this symbol.
     */
    public long flags_field;

    /** An accessor method for the flags of this symbol.
     *  Flags of class symbols should be accessed through the accessor
     *  method to make sure that the class symbol is loaded.
     */
    public long flags() { return flags_field; }

    /** The attributes of this symbol.
     */
    public List<Attribute.Compound> attributes_field;

    /** An accessor method for the attributes of this symbol.
     *  Attributes of class symbols should be accessed through the accessor
     *  method to make sure that the class symbol is loaded.
     */
    public List<Attribute.Compound> getAnnotationMirrors() {
        assert attributes_field != null;
        return attributes_field;
    }

    /** Fetch a particular annotation from a symbol. */
    public Attribute.Compound attribute(Symbol anno) {
        for (Attribute.Compound a : getAnnotationMirrors())
            if (a.type.tsym == anno) return a;
        return null;
    }

    /** The name of this symbol in Utf8 representation.
     */
    public Name name;

    /** The type of this symbol.
     */
    public Type type;

    /** The owner of this symbol.
     */
    public Symbol owner;

    /** The completer of this symbol.
     */
    public Completer completer;

    /** A cache for the type erasure of this symbol.
     */
    public Type erasure_field;

    /** Construct a symbol with given kind, flags, name, type and owner.
     */
    public Symbol(int kind, long flags, Name name, Type type, Symbol owner) {
        this.kind = kind;
        this.flags_field = flags;
        this.type = type;
        this.owner = owner;
        this.completer = null;
        this.erasure_field = null;
        this.attributes_field = List.nil();
        this.name = name;
    }

    /** Clone this symbol with new owner.
     *  Legal only for fields and methods.
     */
    public Symbol clone(Symbol newOwner) {
        throw new AssertionError();
    }

    /** The Java source which this symbol represents.
     *  A description of this symbol; overrides Object.
     */
    public String toString() {
        return name.toString();
    }

    /** A Java source description of the location of this symbol; used for
     *  error reporting.  Use of this method may result in the loss of the
     *  symbol's description.
     */
    public String location() {
        if (owner.name == null || (owner.name.len == 0 && owner.kind != PCK)) {
	    return "";
	}
	return owner.toString();
    }

    public String location(Type site, Types types) {
        if (owner.name == null || owner.name.len == 0) {
            return location();
        }
        if (owner.type.tag == CLASS) {
            Type ownertype = types.asOuterSuper(site, owner);
            if (ownertype != null) return ownertype.toString();
        }
        return owner.toString();
    }

    /** The symbol's erased type.
     */
    public Type erasure(Types types) {
        if (erasure_field == null)
            erasure_field = types.erasure(type);
        return erasure_field;
    }

    /** The external type of a symbol. This is the symbol's erased type
     *  except for constructors of inner classes which get the enclosing
     *  instance class added as first argument.
     */
    public Type externalType(Types types) {
        Type t = erasure(types);
        if (name == name.table.init && owner.hasOuterInstance()) {
            Type outerThisType = types.erasure(owner.type.getEnclosingType());
            return new MethodType(t.getParameterTypes().prepend(outerThisType),
                                  t.getReturnType(),
                                  t.getThrownTypes(),
                                  t.tsym);
        } else {
            return t;
        }
    }

    public boolean isStatic() {
        return
            (flags() & STATIC) != 0 ||
            (owner.flags() & INTERFACE) != 0 && kind != MTH;
    }

    public boolean isInterface() {
        return (flags() & INTERFACE) != 0;
    }

    /** Is this symbol declared (directly or indirectly) local
     *  to a method or variable initializer?
     *  Also includes fields of inner classes which are in
     *  turn local to a method or variable initializer.
     */
    public boolean isLocal() {
        return
            (owner.kind & (VAR | MTH)) != 0 ||
            (owner.kind == TYP && owner.isLocal());
    }

    /** Is this symbol a constructor?
     */
    public boolean isConstructor() {
        return name == name.table.init;
    }

    /** The fully qualified name of this symbol.
     *  This is the same as the symbol's name except for class symbols,
     *  which are handled separately.
     */
    public Name getQualifiedName() {
        return name;
    }

    /** The fully qualified name of this symbol after converting to flat
     *  representation. This is the same as the symbol's name except for
     *  class symbols, which are handled separately.
     */
    public Name flatName() {
        return getQualifiedName();
    }

    /** If this is a class or package, its members, otherwise null.
     */
    public Scope members() {
        return null;
    }

    /** A class is an inner class if it it has an enclosing instance class.
     */
    public boolean isInner() {
        return type.getEnclosingType().tag == CLASS;
    }

    /** An inner class has an outer instance if it is not an interface
     *  it has an enclosing instance class which might be referenced from the class.
     *  Nested classes can see instance members of their enclosing class.
     *  Their constructors carry an additional this$n parameter, inserted
     *  implicitly by the compiler.
     *
     *  @see #isInner
     */
    public boolean hasOuterInstance() {
        return
            type.getEnclosingType().tag == CLASS && (flags() & (INTERFACE | NOOUTERTHIS)) == 0;
    }

    /** The closest enclosing class of this symbol's declaration.
     */
    public ClassSymbol enclClass() {
        Symbol c = this;
        while (c != null &&
               ((c.kind & TYP) == 0 || c.type.tag != CLASS)) {
            c = c.owner;
        }
        return (ClassSymbol)c;
    }

    /** The outermost class which indirectly owns this symbol.
     */
    public ClassSymbol outermostClass() {
        Symbol sym = this;
        Symbol prev = null;
        while (sym.kind != PCK) {
            prev = sym;
            sym = sym.owner;
        }
        return (ClassSymbol) prev;
    }

    /** The package which indirectly owns this symbol.
     */
    public PackageSymbol packge() {
        Symbol sym = this;
        while (sym.kind != PCK) {
            sym = sym.owner;
        }
        return (PackageSymbol) sym;
    }

    /** Is this symbol a subclass of `base'? Only defined for ClassSymbols.
     */
    public boolean isSubClass(Symbol base, Types types) {
        throw new AssertionError("isSubClass " + this);
    }

    /** Fully check membership: hierarchy, protection, and hiding.
     *  Does not exclude methods not inherited due to overriding.
     */
    public boolean isMemberOf(TypeSymbol clazz, Types types) {
        return
            owner == clazz ||
            clazz.isSubClass(owner, types) &&
            isInheritedIn(clazz, types) &&
            !hiddenIn((ClassSymbol)clazz, types);
    }

    /** Is this symbol the same as or enclosed by the given class? */
    public boolean isEnclosedBy(ClassSymbol clazz) {
        for (Symbol sym = this; sym.kind != PCK; sym = sym.owner)
            if (sym == clazz) return true;
        return false;
    }

    /** Check for hiding.  Note that this doesn't handle multiple
     *  (interface) inheritance. */
    private boolean hiddenIn(ClassSymbol clazz, Types types) {
        if (kind == MTH && (flags() & STATIC) == 0) return false;
        while (true) {
            if (owner == clazz) return false;
            Scope.Entry e = clazz.members().lookup(name);
            while (e.scope != null) {
                if (e.sym == this) return false;
                if (e.sym.kind == kind &&
                    (kind != MTH ||
                     (e.sym.flags() & STATIC) != 0 &&
                     types.isSubSignature(e.sym.type, type)))
                    return true;
                e = e.next();
            }
            Type superType = types.supertype(clazz.type);
            if (superType.tag != TypeTags.CLASS) return false;
            clazz = (ClassSymbol)superType.tsym;
        }
    }

    /** Is this symbol inherited into a given class?
     *  PRE: If symbol's owner is a interface,
     *       it is already assumed that the interface is a superinterface
     *       of given class.
     *  @param clazz  The class for which we want to establish membership.
     *                This must be a subclass of the member's owner.
     */
    public boolean isInheritedIn(Symbol clazz, Types types) {
        switch ((int)(flags_field & Flags.AccessFlags)) {
        default: // error recovery
        case PUBLIC:
            return true;
        case PRIVATE:
            return this.owner == clazz;
        case PROTECTED:
            // we model interfaces as extending Object
            return (clazz.flags() & INTERFACE) == 0;
        case 0:
            PackageSymbol thisPackage = this.packge();
            for (Symbol sup = clazz;
                 sup != null && sup != this.owner;
                 sup = types.supertype(sup.type).tsym) {
                if (sup.type.isErroneous())
                    return true; // error recovery
                if ((sup.flags() & COMPOUND) != 0)
                    continue;
                if (sup.packge() != thisPackage)
                    return false;
            }
            return (clazz.flags() & INTERFACE) == 0;
        }
    }

    /** The (variable or method) symbol seen as a member of given
     *  class type`site' (this might change the symbol's type).
     *  This is used exclusively for producing diagnostics.
     */
    public Symbol asMemberOf(Type site, Types types) {
        throw new AssertionError();
    }

    /** Does this method symbol override `other' symbol, when both are seen as
     *  members of class `origin'?  It is assumed that _other is a member
     *  of origin.
     *
     *  It is assumed that both symbols have the same name.  The static
     *  modifier is ignored for this test.
     *
     *  See JLS 8.4.6.1 (without transitivity) and 8.4.6.4
     */
    public boolean overrides(Symbol _other, TypeSymbol origin, Types types, boolean checkResult) {
        return false;
    }

    /** Complete the elaboration of this symbol's definition.
     */
    public void complete() throws CompletionFailure {
        if (completer != null) {
            Completer c = completer;
            completer = null;
            c.complete(this);
        }
    }

    /** True if the symbol represents an entity that exists.
     */
    public boolean exists() {
        return true;
    }

    public Type asType() {
        return type;
    }

    public Symbol getEnclosingElement() {
        return owner;
    }

    public ElementKind getKind() {
        return ElementKind.OTHER;       // most unkind
    }

    public Set<Modifier> getModifiers() {
        return Flags.asModifierSet(flags());
    }

    public Name getSimpleName() {
        return name;
    }

    /**
     * @deprecated this method should never be used by javac internally.
     */
    @Deprecated