resolve.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.comp;

import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.code.*;
import com.sun.tools.javac.jvm.*;
import com.sun.tools.javac.tree.*;

import com.sun.tools.javac.code.Type.*;
import com.sun.tools.javac.code.Symbol.*;
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.*;
import javax.lang.model.element.ElementVisitor;

/** Helper class for name resolution, used mostly by the attribution phase.
 *
 *  <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 Resolve {
    protected static final Context.Key<Resolve> resolveKey =
        new Context.Key<Resolve>();

    Name.Table names;
    Log log;
    Symtab syms;
    Check chk;
    Infer infer;
    ClassReader reader;
    TreeInfo treeinfo;
    Types types;
    public final boolean boxingEnabled; // = source.allowBoxing();
    public final boolean varargsEnabled; // = source.allowVarargs();
    private final boolean debugResolve;

    public static Resolve instance(Context context) {
        Resolve instance = context.get(resolveKey);
        if (instance == null)
            instance = new Resolve(context);
        return instance;
    }

    protected Resolve(Context context) {
        context.put(resolveKey, this);
        syms = Symtab.instance(context);

        varNotFound = new
            ResolveError(ABSENT_VAR, syms.errSymbol, "variable not found");
        wrongMethod = new
            ResolveError(WRONG_MTH, syms.errSymbol, "method not found");
        wrongMethods = new
            ResolveError(WRONG_MTHS, syms.errSymbol, "wrong methods");
        methodNotFound = new
            ResolveError(ABSENT_MTH, syms.errSymbol, "method not found");
        typeNotFound = new
            ResolveError(ABSENT_TYP, syms.errSymbol, "type not found");

        names = Name.Table.instance(context);
        log = Log.instance(context);
        chk = Check.instance(context);
        infer = Infer.instance(context);
        reader = ClassReader.instance(context);
        treeinfo = TreeInfo.instance(context);
        types = Types.instance(context);
        Source source = Source.instance(context);
        boxingEnabled = source.allowBoxing();
        varargsEnabled = source.allowVarargs();
        Options options = Options.instance(context);
        debugResolve = options.get("debugresolve") != null;
    }

    /** error symbols, which are returned when resolution fails
     */
    final ResolveError varNotFound;
    final ResolveError wrongMethod;
    final ResolveError wrongMethods;
    final ResolveError methodNotFound;
    final ResolveError typeNotFound;

/* ************************************************************************
 * Identifier resolution
 *************************************************************************/

    /** An environment is "static" if its static level is greater than
     *  the one of its outer environment
     */
    static boolean isStatic(Env<AttrContext> env) {
        return env.info.staticLevel > env.outer.info.staticLevel;
    }

    /** An environment is an "initializer" if it is a constructor or
     *  an instance initializer.
     */
    static boolean isInitializer(Env<AttrContext> env) {
        Symbol owner = env.info.scope.owner;
        return owner.isConstructor() ||
            owner.owner.kind == TYP &&
            (owner.kind == VAR ||
             owner.kind == MTH && (owner.flags() & BLOCK) != 0) &&
            (owner.flags() & STATIC) == 0;
    }

    /** Is class accessible in given evironment?
     *  @param env    The current environment.
     *  @param c      The class whose accessibility is checked.
     */
    public boolean isAccessible(Env<AttrContext> env, TypeSymbol c) {
        switch ((short)(c.flags() & AccessFlags)) {
        case PRIVATE:
            return
                env.enclClass.sym.outermostClass() ==
                c.owner.outermostClass();
        case 0:
            return
                env.toplevel.packge == c.owner // fast special case
                ||
                env.toplevel.packge == c.packge()
                ||
                // Hack: this case is added since synthesized default constructors
                // of anonymous classes should be allowed to access
                // classes which would be inaccessible otherwise.
                env.enclMethod != null &&
                (env.enclMethod.mods.flags & ANONCONSTR) != 0;
        default: // error recovery
        case PUBLIC:
            return true;
        case PROTECTED:
            return
                env.toplevel.packge == c.owner // fast special case
                ||
                env.toplevel.packge == c.packge()
                ||
                isInnerSubClass(env.enclClass.sym, c.owner);
        }
    }
    //where
        /** Is given class a subclass of given base class, or an inner class
         *  of a subclass?
         *  Return null if no such class exists.
         *  @param c     The class which is the subclass or is contained in it.
         *  @param base  The base class
         */
        private boolean isInnerSubClass(ClassSymbol c, Symbol base) {
            while (c != null && !c.isSubClass(base, types)) {
                c = c.owner.enclClass();
            }
            return c != null;
        }

    boolean isAccessible(Env<AttrContext> env, Type t) {
        return (t.tag == ARRAY)
            ? isAccessible(env, types.elemtype(t))
            : isAccessible(env, t.tsym);
    }

    /** Is symbol accessible as a member of given type in given evironment?
     *  @param env    The current environment.
     *  @param site   The type of which the tested symbol is regarded
     *                as a member.
     *  @param sym    The symbol.
     */
    public boolean isAccessible(Env<AttrContext> env, Type site, Symbol sym) {
        if (sym.name == names.init && sym.owner != site.tsym) return false;
        ClassSymbol sub;
        switch ((short)(sym.flags() & AccessFlags)) {
        case PRIVATE:
            return
                (env.enclClass.sym == sym.owner // fast special case
                 ||
                 env.enclClass.sym.outermostClass() ==
                 sym.owner.outermostClass())
                &&
                sym.isInheritedIn(site.tsym, types);
        case 0:
            return
                (env.toplevel.packge == sym.owner.owner // fast special case
                 ||
                 env.toplevel.packge == sym.packge())
                &&
                isAccessible(env, site)
                &&
                sym.isInheritedIn(site.tsym, types);
        case PROTECTED:
            return
                (env.toplevel.packge == sym.owner.owner // fast special case
                 ||
                 env.toplevel.packge == sym.packge()
                 ||
                 isProtectedAccessible(sym, env.enclClass.sym, site)
                 ||
                 // OK to select instance method or field from 'super' or type name
                 // (but type names should be disallowed elsewhere!)
                 env.info.selectSuper && (sym.flags() & STATIC) == 0 && sym.kind != TYP)
                &&
                isAccessible(env, site)
                &&
                // `sym' is accessible only if not overridden by
                // another symbol which is a member of `site'
                // (because, if it is overridden, `sym' is not strictly
                // speaking a member of `site'.)
                (sym.kind != MTH || sym.isConstructor() ||
                 ((MethodSymbol)sym).implementation(site.tsym, types, true) == sym);
        default: // this case includes erroneous combinations as well
            return isAccessible(env, site);
        }
    }
    //where
        /** Is given protected symbol accessible if it is selected from given site
         *  and the selection takes place in given class?
         *  @param sym     The symbol with protected access
         *  @param c       The class where the access takes place
         *  @site          The type of the qualifier
         */
        private
        boolean isProtectedAccessible(Symbol sym, ClassSymbol c, Type site) {
            while (c != null &&
                   !(c.isSubClass(sym.owner, types) &&
                     (c.flags() & INTERFACE) == 0 &&
                     // In JLS 2e 6.6.2.1, the subclass restriction applies
                     // only to instance fields and methods -- types are excluded
                     // regardless of whether they are declared 'static' or not.
                     ((sym.flags() & STATIC) != 0 || sym.kind == TYP || site.tsym.isSubClass(c, types))))
                c = c.owner.enclClass();
            return c != null;
        }

    /** Try to instantiate the type of a method so that it fits
     *  given type arguments and argument types. If succesful, return
     *  the method's instantiated type, else return null.
     *  The instantiation will take into account an additional leading
     *  formal parameter if the method is an instance method seen as a member
     *  of un underdetermined site In this case, we treat site as an additional
     *  parameter and the parameters of the class containing the method as
     *  additional type variables that get instantiated.
     *
     *  @param env         The current environment
     *  @param site        The type of which the method is a member.
     *  @param m           The method symbol.
     *  @param argtypes    The invocation's given value arguments.
     *  @param typeargtypes    The invocation's given type arguments.
     *  @param allowBoxing Allow boxing conversions of arguments.
     *  @param useVarargs Box trailing arguments into an array for varargs.
     */
    Type rawInstantiate(Env<AttrContext> env,
                        Type site,
                        Symbol m,
                        List<Type> argtypes,
                        List<Type> typeargtypes,
                        boolean allowBoxing,
                        boolean useVarargs,
                        Warner warn)
        throws Infer.NoInstanceException {
        if (useVarargs && (m.flags() & VARARGS) == 0) return null;
        Type mt = types.memberType(site, m);

        // tvars is the list of formal type variables for which type arguments
        // need to inferred.
        List<Type> tvars = env.info.tvars;
        if (typeargtypes == null) typeargtypes = List.nil();
        if (mt.tag != FORALL && typeargtypes.nonEmpty()) {
            // This is not a polymorphic method, but typeargs are supplied
            // which is fine, see JLS3 15.12.2.1
        } else if (mt.tag == FORALL && typeargtypes.nonEmpty()) {
            ForAll pmt = (ForAll) mt;
            if (typeargtypes.length() != pmt.tvars.length())
                return null;
            // Check type arguments are within bounds
            List<Type> formals = pmt.tvars;
            List<Type> actuals = typeargtypes;
            while (formals.nonEmpty() && actuals.nonEmpty()) {
                List<Type> bounds = types.subst(types.getBounds((TypeVar)formals.head),
                                                pmt.tvars, typeargtypes);
                for (; bounds.nonEmpty(); bounds = bounds.tail)
                    if (!types.isSubtypeUnchecked(actuals.head, bounds.head, warn))