/*

 * Copyright (c) 1999, 2017, 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.comp;

import java.net.URI;

import java.util.HashMap;

import java.util.Map;

import java.util.Optional;

import javax.lang.model.element.ExecutableElement;

import javax.lang.model.element.TypeElement;

import javax.lang.model.element.VariableElement;

import javax.lang.model.util.ElementScanner6;

import javax.tools.JavaFileObject;

import javax.tools.JavaFileManager;

import com.sun.tools.javac.api.DuplicateClassChecker;

import com.sun.tools.javac.code.*;

import com.sun.tools.javac.code.Kinds.KindName;

import com.sun.tools.javac.code.Kinds.KindSelector;

import com.sun.tools.javac.code.Scope.*;

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

import com.sun.tools.javac.code.Type.*;

import com.sun.tools.javac.main.Option.PkgInfo;

import com.sun.tools.javac.model.LazyTreeLoader;

import com.sun.tools.javac.resources.CompilerProperties.Errors;

import com.sun.tools.javac.tree.*;

import com.sun.tools.javac.tree.JCTree.*;

import com.sun.tools.javac.util.*;

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;

import com.sun.tools.javac.util.List;

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

import static com.sun.tools.javac.code.Kinds.Kind.*;

/** This class enters symbols for all encountered definitions into

 *  the symbol table. The pass consists of high-level two phases,

 *  organized as follows:

 *

 *  <p>In the first phase, all class symbols are entered into their

 *  enclosing scope, descending recursively down the tree for classes

 *  which are members of other classes. The class symbols are given a

 *  TypeEnter object as completer.

 *

 *  <p>In the second phase classes are completed using

 *  TypeEnter.complete(). Completion might occur on demand, but

 *  any classes that are not completed that way will be eventually

 *  completed by processing the `uncompleted' queue. Completion

 *  entails determination of a class's parameters, supertype and

 *  interfaces, as well as entering all symbols defined in the

 *  class into its scope, with the exception of class symbols which

 *  have been entered in phase 1.

 *

 *  <p>Whereas the first phase is organized as a sweep through all

 *  compiled syntax trees, the second phase is on-demand. Members of a

 *  class are entered when the contents of a class are first

 *  accessed. This is accomplished by installing completer objects in

 *  class symbols for compiled classes which invoke the type-enter

 *  phase for the corresponding class tree.

 *

 *  <p>Classes migrate from one phase to the next via queues:

 *

 *  <pre>{@literal

 *  class enter -> (Enter.uncompleted)         --> type enter

 *              -> (Todo)                      --> attribute

 *                                              (only for toplevel classes)

 *  }</pre>

 *

 *  <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 class Enter extends JCTree.Visitor {

    protected static final Context.Key<Enter> enterKey = new Context.Key<>();

    Annotate annotate;

    Log log;

    Symtab syms;

    Check chk;

    TreeMaker make;

    TypeEnter typeEnter;

    Types types;

    Lint lint;

    Names names;

    JavaFileManager fileManager;

    PkgInfo pkginfoOpt;

    TypeEnvs typeEnvs;

    Modules modules;

    JCDiagnostic.Factory diags;

    private final LazyTreeLoader treeLoader;

    private final DuplicateClassChecker duplicateClassChecker;

    private final Source source;

    private final Todo todo;

    public static Enter instance(Context context) {

        Enter instance = context.get(enterKey);

        if (instance == null)

            instance = new Enter(context);

        return instance;

    }

    protected Enter(Context context) {

        context.put(enterKey, this);

        log = Log.instance(context);

        make = TreeMaker.instance(context);

        syms = Symtab.instance(context);

        chk = Check.instance(context);

        typeEnter = TypeEnter.instance(context);

        types = Types.instance(context);

        annotate = Annotate.instance(context);

        lint = Lint.instance(context);

        names = Names.instance(context);

        modules = Modules.instance(context);

        diags = JCDiagnostic.Factory.instance(context);

        treeLoader = LazyTreeLoader.instance(context);

        duplicateClassChecker = context.get(DuplicateClassChecker.class);

        predefClassDef = make.ClassDef(

            make.Modifiers(PUBLIC),

            syms.predefClass.name,

            List.nil(),

            null,

            List.nil(),

            List.nil());

        predefClassDef.sym = syms.predefClass;

        todo = Todo.instance(context);

        fileManager = context.get(JavaFileManager.class);

        Options options = Options.instance(context);

        pkginfoOpt = PkgInfo.get(options);

        typeEnvs = TypeEnvs.instance(context);

        source = Source.instance(context);

    }

    Map<TypeSymbol,Env<AttrContext>> typeEnvsShadow = null;

    private final Map<URI, JCCompilationUnit> compilationUnits =

            new HashMap<URI, JCCompilationUnit> ();

    public JCCompilationUnit getCompilationUnit (JavaFileObject fobj) {

        return this.compilationUnits.get(fobj.toUri());

    }

    /** Accessor for typeEnvs

     */

    public Env<AttrContext> getEnv(TypeSymbol sym) {

        return typeEnvs.get(sym);

    }

    public Iterable<Env<AttrContext>> getEnvs() {

        return typeEnvs.values();

    }

    public Env<AttrContext> getClassEnv(TypeSymbol sym) {

        Env<AttrContext> localEnv = getEnv(sym);

        if (localEnv == null) return null;

        Env<AttrContext> lintEnv = localEnv;

        while (lintEnv.info.lint == null)

            lintEnv = lintEnv.next;

        localEnv.info.lint = lintEnv.info.lint.augment(sym);

        return localEnv;

    }

    /** The queue of all classes that might still need to be completed;

     *  saved and initialized by main().

     */

    ListBuffer<ClassSymbol> uncompleted;

    /** The queue of modules whose imports still need to be checked. */

    ListBuffer<JCCompilationUnit> unfinishedModules = new ListBuffer<>();

    /** A dummy class to serve as enclClass for toplevel environments.

     */

    private JCClassDecl predefClassDef;

/* ************************************************************************

 * environment construction

 *************************************************************************/

    /** Create a fresh environment for class bodies.

     *  This will create a fresh scope for local symbols of a class, referred

     *  to by the environments info.scope field.

     *  This scope will contain

     *    - symbols for this and super

     *    - symbols for any type parameters

     *  In addition, it serves as an anchor for scopes of methods and initializers

     *  which are nested in this scope via Scope.dup().

     *  This scope should not be confused with the members scope of a class.

     *

     *  @param tree     The class definition.

     *  @param env      The environment current outside of the class definition.

     */

    public Env<AttrContext> classEnv(JCClassDecl tree, Env<AttrContext> env) {

        Env<AttrContext> localEnv =

            env.dup(tree, env.info.dup(WriteableScope.create(tree.sym)));

        localEnv.enclClass = tree;

        localEnv.outer = env;

        localEnv.info.isSelfCall = false;

        localEnv.info.lint = null; // leave this to be filled in by Attr,

                                   // when annotations have been processed

        localEnv.info.isAnonymousDiamond = TreeInfo.isDiamond(env.tree);

        return localEnv;

    }

    /** Create a fresh environment for toplevels.

     *  @param tree     The toplevel tree.

     */

    Env<AttrContext> topLevelEnv(JCCompilationUnit tree) {

        Env<AttrContext> localEnv = new Env<>(tree, new AttrContext());

        localEnv.toplevel = tree;

        localEnv.enclClass = predefClassDef;

        tree.toplevelScope = WriteableScope.create(tree.packge);

        tree.namedImportScope = new NamedImportScope(tree.packge, tree.toplevelScope);

        tree.starImportScope = new StarImportScope(tree.packge);

        localEnv.info.scope = tree.toplevelScope;

        localEnv.info.lint = lint;

        return localEnv;

    }

    public Env<AttrContext> getTopLevelEnv(JCCompilationUnit tree) {

        Env<AttrContext> localEnv = new Env<>(tree, new AttrContext());

        localEnv.toplevel = tree;

        localEnv.enclClass = predefClassDef;

        localEnv.info.scope = tree.toplevelScope;

        localEnv.info.lint = lint;

        return localEnv;

    }

    /** The scope in which a member definition in environment env is to be entered

     *  This is usually the environment's scope, except for class environments,

     *  where the local scope is for type variables, and the this and super symbol

     *  only, and members go into the class member scope.

     */

    WriteableScope enterScope(Env<AttrContext> env) {

        return (env.tree.hasTag(JCTree.Tag.CLASSDEF))

            ? ((JCClassDecl) env.tree).sym.members_field

            : env.info.scope;

    }

    /** Create a fresh environment for modules.

     *

     *  @param tree     The module definition.

     *  @param env      The environment current outside of the module definition.

     */

    public Env<AttrContext> moduleEnv(JCModuleDecl tree, Env<AttrContext> env) {

        Assert.checkNonNull(tree.sym);

        Env<AttrContext> localEnv =

            env.dup(tree, env.info.dup(WriteableScope.create(tree.sym)));

        localEnv.enclClass = predefClassDef;

        localEnv.outer = env;

        localEnv.info.isSelfCall = false;

        localEnv.info.lint = null; // leave this to be filled in by Attr,

                                   // when annotations have been processed

        return localEnv;

    }

    public void shadowTypeEnvs(boolean b) {

        if (b) {

            assert typeEnvsShadow == null;

            typeEnvsShadow = new HashMap<TypeSymbol,Env<AttrContext>>();

        } else {

            for (Map.Entry<TypeSymbol, Env<AttrContext>> entry : typeEnvsShadow.entrySet()) {

                if (entry.getValue() == null)

                    typeEnvs.remove(entry.getKey());

                else

                    typeEnvs.put(entry.getKey(), entry.getValue());

            }

            typeEnvsShadow = null;

        }

    }

    public boolean isShadowed() {

        return typeEnvsShadow != null;

    }

/* ************************************************************************

 * Visitor methods for phase 1: class enter

 *************************************************************************/

    /** Visitor argument: the current environment.

     */

    protected Env<AttrContext> env;

    /** Visitor result: the computed type.

     */

    Type result;

    /** Visitor method: enter all classes in given tree, catching any

     *  completion failure exceptions. Return the tree's type.

     *

     *  @param tree    The tree to be visited.

     *  @param env     The environment visitor argument.

     */

    Type classEnter(JCTree tree, Env<AttrContext> env) {

        Env<AttrContext> prevEnv = this.env;

        try {

            this.env = env;

            annotate.blockAnnotations();

            tree.accept(this);

            return result;

        }  catch (CompletionFailure ex) {

            return chk.completionError(tree.pos(), ex);

        } finally {

            annotate.unblockAnnotations();

            this.env = prevEnv;

        }

    }

    /** Visitor method: enter classes of a list of trees, returning a list of types.

     */

    <T extends JCTree> List<Type> classEnter(List<T> trees, Env<AttrContext> env) {

        ListBuffer<Type> ts = new ListBuffer<>();

        for (List<T> l = trees; l.nonEmpty(); l = l.tail) {

            Type t = classEnter(l.head, env);

            if (t != null)

                ts.append(t);

        }

        return ts.toList();

    }

    @Override

    public void visitTopLevel(JCCompilationUnit tree) {

//        Assert.checkNonNull(tree.modle, tree.sourcefile.toString());

        JavaFileObject prev = log.useSource(tree.sourcefile);

        boolean addEnv = false;

        boolean isPkgInfo = tree.sourcefile.isNameCompatible("package-info",

                                                             JavaFileObject.Kind.SOURCE);

        if (TreeInfo.isModuleInfo(tree)) {

            JCPackageDecl pd = tree.getPackage();

            if (pd != null) {

                log.error(pd.pos(), Errors.NoPkgInModuleInfoJava);

            }

            tree.packge = syms.rootPackage;

            Env<AttrContext> topEnv = topLevelEnv(tree);

            if (tree.modle != syms.noModule) {

                classEnter(tree.defs, topEnv);

                tree.modle.usesProvidesCompleter = modules.getUsesProvidesCompleter();

            }

        } else {

            JCPackageDecl pd = tree.getPackage();

            if (pd != null) {

                tree.packge = pd.packge = syms.enterPackage(tree.modle, TreeInfo.fullName(pd.pid));

                PackageAttributer.attrib(pd.pid, tree.packge);

                if (   pd.annotations.nonEmpty()

                    || pkginfoOpt == PkgInfo.ALWAYS

                    || tree.docComments != null) {

                    if (isPkgInfo) {

                        addEnv = true;

                    } else if (pd.annotations.nonEmpty()) {

                        log.error(pd.annotations.head.pos(),

                                  "pkg.annotations.sb.in.package-info.java");

                    }

                }

            } else {

                tree.packge = tree.modle.unnamedPackage;

            }

            Map<Name, PackageSymbol> visiblePackages = tree.modle.visiblePackages;

            Optional<ModuleSymbol> dependencyWithPackage =

                syms.listPackageModules(tree.packge.fullname)

                    .stream()

                    .filter(m -> m != tree.modle)

                    .filter(cand -> visiblePackages != null && visiblePackages.get(tree.packge.fullname) == syms.getPackage(cand, tree.packge.fullname))

                    .findAny();

            if (dependencyWithPackage.isPresent()) {

                log.error(pd, Errors.PackageInOtherModule(dependencyWithPackage.get()));

            }

            tree.packge.complete(); // Find all classes in package.

            Env<AttrContext> topEnv = topLevelEnv(tree);

            Env<AttrContext> packageEnv = isPkgInfo ? topEnv.dup(pd) : null;

            // Save environment of package-info.java file.

            if (isPkgInfo) {

                Env<AttrContext> env0 = typeEnvs.get(tree.packge);

                if (env0 != null) {

                    JCCompilationUnit tree0 = env0.toplevel;

                    if (!fileManager.isSameFile(tree.sourcefile, tree0.sourcefile)) {

                        log.warning(pd != null ? pd.pid.pos() : null,

                                    "pkg-info.already.seen",

                                    tree.packge);

                    }

                }

                typeEnvs.put(tree.packge, packageEnv);

                for (Symbol q = tree.packge; q != null && q.kind == PCK; q = q.owner)

                    q.flags_field |= EXISTS;

                Name name = names.package_info;

                ClassSymbol c = syms.enterClass(tree.modle, name, tree.packge);

                c.flatname = names.fromString(tree.packge + "." + name);

                c.sourcefile = tree.sourcefile;

                c.completer = Completer.NULL_COMPLETER;

                c.members_field = WriteableScope.create(c);

                tree.packge.package_info = c;

            }

            compilationUnits.put(tree.sourcefile.toUri(), tree);

            classEnter(tree.defs, topEnv);

            if (addEnv) {

                if ((tree.packge.flags_field & APT_CLEANED) != 0)

                    todo.remove(tree.packge);

                todo.append(packageEnv);

            }

        }

        log.useSource(prev);

        result = null;

    }

    private static class PackageAttributer extends TreeScanner {

        private Symbol pkg;

        public static void attrib(JCExpression pid, Symbol pkg) {

            PackageAttributer pa = new PackageAttributer();

            pa.pkg = pkg;

            pa.scan(pid);

        }

        @Override

        public void visitIdent(JCIdent that) {

            that.sym = pkg;

        }

        @Override

        public void visitSelect(JCFieldAccess that) {

            that.sym = pkg;

            pkg = pkg.owner;

            super.visitSelect(that);

        }

    }

    @Override

    public void visitClassDef(JCClassDecl tree) {

        Symbol owner = env.info.scope.owner;

        WriteableScope enclScope = enterScope(env);

        ClassSymbol c = null;

        boolean doEnterClass = true;

        boolean reattr=false, noctx=false;

        if (owner.kind == PCK) {

            // We are seeing a toplevel class.

            PackageSymbol packge = (PackageSymbol)owner;

            for (Symbol q = packge; q != null && q.kind == PCK; q = q.owner)

                q.flags_field |= EXISTS;

            c = syms.enterClass(env.toplevel.modle, tree.name, packge);

            packge.members().enterIfAbsent(c);

            if ((tree.mods.flags & PUBLIC) != 0 && !classNameMatchesFileName(c, env)) {

                KindName topElement = KindName.CLASS;

                if ((tree.mods.flags & ENUM) != 0) {

                    topElement = KindName.ENUM;

                } else if ((tree.mods.flags & INTERFACE) != 0) {

                    topElement = KindName.INTERFACE;

                }

                log.error(tree.pos(),

                          "class.public.should.be.in.file", topElement, tree.name);

            }

        } else {

            if ((enclScope.owner.flags_field & FROMCLASS) != 0) {

                for (Symbol sym : enclScope.getSymbolsByName(tree.name)) {

                    if (sym.kind == TYP) {

                        c = (ClassSymbol)sym;

                        break;

                    }

                }

                if (c != null) {

                    if (chk.getCompiled(c) != null) {

                        c = null;

                    } else {

                        reattr = true;

                        if (owner.kind == TYP) {

                            if ((owner.flags_field & INTERFACE) != 0) {

                                tree.mods.flags |= PUBLIC | STATIC;

                            }

                        }

                        doEnterClass = false;

                    }

                } else if ((enclScope.owner.flags_field & APT_CLEANED) == 0) {

                    ClassSymbol cs = enclScope.owner.outermostClass();

                    treeLoader.couplingError(cs, tree);

                    doEnterClass = false;

                }

            }

            if (c == null) {

                if (!tree.name.isEmpty() &&

                        !chk.checkUniqueClassName(tree.pos(), tree.name, enclScope)) {

                    result = types.createErrorType(tree.name, owner, Type.noType);

                    tree.sym = (ClassSymbol)result.tsym;

                    Env<AttrContext> localEnv = classEnv(tree, env);

                    typeEnvs.put(tree.sym, localEnv);

                    tree.sym.completer = typeEnter;

                    ((ClassType)result).typarams_field = classEnter(tree.typarams, localEnv);

                    if (!tree.sym.isLocal() && uncompleted != null) uncompleted.append(tree.sym);

                    tree.type = tree.sym.type;

                    return;

                }

                if (owner.kind == TYP || owner.kind == ERR) {

                    // We are seeing a member class.

                    c = syms.enterClass(env.toplevel.modle, tree.name, (TypeSymbol)owner);

                    if (c.owner != owner) {

                        //anonymous class loaded from a classfile may be recreated from source (see below)

                        //if this class is a member of such an anonymous class, fix the owner:

                        Assert.check(owner.owner.kind != TYP && owner.owner.kind != ERR, owner::toString);

                        Symbol own = c.owner;

                        Assert.check(c.owner.kind == TYP || c.owner.kind == ERR, own::toString);

                        ClassSymbol cowner = (ClassSymbol) c.owner;

                        if (cowner.members_field != null) {

                            cowner.members_field.remove(c);

                        }

                        c.owner = owner;

                    }

                    if ((owner.flags_field & INTERFACE) != 0) {

                        tree.mods.flags |= PUBLIC | STATIC;

                    }

                    Symbol q = owner;

                    while(q != null && q.kind.matches(KindSelector.TYP)) {

                        q = q.owner;

                    }

                    if (q != null && q.kind != PCK && chk.getCompiled(c) != null) {

                        reattr = true;

                    }

                } else {

                    // We are seeing a local class.

                    if (getIndex(tree) == -1) {

                        c = syms.defineClass(tree.name, owner);

                        c.flatname = chk.localClassName(c);

                        noctx = true;

                    }

                    else {

                        Name flatname = chk.localClassName(owner.enclClass(), tree.name, getIndex(tree));

                        if ((c=chk.getCompiled(env.toplevel.modle, flatname)) != null) {

                            reattr = true;

                        }

                        else {

                            c = syms.enterClass(env.toplevel.modle, flatname, tree.name, owner);

                            if (c.completer.isTerminal())

                                reattr = true;

                        }

                    }

                    if (!c.name.isEmpty())

                        chk.checkTransparentClass(tree.pos(), c, env.info.scope);

                }

            }

        }

        tree.sym = c;

        if (c.kind == ERR && c.type.isErroneous()) {

            c.flags_field &= ~FROMCLASS;

            c.kind = TYP;

            c.type = new ClassType(Type.noType, List.<Type>nil(), c);

        } else if (reattr && c.completer.isTerminal()) {

            new ElementScanner6<Void, Void>() {

                @Override

                public Void visitType(TypeElement te, Void p) {

                    if (te instanceof ClassSymbol && ((ClassSymbol) te).completer.isTerminal()) {

                        ((ClassSymbol) te).flags_field |= FROMCLASS;

                        for (Symbol sym : ((ClassSymbol) te).members().getSymbols()) {

                            try {

                                if (sym != null && sym.owner == te)

                                    scan(sym);

                            } catch (CompletionFailure cf) {}

                        }

                    }

                    return null;

                }

                @Override

                public Void visitExecutable(ExecutableElement ee, Void p) {

                    if (ee instanceof MethodSymbol)

                        ((MethodSymbol) ee).flags_field |= FROMCLASS;

                    return null;

                }

                @Override

                public Void visitVariable(VariableElement ve, Void p) {

                    if (ve instanceof VarSymbol)

                        ((VarSymbol) ve).flags_field |= FROMCLASS;

                    return null;

                }

            }.scan(c);

        }

        // Enter class into `compiled' table and enclosing scope.

        if (!reattr && !noctx && (chk.getCompiled(c) != null

                || (!c.isLocal() && duplicateClassChecker != null && duplicateClassChecker.check(c.fullname, env.toplevel.getSourceFile())))) {

            duplicateClass(tree.pos(), c);

            result = types.createErrorType(tree.name, owner, Type.noType);

            tree.sym = c = (ClassSymbol)result.tsym;

        } else {

            chk.putCompiled(c);

        }

        if (doEnterClass) {

            enclScope.enter(c);

        }

        if (typeEnvsShadow != null) {

            Env<AttrContext> localEnv = typeEnvs.get(c);

            typeEnvsShadow.put(c, localEnv);

        }

        // Set up an environment for class block and store in `typeEnvs'

        // table, to be retrieved later in memberEnter and attribution.

        Env<AttrContext> localEnv = classEnv(tree, env);

        typeEnvs.put(c, localEnv);

        // Fill out class fields.

        boolean notYetCompleted = !c.completer.isTerminal();

        c.completer = Completer.NULL_COMPLETER; // do not allow the initial completer linger on.

        c.sourcefile = env.toplevel.sourcefile;

        if (notYetCompleted || (c.flags_field & FROMCLASS) == 0 && (enclScope.owner.flags_field & FROMCLASS) == 0) {

            c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree);

            c.members_field = WriteableScope.create(c);

            ClassType ct = (ClassType)c.type;

            if (owner.kind != PCK && (c.flags_field & STATIC) == 0) {

                // We are seeing a local or inner class.

                // Set outer_field of this class to closest enclosing class

                // which contains this class in a non-static context

                // (its "enclosing instance class"), provided such a class exists.

                Symbol owner1 = owner;

                while (owner1.kind.matches(KindSelector.VAL_MTH) &&

                       (owner1.flags_field & STATIC) == 0) {

                    owner1 = owner1.owner;

                }

                if (owner1.kind == TYP) {

                    ct.setEnclosingType(owner1.type);

                }

            }

            // Enter type parameters.

            ct.typarams_field = classEnter(tree.typarams, localEnv);

            ct.allparams_field = null;

        } else {

            c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree) | (c.flags_field & (FROMCLASS | APT_CLEANED));

            ClassType ct = (ClassType)c.type;

            if (owner.kind != PCK && (c.flags_field & STATIC) == 0) {

                // We are seeing a local or inner class.

                // Set outer_field of this class to closest enclosing class

                // which contains this class in a non-static context

                // (its "enclosing instance class"), provided such a class exists.

                Symbol owner1 = owner;

                while (owner1.kind.matches(KindSelector.VAL_MTH) &&

                        (owner1.flags_field & STATIC) == 0) {

                    owner1 = owner1.owner;

                }

                if (owner1.kind == TYP) {

                    ct.setEnclosingType(owner1.type);

                }

            }

            boolean wasNull = false;

            if (ct.typarams_field != null) {

                for (List<Type> l = ct.typarams_field; l.nonEmpty(); l = l.tail)

                    localEnv.info.scope.enter(l.head.tsym);

            } else {

                wasNull = true;

            }

            List<Type> classEnter = classEnter(tree.typarams, localEnv);

            if (wasNull) {

                if (!classEnter.isEmpty()) {

                    //the symbol from class does not have any type parameters,

                    //but the symbol in the source code does:

                    ClassSymbol cs = env.info.scope.owner.outermostClass();

                    treeLoader.couplingError(cs, tree);

                } else {

                    ct.typarams_field = List.nil();

                    ct.allparams_field = null;

                }

            }

            if (c.members_field == null) {

                c.members_field = WriteableScope.create(c);

                c.flags_field &= ~FROMCLASS;

            }

            if (c.owner.kind.matches(KindSelector.VAL_MTH)) {

                // local or anonymous class

                for (Symbol ctor : c.members_field.getSymbolsByName(names.init)) {

                    c.members_field.remove(ctor);

                }

            }

       }

        // install further completer for this type.

        c.completer = typeEnter;

        // Add non-local class to uncompleted, to make sure it will be

        // completed later.

        if (!c.isLocal() && uncompleted != null) uncompleted.append(c);

//      System.err.println("entering " + c.fullname + " in " + c.owner);//DEBUG

        // Recursively enter all member classes.

        classEnter(tree.defs, localEnv);

        result = tree.type = c.type;

    }

    //where

        /** Does class have the same name as the file it appears in?

         */

        private static boolean classNameMatchesFileName(ClassSymbol c,

                                                        Env<AttrContext> env) {

            return env.toplevel.sourcefile.isNameCompatible(c.name.toString(),

                                                            JavaFileObject.Kind.SOURCE);

        }

    /** Complain about a duplicate class. */

    protected void duplicateClass(DiagnosticPosition pos, ClassSymbol c) {

        log.error(pos, "duplicate.class", c.fullname);

    }

    protected int getIndex(JCClassDecl clazz) {

        return -1;

    }

    /** Class enter visitor method for type parameters.

     *  Enter a symbol for type parameter in local scope, after checking that it

     *  is unique.

     */

    @Override

    public void visitTypeParameter(JCTypeParameter tree) {

        result = null;

        if ((env.info.scope.owner.flags_field & FROMCLASS) != 0) {

            for (Symbol sym : env.info.scope.getSymbolsByName(tree.name)) {

                if (sym.kind == TYP) {

                    result = sym.type;

                    tree.type = result;

                    break;

                }

            }

            if (result != null)

                return;

            if ((env.info.scope.owner.flags_field & APT_CLEANED) == 0) {

                ClassSymbol cs = env.info.scope.owner.outermostClass();

                treeLoader.couplingError(cs, tree);

            }

        }

        TypeVar a = (tree.type != null)

        ? (TypeVar)tree.type

                : new TypeVar(tree.name, env.info.scope.owner, syms.botType);

        tree.type = a;

        if (chk.checkUnique(tree.pos(), a.tsym, env.info.scope)) {

            env.info.scope.enter(a.tsym);

        }

        result = a;

    }

    @Override

    public void visitModuleDef(JCModuleDecl tree) {

        Env<AttrContext> moduleEnv = moduleEnv(tree, env);

        typeEnvs.put(tree.sym, moduleEnv);

        if (modules.isInModuleGraph(tree.sym)) {

            todo.append(moduleEnv);

        }

    }

    /** Default class enter visitor method: do nothing.

     */

    @Override

    public void visitTree(JCTree tree) {

        result = null;

    }

    /** Main method: enter all classes in a list of toplevel trees.

     *  @param trees      The list of trees to be processed.

     */

    public void main(List<JCCompilationUnit> trees) {

        complete(trees, null);

    }

    /** Main method: enter classes from the list of toplevel trees, possibly

     *  skipping TypeEnter for all but 'c' by placing them on the uncompleted

     *  list.

     *  @param trees      The list of trees to be processed.

     *  @param c          The class symbol to be processed or null to process all.

     */

    public void complete(List<JCCompilationUnit> trees, ClassSymbol c) {

        annotate.blockAnnotations();

        ListBuffer<ClassSymbol> prevUncompleted = uncompleted;

        if (typeEnter.completionEnabled) uncompleted = new ListBuffer<>();

        try {

            // enter all classes, and construct uncompleted list

            classEnter(trees, null);

            // complete all uncompleted classes in memberEnter

            if (typeEnter.completionEnabled) {

                while (uncompleted.nonEmpty()) {

                    ClassSymbol clazz = uncompleted.next();

                    if (c == null || c == clazz || prevUncompleted == null)

                        clazz.complete();

                    else

                        // defer

                        prevUncompleted.append(clazz);

                }

                if (!modules.modulesInitialized()) {

                    for (JCCompilationUnit cut : trees) {

                        if (TreeInfo.isModuleInfo(cut)) {

                            unfinishedModules.append(cut);

                        } else {

                            typeEnter.ensureImportsChecked(List.of(cut));

                        }

                    }

                } else {

                    typeEnter.ensureImportsChecked(unfinishedModules.toList());

                    unfinishedModules.clear();

                    typeEnter.ensureImportsChecked(trees);

                }

            }

        } finally {

            uncompleted = prevUncompleted;

            annotate.unblockAnnotations();

        }

    }

    public void newRound() {

        typeEnvs.clear();

    }

}