langtools/src/share/classes/com/sun/tools/javac/comp/Enter.java - edge/openjdk - Git at Google

 /*
  * 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.comp;

 import java.util.*;
 import javax.tools.JavaFileObject;
 import javax.tools.JavaFileManager;

 import com.sun.tools.javac.code.*;
 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.jvm.*;
 import com.sun.tools.javac.main.Option.PkgInfo;
 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.*;

 /** This class enters symbols for all encountered definitions into
  *  the symbol table. The pass consists of 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
  *  MemberEnter object as completer.
  *
  *  <p>In the second phase classes are completed using
  *  MemberEnter.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 (1) determination of a class's parameters, supertype and
  *  interfaces, as well as (2) entering all symbols defined in the
  *  class into its scope, with the exception of class symbols which
  *  have been entered in phase 1.  (2) depends on (1) having been
  *  completed for a class and all its superclasses and enclosing
  *  classes. That's why, after doing (1), we put classes in a
  *  `halfcompleted' queue. Only when we have performed (1) for a class
  *  and all it's superclasses and enclosing classes, we proceed to
  *  (2).
  *
  *  <p>Whereas the first phase is organized as a sweep through all
  *  compiled syntax trees, the second phase is 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 member-enter
  *  phase for the corresponding class tree.
  *
  *  <p>Classes migrate from one phase to the next via queues:
  *
  *  <pre>{@literal
  *  class enter -> (Enter.uncompleted)         --> member enter (1)
  *              -> (MemberEnter.halfcompleted) --> member enter (2)
  *              -> (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<Enter>();

     Log log;
     Symtab syms;
     Check chk;
     TreeMaker make;
     ClassReader reader;
     Annotate annotate;
     MemberEnter memberEnter;
     Types types;
     Lint lint;
     Names names;
     JavaFileManager fileManager;
     PkgInfo pkginfoOpt;
     TypeEnvs typeEnvs;

     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);
         reader = ClassReader.instance(context);
         make = TreeMaker.instance(context);
         syms = Symtab.instance(context);
         chk = Check.instance(context);
         memberEnter = MemberEnter.instance(context);
         types = Types.instance(context);
         annotate = Annotate.instance(context);
         lint = Lint.instance(context);
         names = Names.instance(context);

         predefClassDef = make.ClassDef(
             make.Modifiers(PUBLIC),
             syms.predefClass.name,
             List.<JCTypeParameter>nil(),
             null,
             List.<JCExpression>nil(),
             List.<JCTree>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);
     }

     /** Accessor for typeEnvs
      */
     public Env<AttrContext> getEnv(TypeSymbol sym) {
         return typeEnvs.get(sym);
     }

     public Env<AttrContext> getClassEnv(TypeSymbol sym) {
         Env<AttrContext> localEnv = getEnv(sym);
         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;

     /** 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(new Scope(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
         return localEnv;
     }

     /** Create a fresh environment for toplevels.
      *  @param tree     The toplevel tree.
      */
     Env<AttrContext> topLevelEnv(JCCompilationUnit tree) {
         Env<AttrContext> localEnv = new Env<AttrContext>(tree, new AttrContext());
         localEnv.toplevel = tree;
         localEnv.enclClass = predefClassDef;
         tree.namedImportScope = new ImportScope(tree.packge);
         tree.starImportScope = new StarImportScope(tree.packge);
         localEnv.info.scope = tree.namedImportScope;
         localEnv.info.lint = lint;
         return localEnv;
     }

     public Env<AttrContext> getTopLevelEnv(JCCompilationUnit tree) {
         Env<AttrContext> localEnv = new Env<AttrContext>(tree, new AttrContext());
         localEnv.toplevel = tree;
         localEnv.enclClass = predefClassDef;
         localEnv.info.scope = tree.namedImportScope;
         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.
      */
     Scope enterScope(Env<AttrContext> env) {
         return (env.tree.hasTag(JCTree.Tag.CLASSDEF))
             ? ((JCClassDecl) env.tree).sym.members_field
             : env.info.scope;
     }

 /* ************************************************************************
  * 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;
             tree.accept(this);
             return result;
         }  catch (CompletionFailure ex) {
             return chk.completionError(tree.pos(), ex);
         } finally {
             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<Type>();
         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) {
         JavaFileObject prev = log.useSource(tree.sourcefile);
         boolean addEnv = false;
         boolean isPkgInfo = tree.sourcefile.isNameCompatible("package-info",
                                                              JavaFileObject.Kind.SOURCE);
         if (tree.pid != null) {
             tree.packge = reader.enterPackage(TreeInfo.fullName(tree.pid));
             if (tree.packageAnnotations.nonEmpty()
                     || pkginfoOpt == PkgInfo.ALWAYS
                     || tree.docComments != null) {
                 if (isPkgInfo) {
                     addEnv = true;
                 } else if (tree.packageAnnotations.nonEmpty()){
                     log.error(tree.packageAnnotations.head.pos(),
                               "pkg.annotations.sb.in.package-info.java");
                 }
             }
         } else {
             tree.packge = syms.unnamedPackage;
         }
         tree.packge.complete(); // Find all classes in package.
         Env<AttrContext> topEnv = topLevelEnv(tree);

         // Save environment of package-info.java file.
         if (isPkgInfo) {
             Env<AttrContext> env0 = typeEnvs.get(tree.packge);
             if (env0 == null) {
                 typeEnvs.put(tree.packge, topEnv);
             } else {
                 JCCompilationUnit tree0 = env0.toplevel;
                 if (!fileManager.isSameFile(tree.sourcefile, tree0.sourcefile)) {
                     log.warning(tree.pid != null ? tree.pid.pos()
                                                  : null,
                                 "pkg-info.already.seen",
                                 tree.packge);
                     if (addEnv || (tree0.packageAnnotations.isEmpty() &&
                                    tree.docComments != null &&
                                    tree.docComments.hasComment(tree))) {
                         typeEnvs.put(tree.packge, topEnv);
                     }
                 }
             }

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

             Name name = names.package_info;
             ClassSymbol c = reader.enterClass(name, tree.packge);
             c.flatname = names.fromString(tree.packge + "." + name);
             c.sourcefile = tree.sourcefile;
             c.completer = null;
             c.members_field = new Scope(c);
             tree.packge.package_info = c;
         }
         classEnter(tree.defs, topEnv);
         if (addEnv) {
             todo.append(topEnv);
         }
         log.useSource(prev);
         result = null;
     }

     @Override
     public void visitClassDef(JCClassDecl tree) {
         Symbol owner = env.info.scope.owner;
         Scope enclScope = enterScope(env);
         ClassSymbol c;
         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 = reader.enterClass(tree.name, packge);
             packge.members().enterIfAbsent(c);
             if ((tree.mods.flags & PUBLIC) != 0 && !classNameMatchesFileName(c, env)) {
                 log.error(tree.pos(),
                           "class.public.should.be.in.file", tree.name);
             }
         } else {
             if (!tree.name.isEmpty() &&
                 !chk.checkUniqueClassName(tree.pos(), tree.name, enclScope)) {
                 result = null;
                 return;
             }
             if (owner.kind == TYP) {
                 // We are seeing a member class.
                 c = reader.enterClass(tree.name, (TypeSymbol)owner);
                 if ((owner.flags_field & INTERFACE) != 0) {
                     tree.mods.flags |= PUBLIC | STATIC;
                 }
             } else {
                 // We are seeing a local class.
                 c = reader.defineClass(tree.name, owner);
                 c.flatname = chk.localClassName(c);
                 if (!c.name.isEmpty())
                     chk.checkTransparentClass(tree.pos(), c, env.info.scope);
             }
         }
         tree.sym = c;

         // Enter class into `compiled' table and enclosing scope.
         if (chk.compiled.get(c.flatname) != null) {
             duplicateClass(tree.pos(), c);
             result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);
             tree.sym = (ClassSymbol)result.tsym;
             return;
         }
         chk.compiled.put(c.flatname, c);
         enclScope.enter(c);

         // 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.
         c.completer = memberEnter;
         c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree);
         c.sourcefile = env.toplevel.sourcefile;
         c.members_field = new Scope(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 & (VAR | MTH)) != 0 &&
                    (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);

         // 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 = 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);
     }

     /** 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) {
         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;
     }

     /** 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 one class from a list of toplevel trees and
      *  place the rest on uncompleted for later processing.
      *  @param trees      The list of trees to be processed.
      *  @param c          The class symbol to be processed.
      */
     public void complete(List<JCCompilationUnit> trees, ClassSymbol c) {
         annotate.enterStart();
         ListBuffer<ClassSymbol> prevUncompleted = uncompleted;
         if (memberEnter.completionEnabled) uncompleted = new ListBuffer<ClassSymbol>();

         try {
             // enter all classes, and construct uncompleted list
             classEnter(trees, null);

             // complete all uncompleted classes in memberEnter
             if  (memberEnter.completionEnabled) {
                 while (uncompleted.nonEmpty()) {
                     ClassSymbol clazz = uncompleted.next();
                     if (c == null || c == clazz || prevUncompleted == null)
                         clazz.complete();
                     else
                         // defer
                         prevUncompleted.append(clazz);
                 }

                 // if there remain any unimported toplevels (these must have
                 // no classes at all), process their import statements as well.
                 for (JCCompilationUnit tree : trees) {
                     if (tree.starImportScope.elems == null) {
                         JavaFileObject prev = log.useSource(tree.sourcefile);
                         Env<AttrContext> topEnv = topLevelEnv(tree);
                         memberEnter.memberEnter(tree, topEnv);
                         log.useSource(prev);
                     }
                 }
             }
         } finally {
             uncompleted = prevUncompleted;
             annotate.enterDone();
         }
     }
 }
	/*
	* 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.comp;

	import java.util.*;
	import javax.tools.JavaFileObject;
	import javax.tools.JavaFileManager;

	import com.sun.tools.javac.code.*;
	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.jvm.*;
	import com.sun.tools.javac.main.Option.PkgInfo;
	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.*;

	/** This class enters symbols for all encountered definitions into
	* the symbol table. The pass consists of 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
	* MemberEnter object as completer.
	*
	* <p>In the second phase classes are completed using
	* MemberEnter.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 (1) determination of a class's parameters, supertype and
	* interfaces, as well as (2) entering all symbols defined in the
	* class into its scope, with the exception of class symbols which
	* have been entered in phase 1. (2) depends on (1) having been
	* completed for a class and all its superclasses and enclosing
	* classes. That's why, after doing (1), we put classes in a
	* `halfcompleted' queue. Only when we have performed (1) for a class
	* and all it's superclasses and enclosing classes, we proceed to
	* (2).
	*
	* <p>Whereas the first phase is organized as a sweep through all
	* compiled syntax trees, the second phase is 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 member-enter
	* phase for the corresponding class tree.
	*
	* <p>Classes migrate from one phase to the next via queues:
	*
	* <pre>{@literal
	* class enter -> (Enter.uncompleted) --> member enter (1)
	* -> (MemberEnter.halfcompleted) --> member enter (2)
	* -> (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<Enter>();

	Log log;
	Symtab syms;
	Check chk;
	TreeMaker make;
	ClassReader reader;
	Annotate annotate;
	MemberEnter memberEnter;
	Types types;
	Lint lint;
	Names names;
	JavaFileManager fileManager;
	PkgInfo pkginfoOpt;
	TypeEnvs typeEnvs;

	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);
	reader = ClassReader.instance(context);
	make = TreeMaker.instance(context);
	syms = Symtab.instance(context);
	chk = Check.instance(context);
	memberEnter = MemberEnter.instance(context);
	types = Types.instance(context);
	annotate = Annotate.instance(context);
	lint = Lint.instance(context);
	names = Names.instance(context);

	predefClassDef = make.ClassDef(
	make.Modifiers(PUBLIC),
	syms.predefClass.name,
	List.<JCTypeParameter>nil(),
	null,
	List.<JCExpression>nil(),
	List.<JCTree>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);
	}

	/** Accessor for typeEnvs
	*/
	public Env<AttrContext> getEnv(TypeSymbol sym) {
	return typeEnvs.get(sym);
	}

	public Env<AttrContext> getClassEnv(TypeSymbol sym) {
	Env<AttrContext> localEnv = getEnv(sym);
	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;

	/** 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(new Scope(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
	return localEnv;
	}

	/** Create a fresh environment for toplevels.
	* @param tree The toplevel tree.
	*/
	Env<AttrContext> topLevelEnv(JCCompilationUnit tree) {
	Env<AttrContext> localEnv = new Env<AttrContext>(tree, new AttrContext());
	localEnv.toplevel = tree;
	localEnv.enclClass = predefClassDef;
	tree.namedImportScope = new ImportScope(tree.packge);
	tree.starImportScope = new StarImportScope(tree.packge);
	localEnv.info.scope = tree.namedImportScope;
	localEnv.info.lint = lint;
	return localEnv;
	}

	public Env<AttrContext> getTopLevelEnv(JCCompilationUnit tree) {
	Env<AttrContext> localEnv = new Env<AttrContext>(tree, new AttrContext());
	localEnv.toplevel = tree;
	localEnv.enclClass = predefClassDef;
	localEnv.info.scope = tree.namedImportScope;
	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.
	*/
	Scope enterScope(Env<AttrContext> env) {
	return (env.tree.hasTag(JCTree.Tag.CLASSDEF))
	? ((JCClassDecl) env.tree).sym.members_field
	: env.info.scope;
	}

	/* ************************************************************************
	* 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;
	tree.accept(this);
	return result;
	} catch (CompletionFailure ex) {
	return chk.completionError(tree.pos(), ex);
	} finally {
	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<Type>();
	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) {
	JavaFileObject prev = log.useSource(tree.sourcefile);
	boolean addEnv = false;
	boolean isPkgInfo = tree.sourcefile.isNameCompatible("package-info",
	JavaFileObject.Kind.SOURCE);
	if (tree.pid != null) {
	tree.packge = reader.enterPackage(TreeInfo.fullName(tree.pid));
	if (tree.packageAnnotations.nonEmpty()
	\|\| pkginfoOpt == PkgInfo.ALWAYS
	\|\| tree.docComments != null) {
	if (isPkgInfo) {
	addEnv = true;
	} else if (tree.packageAnnotations.nonEmpty()){
	log.error(tree.packageAnnotations.head.pos(),
	"pkg.annotations.sb.in.package-info.java");
	}
	}
	} else {
	tree.packge = syms.unnamedPackage;
	}
	tree.packge.complete(); // Find all classes in package.
	Env<AttrContext> topEnv = topLevelEnv(tree);

	// Save environment of package-info.java file.
	if (isPkgInfo) {
	Env<AttrContext> env0 = typeEnvs.get(tree.packge);
	if (env0 == null) {
	typeEnvs.put(tree.packge, topEnv);
	} else {
	JCCompilationUnit tree0 = env0.toplevel;
	if (!fileManager.isSameFile(tree.sourcefile, tree0.sourcefile)) {
	log.warning(tree.pid != null ? tree.pid.pos()
	: null,
	"pkg-info.already.seen",
	tree.packge);
	if (addEnv \|\| (tree0.packageAnnotations.isEmpty() &&
	tree.docComments != null &&
	tree.docComments.hasComment(tree))) {
	typeEnvs.put(tree.packge, topEnv);
	}
	}
	}

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

	Name name = names.package_info;
	ClassSymbol c = reader.enterClass(name, tree.packge);
	c.flatname = names.fromString(tree.packge + "." + name);
	c.sourcefile = tree.sourcefile;
	c.completer = null;
	c.members_field = new Scope(c);
	tree.packge.package_info = c;
	}
	classEnter(tree.defs, topEnv);
	if (addEnv) {
	todo.append(topEnv);
	}
	log.useSource(prev);
	result = null;
	}

	@Override
	public void visitClassDef(JCClassDecl tree) {
	Symbol owner = env.info.scope.owner;
	Scope enclScope = enterScope(env);
	ClassSymbol c;
	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 = reader.enterClass(tree.name, packge);
	packge.members().enterIfAbsent(c);
	if ((tree.mods.flags & PUBLIC) != 0 && !classNameMatchesFileName(c, env)) {
	log.error(tree.pos(),
	"class.public.should.be.in.file", tree.name);
	}
	} else {
	if (!tree.name.isEmpty() &&
	!chk.checkUniqueClassName(tree.pos(), tree.name, enclScope)) {
	result = null;
	return;
	}
	if (owner.kind == TYP) {
	// We are seeing a member class.
	c = reader.enterClass(tree.name, (TypeSymbol)owner);
	if ((owner.flags_field & INTERFACE) != 0) {
	tree.mods.flags \|= PUBLIC \| STATIC;
	}
	} else {
	// We are seeing a local class.
	c = reader.defineClass(tree.name, owner);
	c.flatname = chk.localClassName(c);
	if (!c.name.isEmpty())
	chk.checkTransparentClass(tree.pos(), c, env.info.scope);
	}
	}
	tree.sym = c;

	// Enter class into `compiled' table and enclosing scope.
	if (chk.compiled.get(c.flatname) != null) {
	duplicateClass(tree.pos(), c);
	result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);
	tree.sym = (ClassSymbol)result.tsym;
	return;
	}
	chk.compiled.put(c.flatname, c);
	enclScope.enter(c);

	// 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.
	c.completer = memberEnter;
	c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree);
	c.sourcefile = env.toplevel.sourcefile;
	c.members_field = new Scope(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 & (VAR \| MTH)) != 0 &&
	(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);

	// 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 = 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);
	}

	/** 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) {
	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;
	}

	/** 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 one class from a list of toplevel trees and
	* place the rest on uncompleted for later processing.
	* @param trees The list of trees to be processed.
	* @param c The class symbol to be processed.
	*/
	public void complete(List<JCCompilationUnit> trees, ClassSymbol c) {
	annotate.enterStart();
	ListBuffer<ClassSymbol> prevUncompleted = uncompleted;
	if (memberEnter.completionEnabled) uncompleted = new ListBuffer<ClassSymbol>();

	try {
	// enter all classes, and construct uncompleted list
	classEnter(trees, null);

	// complete all uncompleted classes in memberEnter
	if (memberEnter.completionEnabled) {
	while (uncompleted.nonEmpty()) {
	ClassSymbol clazz = uncompleted.next();
	if (c == null \|\| c == clazz \|\| prevUncompleted == null)
	clazz.complete();
	else
	// defer
	prevUncompleted.append(clazz);
	}

	// if there remain any unimported toplevels (these must have
	// no classes at all), process their import statements as well.
	for (JCCompilationUnit tree : trees) {
	if (tree.starImportScope.elems == null) {
	JavaFileObject prev = log.useSource(tree.sourcefile);
	Env<AttrContext> topEnv = topLevelEnv(tree);
	memberEnter.memberEnter(tree, topEnv);
	log.useSource(prev);
	}
	}
	}
	} finally {
	uncompleted = prevUncompleted;
	annotate.enterDone();
	}
	}
	}