Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 1999, 2012, 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 com.sun.tools.javac.code.*;

 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.util.*;

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

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

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

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

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

 import com.sun.tools.javac.jvm.Target;

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

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

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

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

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

 import static com.sun.tools.javac.jvm.ByteCodes.*;

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

 /** This pass translates away some syntactic sugar: inner classes,

  *  class literals, assertions, foreach loops, etc.

  *

  *  <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 Lower extends TreeTranslator {

     protected static final Context.Key<Lower> lowerKey =

         new Context.Key<Lower>();

     public static Lower instance(Context context) {

         Lower instance = context.get(lowerKey);

         if (instance == null)

             instance = new Lower(context);

         return instance;

     }

     private Names names;

     private Log log;

     private Symtab syms;

     private Resolve rs;

     private Check chk;

     private Attr attr;

     private TreeMaker make;

     private DiagnosticPosition make_pos;

     private ClassWriter writer;

     private ClassReader reader;

     private ConstFold cfolder;

     private Target target;

     private Source source;

     private boolean allowEnums;

     private final Name dollarAssertionsDisabled;

     private final Name classDollar;

     private Types types;

     private boolean debugLower;

     private PkgInfo pkginfoOpt;

     protected Lower(Context context) {

         context.put(lowerKey, this);

         names = Names.instance(context);

         log = Log.instance(context);

         syms = Symtab.instance(context);

         rs = Resolve.instance(context);

         chk = Check.instance(context);

         attr = Attr.instance(context);

         make = TreeMaker.instance(context);

         writer = ClassWriter.instance(context);

         reader = ClassReader.instance(context);

         cfolder = ConstFold.instance(context);

         target = Target.instance(context);

         source = Source.instance(context);

         allowEnums = source.allowEnums();

         dollarAssertionsDisabled = names.

             fromString(target.syntheticNameChar() + "assertionsDisabled");

         classDollar = names.

             fromString("class" + target.syntheticNameChar());

         types = Types.instance(context);

         Options options = Options.instance(context);

         debugLower = options.isSet("debuglower");

         pkginfoOpt = PkgInfo.get(options);

     }

     /** The currently enclosing class.

      */

     ClassSymbol currentClass;

     /** A queue of all translated classes.

      */

     ListBuffer<JCTree> translated;

     /** Environment for symbol lookup, set by translateTopLevelClass.

      */

     Env<AttrContext> attrEnv;

     /** A hash table mapping syntax trees to their ending source positions.

      */

     EndPosTable endPosTable;

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

  * Global mappings

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

     /** A hash table mapping local classes to their definitions.

      */

     Map<ClassSymbol, JCClassDecl> classdefs;

     /** A hash table mapping local classes to a list of pruned trees.

      */

     public Map<ClassSymbol, List<JCTree>> prunedTree = new WeakHashMap<ClassSymbol, List<JCTree>>();

     /** A hash table mapping virtual accessed symbols in outer subclasses

      *  to the actually referred symbol in superclasses.

      */

     Map<Symbol,Symbol> actualSymbols;

     /** The current method definition.

      */

     JCMethodDecl currentMethodDef;

     /** The current method symbol.

      */

     MethodSymbol currentMethodSym;

     /** The currently enclosing outermost class definition.

      */

     JCClassDecl outermostClassDef;

     /** The currently enclosing outermost member definition.

      */

     JCTree outermostMemberDef;

     /** A navigator class for assembling a mapping from local class symbols

      *  to class definition trees.

      *  There is only one case; all other cases simply traverse down the tree.

      */

     class ClassMap extends TreeScanner {

         /** All encountered class defs are entered into classdefs table.

          */

         public void visitClassDef(JCClassDecl tree) {

             classdefs.put(tree.sym, tree);

             super.visitClassDef(tree);

         }

     }

     ClassMap classMap = new ClassMap();

     /** Map a class symbol to its definition.

      *  @param c    The class symbol of which we want to determine the definition.

      */

     JCClassDecl classDef(ClassSymbol c) {

         // First lookup the class in the classdefs table.

         JCClassDecl def = classdefs.get(c);

         if (def == null && outermostMemberDef != null) {

             // If this fails, traverse outermost member definition, entering all

             // local classes into classdefs, and try again.

             classMap.scan(outermostMemberDef);

             def = classdefs.get(c);

         }

         if (def == null) {

             // If this fails, traverse outermost class definition, entering all

             // local classes into classdefs, and try again.

             classMap.scan(outermostClassDef);

             def = classdefs.get(c);

         }

         return def;

     }

     /** A hash table mapping class symbols to lists of free variables.

      *  accessed by them. Only free variables of the method immediately containing

      *  a class are associated with that class.

      */

     Map<ClassSymbol,List<VarSymbol>> freevarCache;

     /** A navigator class for collecting the free variables accessed

      *  from a local class.

      *  There is only one case; all other cases simply traverse down the tree.

      */

     class FreeVarCollector extends TreeScanner {

         /** The owner of the local class.

          */

         Symbol owner;

         /** The local class.

          */

         ClassSymbol clazz;

         /** The list of owner's variables accessed from within the local class,

          *  without any duplicates.

          */

         List<VarSymbol> fvs;

         FreeVarCollector(ClassSymbol clazz) {

             this.clazz = clazz;

             this.owner = clazz.owner;

             this.fvs = List.nil();

         }

         /** Add free variable to fvs list unless it is already there.

          */

         private void addFreeVar(VarSymbol v) {

             for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail)

                 if (l.head == v) return;

             fvs = fvs.prepend(v);

         }

         /** Add all free variables of class c to fvs list

          *  unless they are already there.

          */

         private void addFreeVars(ClassSymbol c) {

             List<VarSymbol> fvs = freevarCache.get(c);

             if (fvs != null) {

                 for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail) {

                     addFreeVar(l.head);

                 }

             }

         }

         /** If tree refers to a variable in owner of local class, add it to

          *  free variables list.

          */

         public void visitIdent(JCIdent tree) {

             result = tree;

             visitSymbol(tree.sym);

         }

         // where

         private void visitSymbol(Symbol _sym) {

             Symbol sym = _sym;

             if (sym.kind == VAR || sym.kind == MTH) {

                 while (sym != null && sym.owner != owner)

                     sym = proxies.lookup(proxyName(sym.name)).sym;

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

                     VarSymbol v = (VarSymbol)sym;

                     if (v.getConstValue() == null) {

                         addFreeVar(v);

                     }

                 } else {

                     if (outerThisStack.head != null &&

                         outerThisStack.head != _sym)

                         visitSymbol(outerThisStack.head);

                 }

             }

         }

         /** If tree refers to a class instance creation expression

          *  add all free variables of the freshly created class.

          */

         public void visitNewClass(JCNewClass tree) {

             ClassSymbol c = (ClassSymbol)tree.constructor.owner;

             addFreeVars(c);

             if (tree.encl == null &&

                 c.hasOuterInstance() &&

                 outerThisStack.head != null)

                 visitSymbol(outerThisStack.head);

             super.visitNewClass(tree);

         }

         /** If tree refers to a qualified this or super expression

          *  for anything but the current class, add the outer this

          *  stack as a free variable.

          */

         public void visitSelect(JCFieldAccess tree) {

             if ((tree.name == names._this || tree.name == names._super) &&

                 tree.selected.type.tsym != clazz &&

                 outerThisStack.head != null)

                 visitSymbol(outerThisStack.head);

             super.visitSelect(tree);

         }

         /** If tree refers to a superclass constructor call,

          *  add all free variables of the superclass.

          */

         public void visitApply(JCMethodInvocation tree) {

             if (TreeInfo.name(tree.meth) == names._super) {

                 addFreeVars((ClassSymbol) TreeInfo.symbol(tree.meth).owner);

                 Symbol constructor = TreeInfo.symbol(tree.meth);

                 ClassSymbol c = (ClassSymbol)constructor.owner;

                 if (c.hasOuterInstance() &&

                     !tree.meth.hasTag(SELECT) &&

                     outerThisStack.head != null)

                     visitSymbol(outerThisStack.head);

             }

             super.visitApply(tree);

         }

     }

     /** Return the variables accessed from within a local class, which

      *  are declared in the local class' owner.

      *  (in reverse order of first access).

      */

     List<VarSymbol> freevars(ClassSymbol c)  {

         if ((c.owner.kind & (VAR | MTH)) != 0) {

             List<VarSymbol> fvs = freevarCache.get(c);

             if (fvs == null) {

                 FreeVarCollector collector = new FreeVarCollector(c);

                 collector.scan(classDef(c));

                 fvs = collector.fvs;

                 freevarCache.put(c, fvs);

             }

             return fvs;

         } else {

             return List.nil();

         }

     }

     Map<TypeSymbol,EnumMapping> enumSwitchMap = new LinkedHashMap<TypeSymbol,EnumMapping>();

     EnumMapping mapForEnum(DiagnosticPosition pos, TypeSymbol enumClass) {

         EnumMapping map = enumSwitchMap.get(enumClass);

         if (map == null)

             enumSwitchMap.put(enumClass, map = new EnumMapping(pos, enumClass));

         return map;

     }

     /** This map gives a translation table to be used for enum

      *  switches.

      *

      *  <p>For each enum that appears as the type of a switch

      *  expression, we maintain an EnumMapping to assist in the

      *  translation, as exemplified by the following example:

      *

      *  <p>we translate

      *  <pre>

      *          switch(colorExpression) {

      *          case red: stmt1;

      *          case green: stmt2;

      *          }

      *  </pre>

      *  into

      *  <pre>

      *          switch(Outer$0.$EnumMap$Color[colorExpression.ordinal()]) {

      *          case 1: stmt1;

      *          case 2: stmt2

      *          }

      *  </pre>

      *  with the auxiliary table initialized as follows:

      *  <pre>

      *          class Outer$0 {

      *              synthetic final int[] $EnumMap$Color = new int[Color.values().length];

      *              static {

      *                  try { $EnumMap$Color[red.ordinal()] = 1; } catch (NoSuchFieldError ex) {}

      *                  try { $EnumMap$Color[green.ordinal()] = 2; } catch (NoSuchFieldError ex) {}

      *              }

      *          }

      *  </pre>

      *  class EnumMapping provides mapping data and support methods for this translation.

      */

     class EnumMapping {

         EnumMapping(DiagnosticPosition pos, TypeSymbol forEnum) {

             this.forEnum = forEnum;

             this.values = new LinkedHashMap<VarSymbol,Integer>();

             this.pos = pos;

             Name varName = names

                 .fromString(target.syntheticNameChar() +

                             "SwitchMap" +

                             target.syntheticNameChar() +

                             writer.xClassName(forEnum.type).toString()

                             .replace('/', '.')

                             .replace('.', target.syntheticNameChar()));

             ClassSymbol outerCacheClass = outerCacheClass();

             this.mapVar = new VarSymbol(STATIC | SYNTHETIC | FINAL,

                                         varName,

                                         new ArrayType(syms.intType, syms.arrayClass),

                                         outerCacheClass);

             enterSynthetic(pos, mapVar, outerCacheClass.members());

         }

         DiagnosticPosition pos = null;

         // the next value to use

         int next = 1; // 0 (unused map elements) go to the default label

         // the enum for which this is a map

         final TypeSymbol forEnum;

         // the field containing the map

         final VarSymbol mapVar;

         // the mapped values

         final Map<VarSymbol,Integer> values;

         JCLiteral forConstant(VarSymbol v) {

             Integer result = values.get(v);

             if (result == null)

                 values.put(v, result = next++);

             return make.Literal(result);

         }

         // generate the field initializer for the map

         void translate() {

             make.at(pos.getStartPosition());

             JCClassDecl owner = classDef((ClassSymbol)mapVar.owner);

             // synthetic static final int[] $SwitchMap$Color = new int[Color.values().length];

             MethodSymbol valuesMethod = lookupMethod(pos,

                                                      names.values,

                                                      forEnum.type,

                                                      List.<Type>nil());

             JCExpression size = make // Color.values().length

                 .Select(make.App(make.QualIdent(valuesMethod)),

                         syms.lengthVar);

             JCExpression mapVarInit = make

                 .NewArray(make.Type(syms.intType), List.of(size), null)

                 .setType(new ArrayType(syms.intType, syms.arrayClass));

             // try { $SwitchMap$Color[red.ordinal()] = 1; } catch (java.lang.NoSuchFieldError ex) {}

             ListBuffer<JCStatement> stmts = new ListBuffer<JCStatement>();

             Symbol ordinalMethod = lookupMethod(pos,

                                                 names.ordinal,

                                                 forEnum.type,

                                                 List.<Type>nil());

             List<JCCatch> catcher = List.<JCCatch>nil()

                 .prepend(make.Catch(make.VarDef(new VarSymbol(PARAMETER, names.ex,

                                                               syms.noSuchFieldErrorType,

                                                               syms.noSymbol),

                                                 null),

                                     make.Block(0, List.<JCStatement>nil())));

             for (Map.Entry<VarSymbol,Integer> e : values.entrySet()) {

                 VarSymbol enumerator = e.getKey();

                 Integer mappedValue = e.getValue();

                 JCExpression assign = make

                     .Assign(make.Indexed(mapVar,

                                          make.App(make.Select(make.QualIdent(enumerator),

                                                               ordinalMethod))),

                             make.Literal(mappedValue))

                     .setType(syms.intType);

                 JCStatement exec = make.Exec(assign);

                 JCStatement _try = make.Try(make.Block(0, List.of(exec)), catcher, null);

                 stmts.append(_try);

             }

             owner.defs = owner.defs

                 .prepend(make.Block(STATIC, stmts.toList()))

                 .prepend(make.VarDef(mapVar, mapVarInit));

         }

     }

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

  * Tree building blocks

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

     /** Equivalent to make.at(pos.getStartPosition()) with side effect of caching

      *  pos as make_pos, for use in diagnostics.

      **/

     TreeMaker make_at(DiagnosticPosition pos) {

         make_pos = pos;

         return make.at(pos);

     }

     /** Make an attributed tree representing a literal. This will be an

      *  Ident node in the case of boolean literals, a Literal node in all

      *  other cases.

      *  @param type       The literal's type.

      *  @param value      The literal's value.

      */

     JCExpression makeLit(Type type, Object value) {

         return make.Literal(type.getTag(), value).setType(type.constType(value));

     }

     /** Make an attributed tree representing null.

      */

     JCExpression makeNull() {

         return makeLit(syms.botType, null);

     }

     /** Make an attributed class instance creation expression.

      *  @param ctype    The class type.

      *  @param args     The constructor arguments.

      */

     JCNewClass makeNewClass(Type ctype, List<JCExpression> args) {

         JCNewClass tree = make.NewClass(null,

             null, make.QualIdent(ctype.tsym), args, null);

         tree.constructor = rs.resolveConstructor(

             make_pos, attrEnv, ctype, TreeInfo.types(args), List.<Type>nil());

         tree.type = ctype;

         return tree;

     }

     /** Make an attributed unary expression.

      *  @param optag    The operators tree tag.

      *  @param arg      The operator's argument.

      */

     JCUnary makeUnary(JCTree.Tag optag, JCExpression arg) {

         JCUnary tree = make.Unary(optag, arg);

         tree.operator = rs.resolveUnaryOperator(

             make_pos, optag, attrEnv, arg.type);

         tree.type = tree.operator.type.getReturnType();

         return tree;

     }

     /** Make an attributed binary expression.

      *  @param optag    The operators tree tag.

      *  @param lhs      The operator's left argument.

      *  @param rhs      The operator's right argument.

      */

     JCBinary makeBinary(JCTree.Tag optag, JCExpression lhs, JCExpression rhs) {

         JCBinary tree = make.Binary(optag, lhs, rhs);

         tree.operator = rs.resolveBinaryOperator(

             make_pos, optag, attrEnv, lhs.type, rhs.type);

         tree.type = tree.operator.type.getReturnType();

         return tree;

     }

     /** Make an attributed assignop expression.

      *  @param optag    The operators tree tag.

      *  @param lhs      The operator's left argument.

      *  @param rhs      The operator's right argument.

      */

     JCAssignOp makeAssignop(JCTree.Tag optag, JCTree lhs, JCTree rhs) {

         JCAssignOp tree = make.Assignop(optag, lhs, rhs);

         tree.operator = rs.resolveBinaryOperator(

             make_pos, tree.getTag().noAssignOp(), attrEnv, lhs.type, rhs.type);

         tree.type = lhs.type;

         return tree;

     }

     /** Convert tree into string object, unless it has already a

      *  reference type..

      */

     JCExpression makeString(JCExpression tree) {

         if (!tree.type.isPrimitiveOrVoid()) {

             return tree;

         } else {

             Symbol valueOfSym = lookupMethod(tree.pos(),

                                              names.valueOf,

                                              syms.stringType,

                                              List.of(tree.type));

             return make.App(make.QualIdent(valueOfSym), List.of(tree));

         }

     }

     /** Create an empty anonymous class definition and enter and complete

      *  its symbol. Return the class definition's symbol.

      *  and create

      *  @param flags    The class symbol's flags

      *  @param owner    The class symbol's owner

      */

     ClassSymbol makeEmptyClass(long flags, ClassSymbol owner) {

         // Create class symbol.

         ClassSymbol c = reader.defineClass(names.empty, owner);

         c.flatname = chk.localClassName(c);

         c.sourcefile = owner.sourcefile;

         c.completer = null;

         c.members_field = new Scope(c);

         c.flags_field = flags;

         ClassType ctype = (ClassType) c.type;

         ctype.supertype_field = syms.objectType;

         ctype.interfaces_field = List.nil();

         JCClassDecl odef = classDef(owner);

         // Enter class symbol in owner scope and compiled table.

         enterSynthetic(odef.pos(), c, owner.members());

         chk.compiled.put(c.flatname, c);

         // Create class definition tree.

         JCClassDecl cdef = make.ClassDef(

             make.Modifiers(flags), names.empty,

             List.<JCTypeParameter>nil(),

             null, List.<JCExpression>nil(), List.<JCTree>nil());

         cdef.sym = c;

         cdef.type = c.type;

         // Append class definition tree to owner's definitions.

         odef.defs = odef.defs.prepend(cdef);

         return c;

     }

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

  * Symbol manipulation utilities

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

     /** Enter a synthetic symbol in a given scope, but complain if there was already one there.

      *  @param pos           Position for error reporting.

      *  @param sym           The symbol.

      *  @param s             The scope.

      */

     private void enterSynthetic(DiagnosticPosition pos, Symbol sym, Scope s) {

         s.enter(sym);

     }

     /** Create a fresh synthetic name within a given scope - the unique name is

      *  obtained by appending '$' chars at the end of the name until no match

      *  is found.

      *

      * @param name base name

      * @param s scope in which the name has to be unique

      * @return fresh synthetic name

      */

     private Name makeSyntheticName(Name name, Scope s) {

         do {

             name = name.append(

                     target.syntheticNameChar(),

                     names.empty);

         } while (lookupSynthetic(name, s) != null);

         return name;

     }

     /** Check whether synthetic symbols generated during lowering conflict

      *  with user-defined symbols.

      *

      *  @param translatedTrees lowered class trees

      */

     void checkConflicts(List<JCTree> translatedTrees) {

         for (JCTree t : translatedTrees) {

             t.accept(conflictsChecker);

         }

     }

     JCTree.Visitor conflictsChecker = new TreeScanner() {

         TypeSymbol currentClass;

         @Override

         public void visitMethodDef(JCMethodDecl that) {

             chk.checkConflicts(that.pos(), that.sym, currentClass);

             super.visitMethodDef(that);

         }

         @Override

         public void visitVarDef(JCVariableDecl that) {

             if (that.sym.owner.kind == TYP) {

                 chk.checkConflicts(that.pos(), that.sym, currentClass);

             }

             super.visitVarDef(that);

         }

         @Override

         public void visitClassDef(JCClassDecl that) {

             TypeSymbol prevCurrentClass = currentClass;

             currentClass = that.sym;

             try {

                 super.visitClassDef(that);

             }

             finally {

                 currentClass = prevCurrentClass;

             }

         }

     };

     /** Look up a synthetic name in a given scope.

      *  @param s            The scope.

      *  @param name         The name.

      */

     private Symbol lookupSynthetic(Name name, Scope s) {

         Symbol sym = s.lookup(name).sym;

         return (sym==null || (sym.flags()&SYNTHETIC)==0) ? null : sym;

     }

     /** Look up a method in a given scope.

      */

     private MethodSymbol lookupMethod(DiagnosticPosition pos, Name name, Type qual, List<Type> args) {

         return rs.resolveInternalMethod(pos, attrEnv, qual, name, args, List.<Type>nil());

     }

     /** Look up a constructor.

      */

     private MethodSymbol lookupConstructor(DiagnosticPosition pos, Type qual, List<Type> args) {

         return rs.resolveInternalConstructor(pos, attrEnv, qual, args, null);

     }

     /** Look up a field.

      */

     private VarSymbol lookupField(DiagnosticPosition pos, Type qual, Name name) {

         return rs.resolveInternalField(pos, attrEnv, qual, name);

     }

     /** Anon inner classes are used as access constructor tags.

      * accessConstructorTag will use an existing anon class if one is available,

      * and synthethise a class (with makeEmptyClass) if one is not available.

      * However, there is a small possibility that an existing class will not

      * be generated as expected if it is inside a conditional with a constant

      * expression. If that is found to be the case, create an empty class here.

      */

     private void checkAccessConstructorTags() {

         for (List<ClassSymbol> l = accessConstrTags; l.nonEmpty(); l = l.tail) {

             ClassSymbol c = l.head;

             if (isTranslatedClassAvailable(c))

                 continue;

             // Create class definition tree.

             JCClassDecl cdef = make.ClassDef(

                 make.Modifiers(STATIC | SYNTHETIC), names.empty,

                 List.<JCTypeParameter>nil(),

                 null, List.<JCExpression>nil(), List.<JCTree>nil());

             cdef.sym = c;

             cdef.type = c.type;

             // add it to the list of classes to be generated

             translated.append(cdef);

         }

     }

     // where

     private boolean isTranslatedClassAvailable(ClassSymbol c) {

         for (JCTree tree: translated) {

             if (tree.hasTag(CLASSDEF)

                     && ((JCClassDecl) tree).sym == c) {

                 return true;

             }

         }

         return false;

     }

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

  * Access methods

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

     /** Access codes for dereferencing, assignment,

      *  and pre/post increment/decrement.

      *  Access codes for assignment operations are determined by method accessCode

      *  below.

      *

      *  All access codes for accesses to the current class are even.

      *  If a member of the superclass should be accessed instead (because

      *  access was via a qualified super), add one to the corresponding code

      *  for the current class, making the number odd.

      *  This numbering scheme is used by the backend to decide whether

      *  to issue an invokevirtual or invokespecial call.

      *

      *  @see Gen#visitSelect(JCFieldAccess tree)

      */

     private static final int

         DEREFcode = 0,

         ASSIGNcode = 2,

         PREINCcode = 4,

         PREDECcode = 6,

         POSTINCcode = 8,

         POSTDECcode = 10,

         FIRSTASGOPcode = 12;

     /** Number of access codes

      */

     private static final int NCODES = accessCode(ByteCodes.lushrl) + 2;

     /** A mapping from symbols to their access numbers.

      */

     private Map<Symbol,Integer> accessNums;

     /** A mapping from symbols to an array of access symbols, indexed by

      *  access code.

      */

     private Map<Symbol,MethodSymbol[]> accessSyms;

     /** A mapping from (constructor) symbols to access constructor symbols.

      */

     private Map<Symbol,MethodSymbol> accessConstrs;

     /** A list of all class symbols used for access constructor tags.

      */

     private List<ClassSymbol> accessConstrTags;

     /** A queue for all accessed symbols.

      */

     private ListBuffer<Symbol> accessed;

     /** Map bytecode of binary operation to access code of corresponding

      *  assignment operation. This is always an even number.

      */

     private static int accessCode(int bytecode) {

         if (ByteCodes.iadd <= bytecode && bytecode <= ByteCodes.lxor)

             return (bytecode - iadd) * 2 + FIRSTASGOPcode;

         else if (bytecode == ByteCodes.string_add)

             return (ByteCodes.lxor + 1 - iadd) * 2 + FIRSTASGOPcode;

         else if (ByteCodes.ishll <= bytecode && bytecode <= ByteCodes.lushrl)

             return (bytecode - ishll + ByteCodes.lxor + 2 - iadd) * 2 + FIRSTASGOPcode;

         else

             return -1;

     }

     /** return access code for identifier,

      *  @param tree     The tree representing the identifier use.

      *  @param enclOp   The closest enclosing operation node of tree,

      *                  null if tree is not a subtree of an operation.

      */

     private static int accessCode(JCTree tree, JCTree enclOp) {

         if (enclOp == null)

             return DEREFcode;

         else if (enclOp.hasTag(ASSIGN) &&

                  tree == TreeInfo.skipParens(((JCAssign) enclOp).lhs))

             return ASSIGNcode;

         else if (enclOp.getTag().isIncOrDecUnaryOp() &&

                  tree == TreeInfo.skipParens(((JCUnary) enclOp).arg))

             return mapTagToUnaryOpCode(enclOp.getTag());

         else if (enclOp.getTag().isAssignop() &&

                  tree == TreeInfo.skipParens(((JCAssignOp) enclOp).lhs))

             return accessCode(((OperatorSymbol) ((JCAssignOp) enclOp).operator).opcode);

         else

             return DEREFcode;

     }

     /** Return binary operator that corresponds to given access code.

      */

     private OperatorSymbol binaryAccessOperator(int acode) {

         for (Scope.Entry e = syms.predefClass.members().elems;

              e != null;

              e = e.sibling) {

             if (e.sym instanceof OperatorSymbol) {

                 OperatorSymbol op = (OperatorSymbol)e.sym;

                 if (accessCode(op.opcode) == acode) return op;

             }

         }

         return null;

     }

     /** Return tree tag for assignment operation corresponding

      *  to given binary operator.

      */

     private static JCTree.Tag treeTag(OperatorSymbol operator) {

         switch (operator.opcode) {

         case ByteCodes.ior: case ByteCodes.lor:

             return BITOR_ASG;

         case ByteCodes.ixor: case ByteCodes.lxor:

             return BITXOR_ASG;

         case ByteCodes.iand: case ByteCodes.land:

             return BITAND_ASG;

         case ByteCodes.ishl: case ByteCodes.lshl:

         case ByteCodes.ishll: case ByteCodes.lshll:

             return SL_ASG;

         case ByteCodes.ishr: case ByteCodes.lshr:

         case ByteCodes.ishrl: case ByteCodes.lshrl:

             return SR_ASG;

         case ByteCodes.iushr: case ByteCodes.lushr:

         case ByteCodes.iushrl: case ByteCodes.lushrl:

             return USR_ASG;

         case ByteCodes.iadd: case ByteCodes.ladd:

         case ByteCodes.fadd: case ByteCodes.dadd:

         case ByteCodes.string_add:

             return PLUS_ASG;

         case ByteCodes.isub: case ByteCodes.lsub:

         case ByteCodes.fsub: case ByteCodes.dsub:

             return MINUS_ASG;

         case ByteCodes.imul: case ByteCodes.lmul:

         case ByteCodes.fmul: case ByteCodes.dmul:

             return MUL_ASG;

         case ByteCodes.idiv: case ByteCodes.ldiv:

         case ByteCodes.fdiv: case ByteCodes.ddiv:

             return DIV_ASG;

         case ByteCodes.imod: case ByteCodes.lmod:

         case ByteCodes.fmod: case ByteCodes.dmod:

             return MOD_ASG;

         default:

             throw new AssertionError();

         }

     }

     /** The name of the access method with number `anum' and access code `acode'.

      */

     Name accessName(int anum, int acode) {

         return names.fromString(

             "access" + target.syntheticNameChar() + anum + acode / 10 + acode % 10);

     }

     /** Return access symbol for a private or protected symbol from an inner class.

      *  @param sym        The accessed private symbol.

      *  @param tree       The accessing tree.

      *  @param enclOp     The closest enclosing operation node of tree,

      *                    null if tree is not a subtree of an operation.

      *  @param protAccess Is access to a protected symbol in another

      *                    package?

      *  @param refSuper   Is access via a (qualified) C.super?

      */

     MethodSymbol accessSymbol(Symbol sym, JCTree tree, JCTree enclOp,

                               boolean protAccess, boolean refSuper) {

         ClassSymbol accOwner = refSuper && protAccess

             // For access via qualified super (T.super.x), place the

             // access symbol on T.

             ? (ClassSymbol)((JCFieldAccess) tree).selected.type.tsym

             // Otherwise pretend that the owner of an accessed

             // protected symbol is the enclosing class of the current

             // class which is a subclass of the symbol's owner.

             : accessClass(sym, protAccess, tree);

         Symbol vsym = sym;

         if (sym.owner != accOwner) {

             vsym = sym.clone(accOwner);

             actualSymbols.put(vsym, sym);

         }

         Integer anum              // The access number of the access method.

             = accessNums.get(vsym);

         if (anum == null) {

             anum = accessed.length();

             accessNums.put(vsym, anum);

             accessSyms.put(vsym, new MethodSymbol[NCODES]);

             accessed.append(vsym);

             // System.out.println("accessing " + vsym + " in " + vsym.location());

         }

         int acode;                // The access code of the access method.

         List<Type> argtypes;      // The argument types of the access method.

         Type restype;             // The result type of the access method.

         List<Type> thrown;        // The thrown exceptions of the access method.

         switch (vsym.kind) {

         case VAR:

             acode = accessCode(tree, enclOp);

             if (acode >= FIRSTASGOPcode) {

                 OperatorSymbol operator = binaryAccessOperator(acode);

                 if (operator.opcode == string_add)

                     argtypes = List.of(syms.objectType);

                 else

                     argtypes = operator.type.getParameterTypes().tail;

             } else if (acode == ASSIGNcode)

                 argtypes = List.of(vsym.erasure(types));

             else

                 argtypes = List.nil();

             restype = vsym.erasure(types);

             thrown = List.nil();

             break;

         case MTH:

             acode = DEREFcode;

             argtypes = vsym.erasure(types).getParameterTypes();

             restype = vsym.erasure(types).getReturnType();

             thrown = vsym.type.getThrownTypes();

             break;

         default:

             throw new AssertionError();

         }

         // For references via qualified super, increment acode by one,

         // making it odd.

         if (protAccess && refSuper) acode++;

         // Instance access methods get instance as first parameter.

         // For protected symbols this needs to be the instance as a member

         // of the type containing the accessed symbol, not the class

         // containing the access method.

         if ((vsym.flags() & STATIC) == 0) {

             argtypes = argtypes.prepend(vsym.owner.erasure(types));

         }

         MethodSymbol[] accessors = accessSyms.get(vsym);

         MethodSymbol accessor = accessors[acode];

         if (accessor == null) {

             accessor = new MethodSymbol(

                 STATIC | SYNTHETIC,

                 accessName(anum.intValue(), acode),

                 new MethodType(argtypes, restype, thrown, syms.methodClass),

                 accOwner);

             enterSynthetic(tree.pos(), accessor, accOwner.members());

             accessors[acode] = accessor;

         }

         return accessor;

     }

     /** The qualifier to be used for accessing a symbol in an outer class.

      *  This is either C.sym or C.this.sym, depending on whether or not

      *  sym is static.

      *  @param sym   The accessed symbol.

      */

     JCExpression accessBase(DiagnosticPosition pos, Symbol sym) {

         return (sym.flags() & STATIC) != 0

             ? access(make.at(pos.getStartPosition()).QualIdent(sym.owner))

             : makeOwnerThis(pos, sym, true);

     }

     /** Do we need an access method to reference private symbol?

      */

     boolean needsPrivateAccess(Symbol sym) {

         if ((sym.flags() & PRIVATE) == 0 || sym.owner == currentClass) {

             return false;

         } else if (sym.name == names.init && (sym.owner.owner.kind & (VAR | MTH)) != 0) {

             // private constructor in local class: relax protection

             sym.flags_field &= ~PRIVATE;

             return false;

         } else {

             return true;

         }

     }

     /** Do we need an access method to reference symbol in other package?

      */

     boolean needsProtectedAccess(Symbol sym, JCTree tree) {

         if ((sym.flags() & PROTECTED) == 0 ||

             sym.owner.owner == currentClass.owner || // fast special case

             sym.packge() == currentClass.packge())

             return false;

         if (!currentClass.isSubClass(sym.owner, types))

             return true;

         if ((sym.flags() & STATIC) != 0 ||

             !tree.hasTag(SELECT) ||

             TreeInfo.name(((JCFieldAccess) tree).selected) == names._super)

             return false;

         return !((JCFieldAccess) tree).selected.type.tsym.isSubClass(currentClass, types);

     }

     /** The class in which an access method for given symbol goes.

      *  @param sym        The access symbol

      *  @param protAccess Is access to a protected symbol in another

      *                    package?

      */

     ClassSymbol accessClass(Symbol sym, boolean protAccess, JCTree tree) {

         if (protAccess) {

             Symbol qualifier = null;

             ClassSymbol c = currentClass;

             if (tree.hasTag(SELECT) && (sym.flags() & STATIC) == 0) {

                 qualifier = ((JCFieldAccess) tree).selected.type.tsym;

                 while (!qualifier.isSubClass(c, types)) {

                     c = c.owner.enclClass();

                 }

                 return c;

             } else {

                 while (!c.isSubClass(sym.owner, types)) {

                     c = c.owner.enclClass();

                 }

             }

             return c;

         } else {

             // the symbol is private

             return sym.owner.enclClass();

         }

     }

     private void addPrunedInfo(JCTree tree) {

         List<JCTree> infoList = prunedTree.get(currentClass);

         infoList = (infoList == null) ? List.of(tree) : infoList.prepend(tree);

         prunedTree.put(currentClass, infoList);

     }

     /** Ensure that identifier is accessible, return tree accessing the identifier.

      *  @param sym      The accessed symbol.

      *  @param tree     The tree referring to the symbol.

      *  @param enclOp   The closest enclosing operation node of tree,

      *                  null if tree is not a subtree of an operation.

      *  @param refSuper Is access via a (qualified) C.super?

      */

     JCExpression access(Symbol sym, JCExpression tree, JCExpression enclOp, boolean refSuper) {

         // Access a free variable via its proxy, or its proxy's proxy

         while (sym.kind == VAR && sym.owner.kind == MTH &&

             sym.owner.enclClass() != currentClass) {

             // A constant is replaced by its constant value.

             Object cv = ((VarSymbol)sym).getConstValue();

             if (cv != null) {

                 make.at(tree.pos);

                 return makeLit(sym.type, cv);

             }

             // Otherwise replace the variable by its proxy.

             sym = proxies.lookup(proxyName(sym.name)).sym;

             Assert.check(sym != null && (sym.flags_field & FINAL) != 0);

             tree = make.at(tree.pos).Ident(sym);

         }

         JCExpression base = (tree.hasTag(SELECT)) ? ((JCFieldAccess) tree).selected : null;

         switch (sym.kind) {

         case TYP:

             if (sym.owner.kind != PCK) {

                 // Convert type idents to

                 // <flat name> or <package name> . <flat name>

                 Name flatname = Convert.shortName(sym.flatName());

                 while (base != null &&

                        TreeInfo.symbol(base) != null &&

                        TreeInfo.symbol(base).kind != PCK) {

                     base = (base.hasTag(SELECT))

                         ? ((JCFieldAccess) base).selected

                         : null;

                 }

                 if (tree.hasTag(IDENT)) {

                     ((JCIdent) tree).name = flatname;

                 } else if (base == null) {

                     tree = make.at(tree.pos).Ident(sym);

                     ((JCIdent) tree).name = flatname;

                 } else {

                     ((JCFieldAccess) tree).selected = base;

                     ((JCFieldAccess) tree).name = flatname;

                 }

             }

             break;

         case MTH: case VAR:

             if (sym.owner.kind == TYP) {

                 // Access methods are required for

                 //  - private members,

                 //  - protected members in a superclass of an

                 //    enclosing class contained in another package.

                 //  - all non-private members accessed via a qualified super.

                 boolean protAccess = refSuper && !needsPrivateAccess(sym)

                     || needsProtectedAccess(sym, tree);

                 boolean accReq = protAccess || needsPrivateAccess(sym);

                 // A base has to be supplied for

                 //  - simple identifiers accessing variables in outer classes.

                 boolean baseReq =

                     base == null &&

                     sym.owner != syms.predefClass &&

                     !sym.isMemberOf(currentClass, types);

                 if (accReq || baseReq) {

                     make.at(tree.pos);

                     // Constants are replaced by their constant value.

                     if (sym.kind == VAR) {

                         Object cv = ((VarSymbol)sym).getConstValue();

                         if (cv != null) {

                             addPrunedInfo(tree);

                             return makeLit(sym.type, cv);

                         }

                     }

                     // Private variables and methods are replaced by calls

                     // to their access methods.

                     if (accReq) {

                         List<JCExpression> args = List.nil();

                         if ((sym.flags() & STATIC) == 0) {

                             // Instance access methods get instance

                             // as first parameter.

                             if (base == null)

                                 base = makeOwnerThis(tree.pos(), sym, true);

                             args = args.prepend(base);

                             base = null;   // so we don't duplicate code

                         }

                         Symbol access = accessSymbol(sym, tree,

                                                      enclOp, protAccess,

                                                      refSuper);

                         JCExpression receiver = make.Select(

                             base != null ? base : make.QualIdent(access.owner),

                             access);

                         return make.App(receiver, args);

                     // Other accesses to members of outer classes get a

                     // qualifier.

                     } else if (baseReq) {

                         return make.at(tree.pos).Select(

                             accessBase(tree.pos(), sym), sym).setType(tree.type);

                     }

                 }

             }

         }

         return tree;

     }

     /** Ensure that identifier is accessible, return tree accessing the identifier.

      *  @param tree     The identifier tree.

      */

     JCExpression access(JCExpression tree) {

         Symbol sym = TreeInfo.symbol(tree);

         return sym == null ? tree : access(sym, tree, null, false);

     }

     /** Return access constructor for a private constructor,

      *  or the constructor itself, if no access constructor is needed.

      *  @param pos       The position to report diagnostics, if any.

      *  @param constr    The private constructor.

      */

     Symbol accessConstructor(DiagnosticPosition pos, Symbol constr) {

         if (needsPrivateAccess(constr)) {

             ClassSymbol accOwner = constr.owner.enclClass();

             MethodSymbol aconstr = accessConstrs.get(constr);

             if (aconstr == null) {

                 List<Type> argtypes = constr.type.getParameterTypes();

                 if ((accOwner.flags_field & ENUM) != 0)

                     argtypes = argtypes

                         .prepend(syms.intType)

                         .prepend(syms.stringType);

                 aconstr = new MethodSymbol(

                     SYNTHETIC,

                     names.init,

                     new MethodType(

                         argtypes.append(

                             accessConstructorTag().erasure(types)),

                         constr.type.getReturnType(),

                         constr.type.getThrownTypes(),

                         syms.methodClass),

                     accOwner);

                 enterSynthetic(pos, aconstr, accOwner.members());

                 accessConstrs.put(constr, aconstr);

                 accessed.append(constr);

             }

             return aconstr;

         } else {

             return constr;

         }

     }

     /** Return an anonymous class nested in this toplevel class.

      */

     ClassSymbol accessConstructorTag() {

         ClassSymbol topClass = currentClass.outermostClass();

         Name flatname = names.fromString("" + topClass.getQualifiedName() +

                                          target.syntheticNameChar() +

                                          "1");

         ClassSymbol ctag = chk.compiled.get(flatname);

         if (ctag == null)

             ctag = makeEmptyClass(STATIC | SYNTHETIC, topClass);

         // keep a record of all tags, to verify that all are generated as required

         accessConstrTags = accessConstrTags.prepend(ctag);

         return ctag;

     }

     /** Add all required access methods for a private symbol to enclosing class.

      *  @param sym       The symbol.

      */

     void makeAccessible(Symbol sym) {

         JCClassDecl cdef = classDef(sym.owner.enclClass());

         if (cdef == null) Assert.error("class def not found: " + sym + " in " + sym.owner);

         if (sym.name == names.init) {

             cdef.defs = cdef.defs.prepend(

                 accessConstructorDef(cdef.pos, sym, accessConstrs.get(sym)));

         } else {

             MethodSymbol[] accessors = accessSyms.get(sym);

             for (int i = 0; i < NCODES; i++) {

                 if (accessors[i] != null)

                     cdef.defs = cdef.defs.prepend(

                         accessDef(cdef.pos, sym, accessors[i], i));

             }

         }

     }

     /** Maps unary operator integer codes to JCTree.Tag objects

      *  @param unaryOpCode the unary operator code

      */

     private static Tag mapUnaryOpCodeToTag(int unaryOpCode){

         switch (unaryOpCode){

             case PREINCcode:

                 return PREINC;

             case PREDECcode:

                 return PREDEC;

             case POSTINCcode:

                 return POSTINC;

             case POSTDECcode:

                 return POSTDEC;

             default:

                 return NO_TAG;

         }

     }

     /** Maps JCTree.Tag objects to unary operator integer codes

      *  @param tag the JCTree.Tag

      */

     private static int mapTagToUnaryOpCode(Tag tag){

         switch (tag){

             case PREINC:

                 return PREINCcode;

             case PREDEC:

                 return PREDECcode;

             case POSTINC:

                 return POSTINCcode;

             case POSTDEC:

                 return POSTDECcode;

             default:

                 return -1;

         }

     }

     /** Construct definition of an access method.

      *  @param pos        The source code position of the definition.

      *  @param vsym       The private or protected symbol.

      *  @param accessor   The access method for the symbol.

      *  @param acode      The access code.

      */

     JCTree accessDef(int pos, Symbol vsym, MethodSymbol accessor, int acode) {

 //      System.err.println("access " + vsym + " with " + accessor);//DEBUG

         currentClass = vsym.owner.enclClass();

         make.at(pos);

         JCMethodDecl md = make.MethodDef(accessor, null);

         // Find actual symbol

         Symbol sym = actualSymbols.get(vsym);

         if (sym == null) sym = vsym;

         JCExpression ref;           // The tree referencing the private symbol.

         List<JCExpression> args;    // Any additional arguments to be passed along.

         if ((sym.flags() & STATIC) != 0) {

             ref = make.Ident(sym);

             args = make.Idents(md.params);

         } else {

             ref = make.Select(make.Ident(md.params.head), sym);

             args = make.Idents(md.params.tail);

         }

         JCStatement stat;          // The statement accessing the private symbol.

         if (sym.kind == VAR) {

             // Normalize out all odd access codes by taking floor modulo 2:

             int acode1 = acode - (acode & 1);

             JCExpression expr;      // The access method's return value.

             switch (acode1) {

             case DEREFcode:

                 expr = ref;

                 break;

             case ASSIGNcode:

                 expr = make.Assign(ref, args.head);

                 break;

             case PREINCcode: case POSTINCcode: case PREDECcode: case POSTDECcode:

                 expr = makeUnary(mapUnaryOpCodeToTag(acode1), ref);

                 break;

             default:

                 expr = make.Assignop(

                     treeTag(binaryAccessOperator(acode1)), ref, args.head);

                 ((JCAssignOp) expr).operator = binaryAccessOperator(acode1);

             }

             stat = make.Return(expr.setType(sym.type));

         } else {

             stat = make.Call(make.App(ref, args));

         }

         md.body = make.Block(0, List.of(stat));

         // Make sure all parameters, result types and thrown exceptions

         // are accessible.

         for (List<JCVariableDecl> l = md.params; l.nonEmpty(); l = l.tail)

             l.head.vartype = access(l.head.vartype);

         md.restype = access(md.restype);

         for (List<JCExpression> l = md.thrown; l.nonEmpty(); l = l.tail)

             l.head = access(l.head);

         return md;

     }

     /** Construct definition of an access constructor.

      *  @param pos        The source code position of the definition.

      *  @param constr     The private constructor.

      *  @param accessor   The access method for the constructor.

      */

     JCTree accessConstructorDef(int pos, Symbol constr, MethodSymbol accessor) {

         make.at(pos);

         JCMethodDecl md = make.MethodDef(accessor,

                                       accessor.externalType(types),

                                       null);

         JCIdent callee = make.Ident(names._this);

         callee.sym = constr;

         callee.type = constr.type;

         md.body =

             make.Block(0, List.<JCStatement>of(

                 make.Call(

                     make.App(

                         callee,

                         make.Idents(md.params.reverse().tail.reverse())))));

         return md;

     }

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

  * Free variables proxies and this$n

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

     /** A scope containing all free variable proxies for currently translated

      *  class, as well as its this$n symbol (if needed).

      *  Proxy scopes are nested in the same way classes are.

      *  Inside a constructor, proxies and any this$n symbol are duplicated

      *  in an additional innermost scope, where they represent the constructor

      *  parameters.

      */

     Scope proxies;

     /** A scope containing all unnamed resource variables/saved

      *  exception variables for translated TWR blocks

      */

     Scope twrVars;

     /** A stack containing the this$n field of the currently translated

      *  classes (if needed) in innermost first order.

      *  Inside a constructor, proxies and any this$n symbol are duplicated

      *  in an additional innermost scope, where they represent the constructor

      *  parameters.

      */

     List<VarSymbol> outerThisStack;

     /** The name of a free variable proxy.

      */

     Name proxyName(Name name) {

         return names.fromString("val" + target.syntheticNameChar() + name);

     }

     /** Proxy definitions for all free variables in given list, in reverse order.

      *  @param pos        The source code position of the definition.

      *  @param freevars   The free variables.

      *  @param owner      The class in which the definitions go.

      */

     List<JCVariableDecl> freevarDefs(int pos, List<VarSymbol> freevars, Symbol owner) {

         long flags = FINAL | SYNTHETIC;

         if (owner.kind == TYP &&

             target.usePrivateSyntheticFields())

             flags |= PRIVATE;

         List<JCVariableDecl> defs = List.nil();

         for (List<VarSymbol> l = freevars; l.nonEmpty(); l = l.tail) {

             VarSymbol v = l.head;

             VarSymbol proxy = new VarSymbol(

                 flags, proxyName(v.name), v.erasure(types), owner);

             proxies.enter(proxy);

             JCVariableDecl vd = make.at(pos).VarDef(proxy, null);

             vd.vartype = access(vd.vartype);

             defs = defs.prepend(vd);

         }

         return defs;

     }

     /** The name of a this$n field

      *  @param type   The class referenced by the this$n field

      */

     Name outerThisName(Type type, Symbol owner) {

         Type t = type.getEnclosingType();

         int nestingLevel = 0;

         while (t.hasTag(CLASS)) {

             t = t.getEnclosingType();

             nestingLevel++;

         }

         Name result = names.fromString("this" + target.syntheticNameChar() + nestingLevel);

         while (owner.kind == TYP && ((ClassSymbol)owner).members().lookup(result).scope != null)

             result = names.fromString(result.toString() + target.syntheticNameChar());

         return result;

     }

     /** Definition for this$n field.

      *  @param pos        The source code position of the definition.

      *  @param owner      The class in which the definition goes.

      */

     JCVariableDecl outerThisDef(int pos, Symbol owner) {

         long flags = FINAL | SYNTHETIC;

         if (owner.kind == TYP &&

             target.usePrivateSyntheticFields())

             flags |= PRIVATE;

         Type target = types.erasure(owner.enclClass().type.getEnclosingType());

         VarSymbol outerThis = new VarSymbol(

             flags, outerThisName(target, owner), target, owner);

         outerThisStack = outerThisStack.prepend(outerThis);

         JCVariableDecl vd = make.at(pos).VarDef(outerThis, null);

         vd.vartype = access(vd.vartype);

         return vd;

     }

     /** Return a list of trees that load the free variables in given list,

      *  in reverse order.

      *  @param pos          The source code position to be used for the trees.

      *  @param freevars     The list of free variables.

      */

     List<JCExpression> loadFreevars(DiagnosticPosition pos, List<VarSymbol> freevars) {

         List<JCExpression> args = List.nil();

         for (List<VarSymbol> l = freevars; l.nonEmpty(); l = l.tail)

             args = args.prepend(loadFreevar(pos, l.head));

         return args;

     }

 //where

         JCExpression loadFreevar(DiagnosticPosition pos, VarSymbol v) {

             return access(v, make.at(pos).Ident(v), null, false);

         }

     /** Construct a tree simulating the expression {@code C.this}.

      *  @param pos           The source code position to be used for the tree.

      *  @param c             The qualifier class.

      */

     JCExpression makeThis(DiagnosticPosition pos, TypeSymbol c) {

         if (currentClass == c) {

             // in this case, `this' works fine

             return make.at(pos).This(c.erasure(types));

         } else {

             // need to go via this$n

             return makeOuterThis(pos, c);

         }

     }

     /**

      * Optionally replace a try statement with the desugaring of a

      * try-with-resources statement.  The canonical desugaring of

      *

      * try ResourceSpecification

      *   Block

      *

      * is

      *

      * {

      *   final VariableModifiers_minus_final R #resource = Expression;

      *   Throwable #primaryException = null;

      *

      *   try ResourceSpecificationtail

      *     Block

      *   catch (Throwable #t) {

      *     #primaryException = t;

      *     throw #t;

      *   } finally {

      *     if (#resource != null) {

      *       if (#primaryException != null) {

      *         try {

      *           #resource.close();

      *         } catch(Throwable #suppressedException) {

      *           #primaryException.addSuppressed(#suppressedException);

      *         }

      *       } else {

      *         #resource.close();

      *       }

      *     }

      *   }

      *

      * @param tree  The try statement to inspect.

      * @return A a desugared try-with-resources tree, or the original

      * try block if there are no resources to manage.

      */

     JCTree makeTwrTry(JCTry tree) {

         make_at(tree.pos());

         twrVars = twrVars.dup();

         JCBlock twrBlock = makeTwrBlock(tree.resources, tree.body, 0);

         if (tree.catchers.isEmpty() && tree.finalizer == null)

             result = translate(twrBlock);

         else

             result = translate(make.Try(twrBlock, tree.catchers, tree.finalizer));

         twrVars = twrVars.leave();

         return result;

     }

     private JCBlock makeTwrBlock(List<JCTree> resources, JCBlock block, int depth) {

         if (resources.isEmpty())

             return block;

         // Add resource declaration or expression to block statements

         ListBuffer<JCStatement> stats = new ListBuffer<JCStatement>();

         JCTree resource = resources.head;

         JCExpression expr = null;

         if (resource instanceof JCVariableDecl) {

             JCVariableDecl var = (JCVariableDecl) resource;

             expr = make.Ident(var.sym).setType(resource.type);

             stats.add(var);

         } else {

             Assert.check(resource instanceof JCExpression);

             VarSymbol syntheticTwrVar =

             new VarSymbol(SYNTHETIC | FINAL,

                           makeSyntheticName(names.fromString("twrVar" +

                                            depth), twrVars),

                           (resource.type.hasTag(BOT)) ?

                           syms.autoCloseableType : resource.type,

                           currentMethodSym);

             twrVars.enter(syntheticTwrVar);

             JCVariableDecl syntheticTwrVarDecl =

                 make.VarDef(syntheticTwrVar, (JCExpression)resource);

             expr = (JCExpression)make.Ident(syntheticTwrVar);

             stats.add(syntheticTwrVarDecl);

         }

         // Add primaryException declaration

         VarSymbol primaryException =

             new VarSymbol(SYNTHETIC,

                           makeSyntheticName(names.fromString("primaryException" +

                           depth), twrVars),

                           syms.throwableType,

                           currentMethodSym);

         twrVars.enter(primaryException);

         JCVariableDecl primaryExceptionTreeDecl = make.VarDef(primaryException, makeNull());

         stats.add(primaryExceptionTreeDecl);

         // Create catch clause that saves exception and then rethrows it

         VarSymbol param =

             new VarSymbol(FINAL|SYNTHETIC,

                           names.fromString("t" +

                                            target.syntheticNameChar()),

                           syms.throwableType,

                           currentMethodSym);

         JCVariableDecl paramTree = make.VarDef(param, null);

         JCStatement assign = make.Assignment(primaryException, make.Ident(param));

         JCStatement rethrowStat = make.Throw(make.Ident(param));

         JCBlock catchBlock = make.Block(0L, List.<JCStatement>of(assign, rethrowStat));

         JCCatch catchClause = make.Catch(paramTree, catchBlock);

         int oldPos = make.pos;

         make.at(TreeInfo.endPos(block));

         JCBlock finallyClause = makeTwrFinallyClause(primaryException, expr);

         make.at(oldPos);

         JCTry outerTry = make.Try(makeTwrBlock(resources.tail, block, depth + 1),

                                   List.<JCCatch>of(catchClause),

                                   finallyClause);

         stats.add(outerTry);

         return make.Block(0L, stats.toList());

     }

     private JCBlock makeTwrFinallyClause(Symbol primaryException, JCExpression resource) {

         // primaryException.addSuppressed(catchException);

         VarSymbol catchException =

             new VarSymbol(0, make.paramName(2),

                           syms.throwableType,

                           currentMethodSym);

         JCStatement addSuppressionStatement =

             make.Exec(makeCall(make.Ident(primaryException),

                                names.addSuppressed,

                                List.<JCExpression>of(make.Ident(catchException))));

         // try { resource.close(); } catch (e) { primaryException.addSuppressed(e); }

         JCBlock tryBlock =

             make.Block(0L, List.<JCStatement>of(makeResourceCloseInvocation(resource)));

         JCVariableDecl catchExceptionDecl = make.VarDef(catchException, null);

         JCBlock catchBlock = make.Block(0L, List.<JCStatement>of(addSuppressionStatement));

         List<JCCatch> catchClauses = List.<JCCatch>of(make.Catch(catchExceptionDecl, catchBlock));

         JCTry tryTree = make.Try(tryBlock, catchClauses, null);

         // if (primaryException != null) {try...} else resourceClose;

         JCIf closeIfStatement = make.If(makeNonNullCheck(make.Ident(primaryException)),

                                         tryTree,

                                         makeResourceCloseInvocation(resource));

         // if (#resource != null) { if (primaryException ...  }

         return make.Block(0L,

                           List.<JCStatement>of(make.If(makeNonNullCheck(resource),

                                                        closeIfStatement,

                                                        null)));

     }

     private JCStatement makeResourceCloseInvocation(JCExpression resource) {

         // convert to AutoCloseable if needed

         if (types.asSuper(resource.type, syms.autoCloseableType.tsym) == null) {

             resource = (JCExpression) convert(resource, syms.autoCloseableType);

         }

         // create resource.close() method invocation

         JCExpression resourceClose = makeCall(resource,

                                               names.close,

                                               List.<JCExpression>nil());

         return make.Exec(resourceClose);

     }

     private JCExpression makeNonNullCheck(JCExpression expression) {

         return makeBinary(NE, expression, makeNull());

     }

     /** Construct a tree that represents the outer instance

      *  {@code C.this}. Never pick the current `this'.

      *  @param pos           The source code position to be used for the tree.

      *  @param c             The qualifier class.

      */

     JCExpression makeOuterThis(DiagnosticPosition pos, TypeSymbol c) {

         List<VarSymbol> ots = outerThisStack;

         if (ots.isEmpty()) {

             log.error(pos, "no.encl.instance.of.type.in.scope", c);

             Assert.error();

             return makeNull();

         }

         VarSymbol ot = ots.head;

         JCExpression tree = access(make.at(pos).Ident(ot));

         TypeSymbol otc = ot.type.tsym;

         while (otc != c) {

             do {

                 ots = ots.tail;

                 if (ots.isEmpty()) {

                     log.error(pos,

                               "no.encl.instance.of.type.in.scope",

                               c);

                     Assert.error(); // should have been caught in Attr

                     return tree;

                 }

                 ot = ots.head;

             } while (ot.owner != otc);

             if (otc.owner.kind != PCK && !otc.hasOuterInstance()) {

                 chk.earlyRefError(pos, c);

                 Assert.error(); // should have been caught in Attr

                 return makeNull();

             }

             tree = access(make.at(pos).Select(tree, ot));

             otc = ot.type.tsym;

         }

         return tree;

     }

     /** Construct a tree that represents the closest outer instance

      *  {@code C.this} such that the given symbol is a member of C.

      *  @param pos           The source code position to be used for the tree.

      *  @param sym           The accessed symbol.

      *  @param preciseMatch  should we accept a type that is a subtype of

      *                       sym's owner, even if it doesn't contain sym

      *                       due to hiding, overriding, or non-inheritance

      *                       due to protection?

      */

     JCExpression makeOwnerThis(DiagnosticPosition pos, Symbol sym, boolean preciseMatch) {

         Symbol c = sym.owner;

         if (preciseMatch ? sym.isMemberOf(currentClass, types)

                          : currentClass.isSubClass(sym.owner, types)) {

             // in this case, `this' works fine

             return make.at(pos).This(c.erasure(types));

         } else {

             // need to go via this$n

             return makeOwnerThisN(pos, sym, preciseMatch);

         }

     }

     /**

      * Similar to makeOwnerThis but will never pick "this".

      */

     JCExpression makeOwnerThisN(DiagnosticPosition pos, Symbol sym, boolean preciseMatch) {

         Symbol c = sym.owner;

         List<VarSymbol> ots = outerThisStack;

         if (ots.isEmpty()) {

             log.error(pos, "no.encl.instance.of.type.in.scope", c);

             Assert.error();

             return makeNull();

         }

         VarSymbol ot = ots.head;

         JCExpression tree = access(make.at(pos).Ident(ot));

         TypeSymbol otc = ot.type.tsym;

         while (!(preciseMatch ? sym.isMemberOf(otc, types) : otc.isSubClass(sym.owner, types))) {

             do {

                 ots = ots.tail;

                 if (ots.isEmpty()) {

                     log.error(pos,

                         "no.encl.instance.of.type.in.scope",

                         c);

                     Assert.error();

                     return tree;

                 }

                 ot = ots.head;

             } while (ot.owner != otc);

             tree = access(make.at(pos).Select(tree, ot));

             otc = ot.type.tsym;

         }

         return tree;

     }

     /** Return tree simulating the assignment {@code this.name = name}, where

      *  name is the name of a free variable.

      */

     JCStatement initField(int pos, Name name) {

         Scope.Entry e = proxies.lookup(name);

         Symbol rhs = e.sym;

         Assert.check(rhs.owner.kind == MTH);

         Symbol lhs = e.next().sym;

         Assert.check(rhs.owner.owner == lhs.owner);

         make.at(pos);

         return

             make.Exec(

                 make.Assign(

                     make.Select(make.This(lhs.owner.erasure(types)), lhs),

                     make.Ident(rhs)).setType(lhs.erasure(types)));

     }

     /** Return tree simulating the assignment {@code this.this$n = this$n}.

      */

     JCStatement initOuterThis(int pos) {

         VarSymbol rhs = outerThisStack.head;

         Assert.check(rhs.owner.kind == MTH);

         VarSymbol lhs = outerThisStack.tail.head;

         Assert.check(rhs.owner.owner == lhs.owner);

         make.at(pos);

         return

             make.Exec(

                 make.Assign(

                     make.Select(make.This(lhs.owner.erasure(types)), lhs),

                     make.Ident(rhs)).setType(lhs.erasure(types)));

     }

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

  * Code for .class

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

     /** Return the symbol of a class to contain a cache of

      *  compiler-generated statics such as class$ and the

      *  $assertionsDisabled flag.  We create an anonymous nested class

      *  (unless one already exists) and return its symbol.  However,

      *  for backward compatibility in 1.4 and earlier we use the

      *  top-level class itself.

      */

     private ClassSymbol outerCacheClass() {

         ClassSymbol clazz = outermostClassDef.sym;

         if ((clazz.flags() & INTERFACE) == 0 &&

             !target.useInnerCacheClass()) return clazz;

         Scope s = clazz.members();

         for (Scope.Entry e = s.elems; e != null; e = e.sibling)

             if (e.sym.kind == TYP &&

                 e.sym.name == names.empty &&

                 (e.sym.flags() & INTERFACE) == 0) return (ClassSymbol) e.sym;

         return makeEmptyClass(STATIC | SYNTHETIC, clazz);

     }

     /** Return symbol for "class$" method. If there is no method definition

      *  for class$, construct one as follows:

      *

      *    class class$(String x0) {

      *      try {

      *        return Class.forName(x0);

      *      } catch (ClassNotFoundException x1) {

      *        throw new NoClassDefFoundError(x1.getMessage());

      *      }

      *    }

      */

     private MethodSymbol classDollarSym(DiagnosticPosition pos) {

         ClassSymbol outerCacheClass = outerCacheClass();

         MethodSymbol classDollarSym =

             (MethodSymbol)lookupSynthetic(classDollar,

                                           outerCacheClass.members());

         if (classDollarSym == null) {

             classDollarSym = new MethodSymbol(

                 STATIC | SYNTHETIC,

                 classDollar,

                 new MethodType(

                     List.of(syms.stringType),

                     types.erasure(syms.classType),

                     List.<Type>nil(),

                     syms.methodClass),

                 outerCacheClass);

             enterSynthetic(pos, classDollarSym, outerCacheClass.members());

             JCMethodDecl md = make.MethodDef(classDollarSym, null);

             try {

                 md.body = classDollarSymBody(pos, md);

             } catch (CompletionFailure ex) {

                 md.body = make.Block(0, List.<JCStatement>nil());

                 chk.completionError(pos, ex);

             }

             JCClassDecl outerCacheClassDef = classDef(outerCacheClass);

             outerCacheClassDef.defs = outerCacheClassDef.defs.prepend(md);

         }

         return classDollarSym;

     }

     /** Generate code for class$(String name). */

     JCBlock classDollarSymBody(DiagnosticPosition pos, JCMethodDecl md) {

         MethodSymbol classDollarSym = md.sym;

         ClassSymbol outerCacheClass = (ClassSymbol)classDollarSym.owner;

         JCBlock returnResult;

         // in 1.4.2 and above, we use

         // Class.forName(String name, boolean init, ClassLoader loader);

         // which requires we cache the current loader in cl$

         if (target.classLiteralsNoInit()) {

             // clsym = "private static ClassLoader cl$"

             VarSymbol clsym = new VarSymbol(STATIC|SYNTHETIC,

                                             names.fromString("cl" + target.syntheticNameChar()),

                                             syms.classLoaderType,

                                             outerCacheClass);

             enterSynthetic(pos, clsym, outerCacheClass.members());

             // emit "private static ClassLoader cl$;"

             JCVariableDecl cldef = make.VarDef(clsym, null);

             JCClassDecl outerCacheClassDef = classDef(outerCacheClass);

             outerCacheClassDef.defs = outerCacheClassDef.defs.prepend(cldef);

             // newcache := "new cache$1[0]"

             JCNewArray newcache = make.

                 NewArray(make.Type(outerCacheClass.type),

                          List.<JCExpression>of(make.Literal(INT, 0).setType(syms.intType)),

                          null);

             newcache.type = new ArrayType(types.erasure(outerCacheClass.type),

                                           syms.arrayClass);

             // forNameSym := java.lang.Class.forName(

             //     String s,boolean init,ClassLoader loader)

             Symbol forNameSym = lookupMethod(make_pos, names.forName,

                                              types.erasure(syms.classType),

                                              List.of(syms.stringType,

                                                      syms.booleanType,

                                                      syms.classLoaderType));

             // clvalue := "(cl$ == null) ?

             // $newcache.getClass().getComponentType().getClassLoader() : cl$"

             JCExpression clvalue =

                 make.Conditional(

                     makeBinary(EQ, make.Ident(clsym), makeNull()),

                     make.Assign(

                         make.Ident(clsym),

                         makeCall(

                             makeCall(makeCall(newcache,

                                               names.getClass,

                                               List.<JCExpression>nil()),

                                      names.getComponentType,

                                      List.<JCExpression>nil()),

                             names.getClassLoader,

                             List.<JCExpression>nil())).setType(syms.classLoaderType),

                     make.Ident(clsym)).setType(syms.classLoaderType);

             // returnResult := "{ return Class.forName(param1, false, cl$); }"

             List<JCExpression> args = List.of(make.Ident(md.params.head.sym),

                                               makeLit(syms.booleanType, 0),

                                               clvalue);

             returnResult = make.

                 Block(0, List.<JCStatement>of(make.

                               Call(make. // return

                                    App(make.

                                        Ident(forNameSym), args))));

         } else {

             // forNameSym := java.lang.Class.forName(String s)

             Symbol forNameSym = lookupMethod(make_pos,

                                              names.forName,

                                              types.erasure(syms.classType),

                                              List.of(syms.stringType));

             // returnResult := "{ return Class.forName(param1); }"

             returnResult = make.

                 Block(0, List.of(make.

                           Call(make. // return

                               App(make.

                                   QualIdent(forNameSym),

                                   List.<JCExpression>of(make.

                                                         Ident(md.params.

                                                               head.sym))))));

         }

         // catchParam := ClassNotFoundException e1

         VarSymbol catchParam =

             new VarSymbol(0, make.paramName(1),

                           syms.classNotFoundExceptionType,

                           classDollarSym);

         JCStatement rethrow;

         if (target.hasInitCause()) {

             // rethrow = "throw new NoClassDefFoundError().initCause(e);

             JCTree throwExpr =

                 makeCall(makeNewClass(syms.noClassDefFoundErrorType,

                                       List.<JCExpression>nil()),

                          names.initCause,

                          List.<JCExpression>of(make.Ident(catchParam)));

             rethrow = make.Throw(throwExpr);

         } else {

             // getMessageSym := ClassNotFoundException.getMessage()

             Symbol getMessageSym = lookupMethod(make_pos,

                                                 names.getMessage,

                                                 syms.classNotFoundExceptionType,

                                                 List.<Type>nil());

             // rethrow = "throw new NoClassDefFoundError(e.getMessage());"

             rethrow = make.

                 Throw(makeNewClass(syms.noClassDefFoundErrorType,

                           List.<JCExpression>of(make.App(make.Select(make.Ident(catchParam),

                                                                      getMessageSym),

                                                          List.<JCExpression>nil()))));

         }

         // rethrowStmt := "( $rethrow )"

         JCBlock rethrowStmt = make.Block(0, List.of(rethrow));

         // catchBlock := "catch ($catchParam) $rethrowStmt"

         JCCatch catchBlock = make.Catch(make.VarDef(catchParam, null),

                                       rethrowStmt);

         // tryCatch := "try $returnResult $catchBlock"

         JCStatement tryCatch = make.Try(returnResult,

                                         List.of(catchBlock), null);

         return make.Block(0, List.of(tryCatch));

     }

     // where

         /** Create an attributed tree of the form left.name(). */

         private JCMethodInvocation makeCall(JCExpression left, Name name, List<JCExpression> args) {

             Assert.checkNonNull(left.type);

             Symbol funcsym = lookupMethod(make_pos, name, left.type,

                                           TreeInfo.types(args));

             return make.App(make.Select(left, funcsym), args);

         }

     /** The Name Of The variable to cache T.class values.

      *  @param sig      The signature of type T.

      */

     private Name cacheName(String sig) {

         StringBuilder buf = new StringBuilder();

         if (sig.startsWith("[")) {

             buf = buf.append("array");

             while (sig.startsWith("[")) {

                 buf = buf.append(target.syntheticNameChar());

                 sig = sig.substring(1);

             }

             if (sig.startsWith("L")) {

                 sig = sig.substring(0, sig.length() - 1);

             }

         } else {

             buf = buf.append("class" + target.syntheticNameChar());

         }

         buf = buf.append(sig.replace('.', target.syntheticNameChar()));

         return names.fromString(buf.toString());

     }

     /** The variable symbol that caches T.class values.

      *  If none exists yet, create a definition.

      *  @param sig      The signature of type T.

      *  @param pos      The position to report diagnostics, if any.

      */

     private VarSymbol cacheSym(DiagnosticPosition pos, String sig) {

         ClassSymbol outerCacheClass = outerCacheClass();

         Name cname = cacheName(sig);

         VarSymbol cacheSym =

             (VarSymbol)lookupSynthetic(cname, outerCacheClass.members());

         if (cacheSym == null) {

             cacheSym = new VarSymbol(

                 STATIC | SYNTHETIC, cname, types.erasure(syms.classType), outerCacheClass);

             enterSynthetic(pos, cacheSym, outerCacheClass.members());

             JCVariableDecl cacheDef = make.VarDef(cacheSym, null);

             JCClassDecl outerCacheClassDef = classDef(outerCacheClass);

             outerCacheClassDef.defs = outerCacheClassDef.defs.prepend(cacheDef);

         }

         return cacheSym;

     }

     /** The tree simulating a T.class expression.

      *  @param clazz      The tree identifying type T.

      */

     private JCExpression classOf(JCTree clazz) {

         return classOfType(clazz.type, clazz.pos());

     }

     private JCExpression classOfType(Type type, DiagnosticPosition pos) {

         switch (type.getTag()) {

         case BYTE: case SHORT: case CHAR: case INT: case LONG: case FLOAT:

         case DOUBLE: case BOOLEAN: case VOID:

             // replace with <BoxedClass>.TYPE

             ClassSymbol c = types.boxedClass(type);

             Symbol typeSym =

                 rs.accessBase(

                     rs.findIdentInType(attrEnv, c.type, names.TYPE, VAR),

                     pos, c.type, names.TYPE, true);

             if (typeSym.kind == VAR)

                 ((VarSymbol)typeSym).getConstValue(); // ensure initializer is evaluated

             return make.QualIdent(typeSym);

         case CLASS: case ARRAY:

             if (target.hasClassLiterals()) {

                 VarSymbol sym = new VarSymbol(

                         STATIC | PUBLIC | FINAL, names._class,

                         syms.classType, type.tsym);

                 return make_at(pos).Select(make.Type(type), sym);

             }

             // replace with <cache == null ? cache = class$(tsig) : cache>

             // where

             //  - <tsig>  is the type signature of T,

             //  - <cache> is the cache variable for tsig.

             String sig =

                 writer.xClassName(type).toString().replace('/', '.');

             Symbol cs = cacheSym(pos, sig);

             return make_at(pos).Conditional(

                 makeBinary(EQ, make.Ident(cs), makeNull()),

                 make.Assign(

                     make.Ident(cs),

                     make.App(

                         make.Ident(classDollarSym(pos)),

                         List.<JCExpression>of(make.Literal(CLASS, sig)

                                               .setType(syms.stringType))))

                 .setType(types.erasure(syms.classType)),

                 make.Ident(cs)).setType(types.erasure(syms.classType));

         default:

             throw new AssertionError();

         }

     }

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

  * Code for enabling/disabling assertions.

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

     // This code is not particularly robust if the user has

     // previously declared a member named '$assertionsDisabled'.

     // The same faulty idiom also appears in the translation of

     // class literals above.  We should report an error if a

     // previous declaration is not synthetic.

     private JCExpression assertFlagTest(DiagnosticPosition pos) {

         // Outermost class may be either true class or an interface.

         ClassSymbol outermostClass = outermostClassDef.sym;

         // note that this is a class, as an interface can't contain a statement.

         ClassSymbol container = currentClass;

         VarSymbol assertDisabledSym =

             (VarSymbol)lookupSynthetic(dollarAssertionsDisabled,

                                        container.members());

         if (assertDisabledSym == null) {

             assertDisabledSym =

                 new VarSymbol(STATIC | FINAL | SYNTHETIC,

                               dollarAssertionsDisabled,

                               syms.booleanType,

                               container);

             enterSynthetic(pos, assertDisabledSym, container.members());

             Symbol desiredAssertionStatusSym = lookupMethod(pos,

                                                             names.desiredAssertionStatus,

                                                             types.erasure(syms.classType),

                                                             List.<Type>nil());

             JCClassDecl containerDef = classDef(container);

             make_at(containerDef.pos());

             JCExpression notStatus = makeUnary(NOT, make.App(make.Select(

                     classOfType(types.erasure(outermostClass.type),

                                 containerDef.pos()),

                     desiredAssertionStatusSym)));

             JCVariableDecl assertDisabledDef = make.VarDef(assertDisabledSym,

                                                    notStatus);

             containerDef.defs = containerDef.defs.prepend(assertDisabledDef);

         }

         make_at(pos);

         return makeUnary(NOT, make.Ident(assertDisabledSym));

     }

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

  * Building blocks for let expressions

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

     interface TreeBuilder {

         JCTree build(JCTree arg);

     }

     /** Construct an expression using the builder, with the given rval

      *  expression as an argument to the builder.  However, the rval

      *  expression must be computed only once, even if used multiple

      *  times in the result of the builder.  We do that by

      *  constructing a "let" expression that saves the rvalue into a

      *  temporary variable and then uses the temporary variable in

      *  place of the expression built by the builder.  The complete

      *  resulting expression is of the form

      *  <pre>

      *    (let <b>TYPE</b> <b>TEMP</b> = <b>RVAL</b>;

      *     in (<b>BUILDER</b>(<b>TEMP</b>)))

      *  </pre>

      *  where <code><b>TEMP</b></code> is a newly declared variable

      *  in the let expression.

      */

     JCTree abstractRval(JCTree rval, Type type, TreeBuilder builder) {

         rval = TreeInfo.skipParens(rval);

         switch (rval.getTag()) {

         case LITERAL:

             return builder.build(rval);

         case IDENT:

             JCIdent id = (JCIdent) rval;

             if ((id.sym.flags() & FINAL) != 0 && id.sym.owner.kind == MTH)

                 return builder.build(rval);

         }

         VarSymbol var =

             new VarSymbol(FINAL|SYNTHETIC,

                           names.fromString(

                                           target.syntheticNameChar()

                                           + "" + rval.hashCode()),

                                       type,

                                       currentMethodSym);

         rval = convert(rval,type);

         JCVariableDecl def = make.VarDef(var, (JCExpression)rval); // XXX cast

         JCTree built = builder.build(make.Ident(var));

         JCTree res = make.LetExpr(def, built);

         res.type = built.type;

         return res;

     }

     // same as above, with the type of the temporary variable computed

     JCTree abstractRval(JCTree rval, TreeBuilder builder) {

         return abstractRval(rval, rval.type, builder);

     }

     // same as above, but for an expression that may be used as either

     // an rvalue or an lvalue.  This requires special handling for

     // Select expressions, where we place the left-hand-side of the

     // select in a temporary, and for Indexed expressions, where we

     // place both the indexed expression and the index value in temps.

     JCTree abstractLval(JCTree lval, final TreeBuilder builder) {

         lval = TreeInfo.skipParens(lval);

         switch (lval.getTag()) {

         case IDENT:

             return builder.build(lval);

         case SELECT: {

             final JCFieldAccess s = (JCFieldAccess)lval;

             JCTree selected = TreeInfo.skipParens(s.selected);

             Symbol lid = TreeInfo.symbol(s.selected);

             if (lid != null && lid.kind == TYP) return builder.build(lval);

             return abstractRval(s.selected, new TreeBuilder() {

                     public JCTree build(final JCTree selected) {

                         return builder.build(make.Select((JCExpression)selected, s.sym));

                     }

                 });

         }

         case INDEXED: {

             final JCArrayAccess i = (JCArrayAccess)lval;

             return abstractRval(i.indexed, new TreeBuilder() {

                     public JCTree build(final JCTree indexed) {

                         return abstractRval(i.index, syms.intType, new TreeBuilder() {

                                 public JCTree build(final JCTree index) {

                                     JCTree newLval = make.Indexed((JCExpression)indexed,

                                                                 (JCExpression)index);

                                     newLval.setType(i.type);

                                     return builder.build(newLval);

                                 }

                             });

                     }

                 });

         }

         case TYPECAST: {

             return abstractLval(((JCTypeCast)lval).expr, builder);

         }

         }

         throw new AssertionError(lval);

     }

     // evaluate and discard the first expression, then evaluate the second.

     JCTree makeComma(final JCTree expr1, final JCTree expr2) {

         return abstractRval(expr1, new TreeBuilder() {

                 public JCTree build(final JCTree discarded) {

                     return expr2;

                 }

             });

     }

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

  * Translation methods

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

     /** Visitor argument: enclosing operator node.

      */

     private JCExpression enclOp;

     /** Visitor method: Translate a single node.

      *  Attach the source position from the old tree to its replacement tree.

      */

     public <T extends JCTree> T translate(T tree) {

         if (tree == null) {

             return null;

         } else {

             make_at(tree.pos());

             T result = super.translate(tree);

             if (endPosTable != null && result != tree) {

                 endPosTable.replaceTree(tree, result);

             }

             return result;

         }

     }

     /** Visitor method: Translate a single node, boxing or unboxing if needed.

      */

     public <T extends JCTree> T translate(T tree, Type type) {

         return (tree == null) ? null : boxIfNeeded(translate(tree), type);

     }

     /** Visitor method: Translate tree.

      */

     public <T extends JCTree> T translate(T tree, JCExpression enclOp) {

         JCExpression prevEnclOp = this.enclOp;

         this.enclOp = enclOp;

         T res = translate(tree);

         this.enclOp = prevEnclOp;

         return res;

     }

     /** Visitor method: Translate list of trees.

      */

     public <T extends JCTree> List<T> translate(List<T> trees, JCExpression enclOp) {

         JCExpression prevEnclOp = this.enclOp;

         this.enclOp = enclOp;

         List<T> res = translate(trees);

         this.enclOp = prevEnclOp;

         return res;

     }

     /** Visitor method: Translate list of trees.

      */

     public <T extends JCTree> List<T> translate(List<T> trees, Type type) {

         if (trees == null) return null;

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

             l.head = translate(l.head, type);

         return trees;

     }

     public void visitTopLevel(JCCompilationUnit tree) {

         if (needPackageInfoClass(tree)) {

             Name name = names.package_info;

             long flags = Flags.ABSTRACT | Flags.INTERFACE;

             if (target.isPackageInfoSynthetic())

                 // package-info is marked SYNTHETIC in JDK 1.6 and later releases

                 flags = flags | Flags.SYNTHETIC;

             JCClassDecl packageAnnotationsClass

                 = make.ClassDef(make.Modifiers(flags,

                                                tree.packageAnnotations),

                                 name, List.<JCTypeParameter>nil(),

                                 null, List.<JCExpression>nil(), List.<JCTree>nil());

             ClassSymbol c = tree.packge.package_info;

             c.flags_field |= flags;

             c.annotations.setAttributes(tree.packge.annotations);

             ClassType ctype = (ClassType) c.type;

             ctype.supertype_field = syms.objectType;

             ctype.interfaces_field = List.nil();

             packageAnnotationsClass.sym = c;

             translated.append(packageAnnotationsClass);

         }

     }

     // where

     private boolean needPackageInfoClass(JCCompilationUnit tree) {

         switch (pkginfoOpt) {

             case ALWAYS:

                 return true;

             case LEGACY:

                 return tree.packageAnnotations.nonEmpty();

             case NONEMPTY:

                 for (Attribute.Compound a :

                          tree.packge.annotations.getAttributes()) {

                     Attribute.RetentionPolicy p = types.getRetention(a);

                     if (p != Attribute.RetentionPolicy.SOURCE)

                         return true;

                 }

                 return false;

         }

         throw new AssertionError();

     }

     public void visitClassDef(JCClassDecl tree) {

         ClassSymbol currentClassPrev = currentClass;

         MethodSymbol currentMethodSymPrev = currentMethodSym;

         currentClass = tree.sym;

         currentMethodSym = null;

         classdefs.put(currentClass, tree);

         proxies = proxies.dup(currentClass);

         List<VarSymbol> prevOuterThisStack = outerThisStack;

         // If this is an enum definition

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

             (types.supertype(currentClass.type).tsym.flags() & ENUM) == 0)

             visitEnumDef(tree);

         // If this is a nested class, define a this$n field for

         // it and add to proxies.

         JCVariableDecl otdef = null;

         if (currentClass.hasOuterInstance())

             otdef = outerThisDef(tree.pos, currentClass);

         // If this is a local class, define proxies for all its free variables.

         List<JCVariableDecl> fvdefs = freevarDefs(

             tree.pos, freevars(currentClass), currentClass);

         // Recursively translate superclass, interfaces.

         tree.extending = translate(tree.extending);

         tree.implementing = translate(tree.implementing);

         if (currentClass.isLocal()) {

             ClassSymbol encl = currentClass.owner.enclClass();

             if (encl.trans_local == null) {

                 encl.trans_local = List.nil();

             }

             encl.trans_local = encl.trans_local.prepend(currentClass);

         }

         // Recursively translate members, taking into account that new members

         // might be created during the translation and prepended to the member

         // list `tree.defs'.

         List<JCTree> seen = List.nil();

         while (tree.defs != seen) {

             List<JCTree> unseen = tree.defs;

             for (List<JCTree> l = unseen; l.nonEmpty() && l != seen; l = l.tail) {

                 JCTree outermostMemberDefPrev = outermostMemberDef;

                 if (outermostMemberDefPrev == null) outermostMemberDef = l.head;

                 l.head = translate(l.head);

                 outermostMemberDef = outermostMemberDefPrev;

             }

             seen = unseen;

         }

         // Convert a protected modifier to public, mask static modifier.

         if ((tree.mods.flags & PROTECTED) != 0) tree.mods.flags |= PUBLIC;

         tree.mods.flags &= ClassFlags;

         // Convert name to flat representation, replacing '.' by '$'.

         tree.name = Convert.shortName(currentClass.flatName());

         // Add this$n and free variables proxy definitions to class.

         for (List<JCVariableDecl> l = fvdefs; l.nonEmpty(); l = l.tail) {

             tree.defs = tree.defs.prepend(l.head);

             enterSynthetic(tree.pos(), l.head.sym, currentClass.members());

         }

         if (currentClass.hasOuterInstance()) {

             tree.defs = tree.defs.prepend(otdef);

             enterSynthetic(tree.pos(), otdef.sym, currentClass.members());

         }

         proxies = proxies.leave();

         outerThisStack = prevOuterThisStack;

         // Append translated tree to `translated' queue.

         translated.append(tree);

         currentClass = currentClassPrev;

         currentMethodSym = currentMethodSymPrev;

         // Return empty block {} as a placeholder for an inner class.

         result = make_at(tree.pos()).Block(0, List.<JCStatement>nil());

     }

     /** Translate an enum class. */

     private void visitEnumDef(JCClassDecl tree) {

         make_at(tree.pos());

         // add the supertype, if needed

         if (tree.extending == null)

             tree.extending = make.Type(types.supertype(tree.type));

         // classOfType adds a cache field to tree.defs unless

         // target.hasClassLiterals().

         JCExpression e_class = classOfType(tree.sym.type, tree.pos()).

             setType(types.erasure(syms.classType));

         // process each enumeration constant, adding implicit constructor parameters

         int nextOrdinal = 0;

         ListBuffer<JCExpression> values = new ListBuffer<JCExpression>();

         ListBuffer<JCTree> enumDefs = new ListBuffer<JCTree>();

         ListBuffer<JCTree> otherDefs = new ListBuffer<JCTree>();

         for (List<JCTree> defs = tree.defs;

              defs.nonEmpty();

              defs=defs.tail) {

             if (defs.head.hasTag(VARDEF) && (((JCVariableDecl) defs.head).mods.flags & ENUM) != 0) {

                 JCVariableDecl var = (JCVariableDecl)defs.head;

                 visitEnumConstantDef(var, nextOrdinal++);

                 values.append(make.QualIdent(var.sym));

                 enumDefs.append(var);

             } else {

                 otherDefs.append(defs.head);

             }

         }

         // private static final T[] #VALUES = { a, b, c };

         Name valuesName = names.fromString(target.syntheticNameChar() + "VALUES");

         while (tree.sym.members().lookup(valuesName).scope != null) // avoid name clash

             valuesName = names.fromString(valuesName + "" + target.syntheticNameChar());

         Type arrayType = new ArrayType(types.erasure(tree.type), syms.arrayClass);

         VarSymbol valuesVar = new VarSymbol(PRIVATE|FINAL|STATIC|SYNTHETIC,

                                             valuesName,

                                             arrayType,

                                             tree.type.tsym);

         JCNewArray newArray = make.NewArray(make.Type(types.erasure(tree.type)),

                                           List.<JCExpression>nil(),

                                           values.toList());

         newArray.type = arrayType;

         enumDefs.append(make.VarDef(valuesVar, newArray));

         tree.sym.members().enter(valuesVar);

         Symbol valuesSym = lookupMethod(tree.pos(), names.values,

                                         tree.type, List.<Type>nil());

         List<JCStatement> valuesBody;

         if (useClone()) {

             // return (T[]) $VALUES.clone();

             JCTypeCast valuesResult =

                 make.TypeCast(valuesSym.type.getReturnType(),

                               make.App(make.Select(make.Ident(valuesVar),

                                                    syms.arrayCloneMethod)));

             valuesBody = List.<JCStatement>of(make.Return(valuesResult));

         } else {

             // template: T[] $result = new T[$values.length];

             Name resultName = names.fromString(target.syntheticNameChar() + "result");

             while (tree.sym.members().lookup(resultName).scope != null) // avoid name clash

                 resultName = names.fromString(resultName + "" + target.syntheticNameChar());

             VarSymbol resultVar = new VarSymbol(FINAL|SYNTHETIC,

                                                 resultName,

                                                 arrayType,

                                                 valuesSym);

             JCNewArray resultArray = make.NewArray(make.Type(types.erasure(tree.type)),

                                   List.of(make.Select(make.Ident(valuesVar), syms.lengthVar)),

                                   null);

             resultArray.type = arrayType;

             JCVariableDecl decl = make.VarDef(resultVar, resultArray);

             // template: System.arraycopy($VALUES, 0, $result, 0, $VALUES.length);

             if (systemArraycopyMethod == null) {

                 systemArraycopyMethod =

                     new MethodSymbol(PUBLIC | STATIC,

                                      names.fromString("arraycopy"),

                                      new MethodType(List.<Type>of(syms.objectType,

                                                             syms.intType,

                                                             syms.objectType,

                                                             syms.intType,

                                                             syms.intType),

                                                     syms.voidType,

                                                     List.<Type>nil(),

                                                     syms.methodClass),

                                      syms.systemType.tsym);

             }

             JCStatement copy =

                 make.Exec(make.App(make.Select(make.Ident(syms.systemType.tsym),

                                                systemArraycopyMethod),

                           List.of(make.Ident(valuesVar), make.Literal(0),

                                   make.Ident(resultVar), make.Literal(0),

                                   make.Select(make.Ident(valuesVar), syms.lengthVar))));

             // template: return $result;

             JCStatement ret = make.Return(make.Ident(resultVar));

             valuesBody = List.<JCStatement>of(decl, copy, ret);

         }

         JCMethodDecl valuesDef =

              make.MethodDef((MethodSymbol)valuesSym, make.Block(0, valuesBody));

         enumDefs.append(valuesDef);

         if (debugLower)

             System.err.println(tree.sym + ".valuesDef = " + valuesDef);

         /** The template for the following code is:

          *

          *     public static E valueOf(String name) {

          *         return (E)Enum.valueOf(E.class, name);

          *     }

          *

          *  where E is tree.sym

          */

         MethodSymbol valueOfSym = lookupMethod(tree.pos(),

                          names.valueOf,

                          tree.sym.type,

                          List.of(syms.stringType));

         Assert.check((valueOfSym.flags() & STATIC) != 0);

         VarSymbol nameArgSym = valueOfSym.params.head;

         JCIdent nameVal = make.Ident(nameArgSym);

         JCStatement enum_ValueOf =

             make.Return(make.TypeCast(tree.sym.type,

                                       makeCall(make.Ident(syms.enumSym),

                                                names.valueOf,

                                                List.of(e_class, nameVal))));

         JCMethodDecl valueOf = make.MethodDef(valueOfSym,

                                            make.Block(0, List.of(enum_ValueOf)));

         nameVal.sym = valueOf.params.head.sym;

         if (debugLower)

             System.err.println(tree.sym + ".valueOf = " + valueOf);

         enumDefs.append(valueOf);

         enumDefs.appendList(otherDefs.toList());

         tree.defs = enumDefs.toList();

         // Add the necessary members for the EnumCompatibleMode

         if (target.compilerBootstrap(tree.sym)) {

             addEnumCompatibleMembers(tree);

         }

     }

         // where

         private MethodSymbol systemArraycopyMethod;

         private boolean useClone() {

             try {

                 Scope.Entry e = syms.objectType.tsym.members().lookup(names.clone);

                 return (e.sym != null);

             }

             catch (CompletionFailure e) {

                 return false;

             }

         }

     /** Translate an enumeration constant and its initializer. */

     private void visitEnumConstantDef(JCVariableDecl var, int ordinal) {

         JCNewClass varDef = (JCNewClass)var.init;

         varDef.args = varDef.args.

             prepend(makeLit(syms.intType, ordinal)).

             prepend(makeLit(syms.stringType, var.name.toString()));

     }

     public void visitMethodDef(JCMethodDecl tree) {

         if (tree.name == names.init && (currentClass.flags_field&ENUM) != 0) {

             // Add "String $enum$name, int $enum$ordinal" to the beginning of the

             // argument list for each constructor of an enum.

             JCVariableDecl nameParam = make_at(tree.pos()).

                 Param(names.fromString(target.syntheticNameChar() +

                                        "enum" + target.syntheticNameChar() + "name"),

                       syms.stringType, tree.sym);

             nameParam.mods.flags |= SYNTHETIC; nameParam.sym.flags_field |= SYNTHETIC;

             JCVariableDecl ordParam = make.

                 Param(names.fromString(target.syntheticNameChar() +

                                        "enum" + target.syntheticNameChar() +

                                        "ordinal"),

                       syms.intType, tree.sym);

             ordParam.mods.flags |= SYNTHETIC; ordParam.sym.flags_field |= SYNTHETIC;

             tree.params = tree.params.prepend(ordParam).prepend(nameParam);

             MethodSymbol m = tree.sym;

             Type olderasure = m.erasure(types);

             m.erasure_field = new MethodType(

                 olderasure.getParameterTypes().prepend(syms.intType).prepend(syms.stringType),

                 olderasure.getReturnType(),

                 olderasure.getThrownTypes(),

                 syms.methodClass);

             if (target.compilerBootstrap(m.owner)) {

                 // Initialize synthetic name field

                 Symbol nameVarSym = lookupSynthetic(names.fromString("$name"),

                                                     tree.sym.owner.members());

                 JCIdent nameIdent = make.Ident(nameParam.sym);

                 JCIdent id1 = make.Ident(nameVarSym);

                 JCAssign newAssign = make.Assign(id1, nameIdent);

                 newAssign.type = id1.type;

                 JCExpressionStatement nameAssign = make.Exec(newAssign);

                 nameAssign.type = id1.type;

                 tree.body.stats = tree.body.stats.prepend(nameAssign);

                 // Initialize synthetic ordinal field

                 Symbol ordinalVarSym = lookupSynthetic(names.fromString("$ordinal"),

                                                        tree.sym.owner.members());

                 JCIdent ordIdent = make.Ident(ordParam.sym);

                 id1 = make.Ident(ordinalVarSym);

                 newAssign = make.Assign(id1, ordIdent);

                 newAssign.type = id1.type;

                 JCExpressionStatement ordinalAssign = make.Exec(newAssign);

                 ordinalAssign.type = id1.type;

                 tree.body.stats = tree.body.stats.prepend(ordinalAssign);

             }

         }

         JCMethodDecl prevMethodDef = currentMethodDef;

         MethodSymbol prevMethodSym = currentMethodSym;

         try {

             currentMethodDef = tree;

             currentMethodSym = tree.sym;

             visitMethodDefInternal(tree);

         } finally {

             currentMethodDef = prevMethodDef;

             currentMethodSym = prevMethodSym;

         }

     }

     //where

     private void visitMethodDefInternal(JCMethodDecl tree) {

         if (tree.name == names.init &&

             (currentClass.isInner() ||

              (currentClass.owner.kind & (VAR | MTH)) != 0)) {

             // We are seeing a constructor of an inner class.

             MethodSymbol m = tree.sym;

             // Push a new proxy scope for constructor parameters.

             // and create definitions for any this$n and proxy parameters.

             proxies = proxies.dup(m);

             List<VarSymbol> prevOuterThisStack = outerThisStack;

             List<VarSymbol> fvs = freevars(currentClass);

             JCVariableDecl otdef = null;

             if (currentClass.hasOuterInstance())

                 otdef = outerThisDef(tree.pos, m);

             List<JCVariableDecl> fvdefs = freevarDefs(tree.pos, fvs, m);

             // Recursively translate result type, parameters and thrown list.

             tree.restype = translate(tree.restype);

             tree.params = translateVarDefs(tree.params);

             tree.thrown = translate(tree.thrown);

             // when compiling stubs, don't process body

             if (tree.body == null) {

                 result = tree;

                 return;

             }

             // Add this$n (if needed) in front of and free variables behind

             // constructor parameter list.

             tree.params = tree.params.appendList(fvdefs);

             if (currentClass.hasOuterInstance())

                 tree.params = tree.params.prepend(otdef);

             // If this is an initial constructor, i.e., it does not start with

             // this(...), insert initializers for this$n and proxies