1 /*

     2  * Copyright (c) 2010, 2012, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package com.sun.tools.javac.comp;

    26 

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

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

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

    30 import com.sun.tools.javac.tree.JCTree.JCMemberReference.ReferenceKind;

    31 import com.sun.tools.javac.tree.TreeMaker;

    32 import com.sun.tools.javac.tree.TreeScanner;

    33 import com.sun.tools.javac.tree.TreeTranslator;

    34 import com.sun.tools.javac.code.Flags;

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

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

    37 import com.sun.tools.javac.code.Symbol.ClassSymbol;

    38 import com.sun.tools.javac.code.Symbol.DynamicMethodSymbol;

    39 import com.sun.tools.javac.code.Symbol.MethodSymbol;

    40 import com.sun.tools.javac.code.Symbol.VarSymbol;

    41 import com.sun.tools.javac.code.Symtab;

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

    43 import com.sun.tools.javac.code.Type.ClassType;

    44 import com.sun.tools.javac.code.Type.MethodType;

    45 import com.sun.tools.javac.code.Types;

    46 import com.sun.tools.javac.comp.LambdaToMethod.LambdaAnalyzer.*;

    47 import com.sun.tools.javac.jvm.*;

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

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

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

    51 import com.sun.source.tree.MemberReferenceTree.ReferenceMode;

    52 

    53 import java.util.HashMap;

    54 import java.util.LinkedHashMap;

    55 import java.util.Map;

    56 

    57 import static com.sun.tools.javac.comp.LambdaToMethod.LambdaSymbolKind.*;

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

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

    60 import static com.sun.tools.javac.code.TypeTag.BOT;

    61 import static com.sun.tools.javac.code.TypeTag.NONE;

    62 import static com.sun.tools.javac.code.TypeTag.VOID;

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

    64 

    65 /**

    66  * This pass desugars lambda expressions into static methods

    67  *

    68  *  <p><b>This is NOT part of any supported API.

    69  *  If you write code that depends on this, you do so at your own risk.

    70  *  This code and its internal interfaces are subject to change or

    71  *  deletion without notice.</b>

    72  */

    73 public class LambdaToMethod extends TreeTranslator {

    74 

    75     private Names names;

    76     private Symtab syms;

    77     private Resolve rs;

    78     private TreeMaker make;

    79     private Types types;

    80     private TransTypes transTypes;

    81     private Env<AttrContext> attrEnv;

    82 

    83     /** the analyzer scanner */

    84     private LambdaAnalyzer analyzer;

    85 

    86     /** map from lambda trees to translation contexts */

    87     private Map<JCTree, TranslationContext<?>> contextMap;

    88 

    89     /** current translation context (visitor argument) */

    90     private TranslationContext<?> context;

    91 

    92     /** list of translated methods

    93      **/

    94     private ListBuffer<JCTree> translatedMethodList;

    95 

    96     // <editor-fold defaultstate="collapsed" desc="Instantiating">

    97     private static final Context.Key<LambdaToMethod> unlambdaKey =

    98             new Context.Key<LambdaToMethod>();

    99 

   100     public static LambdaToMethod instance(Context context) {

   101         LambdaToMethod instance = context.get(unlambdaKey);

   102         if (instance == null) {

   103             instance = new LambdaToMethod(context);

   104         }

   105         return instance;

   106     }

   107 

   108     private LambdaToMethod(Context context) {

   109         names = Names.instance(context);

   110         syms = Symtab.instance(context);

   111         rs = Resolve.instance(context);

   112         make = TreeMaker.instance(context);

   113         types = Types.instance(context);

   114         transTypes = TransTypes.instance(context);

   115         this.analyzer = makeAnalyzer();

   116     }

   117 

   118     private LambdaAnalyzer makeAnalyzer() {

   119         return new LambdaAnalyzer();

   120     }

   121     // </editor-fold>

   122 

   123     // <editor-fold defaultstate="collapsed" desc="translate methods">

   124     @Override

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

   126         TranslationContext<?> newContext = contextMap.get(tree);

   127         return translate(tree, newContext != null ? newContext : context);

   128     }

   129 

   130     public <T extends JCTree> T translate(T tree, TranslationContext<?> newContext) {

   131         TranslationContext<?> prevContext = context;

   132         try {

   133             context = newContext;

   134             return super.translate(tree);

   135         }

   136         finally {

   137             context = prevContext;

   138         }

   139     }

   140 

   141     public <T extends JCTree> List<T> translate(List<T> trees, TranslationContext<?> newContext) {

   142         ListBuffer<T> buf = ListBuffer.lb();

   143         for (T tree : trees) {

   144             buf.append(translate(tree, newContext));

   145         }

   146         return buf.toList();

   147     }

   148 

   149     public JCTree translateTopLevelClass(Env<AttrContext> env, JCTree cdef, TreeMaker make) {

   150         this.make = make;

   151         this.attrEnv = env;

   152         this.context = null;

   153         this.contextMap = new HashMap<JCTree, TranslationContext<?>>();

   154         return translate(cdef);

   155     }

   156     // </editor-fold>

   157 

   158     // <editor-fold defaultstate="collapsed" desc="visitor methods">

   159     /**

   160      * Visit a class.

   161      * Maintain the translatedMethodList across nested classes.

   162      * Append the translatedMethodList to the class after it is translated.

   163      * @param tree

   164      */

   165     @Override

   166     public void visitClassDef(JCClassDecl tree) {

   167         if (tree.sym.owner.kind == PCK) {

   168             //analyze class

   169             analyzer.analyzeClass(tree);

   170         }

   171         ListBuffer<JCTree> prevTranslated = translatedMethodList;

   172         try {

   173             translatedMethodList = ListBuffer.lb();

   174             super.visitClassDef(tree);

   175             //add all translated instance methods here

   176             tree.defs = tree.defs.appendList(translatedMethodList.toList());

   177             for (JCTree lambda : translatedMethodList) {

   178                 tree.sym.members().enter(((JCMethodDecl)lambda).sym);

   179             }

   180             result = tree;

   181         } finally {

   182             translatedMethodList = prevTranslated;

   183         }

   184     }

   185 

   186     /**

   187      * Translate a lambda into a method to be inserted into the class.

   188      * Then replace the lambda site with an invokedynamic call of to lambda

   189      * meta-factory, which will use the lambda method.

   190      * @param tree

   191      */

   192     @Override

   193     public void visitLambda(JCLambda tree) {

   194         LambdaTranslationContext localContext = (LambdaTranslationContext)context;

   195         MethodSymbol sym = (MethodSymbol)localContext.translatedSym;

   196         MethodType lambdaType = (MethodType) sym.type;

   197 

   198         //create the method declaration hoisting the lambda body

   199         JCMethodDecl lambdaDecl = make.MethodDef(make.Modifiers(sym.flags_field),

   200                 sym.name,

   201                 make.QualIdent(lambdaType.getReturnType().tsym),

   202                 List.<JCTypeParameter>nil(),

   203                 localContext.syntheticParams,

   204                 lambdaType.getThrownTypes() == null ?

   205                     List.<JCExpression>nil() :

   206                     make.Types(lambdaType.getThrownTypes()),

   207                 null,

   208                 null);

   209         lambdaDecl.sym = sym;

   210         lambdaDecl.type = lambdaType;

   211 

   212         //translate lambda body

   213         //As the lambda body is translated, all references to lambda locals,

   214         //captured variables, enclosing members are adjusted accordingly

   215         //to refer to the static method parameters (rather than i.e. acessing to

   216         //captured members directly).

   217         lambdaDecl.body = translate(makeLambdaBody(tree, lambdaDecl));

   218 

   219         //Add the method to the list of methods to be added to this class.

   220         translatedMethodList = translatedMethodList.prepend(lambdaDecl);

   221 

   222         //now that we have generated a method for the lambda expression,

   223         //we can translate the lambda into a method reference pointing to the newly

   224         //created method.

   225         //

   226         //Note that we need to adjust the method handle so that it will match the

   227         //signature of the SAM descriptor - this means that the method reference

   228         //should be added the following synthetic arguments:

   229         //

   230         // * the "this" argument if it is an instance method

   231         // * enclosing locals captured by the lambda expression

   232 

   233         ListBuffer<JCExpression> syntheticInits = ListBuffer.lb();

   234 

   235         if (!sym.isStatic()) {

   236             syntheticInits.append(makeThis(

   237                     sym.owner.asType(),

   238                     localContext.owner.enclClass()));

   239         }

   240 

   241         //add captured locals

   242         for (Symbol fv : localContext.getSymbolMap(CAPTURED_VAR).keySet()) {

   243             if (fv != localContext.self) {

   244                 JCTree captured_local = make.Ident(fv).setType(fv.type);

   245                 syntheticInits.append((JCExpression) captured_local);

   246             }

   247         }

   248 

   249         //then, determine the arguments to the indy call

   250         List<JCExpression> indy_args = translate(syntheticInits.toList(), localContext.prev);

   251 

   252         //build a sam instance using an indy call to the meta-factory

   253         int refKind = referenceKind(sym);

   254 

   255         //convert to an invokedynamic call

   256         result = makeMetaFactoryIndyCall(tree, tree.targetType, refKind, sym, indy_args);

   257     }

   258 

   259     private JCIdent makeThis(Type type, Symbol owner) {

   260         VarSymbol _this = new VarSymbol(PARAMETER | FINAL | SYNTHETIC,

   261                 names._this,

   262                 type,

   263                 owner);

   264         return make.Ident(_this);

   265     }

   266 

   267     /**

   268      * Translate a method reference into an invokedynamic call to the

   269      * meta-factory.

   270      * @param tree

   271      */

   272     @Override

   273     public void visitReference(JCMemberReference tree) {

   274         ReferenceTranslationContext localContext = (ReferenceTranslationContext)context;

   275 

   276         //first determine the method symbol to be used to generate the sam instance

   277         //this is either the method reference symbol, or the bridged reference symbol

   278         Symbol refSym = localContext.needsBridge() ?

   279             localContext.bridgeSym :

   280             tree.sym;

   281 

   282         //build the bridge method, if needed

   283         if (localContext.needsBridge()) {

   284             bridgeMemberReference(tree, localContext);

   285         }

   286 

   287         //the qualifying expression is treated as a special captured arg

   288         JCExpression init;

   289         switch(tree.kind) {

   290 

   291             case IMPLICIT_INNER:    /** Inner # new */

   292             case SUPER:             /** super # instMethod */

   293                 init = makeThis(

   294                     localContext.owner.owner.asType(),

   295                     localContext.owner);

   296                 break;

   297 

   298             case BOUND:             /** Expr # instMethod */

   299                 init = tree.getQualifierExpression();

   300                 break;

   301 

   302             case STATIC_EVAL:       /** Expr # staticMethod */

   303             case UNBOUND:           /** Type # instMethod */

   304             case STATIC:            /** Type # staticMethod */

   305             case TOPLEVEL:          /** Top level # new */

   306                 init = null;

   307                 break;

   308 

   309             default:

   310                 throw new InternalError("Should not have an invalid kind");

   311         }

   312 

   313         List<JCExpression> indy_args = init==null? List.<JCExpression>nil() : translate(List.of(init), localContext.prev);

   314 

   315 

   316         //build a sam instance using an indy call to the meta-factory

   317         result = makeMetaFactoryIndyCall(tree, tree.targetType, localContext.referenceKind(), refSym, indy_args);

   318 

   319         //if we had a static reference with non-static qualifier, add a let

   320         //expression to force the evaluation of the qualifier expr

   321         if (tree.hasKind(ReferenceKind.STATIC_EVAL)) {

   322             VarSymbol rec = new VarSymbol(0, names.fromString("rec$"), tree.getQualifierExpression().type, localContext.owner);

   323             JCVariableDecl recDef = make.VarDef(rec, tree.getQualifierExpression());

   324             result = make.LetExpr(recDef, result).setType(tree.type);

   325         }

   326     }

   327 

   328     /**

   329      * Translate identifiers within a lambda to the mapped identifier

   330      * @param tree

   331      */

   332     @Override

   333     public void visitIdent(JCIdent tree) {

   334         if (context == null || !analyzer.lambdaIdentSymbolFilter(tree.sym)) {

   335             super.visitIdent(tree);

   336         } else {

   337             LambdaTranslationContext lambdaContext = (LambdaTranslationContext) context;

   338             if (lambdaContext.getSymbolMap(PARAM).containsKey(tree.sym)) {

   339                 Symbol translatedSym = lambdaContext.getSymbolMap(PARAM).get(tree.sym);

   340                 result = make.Ident(translatedSym).setType(tree.type);

   341             } else if (lambdaContext.getSymbolMap(LOCAL_VAR).containsKey(tree.sym)) {

   342                 Symbol translatedSym = lambdaContext.getSymbolMap(LOCAL_VAR).get(tree.sym);

   343                 result = make.Ident(translatedSym).setType(tree.type);

   344             } else if (lambdaContext.getSymbolMap(CAPTURED_VAR).containsKey(tree.sym)) {

   345                 Symbol translatedSym = lambdaContext.getSymbolMap(CAPTURED_VAR).get(tree.sym);

   346                 result = make.Ident(translatedSym).setType(tree.type);

   347             } else {

   348                 if (tree.sym.owner.kind == Kinds.TYP) {

   349                     for (Map.Entry<Symbol, Symbol> encl_entry : lambdaContext.getSymbolMap(CAPTURED_THIS).entrySet()) {

   350                         if (tree.sym.isMemberOf((ClassSymbol) encl_entry.getKey(), types)) {

   351                             JCExpression enclRef = make.Ident(encl_entry.getValue());

   352                             result = tree.sym.name == names._this

   353                                     ? enclRef.setType(tree.type)

   354                                     : make.Select(enclRef, tree.sym).setType(tree.type);

   355                             result = tree;

   356                             return;

   357                         }

   358                     }

   359                 }

   360                 //access to untranslated symbols (i.e. compile-time constants,

   361                 //members defined inside the lambda body, etc.) )

   362                 super.visitIdent(tree);

   363             }

   364         }

   365     }

   366 

   367     @Override

   368     public void visitVarDef(JCVariableDecl tree) {

   369         LambdaTranslationContext lambdaContext = (LambdaTranslationContext)context;

   370         if (context != null && lambdaContext.getSymbolMap(LOCAL_VAR).containsKey(tree.sym)) {

   371             JCExpression init = translate(tree.init);

   372             result = make.VarDef((VarSymbol)lambdaContext.getSymbolMap(LOCAL_VAR).get(tree.sym), init);

   373         } else {

   374             super.visitVarDef(tree);

   375         }

   376     }

   377 

   378     // </editor-fold>

   379 

   380     // <editor-fold defaultstate="collapsed" desc="Translation helper methods">

   381 

   382     private JCBlock makeLambdaBody(JCLambda tree, JCMethodDecl lambdaMethodDecl) {

   383         return tree.getBodyKind() == JCLambda.BodyKind.EXPRESSION ?

   384                 makeLambdaExpressionBody((JCExpression)tree.body, lambdaMethodDecl) :

   385                 makeLambdaStatementBody((JCBlock)tree.body, lambdaMethodDecl, tree.canCompleteNormally);

   386     }

   387 

   388     private JCBlock makeLambdaExpressionBody(JCExpression expr, JCMethodDecl lambdaMethodDecl) {

   389         Type restype = lambdaMethodDecl.type.getReturnType();

   390         boolean isLambda_void = expr.type.hasTag(VOID);

   391         boolean isTarget_void = restype.hasTag(VOID);

   392         boolean isTarget_Void = types.isSameType(restype, types.boxedClass(syms.voidType).type);

   393         if (isTarget_void) {

   394             //target is void:

   395             // BODY;

   396             JCStatement stat = make.Exec(expr);

   397             return make.Block(0, List.<JCStatement>of(stat));

   398         } else if (isLambda_void && isTarget_Void) {

   399             //void to Void conversion:

   400             // BODY; return null;

   401             ListBuffer<JCStatement> stats = ListBuffer.lb();

   402             stats.append(make.Exec(expr));

   403             stats.append(make.Return(make.Literal(BOT, null).setType(syms.botType)));

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

   405         } else {

   406             //non-void to non-void conversion:

   407             // return (TYPE)BODY;

   408             JCExpression retExpr = transTypes.coerce(attrEnv, expr, restype);

   409             return make.Block(0, List.<JCStatement>of(make.Return(retExpr)));

   410         }

   411     }

   412 

   413     private JCBlock makeLambdaStatementBody(JCBlock block, final JCMethodDecl lambdaMethodDecl, boolean completeNormally) {

   414         final Type restype = lambdaMethodDecl.type.getReturnType();

   415         final boolean isTarget_void = restype.hasTag(VOID);

   416         boolean isTarget_Void = types.isSameType(restype, types.boxedClass(syms.voidType).type);

   417 

   418         class LambdaBodyTranslator extends TreeTranslator {

   419 

   420             @Override

   421             public void visitClassDef(JCClassDecl tree) {

   422                 //do NOT recurse on any inner classes

   423                 result = tree;

   424             }

   425 

   426             @Override

   427             public void visitLambda(JCLambda tree) {

   428                 //do NOT recurse on any nested lambdas

   429                 result = tree;

   430             }

   431 

   432             @Override

   433             public void visitReturn(JCReturn tree) {

   434                 boolean isLambda_void = tree.expr == null;

   435                 if (isTarget_void && !isLambda_void) {

   436                     //Void to void conversion:

   437                     // { TYPE $loc = RET-EXPR; return; }

   438                     VarSymbol loc = makeSyntheticVar(0, names.fromString("$loc"), tree.expr.type, lambdaMethodDecl.sym);

   439                     JCVariableDecl varDef = make.VarDef(loc, tree.expr);

   440                     result = make.Block(0, List.<JCStatement>of(varDef, make.Return(null)));

   441                 } else if (!isTarget_void || !isLambda_void) {

   442                     //non-void to non-void conversion:

   443                     // return (TYPE)RET-EXPR;

   444                     tree.expr = transTypes.coerce(attrEnv, tree.expr, restype);

   445                     result = tree;

   446                 } else {

   447                     result = tree;

   448                 }

   449 

   450             }

   451         }

   452 

   453         JCBlock trans_block = new LambdaBodyTranslator().translate(block);

   454         if (completeNormally && isTarget_Void) {

   455             //there's no return statement and the lambda (possibly inferred)

   456             //return type is java.lang.Void; emit a synthetic return statement

   457             trans_block.stats = trans_block.stats.append(make.Return(make.Literal(BOT, null).setType(syms.botType)));

   458         }

   459         return trans_block;

   460     }

   461 

   462     /**

   463      * Create new synthetic method with given flags, name, type, owner

   464      */

   465     private MethodSymbol makeSyntheticMethod(long flags, Name name, Type type, Symbol owner) {

   466         return new MethodSymbol(flags | SYNTHETIC, name, type, owner);

   467     }

   468 

   469     /**

   470      * Create new synthetic variable with given flags, name, type, owner

   471      */

   472     private VarSymbol makeSyntheticVar(long flags, String name, Type type, Symbol owner) {

   473         return makeSyntheticVar(flags, names.fromString(name), type, owner);

   474     }

   475 

   476     /**

   477      * Create new synthetic variable with given flags, name, type, owner

   478      */

   479     private VarSymbol makeSyntheticVar(long flags, Name name, Type type, Symbol owner) {

   480         return new VarSymbol(flags | SYNTHETIC, name, type, owner);

   481     }

   482 

   483     /**

   484      * Set varargsElement field on a given tree (must be either a new class tree

   485      * or a method call tree)

   486      */

   487     private void setVarargsIfNeeded(JCTree tree, Type varargsElement) {

   488         if (varargsElement != null) {

   489             switch (tree.getTag()) {

   490                 case APPLY: ((JCMethodInvocation)tree).varargsElement = varargsElement; break;

   491                 case NEWCLASS: ((JCNewClass)tree).varargsElement = varargsElement; break;

   492                 default: throw new AssertionError();

   493             }

   494         }

   495     }

   496 

   497     /**

   498      * Convert method/constructor arguments by inserting appropriate cast

   499      * as required by type-erasure - this is needed when bridging a lambda/method

   500      * reference, as the bridged signature might require downcast to be compatible

   501      * with the generated signature.

   502      */

   503     private List<JCExpression> convertArgs(Symbol meth, List<JCExpression> args, Type varargsElement) {

   504        Assert.check(meth.kind == Kinds.MTH);

   505        List<Type> formals = types.erasure(meth.type).getParameterTypes();

   506        if (varargsElement != null) {

   507            Assert.check((meth.flags() & VARARGS) != 0);

   508        }

   509        return transTypes.translateArgs(args, formals, varargsElement, attrEnv);

   510     }

   511 

   512     // </editor-fold>

   513 

   514     private MethodSymbol makeSamDescriptor(Type targetType) {

   515         return (MethodSymbol)types.findDescriptorSymbol(targetType.tsym);

   516     }

   517 

   518     private Type makeFunctionalDescriptorType(Type targetType, MethodSymbol samDescriptor, boolean erased) {

   519         Type descType = types.memberType(targetType, samDescriptor);

   520         return erased ? types.erasure(descType) : descType;

   521     }

   522 

   523     private Type makeFunctionalDescriptorType(Type targetType, boolean erased) {

   524         return makeFunctionalDescriptorType(targetType, makeSamDescriptor(targetType), erased);

   525     }

   526 

   527     /**

   528      * Generate an adapter method "bridge" for a method reference which cannot

   529      * be used directly.

   530      */

   531     private class MemberReferenceBridger {

   532 

   533         private final JCMemberReference tree;

   534         private final ReferenceTranslationContext localContext;

   535         private final ListBuffer<JCExpression> args = ListBuffer.lb();

   536         private final ListBuffer<JCVariableDecl> params = ListBuffer.lb();

   537 

   538         MemberReferenceBridger(JCMemberReference tree, ReferenceTranslationContext localContext) {

   539             this.tree = tree;

   540             this.localContext = localContext;

   541         }

   542 

   543         /**

   544          * Generate the bridge

   545          */

   546         JCMethodDecl bridge() {

   547             int prevPos = make.pos;

   548             try {

   549                 make.at(tree);

   550                 Type samDesc = localContext.bridgedRefSig();

   551                 List<Type> samPTypes = samDesc.getParameterTypes();

   552 

   553                 //an extra argument is prepended to the signature of the bridge in case

   554                 //the member reference is an instance method reference (in which case

   555                 //the receiver expression is passed to the bridge itself).

   556                 Type recType = null;

   557                 switch (tree.kind) {

   558                     case IMPLICIT_INNER:

   559                         recType = tree.sym.owner.type.getEnclosingType();

   560                         break;

   561                     case BOUND:

   562                         recType = tree.getQualifierExpression().type;

   563                         break;

   564                     case UNBOUND:

   565                         recType = samPTypes.head;

   566                         samPTypes = samPTypes.tail;

   567                         break;

   568                 }

   569 

   570                 //generate the parameter list for the bridged member reference - the

   571                 //bridge signature will match the signature of the target sam descriptor

   572 

   573                 VarSymbol rcvr = (recType == null)

   574                         ? null

   575                         : addParameter("rec$", recType, false);

   576 

   577                 List<Type> refPTypes = tree.sym.type.getParameterTypes();

   578                 int refSize = refPTypes.size();

   579                 int samSize = samPTypes.size();

   580                 int last = localContext.needsVarArgsConversion() ? refSize - 1 : refSize;   // Last parameter to copy from referenced method

   581 

   582                 List<Type> l = refPTypes;

   583                 // Use parameter types of the referenced method, excluding final var args

   584                 for (int i = 0; l.nonEmpty() && i < last; ++i) {

   585                     addParameter("x$" + i, l.head, true);

   586                     l = l.tail;

   587                 }

   588                 // Flatten out the var args

   589                 for (int i = last; i < samSize; ++i) {

   590                     addParameter("xva$" + i, tree.varargsElement, true);

   591                 }

   592 

   593                 //generate the bridge method declaration

   594                 JCMethodDecl bridgeDecl = make.MethodDef(make.Modifiers(localContext.bridgeSym.flags()),

   595                         localContext.bridgeSym.name,

   596                         make.QualIdent(samDesc.getReturnType().tsym),

   597                         List.<JCTypeParameter>nil(),

   598                         params.toList(),

   599                         tree.sym.type.getThrownTypes() == null

   600                         ? List.<JCExpression>nil()

   601                         : make.Types(tree.sym.type.getThrownTypes()),

   602                         null,

   603                         null);

   604                 bridgeDecl.sym = (MethodSymbol) localContext.bridgeSym;

   605                 bridgeDecl.type = localContext.bridgeSym.type = types.createMethodTypeWithParameters(samDesc, TreeInfo.types(params.toList()));

   606 

   607                 //bridge method body generation - this can be either a method call or a

   608                 //new instance creation expression, depending on the member reference kind

   609                 JCExpression bridgeExpr = (tree.getMode() == ReferenceMode.INVOKE)

   610                         ? bridgeExpressionInvoke(rcvr)

   611                         : bridgeExpressionNew();

   612 

   613                 //the body is either a return expression containing a method call,

   614                 //or the method call itself, depending on whether the return type of

   615                 //the bridge is non-void/void.

   616                 bridgeDecl.body = makeLambdaExpressionBody(bridgeExpr, bridgeDecl);

   617 

   618                 return bridgeDecl;

   619             } finally {

   620                 make.at(prevPos);

   621             }

   622         }

   623 

   624         /**

   625          * determine the receiver of the bridged method call - the receiver can

   626          * be either the synthetic receiver parameter or a type qualifier; the

   627          * original qualifier expression is never used here, as it might refer

   628          * to symbols not available in the static context of the bridge

   629          */

   630         private JCExpression bridgeExpressionInvoke(VarSymbol rcvr) {

   631             JCExpression qualifier =

   632                     tree.sym.isStatic() ?

   633                         make.Type(tree.sym.owner.type) :

   634                         (rcvr != null) ?

   635                             make.Ident(rcvr) :

   636                             tree.getQualifierExpression();

   637 

   638             //create the qualifier expression

   639             JCFieldAccess select = make.Select(qualifier, tree.sym.name);

   640             select.sym = tree.sym;

   641             select.type = tree.sym.erasure(types);

   642 

   643             //create the method call expression

   644             JCExpression apply = make.Apply(List.<JCExpression>nil(), select,

   645                     convertArgs(tree.sym, args.toList(), tree.varargsElement)).setType(tree.sym.erasure(types).getReturnType());

   646 

   647             apply = transTypes.coerce(apply, localContext.generatedRefSig().getReturnType());

   648             setVarargsIfNeeded(apply, tree.varargsElement);

   649             return apply;

   650         }

   651 

   652         /**

   653          * the enclosing expression is either 'null' (no enclosing type) or set

   654          * to the first bridge synthetic parameter

   655          */

   656         private JCExpression bridgeExpressionNew() {

   657             JCExpression encl = null;

   658             switch (tree.kind) {

   659                 case UNBOUND:

   660                 case IMPLICIT_INNER:

   661                     encl = make.Ident(params.first());

   662             }

   663 

   664             //create the instance creation expression

   665             JCNewClass newClass = make.NewClass(encl,

   666                     List.<JCExpression>nil(),

   667                     make.Type(tree.getQualifierExpression().type),

   668                     convertArgs(tree.sym, args.toList(), tree.varargsElement),

   669                     null);

   670             newClass.constructor = tree.sym;

   671             newClass.constructorType = tree.sym.erasure(types);

   672             newClass.type = tree.getQualifierExpression().type;

   673             setVarargsIfNeeded(newClass, tree.varargsElement);

   674             return newClass;

   675         }

   676 

   677         private VarSymbol addParameter(String name, Type p, boolean genArg) {

   678             VarSymbol vsym = new VarSymbol(0, names.fromString(name), p, localContext.bridgeSym);

   679             params.append(make.VarDef(vsym, null));

   680             if (genArg) {

   681                 args.append(make.Ident(vsym));

   682             }

   683             return vsym;

   684         }

   685     }

   686 

   687     /**

   688      * Bridges a member reference - this is needed when:

   689      * * Var args in the referenced method need to be flattened away

   690      * * super is used

   691      */

   692     private void bridgeMemberReference(JCMemberReference tree, ReferenceTranslationContext localContext) {

   693         JCMethodDecl bridgeDecl = (new MemberReferenceBridger(tree, localContext).bridge());

   694         translatedMethodList = translatedMethodList.prepend(bridgeDecl);

   695     }

   696 

   697     /**

   698      * Generate an indy method call to the meta factory

   699      */

   700     private JCExpression makeMetaFactoryIndyCall(JCExpression tree, Type targetType, int refKind, Symbol refSym, List<JCExpression> indy_args) {

   701         //determine the static bsm args

   702         Type mtype = makeFunctionalDescriptorType(targetType, true);

   703         List<Object> staticArgs = List.<Object>of(

   704                 new Pool.MethodHandle(ClassFile.REF_invokeInterface, types.findDescriptorSymbol(targetType.tsym)),

   705                 new Pool.MethodHandle(refKind, refSym),

   706                 new MethodType(mtype.getParameterTypes(),

   707                         mtype.getReturnType(),

   708                         mtype.getThrownTypes(),

   709                         syms.methodClass));

   710 

   711         //computed indy arg types

   712         ListBuffer<Type> indy_args_types = ListBuffer.lb();

   713         for (JCExpression arg : indy_args) {

   714             indy_args_types.append(arg.type);

   715         }

   716 

   717         //finally, compute the type of the indy call

   718         MethodType indyType = new MethodType(indy_args_types.toList(),

   719                 tree.type,

   720                 List.<Type>nil(),

   721                 syms.methodClass);

   722 

   723         return makeIndyCall(tree, syms.lambdaMetafactory, names.metaFactory, staticArgs, indyType, indy_args);

   724     }

   725 

   726     /**

   727      * Generate an indy method call with given name, type and static bootstrap

   728      * arguments types

   729      */

   730     private JCExpression makeIndyCall(DiagnosticPosition pos, Type site, Name bsmName, List<Object> staticArgs, MethodType indyType, List<JCExpression> indyArgs) {

   731         int prevPos = make.pos;

   732         try {

   733             make.at(pos);

   734             List<Type> bsm_staticArgs = List.of(syms.methodHandleLookupType,

   735                     syms.stringType,

   736                     syms.methodTypeType).appendList(bsmStaticArgToTypes(staticArgs));

   737 

   738             Symbol bsm = rs.resolveInternalMethod(pos, attrEnv, site,

   739                     bsmName, bsm_staticArgs, List.<Type>nil());

   740 

   741             DynamicMethodSymbol dynSym =

   742                     new DynamicMethodSymbol(names.lambda,

   743                                             syms.noSymbol,

   744                                             bsm.isStatic() ? ClassFile.REF_invokeStatic : ClassFile.REF_invokeVirtual,

   745                                             (MethodSymbol)bsm,

   746                                             indyType,

   747                                             staticArgs.toArray());

   748 

   749             JCFieldAccess qualifier = make.Select(make.QualIdent(site.tsym), bsmName);

   750             qualifier.sym = dynSym;

   751             qualifier.type = indyType.getReturnType();

   752 

   753             JCMethodInvocation proxyCall = make.Apply(List.<JCExpression>nil(), qualifier, indyArgs);

   754             proxyCall.type = indyType.getReturnType();

   755             return proxyCall;

   756         } finally {

   757             make.at(prevPos);

   758         }

   759     }

   760     //where

   761     private List<Type> bsmStaticArgToTypes(List<Object> args) {

   762         ListBuffer<Type> argtypes = ListBuffer.lb();

   763         for (Object arg : args) {

   764             argtypes.append(bsmStaticArgToType(arg));

   765         }

   766         return argtypes.toList();

   767     }

   768 

   769     private Type bsmStaticArgToType(Object arg) {

   770         Assert.checkNonNull(arg);

   771         if (arg instanceof ClassSymbol) {

   772             return syms.classType;

   773         } else if (arg instanceof Integer) {

   774             return syms.intType;

   775         } else if (arg instanceof Long) {

   776             return syms.longType;

   777         } else if (arg instanceof Float) {

   778             return syms.floatType;

   779         } else if (arg instanceof Double) {

   780             return syms.doubleType;

   781         } else if (arg instanceof String) {

   782             return syms.stringType;

   783         } else if (arg instanceof Pool.MethodHandle) {

   784             return syms.methodHandleType;

   785         } else if (arg instanceof MethodType) {

   786             return syms.methodTypeType;

   787         } else {

   788             Assert.error("bad static arg " + arg.getClass());

   789             return null;

   790         }

   791     }

   792 

   793     /**

   794      * Get the opcode associated with this method reference

   795      */

   796     private int referenceKind(Symbol refSym) {

   797         if (refSym.isConstructor()) {

   798             return ClassFile.REF_newInvokeSpecial;

   799         } else {

   800             if (refSym.isStatic()) {

   801                 return ClassFile.REF_invokeStatic;

   802             } else if (refSym.enclClass().isInterface()) {

   803                 return ClassFile.REF_invokeInterface;

   804             } else {

   805                 return ClassFile.REF_invokeVirtual;

   806             }

   807         }

   808     }

   809     // </editor-fold>

   810 

   811     // <editor-fold defaultstate="collapsed" desc="Lambda/reference analyzer">\

   812     /**

   813      * This visitor collects information about translation of a lambda expression.

   814      * More specifically, it keeps track of the enclosing contexts and captured locals

   815      * accessed by the lambda being translated (as well as other useful info).

   816      */

   817     class LambdaAnalyzer extends TreeScanner {

   818 

   819         /** the frame stack - used to reconstruct translation info about enclosing scopes */

   820         private List<Frame> frameStack;

   821 

   822         /**

   823          * keep the count of lambda expression (used to generate unambiguous

   824          * names)

   825          */

   826         private int lambdaCount = 0;

   827 

   828         private void analyzeClass(JCClassDecl tree) {

   829             frameStack = List.nil();

   830             scan(tree);

   831         }

   832 

   833         @Override

   834         public void visitBlock(JCBlock tree) {

   835             List<Frame> prevStack = frameStack;

   836             try {

   837                 if (frameStack.nonEmpty() && frameStack.head.tree.hasTag(CLASSDEF)) {

   838                     frameStack = frameStack.prepend(new Frame(tree));

   839                 }

   840                 super.visitBlock(tree);

   841             }

   842             finally {

   843                 frameStack = prevStack;

   844             }

   845         }

   846 

   847         @Override

   848         public void visitClassDef(JCClassDecl tree) {

   849             List<Frame> prevStack = frameStack;

   850             try {

   851                 if (frameStack.nonEmpty() && enclosingLambda() != null) {

   852                     tree.sym.owner = owner();

   853                     LambdaTranslationContext lambdaContext = (LambdaTranslationContext)contextMap.get(enclosingLambda());

   854                     Type encl = lambdaContext.enclosingType();

   855                     if (encl.hasTag(NONE)) {

   856                         //if the translated lambda body occurs in a static context,

   857                         //any class declaration within it must be made static

   858                         tree.sym.flags_field |= STATIC;

   859                         ((ClassType)tree.sym.type).setEnclosingType(Type.noType);

   860                     } else {

   861                         //if the translated lambda body is in an instance context

   862                         //the enclosing type of any class declaration within it

   863                         //must be updated to point to the new enclosing type (if any)

   864                         ((ClassType)tree.sym.type).setEnclosingType(encl);

   865                     }

   866                 }

   867                 frameStack = frameStack.prepend(new Frame(tree));

   868                 super.visitClassDef(tree);

   869             }

   870             finally {

   871                 frameStack = prevStack;

   872             }

   873             if (frameStack.nonEmpty() && enclosingLambda() != null) {

   874                 // Any class defined within a lambda is an implicit 'this' reference

   875                 // because its constructor will reference the enclosing class

   876                 ((LambdaTranslationContext) context()).addSymbol(tree.sym.type.getEnclosingType().tsym, CAPTURED_THIS);

   877             }

   878         }

   879 

   880         @Override

   881         public void visitIdent(JCIdent tree) {

   882             if (context() == null || !lambdaIdentSymbolFilter(tree.sym)) {

   883                 super.visitIdent(tree);

   884             } else {

   885                 if (tree.sym.kind == VAR &&

   886                         tree.sym.owner.kind == MTH &&

   887                         tree.type.constValue() == null) {

   888                     TranslationContext<?> localContext = context();

   889                     while (localContext != null) {

   890                         if (localContext.tree.getTag() == LAMBDA) {

   891                             JCTree block = capturedDecl(localContext.depth, tree.sym);

   892                             if (block == null) break;

   893                             ((LambdaTranslationContext)localContext).addSymbol(tree.sym, CAPTURED_VAR);

   894                         }

   895                         localContext = localContext.prev;

   896                     }

   897                 } else if (tree.sym.owner.kind == TYP) {

   898                     TranslationContext<?> localContext = context();

   899                     while (localContext != null) {

   900                         if (localContext.tree.hasTag(LAMBDA)) {

   901                             JCTree block = capturedDecl(localContext.depth, tree.sym);

   902                             if (block == null) break;

   903                             switch (block.getTag()) {

   904                                 case CLASSDEF:

   905                                     JCClassDecl cdecl = (JCClassDecl)block;

   906                                     ((LambdaTranslationContext)localContext).addSymbol(cdecl.sym, CAPTURED_THIS);

   907                                     break;

   908                                 default:

   909                                     Assert.error("bad block kind");

   910                             }

   911                         }

   912                         localContext = localContext.prev;

   913                     }

   914                 }

   915             }

   916         }

   917 

   918         @Override

   919         public void visitLambda(JCLambda tree) {

   920             List<Frame> prevStack = frameStack;

   921             try {

   922                 LambdaTranslationContext context = (LambdaTranslationContext)makeLambdaContext(tree);

   923                 frameStack = frameStack.prepend(new Frame(tree));

   924                 for (JCVariableDecl param : tree.params) {

   925                     context.addSymbol(param.sym, PARAM);

   926                     frameStack.head.addLocal(param.sym);

   927                 }

   928                 contextMap.put(tree, context);

   929                 scan(tree.body);

   930                 context.complete();

   931             }

   932             finally {

   933                 frameStack = prevStack;

   934             }

   935         }

   936 

   937         @Override

   938         public void visitMethodDef(JCMethodDecl tree) {

   939             List<Frame> prevStack = frameStack;

   940             try {

   941                 frameStack = frameStack.prepend(new Frame(tree));

   942                 super.visitMethodDef(tree);

   943             }

   944             finally {

   945                 frameStack = prevStack;

   946             }

   947         }

   948 

   949         @Override

   950         public void visitNewClass(JCNewClass tree) {

   951             if (lambdaNewClassFilter(context(), tree)) {

   952                 ((LambdaTranslationContext) context()).addSymbol(tree.type.getEnclosingType().tsym, CAPTURED_THIS);

   953             }

   954             super.visitNewClass(tree);

   955         }

   956 

   957         @Override

   958         public void visitReference(JCMemberReference tree) {

   959             scan(tree.getQualifierExpression());

   960             contextMap.put(tree, makeReferenceContext(tree));

   961         }

   962 

   963         @Override

   964         public void visitSelect(JCFieldAccess tree) {

   965             if (context() != null && lambdaSelectSymbolFilter(tree.sym)) {

   966                 TranslationContext<?> localContext = context();

   967                 while (localContext != null) {

   968                     if (localContext.tree.hasTag(LAMBDA)) {

   969                         JCClassDecl clazz = (JCClassDecl)capturedDecl(localContext.depth, tree.sym);

   970                         if (clazz == null) break;

   971                         ((LambdaTranslationContext)localContext).addSymbol(clazz.sym, CAPTURED_THIS);

   972                     }

   973                     localContext = localContext.prev;

   974                 }

   975                 scan(tree.selected);

   976             } else {

   977                 super.visitSelect(tree);

   978             }

   979         }

   980 

   981         @Override

   982         public void visitVarDef(JCVariableDecl tree) {

   983             if (frameStack.head.tree.hasTag(LAMBDA)) {

   984                 ((LambdaTranslationContext)context()).addSymbol(tree.sym, LOCAL_VAR);

   985             }

   986             List<Frame> prevStack = frameStack;

   987             try {

   988                 if (tree.sym.owner.kind == MTH) {

   989                     frameStack.head.addLocal(tree.sym);

   990                 }

   991                 frameStack = frameStack.prepend(new Frame(tree));

   992                 super.visitVarDef(tree);

   993             }

   994             finally {

   995                 frameStack = prevStack;

   996             }

   997         }

   998 

   999         private Name lambdaName() {

  1000             return names.lambda.append(names.fromString("$" + lambdaCount++));

  1001         }

  1002 

  1003         /**

  1004          * Return a valid owner given the current declaration stack

  1005          * (required to skip synthetic lambda symbols)

  1006          */

  1007         private Symbol owner() {

  1008             List<Frame> frameStack2 = frameStack;

  1009             while (frameStack2.nonEmpty()) {

  1010                 switch (frameStack2.head.tree.getTag()) {

  1011                     case VARDEF:

  1012                         if (((JCVariableDecl)frameStack2.head.tree).sym.isLocal()) {

  1013                             frameStack2 = frameStack2.tail;

  1014                             break;

  1015                         }

  1016                         JCClassDecl cdecl = (JCClassDecl)frameStack2.tail.head.tree;

  1017                         return makeSyntheticMethod(((JCVariableDecl)frameStack2.head.tree).sym.flags() & STATIC, names.empty, null, cdecl.sym);

  1018                     case BLOCK:

  1019                         JCClassDecl cdecl2 = (JCClassDecl)frameStack2.tail.head.tree;

  1020                         return makeSyntheticMethod(((JCBlock)frameStack2.head.tree).flags & STATIC | Flags.BLOCK, names.empty, null, cdecl2.sym);

  1021                     case CLASSDEF:

  1022                         return ((JCClassDecl)frameStack2.head.tree).sym;

  1023                     case METHODDEF:

  1024                         return ((JCMethodDecl)frameStack2.head.tree).sym;

  1025                     case LAMBDA:

  1026                         return ((LambdaTranslationContext)contextMap.get(frameStack2.head.tree)).translatedSym;

  1027                     default:

  1028                         frameStack2 = frameStack2.tail;

  1029                 }

  1030             }

  1031             Assert.error();

  1032             return null;

  1033         }

  1034 

  1035         private JCTree enclosingLambda() {

  1036             List<Frame> frameStack2 = frameStack;

  1037             while (frameStack2.nonEmpty()) {

  1038                 switch (frameStack2.head.tree.getTag()) {

  1039                     case CLASSDEF:

  1040                     case METHODDEF:

  1041                         return null;

  1042                     case LAMBDA:

  1043                         return frameStack2.head.tree;

  1044                     default:

  1045                         frameStack2 = frameStack2.tail;

  1046                 }

  1047             }

  1048             Assert.error();

  1049             return null;

  1050         }

  1051 

  1052         /**

  1053          * Return the declaration corresponding to a symbol in the enclosing

  1054          * scope; the depth parameter is used to filter out symbols defined

  1055          * in nested scopes (which do not need to undergo capture).

  1056          */

  1057         private JCTree capturedDecl(int depth, Symbol sym) {

  1058             int currentDepth = frameStack.size() - 1;

  1059             for (Frame block : frameStack) {

  1060                 switch (block.tree.getTag()) {

  1061                     case CLASSDEF:

  1062                         ClassSymbol clazz = ((JCClassDecl)block.tree).sym;

  1063                         if (sym.isMemberOf(clazz, types)) {

  1064                             return currentDepth > depth ? null : block.tree;

  1065                         }

  1066                         break;

  1067                     case VARDEF:

  1068                         if (((JCVariableDecl)block.tree).sym == sym &&

  1069                                 sym.owner.kind == MTH) { //only locals are captured

  1070                             return currentDepth > depth ? null : block.tree;

  1071                         }

  1072                         break;

  1073                     case BLOCK:

  1074                     case METHODDEF:

  1075                     case LAMBDA:

  1076                         if (block.locals != null && block.locals.contains(sym)) {

  1077                             return currentDepth > depth ? null : block.tree;

  1078                         }

  1079                         break;

  1080                     default:

  1081                         Assert.error("bad decl kind " + block.tree.getTag());

  1082                 }

  1083                 currentDepth--;

  1084             }

  1085             return null;

  1086         }

  1087 

  1088         private TranslationContext<?> context() {

  1089             for (Frame frame : frameStack) {

  1090                 TranslationContext<?> context = contextMap.get(frame.tree);

  1091                 if (context != null) {

  1092                     return context;

  1093                 }

  1094             }

  1095             return null;

  1096         }

  1097 

  1098         /**

  1099          *  This is used to filter out those identifiers that needs to be adjusted

  1100          *  when translating away lambda expressions

  1101          */

  1102         private boolean lambdaIdentSymbolFilter(Symbol sym) {

  1103             return (sym.kind == VAR || sym.kind == MTH)

  1104                     && !sym.isStatic()

  1105                     && sym.name != names.init;

  1106         }

  1107 

  1108         private boolean lambdaSelectSymbolFilter(Symbol sym) {

  1109             return (sym.kind == VAR || sym.kind == MTH) &&

  1110                         !sym.isStatic() &&

  1111                         (sym.name == names._this ||

  1112                         sym.name == names._super);

  1113         }

  1114 

  1115         /**

  1116          * This is used to filter out those new class expressions that need to

  1117          * be qualified with an enclosing tree

  1118          */

  1119         private boolean lambdaNewClassFilter(TranslationContext<?> context, JCNewClass tree) {

  1120             if (context != null

  1121                     && tree.encl == null

  1122                     && tree.def == null

  1123                     && tree.type.getEnclosingType().hasTag(NONE)) {

  1124                 Type encl = tree.type.getEnclosingType();

  1125                 Type current = context.owner.enclClass().type;

  1126                 while (current.hasTag(NONE)) {

  1127                     if (current.tsym.isSubClass(encl.tsym, types)) {

  1128                         return true;

  1129                     }

  1130                     current = current.getEnclosingType();

  1131                 }

  1132                 return false;

  1133             } else {

  1134                 return false;

  1135             }