jdk8-mips64-public/langtools: src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java@37031963493e (annotated)

src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java@37031963493e (annotated)

src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java

Fri, 12 Jul 2013 13:11:12 -0700

author: jjg
date: Fri, 12 Jul 2013 13:11:12 -0700
changeset 1895: 37031963493e
parent 1889: b0386f0dc28e
child 1897: 866c87c01285
permissions: -rw-r--r--

8020278: NPE in javadoc
Reviewed-by: mcimadamore, vromero

 /*
  * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 package com.sun.tools.javac.comp;
 import com.sun.tools.javac.code.*;
 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.code.Symbol.*;
 import com.sun.tools.javac.code.Type.*;
 import com.sun.tools.javac.comp.Attr.ResultInfo;
 import com.sun.tools.javac.comp.Infer.InferenceContext;
 import com.sun.tools.javac.comp.Resolve.MethodResolutionPhase;
 import com.sun.tools.javac.tree.JCTree.*;
 import javax.tools.JavaFileObject;
 import java.util.ArrayList;
 import java.util.EnumSet;
 import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Queue;
 import java.util.Set;
 import java.util.WeakHashMap;
 import static com.sun.tools.javac.code.TypeTag.*;
 import static com.sun.tools.javac.tree.JCTree.Tag.*;
 /**
  * This is an helper class that is used to perform deferred type-analysis.
  * Each time a poly expression occurs in argument position, javac attributes it
  * with a temporary 'deferred type' that is checked (possibly multiple times)
  * against an expected formal type.
  *
  *  <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 DeferredAttr extends JCTree.Visitor {
     protected static final Context.Key<DeferredAttr> deferredAttrKey =
         new Context.Key<DeferredAttr>();
     final Attr attr;
     final Check chk;
     final JCDiagnostic.Factory diags;
     final Enter enter;
     final Infer infer;
     final Resolve rs;
     final Log log;
     final Symtab syms;
     final TreeMaker make;
     final Types types;
     public static DeferredAttr instance(Context context) {
         DeferredAttr instance = context.get(deferredAttrKey);
         if (instance == null)
             instance = new DeferredAttr(context);
         return instance;
     }
     protected DeferredAttr(Context context) {
         context.put(deferredAttrKey, this);
         attr = Attr.instance(context);
         chk = Check.instance(context);
         diags = JCDiagnostic.Factory.instance(context);
         enter = Enter.instance(context);
         infer = Infer.instance(context);
         rs = Resolve.instance(context);
         log = Log.instance(context);
         syms = Symtab.instance(context);
         make = TreeMaker.instance(context);
         types = Types.instance(context);
         Names names = Names.instance(context);
         stuckTree = make.Ident(names.empty).setType(Type.stuckType);
     }
     /** shared tree for stuck expressions */
     final JCTree stuckTree;
     /**
      * This type represents a deferred type. A deferred type starts off with
      * no information on the underlying expression type. Such info needs to be
      * discovered through type-checking the deferred type against a target-type.
      * Every deferred type keeps a pointer to the AST node from which it originated.
      */
     public class DeferredType extends Type {
         public JCExpression tree;
         Env<AttrContext> env;
         AttrMode mode;
         SpeculativeCache speculativeCache;
         DeferredType(JCExpression tree, Env<AttrContext> env) {
             super(null);
             this.tree = tree;
             this.env = env.dup(tree, env.info.dup());
             this.speculativeCache = new SpeculativeCache();
         }
         @Override
         public TypeTag getTag() {
             return DEFERRED;
         }
         /**
          * A speculative cache is used to keep track of all overload resolution rounds
          * that triggered speculative attribution on a given deferred type. Each entry
          * stores a pointer to the speculative tree and the resolution phase in which the entry
          * has been added.
          */
         class SpeculativeCache {
             private Map<Symbol, List<Entry>> cache =
                     new WeakHashMap<Symbol, List<Entry>>();
             class Entry {
                 JCTree speculativeTree;
                 Resolve.MethodResolutionPhase phase;
                 public Entry(JCTree speculativeTree, MethodResolutionPhase phase) {
                     this.speculativeTree = speculativeTree;
                     this.phase = phase;
                 }
                 boolean matches(Resolve.MethodResolutionPhase phase) {
                     return this.phase == phase;
                 }
             }
             /**
              * Retrieve a speculative cache entry corresponding to given symbol
              * and resolution phase
              */
             Entry get(Symbol msym, MethodResolutionPhase phase) {
                 List<Entry> entries = cache.get(msym);
                 if (entries == null) return null;
                 for (Entry e : entries) {
                     if (e.matches(phase)) return e;
                 }
                 return null;
             }
             /**
              * Stores a speculative cache entry corresponding to given symbol
              * and resolution phase
              */
             void put(Symbol msym, JCTree speculativeTree, MethodResolutionPhase phase) {
                 List<Entry> entries = cache.get(msym);
                 if (entries == null) {
                     entries = List.nil();
                 }
                 cache.put(msym, entries.prepend(new Entry(speculativeTree, phase)));
             }
         }
         /**
          * Get the type that has been computed during a speculative attribution round
          */
         Type speculativeType(Symbol msym, MethodResolutionPhase phase) {
             SpeculativeCache.Entry e = speculativeCache.get(msym, phase);
             return e != null ? e.speculativeTree.type : Type.noType;
         }
         /**
          * Check a deferred type against a potential target-type. Depending on
          * the current attribution mode, a normal vs. speculative attribution
          * round is performed on the underlying AST node. There can be only one
          * speculative round for a given target method symbol; moreover, a normal
          * attribution round must follow one or more speculative rounds.
          */
         Type check(ResultInfo resultInfo) {
             return check(resultInfo, stuckVars(tree, env, resultInfo), basicCompleter);
         }
         Type check(ResultInfo resultInfo, List<Type> stuckVars, DeferredTypeCompleter deferredTypeCompleter) {
             DeferredAttrContext deferredAttrContext =
                     resultInfo.checkContext.deferredAttrContext();
             Assert.check(deferredAttrContext != emptyDeferredAttrContext);
             if (stuckVars.nonEmpty()) {
                 deferredAttrContext.addDeferredAttrNode(this, resultInfo, stuckVars);
                 return Type.noType;
             } else {
                 try {
                     return deferredTypeCompleter.complete(this, resultInfo, deferredAttrContext);
                 } finally {
                     mode = deferredAttrContext.mode;
                 }
             }
         }
     }
     /**
      * A completer for deferred types. Defines an entry point for type-checking
      * a deferred type.
      */
     interface DeferredTypeCompleter {
         /**
          * Entry point for type-checking a deferred type. Depending on the
          * circumstances, type-checking could amount to full attribution
          * or partial structural check (aka potential applicability).
          */
         Type complete(DeferredType dt, ResultInfo resultInfo, DeferredAttrContext deferredAttrContext);
     }
     /**
      * A basic completer for deferred types. This completer type-checks a deferred type
      * using attribution; depending on the attribution mode, this could be either standard
      * or speculative attribution.
      */
     DeferredTypeCompleter basicCompleter = new DeferredTypeCompleter() {
         public Type complete(DeferredType dt, ResultInfo resultInfo, DeferredAttrContext deferredAttrContext) {
             switch (deferredAttrContext.mode) {
                 case SPECULATIVE:
                     //Note: if a symbol is imported twice we might do two identical
                     //speculative rounds...
                     Assert.check(dt.mode == null || dt.mode == AttrMode.SPECULATIVE);
                     JCTree speculativeTree = attribSpeculative(dt.tree, dt.env, resultInfo);
                     dt.speculativeCache.put(deferredAttrContext.msym, speculativeTree, deferredAttrContext.phase);
                     return speculativeTree.type;
                 case CHECK:
                     Assert.check(dt.mode != null);
                     return attr.attribTree(dt.tree, dt.env, resultInfo);
             }
             Assert.error();
             return null;
         }
     };
     DeferredTypeCompleter dummyCompleter = new DeferredTypeCompleter() {
         public Type complete(DeferredType dt, ResultInfo resultInfo, DeferredAttrContext deferredAttrContext) {
             Assert.check(deferredAttrContext.mode == AttrMode.CHECK);
             return dt.tree.type = Type.noType;
         }
     };
     /**
      * The 'mode' in which the deferred type is to be type-checked
      */
     public enum AttrMode {
         /**
          * A speculative type-checking round is used during overload resolution
          * mainly to generate constraints on inference variables. Side-effects
          * arising from type-checking the expression associated with the deferred
          * type are reversed after the speculative round finishes. This means the
          * expression tree will be left in a blank state.
          */
         SPECULATIVE,
         /**
          * This is the plain type-checking mode. Produces side-effects on the underlying AST node
          */
         CHECK;
     }
     /**
      * Routine that performs speculative type-checking; the input AST node is
      * cloned (to avoid side-effects cause by Attr) and compiler state is
      * restored after type-checking. All diagnostics (but critical ones) are
      * disabled during speculative type-checking.
      */
     JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo) {
         final JCTree newTree = new TreeCopier<Object>(make).copy(tree);
         Env<AttrContext> speculativeEnv = env.dup(newTree, env.info.dup(env.info.scope.dupUnshared()));
         speculativeEnv.info.scope.owner = env.info.scope.owner;
         Log.DeferredDiagnosticHandler deferredDiagnosticHandler =
                 new Log.DeferredDiagnosticHandler(log, new Filter<JCDiagnostic>() {
             public boolean accepts(final JCDiagnostic d) {
                 class PosScanner extends TreeScanner {
                     boolean found = false;
                     @Override
                     public void scan(JCTree tree) {
                         if (tree != null &&
                                 tree.pos() == d.getDiagnosticPosition()) {
                             found = true;
                         }
                         super.scan(tree);
                     }
                 };
                 PosScanner posScanner = new PosScanner();
                 posScanner.scan(newTree);
                 return posScanner.found;
             }
         });
         try {
             attr.attribTree(newTree, speculativeEnv, resultInfo);
             unenterScanner.scan(newTree);
             return newTree;
         } finally {
             unenterScanner.scan(newTree);
             log.popDiagnosticHandler(deferredDiagnosticHandler);
         }
     }
     //where
         protected TreeScanner unenterScanner = new TreeScanner() {
             @Override
             public void visitClassDef(JCClassDecl tree) {
                 ClassSymbol csym = tree.sym;
                 //if something went wrong during method applicability check
                 //it is possible that nested expressions inside argument expression
                 //are left unchecked - in such cases there's nothing to clean up.
                 if (csym == null) return;
                 enter.typeEnvs.remove(csym);
                 chk.compiled.remove(csym.flatname);
                 syms.classes.remove(csym.flatname);
                 super.visitClassDef(tree);
             }
         };
     /**
      * A deferred context is created on each method check. A deferred context is
      * used to keep track of information associated with the method check, such as
      * the symbol of the method being checked, the overload resolution phase,
      * the kind of attribution mode to be applied to deferred types and so forth.
      * As deferred types are processed (by the method check routine) stuck AST nodes
      * are added (as new deferred attribution nodes) to this context. The complete()
      * routine makes sure that all pending nodes are properly processed, by
      * progressively instantiating all inference variables on which one or more
      * deferred attribution node is stuck.
      */
     class DeferredAttrContext {
         /** attribution mode */
         final AttrMode mode;
         /** symbol of the method being checked */
         final Symbol msym;
         /** method resolution step */
         final Resolve.MethodResolutionPhase phase;
         /** inference context */
         final InferenceContext inferenceContext;
         /** parent deferred context */
         final DeferredAttrContext parent;
         /** Warner object to report warnings */
         final Warner warn;
         /** list of deferred attribution nodes to be processed */
         ArrayList<DeferredAttrNode> deferredAttrNodes = new ArrayList<DeferredAttrNode>();
         DeferredAttrContext(AttrMode mode, Symbol msym, MethodResolutionPhase phase,
                 InferenceContext inferenceContext, DeferredAttrContext parent, Warner warn) {
             this.mode = mode;
             this.msym = msym;
             this.phase = phase;
             this.parent = parent;
             this.warn = warn;
             this.inferenceContext = inferenceContext;
         }
         /**
          * Adds a node to the list of deferred attribution nodes - used by Resolve.rawCheckArgumentsApplicable
          * Nodes added this way act as 'roots' for the out-of-order method checking process.
          */
         void addDeferredAttrNode(final DeferredType dt, ResultInfo resultInfo, List<Type> stuckVars) {
             deferredAttrNodes.add(new DeferredAttrNode(dt, resultInfo, stuckVars));
         }
         /**
          * Incrementally process all nodes, by skipping 'stuck' nodes and attributing
          * 'unstuck' ones. If at any point no progress can be made (no 'unstuck' nodes)
          * some inference variable might get eagerly instantiated so that all nodes
          * can be type-checked.
          */
         void complete() {
             while (!deferredAttrNodes.isEmpty()) {
                 Set<Type> stuckVars = new LinkedHashSet<Type>();
                 boolean progress = false;
                 //scan a defensive copy of the node list - this is because a deferred
                 //attribution round can add new nodes to the list
                 for (DeferredAttrNode deferredAttrNode : List.from(deferredAttrNodes)) {
                     if (!deferredAttrNode.process(this)) {
                         stuckVars.addAll(deferredAttrNode.stuckVars);
                     } else {
                         deferredAttrNodes.remove(deferredAttrNode);
                         progress = true;
                     }
                 }
                 if (!progress) {
                     //remove all variables that have already been instantiated
                     //from the list of stuck variables
                     inferenceContext.solveAny(List.from(stuckVars), warn);
                     inferenceContext.notifyChange();
                 }
             }
         }
     }
     /**
      * Class representing a deferred attribution node. It keeps track of
      * a deferred type, along with the expected target type information.
      */
     class DeferredAttrNode implements Infer.FreeTypeListener {
         /** underlying deferred type */
         DeferredType dt;
         /** underlying target type information */
         ResultInfo resultInfo;
         /** list of uninferred inference variables causing this node to be stuck */
         List<Type> stuckVars;
         DeferredAttrNode(DeferredType dt, ResultInfo resultInfo, List<Type> stuckVars) {
             this.dt = dt;
             this.resultInfo = resultInfo;
             this.stuckVars = stuckVars;
             if (!stuckVars.isEmpty()) {
                 resultInfo.checkContext.inferenceContext().addFreeTypeListener(stuckVars, this);
             }
         }
         @Override
         public void typesInferred(InferenceContext inferenceContext) {
             stuckVars = List.nil();
             resultInfo = resultInfo.dup(inferenceContext.asInstType(resultInfo.pt));
         }
         /**
          * Process a deferred attribution node.
          * Invariant: a stuck node cannot be processed.
          */
         @SuppressWarnings("fallthrough")
         boolean process(DeferredAttrContext deferredAttrContext) {
             switch (deferredAttrContext.mode) {
                 case SPECULATIVE:
                     dt.check(resultInfo, List.<Type>nil(), new StructuralStuckChecker());
                     return true;
                 case CHECK:
                     if (stuckVars.nonEmpty()) {
                         //stuck expression - see if we can propagate
                         if (deferredAttrContext.parent != emptyDeferredAttrContext &&
                                 Type.containsAny(deferredAttrContext.parent.inferenceContext.inferencevars, List.from(stuckVars))) {
                             deferredAttrContext.parent.deferredAttrNodes.add(this);
                             dt.check(resultInfo, List.<Type>nil(), dummyCompleter);
                             return true;
                         } else {
                             return false;
                         }
                     } else {
                         dt.check(resultInfo, stuckVars, basicCompleter);
                         return true;
                     }
                 default:
                     throw new AssertionError("Bad mode");
             }
         }
         /**
          * Structural checker for stuck expressions
          */
         class StructuralStuckChecker extends TreeScanner implements DeferredTypeCompleter {
             ResultInfo resultInfo;
             InferenceContext inferenceContext;
             Env<AttrContext> env;
             public Type complete(DeferredType dt, ResultInfo resultInfo, DeferredAttrContext deferredAttrContext) {
                 this.resultInfo = resultInfo;
                 this.inferenceContext = deferredAttrContext.inferenceContext;
                 this.env = dt.env.dup(dt.tree, dt.env.info.dup());
                 dt.tree.accept(this);
                 dt.speculativeCache.put(deferredAttrContext.msym, stuckTree, deferredAttrContext.phase);
                 return Type.noType;
             }
             @Override
             public void visitLambda(JCLambda tree) {
                 Check.CheckContext checkContext = resultInfo.checkContext;
                 Type pt = resultInfo.pt;
                 if (inferenceContext.inferencevars.contains(pt)) {
                     //ok
                     return;
                 } else {
                     //must be a functional descriptor
                     try {
                         Type desc = types.findDescriptorType(pt);
                         if (desc.getParameterTypes().length() != tree.params.length()) {
                             checkContext.report(tree, diags.fragment("incompatible.arg.types.in.lambda"));
                         }
                     } catch (Types.FunctionDescriptorLookupError ex) {
                         checkContext.report(null, ex.getDiagnostic());
                     }
                 }
             }
             @Override
             public void visitNewClass(JCNewClass tree) {
                 //do nothing
             }
             @Override
             public void visitApply(JCMethodInvocation tree) {
                 //do nothing
             }
             @Override
             public void visitReference(JCMemberReference tree) {
                 Check.CheckContext checkContext = resultInfo.checkContext;
                 Type pt = resultInfo.pt;
                 if (inferenceContext.inferencevars.contains(pt)) {
                     //ok
                     return;
                 } else {
                     try {
                         types.findDescriptorType(pt);
                     } catch (Types.FunctionDescriptorLookupError ex) {
                         checkContext.report(null, ex.getDiagnostic());
                     }
                     JCExpression exprTree = (JCExpression)attribSpeculative(tree.getQualifierExpression(), env,
                             attr.memberReferenceQualifierResult(tree));
                     ListBuffer<Type> argtypes = ListBuffer.lb();
                     for (Type t : types.findDescriptorType(pt).getParameterTypes()) {
                         argtypes.append(Type.noType);
                     }
                     JCMemberReference mref2 = new TreeCopier<Void>(make).copy(tree);
                     mref2.expr = exprTree;
                     Pair<Symbol, ?> lookupRes =
                             rs.resolveMemberReference(tree, env, mref2, exprTree.type,
                                 tree.name, argtypes.toList(), null, true, rs.arityMethodCheck);
                     switch (lookupRes.fst.kind) {
                         //note: as argtypes are erroneous types, type-errors must
                         //have been caused by arity mismatch
                         case Kinds.ABSENT_MTH:
                         case Kinds.WRONG_MTH:
                         case Kinds.WRONG_MTHS:
                         case Kinds.STATICERR:
                         case Kinds.MISSING_ENCL:
                            checkContext.report(null, diags.fragment("incompatible.arg.types.in.mref"));
                     }
                 }
             }
         }
     }
     /** an empty deferred attribution context - all methods throw exceptions */
     final DeferredAttrContext emptyDeferredAttrContext =
             new DeferredAttrContext(AttrMode.CHECK, null, MethodResolutionPhase.BOX, null, null, null) {
                 @Override
                 void addDeferredAttrNode(DeferredType dt, ResultInfo ri, List<Type> stuckVars) {
                     Assert.error("Empty deferred context!");
                 }
                 @Override
                 void complete() {
                     Assert.error("Empty deferred context!");
                 }
             };
     /**
      * Map a list of types possibly containing one or more deferred types
      * into a list of ordinary types. Each deferred type D is mapped into a type T,
      * where T is computed by retrieving the type that has already been
      * computed for D during a previous deferred attribution round of the given kind.
      */
     class DeferredTypeMap extends Type.Mapping {
         DeferredAttrContext deferredAttrContext;
         protected DeferredTypeMap(AttrMode mode, Symbol msym, MethodResolutionPhase phase) {
             super(String.format("deferredTypeMap[%s]", mode));
             this.deferredAttrContext = new DeferredAttrContext(mode, msym, phase,
                     infer.emptyContext, emptyDeferredAttrContext, types.noWarnings);
         }
         protected boolean validState(DeferredType dt) {
             return dt.mode != null &&
                     deferredAttrContext.mode.ordinal() <= dt.mode.ordinal();
         }
         @Override
         public Type apply(Type t) {
             if (!t.hasTag(DEFERRED)) {
                 return t.map(this);
             } else {
                 DeferredType dt = (DeferredType)t;
                 Assert.check(validState(dt));
                 return typeOf(dt);
             }
         }
         protected Type typeOf(DeferredType dt) {
             switch (deferredAttrContext.mode) {
                 case CHECK:
                     return dt.tree.type == null ? Type.noType : dt.tree.type;
                 case SPECULATIVE:
                     return dt.speculativeType(deferredAttrContext.msym, deferredAttrContext.phase);
             }
             Assert.error();
             return null;
         }
     }
     /**
      * Specialized recovery deferred mapping.
      * Each deferred type D is mapped into a type T, where T is computed either by
      * (i) retrieving the type that has already been computed for D during a previous
      * attribution round (as before), or (ii) by synthesizing a new type R for D
      * (the latter step is useful in a recovery scenario).
      */
     public class RecoveryDeferredTypeMap extends DeferredTypeMap {
         public RecoveryDeferredTypeMap(AttrMode mode, Symbol msym, MethodResolutionPhase phase) {
             super(mode, msym, phase != null ? phase : MethodResolutionPhase.BOX);
         }
         @Override
         protected Type typeOf(DeferredType dt) {
             Type owntype = super.typeOf(dt);
             return owntype == Type.noType ?
                         recover(dt) : owntype;
         }
         @Override
         protected boolean validState(DeferredType dt) {
             return true;
         }
         /**
          * Synthesize a type for a deferred type that hasn't been previously
          * reduced to an ordinary type. Functional deferred types and conditionals
          * are mapped to themselves, in order to have a richer diagnostic
          * representation. Remaining deferred types are attributed using
          * a default expected type (j.l.Object).
          */
         private Type recover(DeferredType dt) {
             dt.check(attr.new RecoveryInfo(deferredAttrContext) {
                 @Override
                 protected Type check(DiagnosticPosition pos, Type found) {
                     return chk.checkNonVoid(pos, super.check(pos, found));
                 }
             });
             return super.apply(dt);
         }
     }
     /**
      * Retrieves the list of inference variables that need to be inferred before
      * an AST node can be type-checked
      */
     @SuppressWarnings("fallthrough")
     List<Type> stuckVars(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo) {
                 if (resultInfo.pt.hasTag(NONE) || resultInfo.pt.isErroneous()) {
             return List.nil();
         } else {
             return stuckVarsInternal(tree, resultInfo.pt, resultInfo.checkContext.inferenceContext());
         }
     }
     //where
         private List<Type> stuckVarsInternal(JCTree tree, Type pt, Infer.InferenceContext inferenceContext) {
             StuckChecker sc = new StuckChecker(pt, inferenceContext);
             sc.scan(tree);
             return List.from(sc.stuckVars);
         }
     /**
      * A special tree scanner that would only visit portions of a given tree.
      * The set of nodes visited by the scanner can be customized at construction-time.
      */
     abstract static class FilterScanner extends TreeScanner {
         final Filter<JCTree> treeFilter;
         FilterScanner(final Set<JCTree.Tag> validTags) {
             this.treeFilter = new Filter<JCTree>() {
                 public boolean accepts(JCTree t) {
                     return validTags.contains(t.getTag());
                 }
             };
         }
         @Override
         public void scan(JCTree tree) {
             if (tree != null) {
                 if (treeFilter.accepts(tree)) {
                     super.scan(tree);
                 } else {
                     skip(tree);
                 }
             }
         }
         /**
          * handler that is executed when a node has been discarded
          */
         abstract void skip(JCTree tree);
     }
     /**
      * A tree scanner suitable for visiting the target-type dependent nodes of
      * a given argument expression.
      */
     static class PolyScanner extends FilterScanner {
         PolyScanner() {
             super(EnumSet.of(CONDEXPR, PARENS, LAMBDA, REFERENCE));
         }
         @Override
         void skip(JCTree tree) {
             //do nothing
         }
     }
     /**
      * A tree scanner suitable for visiting the target-type dependent nodes nested
      * within a lambda expression body.
      */
     static class LambdaReturnScanner extends FilterScanner {
         LambdaReturnScanner() {
             super(EnumSet.of(BLOCK, CASE, CATCH, DOLOOP, FOREACHLOOP,
                     FORLOOP, RETURN, SYNCHRONIZED, SWITCH, TRY, WHILELOOP));
         }
         @Override
         void skip(JCTree tree) {
             //do nothing
         }
     }
     /**
      * This visitor is used to check that structural expressions conform
      * to their target - this step is required as inference could end up
      * inferring types that make some of the nested expressions incompatible
      * with their corresponding instantiated target
      */
     class StuckChecker extends PolyScanner {
         Type pt;
         Infer.InferenceContext inferenceContext;
         Set<Type> stuckVars = new LinkedHashSet<Type>();
         StuckChecker(Type pt, Infer.InferenceContext inferenceContext) {
             this.pt = pt;
             this.inferenceContext = inferenceContext;
         }
         @Override
         public void visitLambda(JCLambda tree) {
             if (inferenceContext.inferenceVars().contains(pt)) {
                 stuckVars.add(pt);
             }
             if (!types.isFunctionalInterface(pt)) {
                 return;
             }
             Type descType = types.findDescriptorType(pt);
             List<Type> freeArgVars = inferenceContext.freeVarsIn(descType.getParameterTypes());
             if (tree.paramKind == JCLambda.ParameterKind.IMPLICIT &&
                     freeArgVars.nonEmpty()) {
                 stuckVars.addAll(freeArgVars);
             }
             scanLambdaBody(tree, descType.getReturnType());
         }
         @Override
         public void visitReference(JCMemberReference tree) {
             scan(tree.expr);
             if (inferenceContext.inferenceVars().contains(pt)) {
                 stuckVars.add(pt);
                 return;
             }
             if (!types.isFunctionalInterface(pt)) {
                 return;
             }
             Type descType = types.findDescriptorType(pt);
             List<Type> freeArgVars = inferenceContext.freeVarsIn(descType.getParameterTypes());
             stuckVars.addAll(freeArgVars);
         }
         void scanLambdaBody(JCLambda lambda, final Type pt) {
             if (lambda.getBodyKind() == JCTree.JCLambda.BodyKind.EXPRESSION) {
                 stuckVars.addAll(stuckVarsInternal(lambda.body, pt, inferenceContext));
             } else {
                 LambdaReturnScanner lambdaScanner = new LambdaReturnScanner() {
                     @Override
                     public void visitReturn(JCReturn tree) {
                         if (tree.expr != null) {
                             stuckVars.addAll(stuckVarsInternal(tree.expr, pt, inferenceContext));
                         }
                     }
                 };
                 lambdaScanner.scan(lambda.body);
             }
         }
     }
     /**
      * Does the argument expression {@code expr} need speculative type-checking?
      */
     boolean isDeferred(Env<AttrContext> env, JCExpression expr) {
         DeferredChecker dc = new DeferredChecker(env);
         dc.scan(expr);
         return dc.result.isPoly();
     }
     /**
      * The kind of an argument expression. This is used by the analysis that
      * determines as to whether speculative attribution is necessary.
      */
     enum ArgumentExpressionKind {
         /** kind that denotes poly argument expression */
         POLY,
         /** kind that denotes a standalone expression */
         NO_POLY,
         /** kind that denotes a primitive/boxed standalone expression */
         PRIMITIVE;
         /**
          * Does this kind denote a poly argument expression
          */
         public final boolean isPoly() {
             return this == POLY;
         }
         /**
          * Does this kind denote a primitive standalone expression
          */
         public final boolean isPrimitive() {
             return this == PRIMITIVE;
         }
         /**
          * Compute the kind of a standalone expression of a given type
          */
         static ArgumentExpressionKind standaloneKind(Type type, Types types) {
             return types.unboxedTypeOrType(type).isPrimitive() ?
                     ArgumentExpressionKind.PRIMITIVE :
                     ArgumentExpressionKind.NO_POLY;
         }
         /**
          * Compute the kind of a method argument expression given its symbol
          */
         static ArgumentExpressionKind methodKind(Symbol sym, Types types) {
             Type restype = sym.type.getReturnType();
             if (sym.type.hasTag(FORALL) &&
                     restype.containsAny(((ForAll)sym.type).tvars)) {
                 return ArgumentExpressionKind.POLY;
             } else {
                 return ArgumentExpressionKind.standaloneKind(restype, types);
             }
         }
     }
     /**
      * Tree scanner used for checking as to whether an argument expression
      * requires speculative attribution
      */
     final class DeferredChecker extends FilterScanner {
         Env<AttrContext> env;
         ArgumentExpressionKind result;
         public DeferredChecker(Env<AttrContext> env) {
             super(deferredCheckerTags);
             this.env = env;
         }
         @Override
         public void visitLambda(JCLambda tree) {
             //a lambda is always a poly expression
             result = ArgumentExpressionKind.POLY;
         }
         @Override
         public void visitReference(JCMemberReference tree) {
             //a method reference is always a poly expression
             result = ArgumentExpressionKind.POLY;
         }
         @Override
         public void visitTypeCast(JCTypeCast tree) {
             //a cast is always a standalone expression
             result = ArgumentExpressionKind.NO_POLY;
         }
         @Override
         public void visitConditional(JCConditional tree) {
             scan(tree.truepart);
             if (!result.isPrimitive()) {
                 result = ArgumentExpressionKind.POLY;
                 return;
             }
             scan(tree.falsepart);
             result = reduce(ArgumentExpressionKind.PRIMITIVE);
         }
         @Override
         public void visitNewClass(JCNewClass tree) {
             result = (TreeInfo.isDiamond(tree) || attr.findDiamonds) ?
                     ArgumentExpressionKind.POLY : ArgumentExpressionKind.NO_POLY;
         }
         @Override
         public void visitApply(JCMethodInvocation tree) {
             Name name = TreeInfo.name(tree.meth);
             //fast path
             if (tree.typeargs.nonEmpty() ||
                     name == name.table.names._this ||
                     name == name.table.names._super) {
                 result = ArgumentExpressionKind.NO_POLY;
                 return;
             }
             //slow path
             final JCExpression rec = tree.meth.hasTag(SELECT) ?
                     ((JCFieldAccess)tree.meth).selected :
                     null;
             if (rec != null && !isSimpleReceiver(rec)) {
                 //give up if receiver is too complex (to cut down analysis time)
                 result = ArgumentExpressionKind.POLY;
                 return;
             }
             Type site = rec != null ?
                     attribSpeculative(rec, env, attr.unknownTypeExprInfo).type :
                     env.enclClass.sym.type;
             while (site.hasTag(TYPEVAR)) {
                 site = site.getUpperBound();
             }
             ListBuffer<Type> args = ListBuffer.lb();
             for (int i = 0; i < tree.args.length(); i ++) {
                 args.append(Type.noType);
             }
             Resolve.LookupHelper lh = rs.new LookupHelper(name, site, args.toList(), List.<Type>nil(), MethodResolutionPhase.VARARITY) {
                 @Override
                 Symbol lookup(Env<AttrContext> env, MethodResolutionPhase phase) {
                     return rec == null ?
                         rs.findFun(env, name, argtypes, typeargtypes, phase.isBoxingRequired(), phase.isVarargsRequired()) :
                         rs.findMethod(env, site, name, argtypes, typeargtypes, phase.isBoxingRequired(), phase.isVarargsRequired(), false);
                 }
                 @Override
                 Symbol access(Env<AttrContext> env, DiagnosticPosition pos, Symbol location, Symbol sym) {
                     return sym;
                 }
             };
             Symbol sym = rs.lookupMethod(env, tree, site.tsym, rs.arityMethodCheck, lh);
             if (sym.kind == Kinds.AMBIGUOUS) {
                 Resolve.AmbiguityError err = (Resolve.AmbiguityError)sym.baseSymbol();
                 result = ArgumentExpressionKind.PRIMITIVE;
                 for (Symbol s : err.ambiguousSyms) {
                     if (result.isPoly()) break;
                     if (s.kind == Kinds.MTH) {
                         result = reduce(ArgumentExpressionKind.methodKind(s, types));
                     }
                 }
             } else {
                 result = (sym.kind == Kinds.MTH) ?
                     ArgumentExpressionKind.methodKind(sym, types) :
                     ArgumentExpressionKind.NO_POLY;
             }
         }
         //where
             private boolean isSimpleReceiver(JCTree rec) {
                 switch (rec.getTag()) {
                     case IDENT:
                         return true;
                     case SELECT:
                         return isSimpleReceiver(((JCFieldAccess)rec).selected);
                     case TYPEAPPLY:
                     case TYPEARRAY:
                         return true;
                     case ANNOTATED_TYPE:
                         return isSimpleReceiver(((JCAnnotatedType)rec).underlyingType);
                     default:
                         return false;
                 }
             }
             private ArgumentExpressionKind reduce(ArgumentExpressionKind kind) {
                 switch (result) {
                     case PRIMITIVE: return kind;
                     case NO_POLY: return kind.isPoly() ? kind : result;
                     case POLY: return result;
                     default:
                         Assert.error();
                         return null;
                 }
             }
         @Override
         public void visitLiteral(JCLiteral tree) {
             Type litType = attr.litType(tree.typetag);
             result = ArgumentExpressionKind.standaloneKind(litType, types);
         }
         @Override
         void skip(JCTree tree) {
             result = ArgumentExpressionKind.NO_POLY;
         }
     }
     //where
     private EnumSet<JCTree.Tag> deferredCheckerTags =
             EnumSet.of(LAMBDA, REFERENCE, PARENS, TYPECAST,
                     CONDEXPR, NEWCLASS, APPLY, LITERAL);
 }

Mercurial > jdk8-mips64-public > langtools / annotate

src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java@37031963493e (annotated)

src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java