jdk8-mips64-public/langtools: src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java@d07340b61e6a (annotated)

src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java@d07340b61e6a (annotated)

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

Tue, 08 Jan 2013 10:17:29 +0100

author: mcimadamore
date: Tue, 08 Jan 2013 10:17:29 +0100
changeset 1481: d07340b61e6a
parent 1415: 01c9d4161882
child 1510: 7873d37f5b37
permissions: -rw-r--r--

8005184: Restructure DeferredAttr to allow pluggable deferred type completers
Summary: Add hooks to generalize deferred type completion via custom helper objects
Reviewed-by: jjg

 /*
  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 package com.sun.tools.javac.comp;
 import com.sun.tools.javac.code.*;
 import com.sun.tools.javac.tree.*;
 import com.sun.tools.javac.util.*;
 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 Enter enter;
     final Infer infer;
     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);
         enter = Enter.instance(context);
         infer = Infer.instance(context);
         log = Log.instance(context);
         syms = Symtab.instance(context);
         make = TreeMaker.instance(context);
         types = Types.instance(context);
     }
     /**
      * 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(DEFERRED, null);
             this.tree = tree;
             this.env = env.dup(tree, env.info.dup());
             this.speculativeCache = new SpeculativeCache();
         }
         /**
          * 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:
                     Assert.check(dt.mode == null ||
                             (dt.mode == AttrMode.SPECULATIVE &&
                             dt.speculativeType(deferredAttrContext.msym, deferredAttrContext.phase).hasTag(NONE)));
                     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 == AttrMode.SPECULATIVE);
                     return attr.attribTree(dt.tree, dt.env, resultInfo);
             }
             Assert.error();
             return null;
         }
     };
     /**
      * 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) {
         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;
         final JavaFileObject currentSource = log.currentSourceFile();
         Log.DeferredDiagnosticHandler deferredDiagnosticHandler =
                 new Log.DeferredDiagnosticHandler(log, new Filter<JCDiagnostic>() {
             public boolean accepts(JCDiagnostic t) {
                 return t.getDiagnosticSource().getFile().equals(currentSource);
             }
         });
         try {
             attr.attribTree(newTree, speculativeEnv, resultInfo);
             unenterScanner.scan(newTree);
             return newTree;
         } catch (Abort ex) {
             //if some very bad condition occurred during deferred attribution
             //we should dump all errors before killing javac
             deferredDiagnosticHandler.reportDeferredDiagnostics();
             throw ex;
         } 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;
         /** list of deferred attribution nodes to be processed */
         ArrayList<DeferredAttrNode> deferredAttrNodes = new ArrayList<DeferredAttrNode>();
         DeferredAttrContext(AttrMode mode, Symbol msym, MethodResolutionPhase phase, InferenceContext inferenceContext) {
             this.mode = mode;
             this.msym = msym;
             this.phase = phase;
             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.isStuck()) {
                         deferredAttrNode.process();
                         deferredAttrNodes.remove(deferredAttrNode);
                         progress = true;
                     } else {
                         stuckVars.addAll(deferredAttrNode.stuckVars);
                     }
                 }
                 if (!progress) {
                     //remove all variables that have already been instantiated
                     //from the list of stuck variables
                     inferenceContext.solveAny(inferenceContext.freeVarsIn(List.from(stuckVars)), types, infer);
                     inferenceContext.notifyChange(types);
                 }
             }
         }
         /**
          * Class representing a deferred attribution node. It keeps track of
          * a deferred type, along with the expected target type information.
          */
         class DeferredAttrNode implements Infer.InferenceContext.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, types));
             }
             /**
              * is this node stuck?
              */
             boolean isStuck() {
                 return stuckVars.nonEmpty();
             }
             /**
              * Process a deferred attribution node.
              * Invariant: a stuck node cannot be processed.
              */
             void process() {
                 if (isStuck()) {
                     throw new IllegalStateException("Cannot process a stuck deferred node");
                 }
                 dt.check(resultInfo);
             }
         }
     }
     /** an empty deferred attribution context - all methods throw exceptions */
     final DeferredAttrContext emptyDeferredAttrContext =
             new DeferredAttrContext(AttrMode.CHECK, null, MethodResolutionPhase.BOX, 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);
         }
         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));
             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.tsym)) {
                 return;
             }
             Type descType = types.findDescriptorType(pt);
             List<Type> freeArgVars = inferenceContext.freeVarsIn(descType.getParameterTypes());
             if (!TreeInfo.isExplicitLambda(tree) &&
                     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.tsym)) {
                 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);
             }
         }
     }
 }

Mercurial > jdk8-mips64-public > langtools / annotate

src/share/classes/com/sun/tools/javac/comp/DeferredAttr.java@d07340b61e6a (annotated)

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