Infer.java revision 3261:527e819dbc95
1/* 2 * Copyright (c) 1999, 2016, 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 26package com.sun.tools.javac.comp; 27 28import com.sun.tools.javac.code.Type.UndetVar.UndetVarListener; 29import com.sun.tools.javac.tree.JCTree; 30import com.sun.tools.javac.tree.JCTree.JCTypeCast; 31import com.sun.tools.javac.tree.TreeInfo; 32import com.sun.tools.javac.util.*; 33import com.sun.tools.javac.util.GraphUtils.DottableNode; 34import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition; 35import com.sun.tools.javac.util.List; 36import com.sun.tools.javac.code.*; 37import com.sun.tools.javac.code.Type.*; 38import com.sun.tools.javac.code.Type.UndetVar.InferenceBound; 39import com.sun.tools.javac.code.Symbol.*; 40import com.sun.tools.javac.comp.DeferredAttr.AttrMode; 41import com.sun.tools.javac.comp.DeferredAttr.DeferredAttrContext; 42import com.sun.tools.javac.comp.Infer.GraphSolver.InferenceGraph; 43import com.sun.tools.javac.comp.Infer.GraphSolver.InferenceGraph.Node; 44import com.sun.tools.javac.comp.Resolve.InapplicableMethodException; 45import com.sun.tools.javac.comp.Resolve.VerboseResolutionMode; 46 47import java.io.IOException; 48import java.io.Writer; 49import java.nio.file.Files; 50import java.nio.file.Path; 51import java.nio.file.Paths; 52import java.util.ArrayList; 53import java.util.Collection; 54import java.util.Collections; 55import java.util.EnumMap; 56import java.util.EnumSet; 57import java.util.HashMap; 58import java.util.HashSet; 59import java.util.LinkedHashSet; 60import java.util.Map; 61import java.util.Properties; 62import java.util.Set; 63import java.util.function.BiFunction; 64import java.util.function.BiPredicate; 65 66import static com.sun.tools.javac.code.TypeTag.*; 67 68/** Helper class for type parameter inference, used by the attribution phase. 69 * 70 * <p><b>This is NOT part of any supported API. 71 * If you write code that depends on this, you do so at your own risk. 72 * This code and its internal interfaces are subject to change or 73 * deletion without notice.</b> 74 */ 75public class Infer { 76 protected static final Context.Key<Infer> inferKey = new Context.Key<>(); 77 78 Resolve rs; 79 Check chk; 80 Symtab syms; 81 Types types; 82 JCDiagnostic.Factory diags; 83 Log log; 84 85 /** should the graph solver be used? */ 86 boolean allowGraphInference; 87 88 /** 89 * folder in which the inference dependency graphs should be written. 90 */ 91 final private String dependenciesFolder; 92 93 /** 94 * List of graphs awaiting to be dumped to a file. 95 */ 96 private List<String> pendingGraphs; 97 98 public static Infer instance(Context context) { 99 Infer instance = context.get(inferKey); 100 if (instance == null) 101 instance = new Infer(context); 102 return instance; 103 } 104 105 protected Infer(Context context) { 106 context.put(inferKey, this); 107 108 rs = Resolve.instance(context); 109 chk = Check.instance(context); 110 syms = Symtab.instance(context); 111 types = Types.instance(context); 112 diags = JCDiagnostic.Factory.instance(context); 113 log = Log.instance(context); 114 inferenceException = new InferenceException(diags); 115 Options options = Options.instance(context); 116 allowGraphInference = Source.instance(context).allowGraphInference() 117 && options.isUnset("useLegacyInference"); 118 dependenciesFolder = options.get("dumpInferenceGraphsTo"); 119 pendingGraphs = List.nil(); 120 121 emptyContext = new InferenceContext(this, List.<Type>nil()); 122 } 123 124 /** A value for prototypes that admit any type, including polymorphic ones. */ 125 public static final Type anyPoly = new JCNoType(); 126 127 /** 128 * This exception class is design to store a list of diagnostics corresponding 129 * to inference errors that can arise during a method applicability check. 130 */ 131 public static class InferenceException extends InapplicableMethodException { 132 private static final long serialVersionUID = 0; 133 134 List<JCDiagnostic> messages = List.nil(); 135 136 InferenceException(JCDiagnostic.Factory diags) { 137 super(diags); 138 } 139 140 @Override 141 InapplicableMethodException setMessage() { 142 //no message to set 143 return this; 144 } 145 146 @Override 147 InapplicableMethodException setMessage(JCDiagnostic diag) { 148 messages = messages.append(diag); 149 return this; 150 } 151 152 @Override 153 public JCDiagnostic getDiagnostic() { 154 return messages.head; 155 } 156 157 void clear() { 158 messages = List.nil(); 159 } 160 } 161 162 protected final InferenceException inferenceException; 163 164 // <editor-fold defaultstate="collapsed" desc="Inference routines"> 165 /** 166 * Main inference entry point - instantiate a generic method type 167 * using given argument types and (possibly) an expected target-type. 168 */ 169 Type instantiateMethod( Env<AttrContext> env, 170 List<Type> tvars, 171 MethodType mt, 172 Attr.ResultInfo resultInfo, 173 MethodSymbol msym, 174 List<Type> argtypes, 175 boolean allowBoxing, 176 boolean useVarargs, 177 Resolve.MethodResolutionContext resolveContext, 178 Warner warn) throws InferenceException { 179 //-System.err.println("instantiateMethod(" + tvars + ", " + mt + ", " + argtypes + ")"); //DEBUG 180 final InferenceContext inferenceContext = new InferenceContext(this, tvars); //B0 181 inferenceException.clear(); 182 try { 183 DeferredAttr.DeferredAttrContext deferredAttrContext = 184 resolveContext.deferredAttrContext(msym, inferenceContext, resultInfo, warn); 185 186 resolveContext.methodCheck.argumentsAcceptable(env, deferredAttrContext, //B2 187 argtypes, mt.getParameterTypes(), warn); 188 189 if (allowGraphInference && resultInfo != null && resultInfo.pt == anyPoly) { 190 doIncorporation(inferenceContext, warn); 191 //we are inside method attribution - just return a partially inferred type 192 return new PartiallyInferredMethodType(mt, inferenceContext, env, warn); 193 } else if (allowGraphInference && 194 resultInfo != null && 195 !warn.hasNonSilentLint(Lint.LintCategory.UNCHECKED)) { 196 //inject return constraints earlier 197 doIncorporation(inferenceContext, warn); //propagation 198 199 boolean shouldPropagate = resultInfo.checkContext.inferenceContext().free(resultInfo.pt); 200 201 InferenceContext minContext = shouldPropagate ? 202 inferenceContext.min(roots(mt, deferredAttrContext), true, warn) : 203 inferenceContext; 204 205 Type newRestype = generateReturnConstraints(env.tree, resultInfo, //B3 206 mt, minContext); 207 mt = (MethodType)types.createMethodTypeWithReturn(mt, newRestype); 208 209 //propagate outwards if needed 210 if (shouldPropagate) { 211 //propagate inference context outwards and exit 212 minContext.dupTo(resultInfo.checkContext.inferenceContext()); 213 deferredAttrContext.complete(); 214 return mt; 215 } 216 } 217 218 deferredAttrContext.complete(); 219 220 // minimize as yet undetermined type variables 221 if (allowGraphInference) { 222 inferenceContext.solve(warn); 223 } else { 224 inferenceContext.solveLegacy(true, warn, LegacyInferenceSteps.EQ_LOWER.steps); //minimizeInst 225 } 226 227 mt = (MethodType)inferenceContext.asInstType(mt); 228 229 if (!allowGraphInference && 230 inferenceContext.restvars().nonEmpty() && 231 resultInfo != null && 232 !warn.hasNonSilentLint(Lint.LintCategory.UNCHECKED)) { 233 generateReturnConstraints(env.tree, resultInfo, mt, inferenceContext); 234 inferenceContext.solveLegacy(false, warn, LegacyInferenceSteps.EQ_UPPER.steps); //maximizeInst 235 mt = (MethodType)inferenceContext.asInstType(mt); 236 } 237 238 if (resultInfo != null && rs.verboseResolutionMode.contains(VerboseResolutionMode.DEFERRED_INST)) { 239 log.note(env.tree.pos, "deferred.method.inst", msym, mt, resultInfo.pt); 240 } 241 242 // return instantiated version of method type 243 return mt; 244 } finally { 245 if (resultInfo != null || !allowGraphInference) { 246 inferenceContext.notifyChange(); 247 } else { 248 inferenceContext.notifyChange(inferenceContext.boundedVars()); 249 } 250 if (resultInfo == null) { 251 /* if the is no result info then we can clear the capture types 252 * cache without affecting any result info check 253 */ 254 inferenceContext.captureTypeCache.clear(); 255 } 256 dumpGraphsIfNeeded(env.tree, msym, resolveContext); 257 } 258 } 259 //where 260 private List<Type> roots(MethodType mt, DeferredAttrContext deferredAttrContext) { 261 ListBuffer<Type> roots = new ListBuffer<>(); 262 roots.add(mt.getReturnType()); 263 if (deferredAttrContext != null && deferredAttrContext.mode == AttrMode.CHECK) { 264 roots.addAll(mt.getThrownTypes()); 265 for (DeferredAttr.DeferredAttrNode n : deferredAttrContext.deferredAttrNodes) { 266 roots.addAll(n.deferredStuckPolicy.stuckVars()); 267 roots.addAll(n.deferredStuckPolicy.depVars()); 268 } 269 } 270 return roots.toList(); 271 } 272 273 /** 274 * A partially infered method/constructor type; such a type can be checked multiple times 275 * against different targets. 276 */ 277 public class PartiallyInferredMethodType extends MethodType { 278 public PartiallyInferredMethodType(MethodType mtype, InferenceContext inferenceContext, Env<AttrContext> env, Warner warn) { 279 super(mtype.getParameterTypes(), mtype.getReturnType(), mtype.getThrownTypes(), mtype.tsym); 280 this.inferenceContext = inferenceContext; 281 this.env = env; 282 this.warn = warn; 283 } 284 285 /** The inference context. */ 286 final InferenceContext inferenceContext; 287 288 /** The attribution environment. */ 289 Env<AttrContext> env; 290 291 /** The warner. */ 292 final Warner warn; 293 294 @Override 295 public boolean isPartial() { 296 return true; 297 } 298 299 /** 300 * Checks this type against a target; this means generating return type constraints, solve 301 * and then roll back the results (to avoid poolluting the context). 302 */ 303 Type check(Attr.ResultInfo resultInfo) { 304 Warner noWarnings = new Warner(null); 305 inferenceException.clear(); 306 List<Type> saved_undet = null; 307 try { 308 /** we need to save the inference context before generating target type constraints. 309 * This constraints may pollute the inference context and make it useless in case we 310 * need to use it several times: with several targets. 311 */ 312 saved_undet = inferenceContext.save(); 313 if (allowGraphInference && !warn.hasNonSilentLint(Lint.LintCategory.UNCHECKED)) { 314 boolean shouldPropagate = resultInfo.checkContext.inferenceContext().free(resultInfo.pt); 315 316 InferenceContext minContext = shouldPropagate ? 317 inferenceContext.min(roots(asMethodType(), null), false, warn) : 318 inferenceContext; 319 320 MethodType other = (MethodType)minContext.update(asMethodType()); 321 Type newRestype = generateReturnConstraints(env.tree, resultInfo, //B3 322 other, minContext); 323 324 if (shouldPropagate) { 325 //propagate inference context outwards and exit 326 minContext.dupTo(resultInfo.checkContext.inferenceContext(), 327 resultInfo.checkContext.deferredAttrContext().insideOverloadPhase()); 328 return newRestype; 329 } 330 } 331 inferenceContext.solve(noWarnings); 332 return inferenceContext.asInstType(this).getReturnType(); 333 } catch (InferenceException ex) { 334 resultInfo.checkContext.report(null, ex.getDiagnostic()); 335 Assert.error(); //cannot get here (the above should throw) 336 return null; 337 } finally { 338 if (saved_undet != null) { 339 inferenceContext.rollback(saved_undet); 340 } 341 } 342 } 343 } 344 345 private void dumpGraphsIfNeeded(DiagnosticPosition pos, Symbol msym, Resolve.MethodResolutionContext rsContext) { 346 int round = 0; 347 try { 348 for (String graph : pendingGraphs.reverse()) { 349 Assert.checkNonNull(dependenciesFolder); 350 Name name = msym.name == msym.name.table.names.init ? 351 msym.owner.name : msym.name; 352 String filename = String.format("%s@%s[mode=%s,step=%s]_%d.dot", 353 name, 354 pos.getStartPosition(), 355 rsContext.attrMode(), 356 rsContext.step, 357 round); 358 Path dotFile = Paths.get(dependenciesFolder, filename); 359 try (Writer w = Files.newBufferedWriter(dotFile)) { 360 w.append(graph); 361 } 362 round++; 363 } 364 } catch (IOException ex) { 365 Assert.error("Error occurred when dumping inference graph: " + ex.getMessage()); 366 } finally { 367 pendingGraphs = List.nil(); 368 } 369 } 370 371 /** 372 * Generate constraints from the generic method's return type. If the method 373 * call occurs in a context where a type T is expected, use the expected 374 * type to derive more constraints on the generic method inference variables. 375 */ 376 Type generateReturnConstraints(JCTree tree, Attr.ResultInfo resultInfo, 377 MethodType mt, InferenceContext inferenceContext) { 378 InferenceContext rsInfoInfContext = resultInfo.checkContext.inferenceContext(); 379 Type from = mt.getReturnType(); 380 if (mt.getReturnType().containsAny(inferenceContext.inferencevars) && 381 rsInfoInfContext != emptyContext) { 382 from = types.capture(from); 383 //add synthetic captured ivars 384 for (Type t : from.getTypeArguments()) { 385 if (t.hasTag(TYPEVAR) && ((TypeVar)t).isCaptured()) { 386 inferenceContext.addVar((TypeVar)t); 387 } 388 } 389 } 390 Type qtype = inferenceContext.asUndetVar(from); 391 Type to = resultInfo.pt; 392 393 if (qtype.hasTag(VOID)) { 394 to = syms.voidType; 395 } else if (to.hasTag(NONE)) { 396 to = from.isPrimitive() ? from : syms.objectType; 397 } else if (qtype.hasTag(UNDETVAR)) { 398 if (resultInfo.pt.isReference()) { 399 to = generateReturnConstraintsUndetVarToReference( 400 tree, (UndetVar)qtype, to, resultInfo, inferenceContext); 401 } else { 402 if (to.isPrimitive()) { 403 to = generateReturnConstraintsPrimitive(tree, (UndetVar)qtype, to, 404 resultInfo, inferenceContext); 405 } 406 } 407 } else if (rsInfoInfContext.free(resultInfo.pt)) { 408 //propagation - cache captured vars 409 qtype = inferenceContext.asUndetVar(rsInfoInfContext.cachedCapture(tree, from, false)); 410 } 411 Assert.check(allowGraphInference || !rsInfoInfContext.free(to), 412 "legacy inference engine cannot handle constraints on both sides of a subtyping assertion"); 413 //we need to skip capture? 414 Warner retWarn = new Warner(); 415 if (!resultInfo.checkContext.compatible(qtype, rsInfoInfContext.asUndetVar(to), retWarn) || 416 //unchecked conversion is not allowed in source 7 mode 417 (!allowGraphInference && retWarn.hasLint(Lint.LintCategory.UNCHECKED))) { 418 throw inferenceException 419 .setMessage("infer.no.conforming.instance.exists", 420 inferenceContext.restvars(), mt.getReturnType(), to); 421 } 422 return from; 423 } 424 425 private Type generateReturnConstraintsPrimitive(JCTree tree, UndetVar from, 426 Type to, Attr.ResultInfo resultInfo, InferenceContext inferenceContext) { 427 if (!allowGraphInference) { 428 //if legacy, just return boxed type 429 return types.boxedClass(to).type; 430 } 431 //if graph inference we need to skip conflicting boxed bounds... 432 for (Type t : from.getBounds(InferenceBound.EQ, InferenceBound.UPPER, 433 InferenceBound.LOWER)) { 434 Type boundAsPrimitive = types.unboxedType(t); 435 if (boundAsPrimitive == null || boundAsPrimitive.hasTag(NONE)) { 436 continue; 437 } 438 return generateReferenceToTargetConstraint(tree, from, to, 439 resultInfo, inferenceContext); 440 } 441 return types.boxedClass(to).type; 442 } 443 444 private Type generateReturnConstraintsUndetVarToReference(JCTree tree, 445 UndetVar from, Type to, Attr.ResultInfo resultInfo, 446 InferenceContext inferenceContext) { 447 Type captureOfTo = types.capture(to); 448 /* T is a reference type, but is not a wildcard-parameterized type, and either 449 */ 450 if (captureOfTo == to) { //not a wildcard parameterized type 451 /* i) B2 contains a bound of one of the forms alpha = S or S <: alpha, 452 * where S is a wildcard-parameterized type, or 453 */ 454 for (Type t : from.getBounds(InferenceBound.EQ, InferenceBound.LOWER)) { 455 Type captureOfBound = types.capture(t); 456 if (captureOfBound != t) { 457 return generateReferenceToTargetConstraint(tree, from, to, 458 resultInfo, inferenceContext); 459 } 460 } 461 462 /* ii) B2 contains two bounds of the forms S1 <: alpha and S2 <: alpha, 463 * where S1 and S2 have supertypes that are two different 464 * parameterizations of the same generic class or interface. 465 */ 466 for (Type aLowerBound : from.getBounds(InferenceBound.LOWER)) { 467 for (Type anotherLowerBound : from.getBounds(InferenceBound.LOWER)) { 468 if (aLowerBound != anotherLowerBound && 469 !inferenceContext.free(aLowerBound) && 470 !inferenceContext.free(anotherLowerBound) && 471 commonSuperWithDiffParameterization(aLowerBound, anotherLowerBound)) { 472 return generateReferenceToTargetConstraint(tree, from, to, 473 resultInfo, inferenceContext); 474 } 475 } 476 } 477 } 478 479 /* T is a parameterization of a generic class or interface, G, 480 * and B2 contains a bound of one of the forms alpha = S or S <: alpha, 481 * where there exists no type of the form G<...> that is a 482 * supertype of S, but the raw type G is a supertype of S 483 */ 484 if (to.isParameterized()) { 485 for (Type t : from.getBounds(InferenceBound.EQ, InferenceBound.LOWER)) { 486 Type sup = types.asSuper(t, to.tsym); 487 if (sup != null && sup.isRaw()) { 488 return generateReferenceToTargetConstraint(tree, from, to, 489 resultInfo, inferenceContext); 490 } 491 } 492 } 493 return to; 494 } 495 496 private boolean commonSuperWithDiffParameterization(Type t, Type s) { 497 for (Pair<Type, Type> supers : getParameterizedSupers(t, s)) { 498 if (!types.isSameType(supers.fst, supers.snd)) return true; 499 } 500 return false; 501 } 502 503 private Type generateReferenceToTargetConstraint(JCTree tree, UndetVar from, 504 Type to, Attr.ResultInfo resultInfo, 505 InferenceContext inferenceContext) { 506 inferenceContext.solve(List.of(from.qtype), new Warner()); 507 inferenceContext.notifyChange(); 508 Type capturedType = resultInfo.checkContext.inferenceContext() 509 .cachedCapture(tree, from.getInst(), false); 510 if (types.isConvertible(capturedType, 511 resultInfo.checkContext.inferenceContext().asUndetVar(to))) { 512 //effectively skip additional return-type constraint generation (compatibility) 513 return syms.objectType; 514 } 515 return to; 516 } 517 518 /** 519 * Infer cyclic inference variables as described in 15.12.2.8. 520 */ 521 void instantiateAsUninferredVars(List<Type> vars, InferenceContext inferenceContext) { 522 ListBuffer<Type> todo = new ListBuffer<>(); 523 //step 1 - create fresh tvars 524 for (Type t : vars) { 525 UndetVar uv = (UndetVar)inferenceContext.asUndetVar(t); 526 List<Type> upperBounds = uv.getBounds(InferenceBound.UPPER); 527 if (Type.containsAny(upperBounds, vars)) { 528 TypeSymbol fresh_tvar = new TypeVariableSymbol(Flags.SYNTHETIC, uv.qtype.tsym.name, null, uv.qtype.tsym.owner); 529 fresh_tvar.type = new TypeVar(fresh_tvar, types.makeIntersectionType(uv.getBounds(InferenceBound.UPPER)), null); 530 todo.append(uv); 531 uv.setInst(fresh_tvar.type); 532 } else if (upperBounds.nonEmpty()) { 533 uv.setInst(types.glb(upperBounds)); 534 } else { 535 uv.setInst(syms.objectType); 536 } 537 } 538 //step 2 - replace fresh tvars in their bounds 539 List<Type> formals = vars; 540 for (Type t : todo) { 541 UndetVar uv = (UndetVar)t; 542 TypeVar ct = (TypeVar)uv.getInst(); 543 ct.bound = types.glb(inferenceContext.asInstTypes(types.getBounds(ct))); 544 if (ct.bound.isErroneous()) { 545 //report inference error if glb fails 546 reportBoundError(uv, InferenceBound.UPPER); 547 } 548 formals = formals.tail; 549 } 550 } 551 552 /** 553 * Compute a synthetic method type corresponding to the requested polymorphic 554 * method signature. The target return type is computed from the immediately 555 * enclosing scope surrounding the polymorphic-signature call. 556 */ 557 Type instantiatePolymorphicSignatureInstance(Env<AttrContext> env, 558 MethodSymbol spMethod, // sig. poly. method or null if none 559 Resolve.MethodResolutionContext resolveContext, 560 List<Type> argtypes) { 561 final Type restype; 562 563 //The return type for a polymorphic signature call is computed from 564 //the enclosing tree E, as follows: if E is a cast, then use the 565 //target type of the cast expression as a return type; if E is an 566 //expression statement, the return type is 'void' - otherwise the 567 //return type is simply 'Object'. A correctness check ensures that 568 //env.next refers to the lexically enclosing environment in which 569 //the polymorphic signature call environment is nested. 570 571 switch (env.next.tree.getTag()) { 572 case TYPECAST: 573 JCTypeCast castTree = (JCTypeCast)env.next.tree; 574 restype = (TreeInfo.skipParens(castTree.expr) == env.tree) ? 575 castTree.clazz.type : 576 syms.objectType; 577 break; 578 case EXEC: 579 JCTree.JCExpressionStatement execTree = 580 (JCTree.JCExpressionStatement)env.next.tree; 581 restype = (TreeInfo.skipParens(execTree.expr) == env.tree) ? 582 syms.voidType : 583 syms.objectType; 584 break; 585 default: 586 restype = syms.objectType; 587 } 588 589 List<Type> paramtypes = argtypes.map(new ImplicitArgType(spMethod, resolveContext.step)); 590 List<Type> exType = spMethod != null ? 591 spMethod.getThrownTypes() : 592 List.of(syms.throwableType); // make it throw all exceptions 593 594 MethodType mtype = new MethodType(paramtypes, 595 restype, 596 exType, 597 syms.methodClass); 598 return mtype; 599 } 600 //where 601 class ImplicitArgType extends DeferredAttr.DeferredTypeMap { 602 603 public ImplicitArgType(Symbol msym, Resolve.MethodResolutionPhase phase) { 604 (rs.deferredAttr).super(AttrMode.SPECULATIVE, msym, phase); 605 } 606 607 @Override 608 public Type visitClassType(ClassType t, Void aVoid) { 609 return types.erasure(t); 610 } 611 612 @Override 613 public Type visitType(Type t, Void _unused) { 614 if (t.hasTag(DEFERRED)) { 615 return visit(super.visitType(t, null)); 616 } else if (t.hasTag(BOT)) 617 // nulls type as the marker type Null (which has no instances) 618 // infer as java.lang.Void for now 619 t = types.boxedClass(syms.voidType).type; 620 return t; 621 } 622 } 623 624 TypeMapping<Void> fromTypeVarFun = new TypeMapping<Void>() { 625 @Override 626 public Type visitTypeVar(TypeVar tv, Void aVoid) { 627 return new UndetVar(tv, incorporationEngine(), types); 628 } 629 630 @Override 631 public Type visitCapturedType(CapturedType t, Void aVoid) { 632 return new CapturedUndetVar(t, incorporationEngine(), types); 633 } 634 }; 635 636 /** 637 * This method is used to infer a suitable target SAM in case the original 638 * SAM type contains one or more wildcards. An inference process is applied 639 * so that wildcard bounds, as well as explicit lambda/method ref parameters 640 * (where applicable) are used to constraint the solution. 641 */ 642 public Type instantiateFunctionalInterface(DiagnosticPosition pos, Type funcInterface, 643 List<Type> paramTypes, Check.CheckContext checkContext) { 644 if (types.capture(funcInterface) == funcInterface) { 645 //if capture doesn't change the type then return the target unchanged 646 //(this means the target contains no wildcards!) 647 return funcInterface; 648 } else { 649 Type formalInterface = funcInterface.tsym.type; 650 InferenceContext funcInterfaceContext = 651 new InferenceContext(this, funcInterface.tsym.type.getTypeArguments()); 652 653 Assert.check(paramTypes != null); 654 //get constraints from explicit params (this is done by 655 //checking that explicit param types are equal to the ones 656 //in the functional interface descriptors) 657 List<Type> descParameterTypes = types.findDescriptorType(formalInterface).getParameterTypes(); 658 if (descParameterTypes.size() != paramTypes.size()) { 659 checkContext.report(pos, diags.fragment("incompatible.arg.types.in.lambda")); 660 return types.createErrorType(funcInterface); 661 } 662 for (Type p : descParameterTypes) { 663 if (!types.isSameType(funcInterfaceContext.asUndetVar(p), paramTypes.head)) { 664 checkContext.report(pos, diags.fragment("no.suitable.functional.intf.inst", funcInterface)); 665 return types.createErrorType(funcInterface); 666 } 667 paramTypes = paramTypes.tail; 668 } 669 670 try { 671 funcInterfaceContext.solve(funcInterfaceContext.boundedVars(), types.noWarnings); 672 } catch (InferenceException ex) { 673 checkContext.report(pos, diags.fragment("no.suitable.functional.intf.inst", funcInterface)); 674 } 675 676 List<Type> actualTypeargs = funcInterface.getTypeArguments(); 677 for (Type t : funcInterfaceContext.undetvars) { 678 UndetVar uv = (UndetVar)t; 679 if (uv.getInst() == null) { 680 uv.setInst(actualTypeargs.head); 681 } 682 actualTypeargs = actualTypeargs.tail; 683 } 684 685 Type owntype = funcInterfaceContext.asInstType(formalInterface); 686 if (!chk.checkValidGenericType(owntype)) { 687 //if the inferred functional interface type is not well-formed, 688 //or if it's not a subtype of the original target, issue an error 689 checkContext.report(pos, diags.fragment("no.suitable.functional.intf.inst", funcInterface)); 690 } 691 //propagate constraints as per JLS 18.2.1 692 checkContext.compatible(owntype, funcInterface, types.noWarnings); 693 return owntype; 694 } 695 } 696 // </editor-fold> 697 698 // <editor-fold defaultstate="collapsed" desc="Incorporation"> 699 700 /** 701 * This class is the root of all incorporation actions. 702 */ 703 public abstract class IncorporationAction { 704 UndetVar uv; 705 Type t; 706 707 IncorporationAction(UndetVar uv, Type t) { 708 this.uv = uv; 709 this.t = t; 710 } 711 712 /** 713 * Incorporation action entry-point. Subclasses should define the logic associated with 714 * this incorporation action. 715 */ 716 abstract void apply(InferenceContext ic, Warner warn); 717 718 /** 719 * Helper function: perform subtyping through incorporation cache. 720 */ 721 boolean isSubtype(Type s, Type t, Warner warn) { 722 return doIncorporationOp(IncorporationBinaryOpKind.IS_SUBTYPE, s, t, warn); 723 } 724 725 /** 726 * Helper function: perform type-equivalence through incorporation cache. 727 */ 728 boolean isSameType(Type s, Type t) { 729 return doIncorporationOp(IncorporationBinaryOpKind.IS_SAME_TYPE, s, t, null); 730 } 731 732 @Override 733 public String toString() { 734 return String.format("%s[undet=%s,t=%s]", getClass().getSimpleName(), uv.qtype, t); 735 } 736 } 737 738 /** 739 * Bound-check incorporation action. A newly added bound is checked against existing bounds, 740 * to verify its compatibility; each bound is checked using either subtyping or type equivalence. 741 */ 742 class CheckBounds extends IncorporationAction { 743 744 InferenceBound from; 745 BiFunction<InferenceContext, Type, Type> typeFunc; 746 BiPredicate<InferenceContext, Type> optFilter; 747 748 CheckBounds(UndetVar uv, Type t, InferenceBound from) { 749 this(uv, t, InferenceContext::asUndetVar, null, from); 750 } 751 752 CheckBounds(UndetVar uv, Type t, BiFunction<InferenceContext, Type, Type> typeFunc, 753 BiPredicate<InferenceContext, Type> typeFilter, InferenceBound from) { 754 super(uv, t); 755 this.from = from; 756 this.typeFunc = typeFunc; 757 this.optFilter = typeFilter; 758 } 759 760 @Override 761 void apply(InferenceContext inferenceContext, Warner warn) { 762 t = typeFunc.apply(inferenceContext, t); 763 if (optFilter != null && optFilter.test(inferenceContext, t)) return; 764 for (InferenceBound to : boundsToCheck()) { 765 for (Type b : uv.getBounds(to)) { 766 b = typeFunc.apply(inferenceContext, b); 767 if (optFilter != null && optFilter.test(inferenceContext, b)) continue; 768 boolean success = checkBound(t, b, from, to, warn); 769 if (!success) { 770 report(from, to); 771 } 772 } 773 } 774 } 775 776 /** 777 * The list of bound kinds to be checked. 778 */ 779 EnumSet<InferenceBound> boundsToCheck() { 780 return (from == InferenceBound.EQ) ? 781 EnumSet.allOf(InferenceBound.class) : 782 EnumSet.complementOf(EnumSet.of(from)); 783 } 784 785 /** 786 * Is source type 's' compatible with target type 't' given source and target bound kinds? 787 */ 788 boolean checkBound(Type s, Type t, InferenceBound ib_s, InferenceBound ib_t, Warner warn) { 789 if (ib_s.lessThan(ib_t)) { 790 return isSubtype(s, t, warn); 791 } else if (ib_t.lessThan(ib_s)) { 792 return isSubtype(t, s, warn); 793 } else { 794 return isSameType(s, t); 795 } 796 } 797 798 /** 799 * Report a bound check error. 800 */ 801 void report(InferenceBound from, InferenceBound to) { 802 //this is a workaround to preserve compatibility with existing messages 803 if (from == to) { 804 reportBoundError(uv, from); 805 } else if (from == InferenceBound.LOWER || to == InferenceBound.EQ) { 806 reportBoundError(uv, to, from); 807 } else { 808 reportBoundError(uv, from, to); 809 } 810 } 811 812 @Override 813 public String toString() { 814 return String.format("%s[undet=%s,t=%s,bound=%s]", getClass().getSimpleName(), uv.qtype, t, from); 815 } 816 } 817 818 /** 819 * Custom check executed by the legacy incorporation engine. Newly added bounds are checked 820 * against existing eq bounds. 821 */ 822 class EqCheckLegacy extends CheckBounds { 823 EqCheckLegacy(UndetVar uv, Type t, InferenceBound from) { 824 super(uv, t, InferenceContext::asInstType, InferenceContext::free, from); 825 } 826 827 @Override 828 EnumSet<InferenceBound> boundsToCheck() { 829 return (from == InferenceBound.EQ) ? 830 EnumSet.allOf(InferenceBound.class) : 831 EnumSet.of(InferenceBound.EQ); 832 } 833 } 834 835 /** 836 * Check that the inferred type conforms to all bounds. 837 */ 838 class CheckInst extends CheckBounds { 839 840 EnumSet<InferenceBound> to; 841 842 CheckInst(UndetVar uv, InferenceBound ib, InferenceBound... rest) { 843 super(uv, uv.getInst(), InferenceBound.EQ); 844 this.to = EnumSet.of(ib, rest); 845 } 846 847 @Override 848 EnumSet<InferenceBound> boundsToCheck() { 849 return to; 850 } 851 852 @Override 853 void report(InferenceBound from, InferenceBound to) { 854 reportInstError(uv, to); 855 } 856 } 857 858 /** 859 * Replace undetvars in bounds and check that the inferred type conforms to all bounds. 860 */ 861 class SubstBounds extends CheckInst { 862 SubstBounds(UndetVar uv) { 863 super(uv, InferenceBound.LOWER, InferenceBound.EQ, InferenceBound.UPPER); 864 } 865 866 @Override 867 void apply(InferenceContext inferenceContext, Warner warn) { 868 for (Type undet : inferenceContext.undetvars) { 869 //we could filter out variables not mentioning uv2... 870 UndetVar uv2 = (UndetVar)undet; 871 uv2.substBounds(List.of(uv.qtype), List.of(uv.getInst()), types); 872 checkCompatibleUpperBounds(uv2, inferenceContext); 873 } 874 super.apply(inferenceContext, warn); 875 } 876 877 /** 878 * Make sure that the upper bounds we got so far lead to a solvable inference 879 * variable by making sure that a glb exists. 880 */ 881 void checkCompatibleUpperBounds(UndetVar uv, InferenceContext inferenceContext) { 882 List<Type> hibounds = 883 Type.filter(uv.getBounds(InferenceBound.UPPER), new BoundFilter(inferenceContext)); 884 final Type hb; 885 if (hibounds.isEmpty()) 886 hb = syms.objectType; 887 else if (hibounds.tail.isEmpty()) 888 hb = hibounds.head; 889 else 890 hb = types.glb(hibounds); 891 if (hb == null || hb.isErroneous()) 892 reportBoundError(uv, InferenceBound.UPPER); 893 } 894 } 895 896 /** 897 * Perform pairwise comparison between common generic supertypes of two upper bounds. 898 */ 899 class CheckUpperBounds extends IncorporationAction { 900 901 public CheckUpperBounds(UndetVar uv, Type t) { 902 super(uv, t); 903 } 904 905 @Override 906 void apply(InferenceContext inferenceContext, Warner warn) { 907 List<Type> boundList = uv.getBounds(InferenceBound.UPPER).stream() 908 .collect(types.closureCollector(true, types::isSameType)); 909 for (Type b2 : boundList) { 910 if (t == b2) continue; 911 /* This wildcard check is temporary workaround. This code may need to be 912 * revisited once spec bug JDK-7034922 is fixed. 913 */ 914 if (t != b2 && !t.hasTag(WILDCARD) && !b2.hasTag(WILDCARD)) { 915 for (Pair<Type, Type> commonSupers : getParameterizedSupers(t, b2)) { 916 List<Type> allParamsSuperBound1 = commonSupers.fst.allparams(); 917 List<Type> allParamsSuperBound2 = commonSupers.snd.allparams(); 918 while (allParamsSuperBound1.nonEmpty() && allParamsSuperBound2.nonEmpty()) { 919 //traverse the list of all params comparing them 920 if (!allParamsSuperBound1.head.hasTag(WILDCARD) && 921 !allParamsSuperBound2.head.hasTag(WILDCARD)) { 922 if (!isSameType(inferenceContext.asUndetVar(allParamsSuperBound1.head), 923 inferenceContext.asUndetVar(allParamsSuperBound2.head))) { 924 reportBoundError(uv, InferenceBound.UPPER); 925 } 926 } 927 allParamsSuperBound1 = allParamsSuperBound1.tail; 928 allParamsSuperBound2 = allParamsSuperBound2.tail; 929 } 930 Assert.check(allParamsSuperBound1.isEmpty() && allParamsSuperBound2.isEmpty()); 931 } 932 } 933 } 934 } 935 } 936 937 /** 938 * Perform propagation of bounds. Given a constraint of the kind {@code alpha <: T}, three 939 * kind of propagation occur: 940 * 941 * <li>T is copied into all matching bounds (i.e. lower/eq bounds) B of alpha such that B=beta (forward propagation)</li> 942 * <li>if T=beta, matching bounds (i.e. upper bounds) of beta are copied into alpha (backwards propagation)</li> 943 * <li>if T=beta, sets a symmetric bound on beta (i.e. beta :> alpha) (symmetric propagation) </li> 944 */ 945 class PropagateBounds extends IncorporationAction { 946 947 InferenceBound ib; 948 949 public PropagateBounds(UndetVar uv, Type t, InferenceBound ib) { 950 super(uv, t); 951 this.ib = ib; 952 } 953 954 void apply(InferenceContext inferenceContext, Warner warner) { 955 Type undetT = inferenceContext.asUndetVar(t); 956 if (undetT.hasTag(UNDETVAR) && !((UndetVar)undetT).isCaptured()) { 957 UndetVar uv2 = (UndetVar)undetT; 958 //symmetric propagation 959 uv2.addBound(ib.complement(), uv, types); 960 //backwards propagation 961 for (InferenceBound ib2 : backwards()) { 962 for (Type b : uv2.getBounds(ib2)) { 963 uv.addBound(ib2, b, types); 964 } 965 } 966 } 967 //forward propagation 968 for (InferenceBound ib2 : forward()) { 969 for (Type l : uv.getBounds(ib2)) { 970 Type undet = inferenceContext.asUndetVar(l); 971 if (undet.hasTag(TypeTag.UNDETVAR) && !((UndetVar)undet).isCaptured()) { 972 UndetVar uv2 = (UndetVar)undet; 973 uv2.addBound(ib, inferenceContext.asInstType(t), types); 974 } 975 } 976 } 977 } 978 979 EnumSet<InferenceBound> forward() { 980 return (ib == InferenceBound.EQ) ? 981 EnumSet.of(InferenceBound.EQ) : EnumSet.complementOf(EnumSet.of(ib)); 982 } 983 984 EnumSet<InferenceBound> backwards() { 985 return (ib == InferenceBound.EQ) ? 986 EnumSet.allOf(InferenceBound.class) : EnumSet.of(ib); 987 } 988 989 @Override 990 public String toString() { 991 return String.format("%s[undet=%s,t=%s,bound=%s]", getClass().getSimpleName(), uv.qtype, t, ib); 992 } 993 } 994 995 /** 996 * This class models an incorporation engine. The engine is responsible for listening to 997 * changes in inference variables and register incorporation actions accordingly. 998 */ 999 abstract class AbstractIncorporationEngine implements UndetVarListener { 1000 1001 @Override 1002 public void varInstantiated(UndetVar uv) { 1003 uv.incorporationActions.addFirst(new SubstBounds(uv)); 1004 } 1005 1006 @Override 1007 public void varBoundChanged(UndetVar uv, InferenceBound ib, Type bound, boolean update) { 1008 if (uv.isCaptured()) return; 1009 uv.incorporationActions.addAll(getIncorporationActions(uv, ib, bound, update)); 1010 } 1011 1012 abstract List<IncorporationAction> getIncorporationActions(UndetVar uv, InferenceBound ib, Type t, boolean update); 1013 } 1014 1015 /** 1016 * A legacy incorporation engine. Used for source <= 7. 1017 */ 1018 AbstractIncorporationEngine legacyEngine = new AbstractIncorporationEngine() { 1019 1020 List<IncorporationAction> getIncorporationActions(UndetVar uv, InferenceBound ib, Type t, boolean update) { 1021 ListBuffer<IncorporationAction> actions = new ListBuffer<>(); 1022 Type inst = uv.getInst(); 1023 if (inst != null) { 1024 actions.add(new CheckInst(uv, ib)); 1025 } 1026 actions.add(new EqCheckLegacy(uv, t, ib)); 1027 return actions.toList(); 1028 } 1029 }; 1030 1031 /** 1032 * The standard incorporation engine. Used for source >= 8. 1033 */ 1034 AbstractIncorporationEngine graphEngine = new AbstractIncorporationEngine() { 1035 1036 @Override 1037 List<IncorporationAction> getIncorporationActions(UndetVar uv, InferenceBound ib, Type t, boolean update) { 1038 ListBuffer<IncorporationAction> actions = new ListBuffer<>(); 1039 Type inst = uv.getInst(); 1040 if (inst != null) { 1041 actions.add(new CheckInst(uv, ib)); 1042 } 1043 actions.add(new CheckBounds(uv, t, ib)); 1044 1045 if (update) { 1046 return actions.toList(); 1047 } 1048 1049 if (ib == InferenceBound.UPPER) { 1050 actions.add(new CheckUpperBounds(uv, t)); 1051 } 1052 1053 actions.add(new PropagateBounds(uv, t, ib)); 1054 1055 return actions.toList(); 1056 } 1057 }; 1058 1059 /** 1060 * Get the incorporation engine to be used in this compilation. 1061 */ 1062 AbstractIncorporationEngine incorporationEngine() { 1063 return allowGraphInference ? graphEngine : legacyEngine; 1064 } 1065 1066 /** max number of incorporation rounds. */ 1067 static final int MAX_INCORPORATION_STEPS = 10000; 1068 1069 /** 1070 * Check bounds and perform incorporation. 1071 */ 1072 void doIncorporation(InferenceContext inferenceContext, Warner warn) throws InferenceException { 1073 try { 1074 boolean progress = true; 1075 int round = 0; 1076 while (progress && round < MAX_INCORPORATION_STEPS) { 1077 progress = false; 1078 for (Type t : inferenceContext.undetvars) { 1079 UndetVar uv = (UndetVar)t; 1080 if (!uv.incorporationActions.isEmpty()) { 1081 progress = true; 1082 uv.incorporationActions.removeFirst().apply(inferenceContext, warn); 1083 } 1084 } 1085 round++; 1086 } 1087 } finally { 1088 incorporationCache.clear(); 1089 } 1090 } 1091 1092 /* If for two types t and s there is a least upper bound that contains 1093 * parameterized types G1, G2 ... Gn, then there exists supertypes of 't' of the form 1094 * G1<T1, ..., Tn>, G2<T1, ..., Tn>, ... Gn<T1, ..., Tn> and supertypes of 's' of the form 1095 * G1<S1, ..., Sn>, G2<S1, ..., Sn>, ... Gn<S1, ..., Sn> which will be returned by this method. 1096 * If no such common supertypes exists then an empty list is returned. 1097 * 1098 * As an example for the following input: 1099 * 1100 * t = java.util.ArrayList<java.lang.String> 1101 * s = java.util.List<T> 1102 * 1103 * we get this ouput (singleton list): 1104 * 1105 * [Pair[java.util.List<java.lang.String>,java.util.List<T>]] 1106 */ 1107 private List<Pair<Type, Type>> getParameterizedSupers(Type t, Type s) { 1108 Type lubResult = types.lub(t, s); 1109 if (lubResult == syms.errType || lubResult == syms.botType) { 1110 return List.nil(); 1111 } 1112 List<Type> supertypesToCheck = lubResult.isIntersection() ? 1113 ((IntersectionClassType)lubResult).getComponents() : 1114 List.of(lubResult); 1115 ListBuffer<Pair<Type, Type>> commonSupertypes = new ListBuffer<>(); 1116 for (Type sup : supertypesToCheck) { 1117 if (sup.isParameterized()) { 1118 Type asSuperOfT = asSuper(t, sup); 1119 Type asSuperOfS = asSuper(s, sup); 1120 commonSupertypes.add(new Pair<>(asSuperOfT, asSuperOfS)); 1121 } 1122 } 1123 return commonSupertypes.toList(); 1124 } 1125 //where 1126 private Type asSuper(Type t, Type sup) { 1127 return (sup.hasTag(ARRAY)) ? 1128 new ArrayType(asSuper(types.elemtype(t), types.elemtype(sup)), syms.arrayClass) : 1129 types.asSuper(t, sup.tsym); 1130 } 1131 1132 boolean doIncorporationOp(IncorporationBinaryOpKind opKind, Type op1, Type op2, Warner warn) { 1133 IncorporationBinaryOp newOp = new IncorporationBinaryOp(opKind, op1, op2); 1134 Boolean res = incorporationCache.get(newOp); 1135 if (res == null) { 1136 incorporationCache.put(newOp, res = newOp.apply(warn)); 1137 } 1138 return res; 1139 } 1140 1141 /** 1142 * Three kinds of basic operation are supported as part of an incorporation step: 1143 * (i) subtype check, (ii) same type check and (iii) bound addition (either 1144 * upper/lower/eq bound). 1145 */ 1146 enum IncorporationBinaryOpKind { 1147 IS_SUBTYPE() { 1148 @Override 1149 boolean apply(Type op1, Type op2, Warner warn, Types types) { 1150 return types.isSubtypeUnchecked(op1, op2, warn); 1151 } 1152 }, 1153 IS_SAME_TYPE() { 1154 @Override 1155 boolean apply(Type op1, Type op2, Warner warn, Types types) { 1156 return types.isSameType(op1, op2); 1157 } 1158 }; 1159 1160 abstract boolean apply(Type op1, Type op2, Warner warn, Types types); 1161 } 1162 1163 /** 1164 * This class encapsulates a basic incorporation operation; incorporation 1165 * operations takes two type operands and a kind. Each operation performed 1166 * during an incorporation round is stored in a cache, so that operations 1167 * are not executed unnecessarily (which would potentially lead to adding 1168 * same bounds over and over). 1169 */ 1170 class IncorporationBinaryOp { 1171 1172 IncorporationBinaryOpKind opKind; 1173 Type op1; 1174 Type op2; 1175 1176 IncorporationBinaryOp(IncorporationBinaryOpKind opKind, Type op1, Type op2) { 1177 this.opKind = opKind; 1178 this.op1 = op1; 1179 this.op2 = op2; 1180 } 1181 1182 @Override 1183 public boolean equals(Object o) { 1184 if (!(o instanceof IncorporationBinaryOp)) { 1185 return false; 1186 } else { 1187 IncorporationBinaryOp that = (IncorporationBinaryOp)o; 1188 return opKind == that.opKind && 1189 types.isSameType(op1, that.op1, true) && 1190 types.isSameType(op2, that.op2, true); 1191 } 1192 } 1193 1194 @Override 1195 public int hashCode() { 1196 int result = opKind.hashCode(); 1197 result *= 127; 1198 result += types.hashCode(op1); 1199 result *= 127; 1200 result += types.hashCode(op2); 1201 return result; 1202 } 1203 1204 boolean apply(Warner warn) { 1205 return opKind.apply(op1, op2, warn, types); 1206 } 1207 } 1208 1209 /** an incorporation cache keeps track of all executed incorporation-related operations */ 1210 Map<IncorporationBinaryOp, Boolean> incorporationCache = new HashMap<>(); 1211 1212 protected static class BoundFilter implements Filter<Type> { 1213 1214 InferenceContext inferenceContext; 1215 1216 public BoundFilter(InferenceContext inferenceContext) { 1217 this.inferenceContext = inferenceContext; 1218 } 1219 1220 @Override 1221 public boolean accepts(Type t) { 1222 return !t.isErroneous() && !inferenceContext.free(t) && 1223 !t.hasTag(BOT); 1224 } 1225 } 1226 1227 /** 1228 * Incorporation error: mismatch between inferred type and given bound. 1229 */ 1230 void reportInstError(UndetVar uv, InferenceBound ib) { 1231 reportInferenceError( 1232 String.format("inferred.do.not.conform.to.%s.bounds", StringUtils.toLowerCase(ib.name())), 1233 uv.getInst(), 1234 uv.getBounds(ib)); 1235 } 1236 1237 /** 1238 * Incorporation error: mismatch between two (or more) bounds of same kind. 1239 */ 1240 void reportBoundError(UndetVar uv, InferenceBound ib) { 1241 reportInferenceError( 1242 String.format("incompatible.%s.bounds", StringUtils.toLowerCase(ib.name())), 1243 uv.qtype, 1244 uv.getBounds(ib)); 1245 } 1246 1247 /** 1248 * Incorporation error: mismatch between two (or more) bounds of different kinds. 1249 */ 1250 void reportBoundError(UndetVar uv, InferenceBound ib1, InferenceBound ib2) { 1251 reportInferenceError( 1252 String.format("incompatible.%s.%s.bounds", 1253 StringUtils.toLowerCase(ib1.name()), 1254 StringUtils.toLowerCase(ib2.name())), 1255 uv.qtype, 1256 uv.getBounds(ib1), 1257 uv.getBounds(ib2)); 1258 } 1259 1260 /** 1261 * Helper method: reports an inference error. 1262 */ 1263 void reportInferenceError(String key, Object... args) { 1264 throw inferenceException.setMessage(key, args); 1265 } 1266 // </editor-fold> 1267 1268 // <editor-fold defaultstate="collapsed" desc="Inference engine"> 1269 /** 1270 * Graph inference strategy - act as an input to the inference solver; a strategy is 1271 * composed of two ingredients: (i) find a node to solve in the inference graph, 1272 * and (ii) tell th engine when we are done fixing inference variables 1273 */ 1274 interface GraphStrategy { 1275 1276 /** 1277 * A NodeNotFoundException is thrown whenever an inference strategy fails 1278 * to pick the next node to solve in the inference graph. 1279 */ 1280 public static class NodeNotFoundException extends RuntimeException { 1281 private static final long serialVersionUID = 0; 1282 1283 InferenceGraph graph; 1284 1285 public NodeNotFoundException(InferenceGraph graph) { 1286 this.graph = graph; 1287 } 1288 } 1289 /** 1290 * Pick the next node (leaf) to solve in the graph 1291 */ 1292 Node pickNode(InferenceGraph g) throws NodeNotFoundException; 1293 /** 1294 * Is this the last step? 1295 */ 1296 boolean done(); 1297 } 1298 1299 /** 1300 * Simple solver strategy class that locates all leaves inside a graph 1301 * and picks the first leaf as the next node to solve 1302 */ 1303 abstract class LeafSolver implements GraphStrategy { 1304 public Node pickNode(InferenceGraph g) { 1305 if (g.nodes.isEmpty()) { 1306 //should not happen 1307 throw new NodeNotFoundException(g); 1308 } 1309 return g.nodes.get(0); 1310 } 1311 } 1312 1313 /** 1314 * This solver uses an heuristic to pick the best leaf - the heuristic 1315 * tries to select the node that has maximal probability to contain one 1316 * or more inference variables in a given list 1317 */ 1318 abstract class BestLeafSolver extends LeafSolver { 1319 1320 /** list of ivars of which at least one must be solved */ 1321 List<Type> varsToSolve; 1322 1323 BestLeafSolver(List<Type> varsToSolve) { 1324 this.varsToSolve = varsToSolve; 1325 } 1326 1327 /** 1328 * Computes a path that goes from a given node to the leafs in the graph. 1329 * Typically this will start from a node containing a variable in 1330 * {@code varsToSolve}. For any given path, the cost is computed as the total 1331 * number of type-variables that should be eagerly instantiated across that path. 1332 */ 1333 Pair<List<Node>, Integer> computeTreeToLeafs(Node n) { 1334 Pair<List<Node>, Integer> cachedPath = treeCache.get(n); 1335 if (cachedPath == null) { 1336 //cache miss 1337 if (n.isLeaf()) { 1338 //if leaf, stop 1339 cachedPath = new Pair<>(List.of(n), n.data.length()); 1340 } else { 1341 //if non-leaf, proceed recursively 1342 Pair<List<Node>, Integer> path = new Pair<>(List.of(n), n.data.length()); 1343 for (Node n2 : n.getAllDependencies()) { 1344 if (n2 == n) continue; 1345 Pair<List<Node>, Integer> subpath = computeTreeToLeafs(n2); 1346 path = new Pair<>(path.fst.prependList(subpath.fst), 1347 path.snd + subpath.snd); 1348 } 1349 cachedPath = path; 1350 } 1351 //save results in cache 1352 treeCache.put(n, cachedPath); 1353 } 1354 return cachedPath; 1355 } 1356 1357 /** cache used to avoid redundant computation of tree costs */ 1358 final Map<Node, Pair<List<Node>, Integer>> treeCache = new HashMap<>(); 1359 1360 /** constant value used to mark non-existent paths */ 1361 final Pair<List<Node>, Integer> noPath = new Pair<>(null, Integer.MAX_VALUE); 1362 1363 /** 1364 * Pick the leaf that minimize cost 1365 */ 1366 @Override 1367 public Node pickNode(final InferenceGraph g) { 1368 treeCache.clear(); //graph changes at every step - cache must be cleared 1369 Pair<List<Node>, Integer> bestPath = noPath; 1370 for (Node n : g.nodes) { 1371 if (!Collections.disjoint(n.data, varsToSolve)) { 1372 Pair<List<Node>, Integer> path = computeTreeToLeafs(n); 1373 //discard all paths containing at least a node in the 1374 //closure computed above 1375 if (path.snd < bestPath.snd) { 1376 bestPath = path; 1377 } 1378 } 1379 } 1380 if (bestPath == noPath) { 1381 //no path leads there 1382 throw new NodeNotFoundException(g); 1383 } 1384 return bestPath.fst.head; 1385 } 1386 } 1387 1388 /** 1389 * The inference process can be thought of as a sequence of steps. Each step 1390 * instantiates an inference variable using a subset of the inference variable 1391 * bounds, if certain condition are met. Decisions such as the sequence in which 1392 * steps are applied, or which steps are to be applied are left to the inference engine. 1393 */ 1394 enum InferenceStep { 1395 1396 /** 1397 * Instantiate an inference variables using one of its (ground) equality 1398 * constraints 1399 */ 1400 EQ(InferenceBound.EQ) { 1401 @Override 1402 Type solve(UndetVar uv, InferenceContext inferenceContext) { 1403 return filterBounds(uv, inferenceContext).head; 1404 } 1405 }, 1406 /** 1407 * Instantiate an inference variables using its (ground) lower bounds. Such 1408 * bounds are merged together using lub(). 1409 */ 1410 LOWER(InferenceBound.LOWER) { 1411 @Override 1412 Type solve(UndetVar uv, InferenceContext inferenceContext) { 1413 Infer infer = inferenceContext.infer; 1414 List<Type> lobounds = filterBounds(uv, inferenceContext); 1415 //note: lobounds should have at least one element 1416 Type owntype = lobounds.tail.tail == null ? lobounds.head : infer.types.lub(lobounds); 1417 if (owntype.isPrimitive() || owntype.hasTag(ERROR)) { 1418 throw infer.inferenceException 1419 .setMessage("no.unique.minimal.instance.exists", 1420 uv.qtype, lobounds); 1421 } else { 1422 return owntype; 1423 } 1424 } 1425 }, 1426 /** 1427 * Infer uninstantiated/unbound inference variables occurring in 'throws' 1428 * clause as RuntimeException 1429 */ 1430 THROWS(InferenceBound.UPPER) { 1431 @Override 1432 public boolean accepts(UndetVar t, InferenceContext inferenceContext) { 1433 if ((t.qtype.tsym.flags() & Flags.THROWS) == 0) { 1434 //not a throws undet var 1435 return false; 1436 } 1437 if (t.getBounds(InferenceBound.EQ, InferenceBound.LOWER, InferenceBound.UPPER) 1438 .diff(t.getDeclaredBounds()).nonEmpty()) { 1439 //not an unbounded undet var 1440 return false; 1441 } 1442 Infer infer = inferenceContext.infer; 1443 for (Type db : t.getDeclaredBounds()) { 1444 if (t.isInterface()) continue; 1445 if (infer.types.asSuper(infer.syms.runtimeExceptionType, db.tsym) != null) { 1446 //declared bound is a supertype of RuntimeException 1447 return true; 1448 } 1449 } 1450 //declared bound is more specific then RuntimeException - give up 1451 return false; 1452 } 1453 1454 @Override 1455 Type solve(UndetVar uv, InferenceContext inferenceContext) { 1456 return inferenceContext.infer.syms.runtimeExceptionType; 1457 } 1458 }, 1459 /** 1460 * Instantiate an inference variables using its (ground) upper bounds. Such 1461 * bounds are merged together using glb(). 1462 */ 1463 UPPER(InferenceBound.UPPER) { 1464 @Override 1465 Type solve(UndetVar uv, InferenceContext inferenceContext) { 1466 Infer infer = inferenceContext.infer; 1467 List<Type> hibounds = filterBounds(uv, inferenceContext); 1468 //note: hibounds should have at least one element 1469 Type owntype = hibounds.tail.tail == null ? hibounds.head : infer.types.glb(hibounds); 1470 if (owntype.isPrimitive() || owntype.hasTag(ERROR)) { 1471 throw infer.inferenceException 1472 .setMessage("no.unique.maximal.instance.exists", 1473 uv.qtype, hibounds); 1474 } else { 1475 return owntype; 1476 } 1477 } 1478 }, 1479 /** 1480 * Like the former; the only difference is that this step can only be applied 1481 * if all upper bounds are ground. 1482 */ 1483 UPPER_LEGACY(InferenceBound.UPPER) { 1484 @Override 1485 public boolean accepts(UndetVar t, InferenceContext inferenceContext) { 1486 return !inferenceContext.free(t.getBounds(ib)) && !t.isCaptured(); 1487 } 1488 1489 @Override 1490 Type solve(UndetVar uv, InferenceContext inferenceContext) { 1491 return UPPER.solve(uv, inferenceContext); 1492 } 1493 }, 1494 /** 1495 * Like the former; the only difference is that this step can only be applied 1496 * if all upper/lower bounds are ground. 1497 */ 1498 CAPTURED(InferenceBound.UPPER) { 1499 @Override 1500 public boolean accepts(UndetVar t, InferenceContext inferenceContext) { 1501 return t.isCaptured() && 1502 !inferenceContext.free(t.getBounds(InferenceBound.UPPER, InferenceBound.LOWER)); 1503 } 1504 1505 @Override 1506 Type solve(UndetVar uv, InferenceContext inferenceContext) { 1507 Infer infer = inferenceContext.infer; 1508 Type upper = UPPER.filterBounds(uv, inferenceContext).nonEmpty() ? 1509 UPPER.solve(uv, inferenceContext) : 1510 infer.syms.objectType; 1511 Type lower = LOWER.filterBounds(uv, inferenceContext).nonEmpty() ? 1512 LOWER.solve(uv, inferenceContext) : 1513 infer.syms.botType; 1514 CapturedType prevCaptured = (CapturedType)uv.qtype; 1515 return new CapturedType(prevCaptured.tsym.name, prevCaptured.tsym.owner, 1516 upper, lower, prevCaptured.wildcard); 1517 } 1518 }; 1519 1520 final InferenceBound ib; 1521 1522 InferenceStep(InferenceBound ib) { 1523 this.ib = ib; 1524 } 1525 1526 /** 1527 * Find an instantiated type for a given inference variable within 1528 * a given inference context 1529 */ 1530 abstract Type solve(UndetVar uv, InferenceContext inferenceContext); 1531 1532 /** 1533 * Can the inference variable be instantiated using this step? 1534 */ 1535 public boolean accepts(UndetVar t, InferenceContext inferenceContext) { 1536 return filterBounds(t, inferenceContext).nonEmpty() && !t.isCaptured(); 1537 } 1538 1539 /** 1540 * Return the subset of ground bounds in a given bound set (i.e. eq/lower/upper) 1541 */ 1542 List<Type> filterBounds(UndetVar uv, InferenceContext inferenceContext) { 1543 return Type.filter(uv.getBounds(ib), new BoundFilter(inferenceContext)); 1544 } 1545 } 1546 1547 /** 1548 * This enumeration defines the sequence of steps to be applied when the 1549 * solver works in legacy mode. The steps in this enumeration reflect 1550 * the behavior of old inference routine (see JLS SE 7 15.12.2.7/15.12.2.8). 1551 */ 1552 enum LegacyInferenceSteps { 1553 1554 EQ_LOWER(EnumSet.of(InferenceStep.EQ, InferenceStep.LOWER)), 1555 EQ_UPPER(EnumSet.of(InferenceStep.EQ, InferenceStep.UPPER_LEGACY)); 1556 1557 final EnumSet<InferenceStep> steps; 1558 1559 LegacyInferenceSteps(EnumSet<InferenceStep> steps) { 1560 this.steps = steps; 1561 } 1562 } 1563 1564 /** 1565 * This enumeration defines the sequence of steps to be applied when the 1566 * graph solver is used. This order is defined so as to maximize compatibility 1567 * w.r.t. old inference routine (see JLS SE 7 15.12.2.7/15.12.2.8). 1568 */ 1569 enum GraphInferenceSteps { 1570 1571 EQ(EnumSet.of(InferenceStep.EQ)), 1572 EQ_LOWER(EnumSet.of(InferenceStep.EQ, InferenceStep.LOWER)), 1573 EQ_LOWER_THROWS_UPPER_CAPTURED(EnumSet.of(InferenceStep.EQ, InferenceStep.LOWER, InferenceStep.UPPER, InferenceStep.THROWS, InferenceStep.CAPTURED)); 1574 1575 final EnumSet<InferenceStep> steps; 1576 1577 GraphInferenceSteps(EnumSet<InferenceStep> steps) { 1578 this.steps = steps; 1579 } 1580 } 1581 1582 /** 1583 * There are two kinds of dependencies between inference variables. The basic 1584 * kind of dependency (or bound dependency) arises when a variable mention 1585 * another variable in one of its bounds. There's also a more subtle kind 1586 * of dependency that arises when a variable 'might' lead to better constraints 1587 * on another variable (this is typically the case with variables holding up 1588 * stuck expressions). 1589 */ 1590 enum DependencyKind implements GraphUtils.DependencyKind { 1591 1592 /** bound dependency */ 1593 BOUND("dotted"), 1594 /** stuck dependency */ 1595 STUCK("dashed"); 1596 1597 final String dotSyle; 1598 1599 private DependencyKind(String dotSyle) { 1600 this.dotSyle = dotSyle; 1601 } 1602 } 1603 1604 /** 1605 * This is the graph inference solver - the solver organizes all inference variables in 1606 * a given inference context by bound dependencies - in the general case, such dependencies 1607 * would lead to a cyclic directed graph (hence the name); the dependency info is used to build 1608 * an acyclic graph, where all cyclic variables are bundled together. An inference 1609 * step corresponds to solving a node in the acyclic graph - this is done by 1610 * relying on a given strategy (see GraphStrategy). 1611 */ 1612 class GraphSolver { 1613 1614 InferenceContext inferenceContext; 1615 Map<Type, Set<Type>> stuckDeps; 1616 Warner warn; 1617 1618 GraphSolver(InferenceContext inferenceContext, Map<Type, Set<Type>> stuckDeps, Warner warn) { 1619 this.inferenceContext = inferenceContext; 1620 this.stuckDeps = stuckDeps; 1621 this.warn = warn; 1622 } 1623 1624 /** 1625 * Solve variables in a given inference context. The amount of variables 1626 * to be solved, and the way in which the underlying acyclic graph is explored 1627 * depends on the selected solver strategy. 1628 */ 1629 void solve(GraphStrategy sstrategy) { 1630 doIncorporation(inferenceContext, warn); //initial propagation of bounds 1631 InferenceGraph inferenceGraph = new InferenceGraph(stuckDeps); 1632 while (!sstrategy.done()) { 1633 if (dependenciesFolder != null) { 1634 //add this graph to the pending queue 1635 pendingGraphs = pendingGraphs.prepend(inferenceGraph.toDot()); 1636 } 1637 InferenceGraph.Node nodeToSolve = sstrategy.pickNode(inferenceGraph); 1638 List<Type> varsToSolve = List.from(nodeToSolve.data); 1639 List<Type> saved_undet = inferenceContext.save(); 1640 try { 1641 //repeat until all variables are solved 1642 outer: while (Type.containsAny(inferenceContext.restvars(), varsToSolve)) { 1643 //for each inference phase 1644 for (GraphInferenceSteps step : GraphInferenceSteps.values()) { 1645 if (inferenceContext.solveBasic(varsToSolve, step.steps).nonEmpty()) { 1646 doIncorporation(inferenceContext, warn); 1647 continue outer; 1648 } 1649 } 1650 //no progress 1651 throw inferenceException.setMessage(); 1652 } 1653 } 1654 catch (InferenceException ex) { 1655 //did we fail because of interdependent ivars? 1656 inferenceContext.rollback(saved_undet); 1657 instantiateAsUninferredVars(varsToSolve, inferenceContext); 1658 doIncorporation(inferenceContext, warn); 1659 } 1660 inferenceGraph.deleteNode(nodeToSolve); 1661 } 1662 } 1663 1664 /** 1665 * The dependencies between the inference variables that need to be solved 1666 * form a (possibly cyclic) graph. This class reduces the original dependency graph 1667 * to an acyclic version, where cyclic nodes are folded into a single 'super node'. 1668 */ 1669 class InferenceGraph { 1670 1671 /** 1672 * This class represents a node in the graph. Each node corresponds 1673 * to an inference variable and has edges (dependencies) on other 1674 * nodes. The node defines an entry point that can be used to receive 1675 * updates on the structure of the graph this node belongs to (used to 1676 * keep dependencies in sync). 1677 */ 1678 class Node extends GraphUtils.TarjanNode<ListBuffer<Type>, Node> implements DottableNode<ListBuffer<Type>, Node> { 1679 1680 /** map listing all dependencies (grouped by kind) */ 1681 EnumMap<DependencyKind, Set<Node>> deps; 1682 1683 Node(Type ivar) { 1684 super(ListBuffer.of(ivar)); 1685 this.deps = new EnumMap<>(DependencyKind.class); 1686 } 1687 1688 @Override 1689 public GraphUtils.DependencyKind[] getSupportedDependencyKinds() { 1690 return DependencyKind.values(); 1691 } 1692 1693 public Iterable<? extends Node> getAllDependencies() { 1694 return getDependencies(DependencyKind.values()); 1695 } 1696 1697 @Override 1698 public Collection<? extends Node> getDependenciesByKind(GraphUtils.DependencyKind dk) { 1699 return getDependencies((DependencyKind)dk); 1700 } 1701 1702 /** 1703 * Retrieves all dependencies with given kind(s). 1704 */ 1705 protected Set<Node> getDependencies(DependencyKind... depKinds) { 1706 Set<Node> buf = new LinkedHashSet<>(); 1707 for (DependencyKind dk : depKinds) { 1708 Set<Node> depsByKind = deps.get(dk); 1709 if (depsByKind != null) { 1710 buf.addAll(depsByKind); 1711 } 1712 } 1713 return buf; 1714 } 1715 1716 /** 1717 * Adds dependency with given kind. 1718 */ 1719 protected void addDependency(DependencyKind dk, Node depToAdd) { 1720 Set<Node> depsByKind = deps.get(dk); 1721 if (depsByKind == null) { 1722 depsByKind = new LinkedHashSet<>(); 1723 deps.put(dk, depsByKind); 1724 } 1725 depsByKind.add(depToAdd); 1726 } 1727 1728 /** 1729 * Add multiple dependencies of same given kind. 1730 */ 1731 protected void addDependencies(DependencyKind dk, Set<Node> depsToAdd) { 1732 for (Node n : depsToAdd) { 1733 addDependency(dk, n); 1734 } 1735 } 1736 1737 /** 1738 * Remove a dependency, regardless of its kind. 1739 */ 1740 protected Set<DependencyKind> removeDependency(Node n) { 1741 Set<DependencyKind> removedKinds = new HashSet<>(); 1742 for (DependencyKind dk : DependencyKind.values()) { 1743 Set<Node> depsByKind = deps.get(dk); 1744 if (depsByKind == null) continue; 1745 if (depsByKind.remove(n)) { 1746 removedKinds.add(dk); 1747 } 1748 } 1749 return removedKinds; 1750 } 1751 1752 /** 1753 * Compute closure of a give node, by recursively walking 1754 * through all its dependencies (of given kinds) 1755 */ 1756 protected Set<Node> closure(DependencyKind... depKinds) { 1757 boolean progress = true; 1758 Set<Node> closure = new HashSet<>(); 1759 closure.add(this); 1760 while (progress) { 1761 progress = false; 1762 for (Node n1 : new HashSet<>(closure)) { 1763 progress = closure.addAll(n1.getDependencies(depKinds)); 1764 } 1765 } 1766 return closure; 1767 } 1768 1769 /** 1770 * Is this node a leaf? This means either the node has no dependencies, 1771 * or it just has self-dependencies. 1772 */ 1773 protected boolean isLeaf() { 1774 //no deps, or only one self dep 1775 Set<Node> allDeps = getDependencies(DependencyKind.BOUND, DependencyKind.STUCK); 1776 if (allDeps.isEmpty()) return true; 1777 for (Node n : allDeps) { 1778 if (n != this) { 1779 return false; 1780 } 1781 } 1782 return true; 1783 } 1784 1785 /** 1786 * Merge this node with another node, acquiring its dependencies. 1787 * This routine is used to merge all cyclic node together and 1788 * form an acyclic graph. 1789 */ 1790 protected void mergeWith(List<? extends Node> nodes) { 1791 for (Node n : nodes) { 1792 Assert.check(n.data.length() == 1, "Attempt to merge a compound node!"); 1793 data.appendList(n.data); 1794 for (DependencyKind dk : DependencyKind.values()) { 1795 addDependencies(dk, n.getDependencies(dk)); 1796 } 1797 } 1798 //update deps 1799 EnumMap<DependencyKind, Set<Node>> deps2 = new EnumMap<>(DependencyKind.class); 1800 for (DependencyKind dk : DependencyKind.values()) { 1801 for (Node d : getDependencies(dk)) { 1802 Set<Node> depsByKind = deps2.get(dk); 1803 if (depsByKind == null) { 1804 depsByKind = new LinkedHashSet<>(); 1805 deps2.put(dk, depsByKind); 1806 } 1807 if (data.contains(d.data.first())) { 1808 depsByKind.add(this); 1809 } else { 1810 depsByKind.add(d); 1811 } 1812 } 1813 } 1814 deps = deps2; 1815 } 1816 1817 /** 1818 * Notify all nodes that something has changed in the graph 1819 * topology. 1820 */ 1821 private void graphChanged(Node from, Node to) { 1822 for (DependencyKind dk : removeDependency(from)) { 1823 if (to != null) { 1824 addDependency(dk, to); 1825 } 1826 } 1827 } 1828 1829 @Override 1830 public Properties nodeAttributes() { 1831 Properties p = new Properties(); 1832 p.put("label", "\"" + toString() + "\""); 1833 return p; 1834 } 1835 1836 @Override 1837 public Properties dependencyAttributes(Node sink, GraphUtils.DependencyKind dk) { 1838 Properties p = new Properties(); 1839 p.put("style", ((DependencyKind)dk).dotSyle); 1840 if (dk == DependencyKind.STUCK) return p; 1841 else { 1842 StringBuilder buf = new StringBuilder(); 1843 String sep = ""; 1844 for (Type from : data) { 1845 UndetVar uv = (UndetVar)inferenceContext.asUndetVar(from); 1846 for (Type bound : uv.getBounds(InferenceBound.values())) { 1847 if (bound.containsAny(List.from(sink.data))) { 1848 buf.append(sep); 1849 buf.append(bound); 1850 sep = ","; 1851 } 1852 } 1853 } 1854 p.put("label", "\"" + buf.toString() + "\""); 1855 } 1856 return p; 1857 } 1858 } 1859 1860 /** the nodes in the inference graph */ 1861 ArrayList<Node> nodes; 1862 1863 InferenceGraph(Map<Type, Set<Type>> optDeps) { 1864 initNodes(optDeps); 1865 } 1866 1867 /** 1868 * Basic lookup helper for retrieving a graph node given an inference 1869 * variable type. 1870 */ 1871 public Node findNode(Type t) { 1872 for (Node n : nodes) { 1873 if (n.data.contains(t)) { 1874 return n; 1875 } 1876 } 1877 return null; 1878 } 1879 1880 /** 1881 * Delete a node from the graph. This update the underlying structure 1882 * of the graph (including dependencies) via listeners updates. 1883 */ 1884 public void deleteNode(Node n) { 1885 Assert.check(nodes.contains(n)); 1886 nodes.remove(n); 1887 notifyUpdate(n, null); 1888 } 1889 1890 /** 1891 * Notify all nodes of a change in the graph. If the target node is 1892 * {@code null} the source node is assumed to be removed. 1893 */ 1894 void notifyUpdate(Node from, Node to) { 1895 for (Node n : nodes) { 1896 n.graphChanged(from, to); 1897 } 1898 } 1899 1900 /** 1901 * Create the graph nodes. First a simple node is created for every inference 1902 * variables to be solved. Then Tarjan is used to found all connected components 1903 * in the graph. For each component containing more than one node, a super node is 1904 * created, effectively replacing the original cyclic nodes. 1905 */ 1906 void initNodes(Map<Type, Set<Type>> stuckDeps) { 1907 //add nodes 1908 nodes = new ArrayList<>(); 1909 for (Type t : inferenceContext.restvars()) { 1910 nodes.add(new Node(t)); 1911 } 1912 //add dependencies 1913 for (Node n_i : nodes) { 1914 Type i = n_i.data.first(); 1915 Set<Type> optDepsByNode = stuckDeps.get(i); 1916 for (Node n_j : nodes) { 1917 Type j = n_j.data.first(); 1918 UndetVar uv_i = (UndetVar)inferenceContext.asUndetVar(i); 1919 if (Type.containsAny(uv_i.getBounds(InferenceBound.values()), List.of(j))) { 1920 //update i's bound dependencies 1921 n_i.addDependency(DependencyKind.BOUND, n_j); 1922 } 1923 if (optDepsByNode != null && optDepsByNode.contains(j)) { 1924 //update i's stuck dependencies 1925 n_i.addDependency(DependencyKind.STUCK, n_j); 1926 } 1927 } 1928 } 1929 //merge cyclic nodes 1930 ArrayList<Node> acyclicNodes = new ArrayList<>(); 1931 for (List<? extends Node> conSubGraph : GraphUtils.tarjan(nodes)) { 1932 if (conSubGraph.length() > 1) { 1933 Node root = conSubGraph.head; 1934 root.mergeWith(conSubGraph.tail); 1935 for (Node n : conSubGraph) { 1936 notifyUpdate(n, root); 1937 } 1938 } 1939 acyclicNodes.add(conSubGraph.head); 1940 } 1941 nodes = acyclicNodes; 1942 } 1943 1944 /** 1945 * Debugging: dot representation of this graph 1946 */ 1947 String toDot() { 1948 StringBuilder buf = new StringBuilder(); 1949 for (Type t : inferenceContext.undetvars) { 1950 UndetVar uv = (UndetVar)t; 1951 buf.append(String.format("var %s - upper bounds = %s, lower bounds = %s, eq bounds = %s\\n", 1952 uv.qtype, uv.getBounds(InferenceBound.UPPER), uv.getBounds(InferenceBound.LOWER), 1953 uv.getBounds(InferenceBound.EQ))); 1954 } 1955 return GraphUtils.toDot(nodes, "inferenceGraph" + hashCode(), buf.toString()); 1956 } 1957 } 1958 } 1959 // </editor-fold> 1960 1961 // <editor-fold defaultstate="collapsed" desc="Inference context"> 1962 /** 1963 * Functional interface for defining inference callbacks. Certain actions 1964 * (i.e. subtyping checks) might need to be redone after all inference variables 1965 * have been fixed. 1966 */ 1967 interface FreeTypeListener { 1968 void typesInferred(InferenceContext inferenceContext); 1969 } 1970 1971 final InferenceContext emptyContext; 1972 // </editor-fold> 1973} 1974