| /* |
| * Copyright (c) 1999, 2009, 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.tree.JCTree; |
| import com.sun.tools.javac.tree.JCTree.JCTypeCast; |
| import com.sun.tools.javac.util.*; |
| import com.sun.tools.javac.util.List; |
| import com.sun.tools.javac.code.*; |
| import com.sun.tools.javac.code.Type.*; |
| import com.sun.tools.javac.code.Type.ForAll.ConstraintKind; |
| import com.sun.tools.javac.code.Symbol.*; |
| import com.sun.tools.javac.util.JCDiagnostic; |
| |
| import static com.sun.tools.javac.code.TypeTags.*; |
| |
| /** Helper class for type parameter inference, used by the attribution phase. |
| * |
| * <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 Infer { |
| protected static final Context.Key<Infer> inferKey = |
| new Context.Key<Infer>(); |
| |
| /** A value for prototypes that admit any type, including polymorphic ones. */ |
| public static final Type anyPoly = new Type(NONE, null); |
| |
| Symtab syms; |
| Types types; |
| Check chk; |
| Resolve rs; |
| JCDiagnostic.Factory diags; |
| |
| public static Infer instance(Context context) { |
| Infer instance = context.get(inferKey); |
| if (instance == null) |
| instance = new Infer(context); |
| return instance; |
| } |
| |
| protected Infer(Context context) { |
| context.put(inferKey, this); |
| syms = Symtab.instance(context); |
| types = Types.instance(context); |
| rs = Resolve.instance(context); |
| chk = Check.instance(context); |
| diags = JCDiagnostic.Factory.instance(context); |
| ambiguousNoInstanceException = |
| new NoInstanceException(true, diags); |
| unambiguousNoInstanceException = |
| new NoInstanceException(false, diags); |
| invalidInstanceException = |
| new InvalidInstanceException(diags); |
| |
| } |
| |
| public static class InferenceException extends RuntimeException { |
| private static final long serialVersionUID = 0; |
| |
| JCDiagnostic diagnostic; |
| JCDiagnostic.Factory diags; |
| |
| InferenceException(JCDiagnostic.Factory diags) { |
| this.diagnostic = null; |
| this.diags = diags; |
| } |
| |
| InferenceException setMessage(String key, Object... args) { |
| this.diagnostic = diags.fragment(key, args); |
| return this; |
| } |
| |
| public JCDiagnostic getDiagnostic() { |
| return diagnostic; |
| } |
| } |
| |
| public static class NoInstanceException extends InferenceException { |
| private static final long serialVersionUID = 1; |
| |
| boolean isAmbiguous; // exist several incomparable best instances? |
| |
| NoInstanceException(boolean isAmbiguous, JCDiagnostic.Factory diags) { |
| super(diags); |
| this.isAmbiguous = isAmbiguous; |
| } |
| } |
| |
| public static class InvalidInstanceException extends InferenceException { |
| private static final long serialVersionUID = 2; |
| |
| InvalidInstanceException(JCDiagnostic.Factory diags) { |
| super(diags); |
| } |
| } |
| |
| private final NoInstanceException ambiguousNoInstanceException; |
| private final NoInstanceException unambiguousNoInstanceException; |
| private final InvalidInstanceException invalidInstanceException; |
| |
| /*************************************************************************** |
| * Auxiliary type values and classes |
| ***************************************************************************/ |
| |
| /** A mapping that turns type variables into undetermined type variables. |
| */ |
| Mapping fromTypeVarFun = new Mapping("fromTypeVarFun") { |
| public Type apply(Type t) { |
| if (t.tag == TYPEVAR) return new UndetVar(t); |
| else return t.map(this); |
| } |
| }; |
| |
| /** A mapping that returns its type argument with every UndetVar replaced |
| * by its `inst' field. Throws a NoInstanceException |
| * if this not possible because an `inst' field is null. |
| * Note: mutually referring undertvars will be left uninstantiated |
| * (that is, they will be replaced by the underlying type-variable). |
| */ |
| |
| Mapping getInstFun = new Mapping("getInstFun") { |
| public Type apply(Type t) { |
| switch (t.tag) { |
| case UNKNOWN: |
| throw ambiguousNoInstanceException |
| .setMessage("undetermined.type"); |
| case UNDETVAR: |
| UndetVar that = (UndetVar) t; |
| if (that.inst == null) |
| throw ambiguousNoInstanceException |
| .setMessage("type.variable.has.undetermined.type", |
| that.qtype); |
| return isConstraintCyclic(that) ? |
| that.qtype : |
| apply(that.inst); |
| default: |
| return t.map(this); |
| } |
| } |
| |
| private boolean isConstraintCyclic(UndetVar uv) { |
| Types.UnaryVisitor<Boolean> constraintScanner = |
| new Types.UnaryVisitor<Boolean>() { |
| |
| List<Type> seen = List.nil(); |
| |
| Boolean visit(List<Type> ts) { |
| for (Type t : ts) { |
| if (visit(t)) return true; |
| } |
| return false; |
| } |
| |
| public Boolean visitType(Type t, Void ignored) { |
| return false; |
| } |
| |
| @Override |
| public Boolean visitClassType(ClassType t, Void ignored) { |
| if (t.isCompound()) { |
| return visit(types.supertype(t)) || |
| visit(types.interfaces(t)); |
| } else { |
| return visit(t.getTypeArguments()); |
| } |
| } |
| @Override |
| public Boolean visitWildcardType(WildcardType t, Void ignored) { |
| return visit(t.type); |
| } |
| |
| @Override |
| public Boolean visitUndetVar(UndetVar t, Void ignored) { |
| if (seen.contains(t)) { |
| return true; |
| } else { |
| seen = seen.prepend(t); |
| return visit(t.inst); |
| } |
| } |
| }; |
| return constraintScanner.visit(uv); |
| } |
| }; |
| |
| /*************************************************************************** |
| * Mini/Maximization of UndetVars |
| ***************************************************************************/ |
| |
| /** Instantiate undetermined type variable to its minimal upper bound. |
| * Throw a NoInstanceException if this not possible. |
| */ |
| void maximizeInst(UndetVar that, Warner warn) throws NoInstanceException { |
| if (that.inst == null) { |
| if (that.hibounds.isEmpty()) |
| that.inst = syms.objectType; |
| else if (that.hibounds.tail.isEmpty()) |
| that.inst = that.hibounds.head; |
| else |
| that.inst = types.glb(that.hibounds); |
| } |
| if (that.inst == null || |
| that.inst.isErroneous()) |
| throw ambiguousNoInstanceException |
| .setMessage("no.unique.maximal.instance.exists", |
| that.qtype, that.hibounds); |
| } |
| //where |
| private boolean isSubClass(Type t, final List<Type> ts) { |
| t = t.baseType(); |
| if (t.tag == TYPEVAR) { |
| List<Type> bounds = types.getBounds((TypeVar)t); |
| for (Type s : ts) { |
| if (!types.isSameType(t, s.baseType())) { |
| for (Type bound : bounds) { |
| if (!isSubClass(bound, List.of(s.baseType()))) |
| return false; |
| } |
| } |
| } |
| } else { |
| for (Type s : ts) { |
| if (!t.tsym.isSubClass(s.baseType().tsym, types)) |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** Instantiate undetermined type variable to the lub of all its lower bounds. |
| * Throw a NoInstanceException if this not possible. |
| */ |
| void minimizeInst(UndetVar that, Warner warn) throws NoInstanceException { |
| if (that.inst == null) { |
| if (that.lobounds.isEmpty()) |
| that.inst = syms.botType; |
| else if (that.lobounds.tail.isEmpty()) |
| that.inst = that.lobounds.head.isPrimitive() ? syms.errType : that.lobounds.head; |
| else { |
| that.inst = types.lub(that.lobounds); |
| } |
| if (that.inst == null || that.inst.tag == ERROR) |
| throw ambiguousNoInstanceException |
| .setMessage("no.unique.minimal.instance.exists", |
| that.qtype, that.lobounds); |
| // VGJ: sort of inlined maximizeInst() below. Adding |
| // bounds can cause lobounds that are above hibounds. |
| if (that.hibounds.isEmpty()) |
| return; |
| Type hb = null; |
| if (that.hibounds.tail.isEmpty()) |
| hb = that.hibounds.head; |
| else for (List<Type> bs = that.hibounds; |
| bs.nonEmpty() && hb == null; |
| bs = bs.tail) { |
| if (isSubClass(bs.head, that.hibounds)) |
| hb = types.fromUnknownFun.apply(bs.head); |
| } |
| if (hb == null || |
| !types.isSubtypeUnchecked(hb, that.hibounds, warn) || |
| !types.isSubtypeUnchecked(that.inst, hb, warn)) |
| throw ambiguousNoInstanceException; |
| } |
| } |
| |
| /*************************************************************************** |
| * Exported Methods |
| ***************************************************************************/ |
| |
| /** Try to instantiate expression type `that' to given type `to'. |
| * If a maximal instantiation exists which makes this type |
| * a subtype of type `to', return the instantiated type. |
| * If no instantiation exists, or if several incomparable |
| * best instantiations exist throw a NoInstanceException. |
| */ |
| public Type instantiateExpr(ForAll that, |
| Type to, |
| Warner warn) throws InferenceException { |
| List<Type> undetvars = Type.map(that.tvars, fromTypeVarFun); |
| for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail) { |
| UndetVar uv = (UndetVar) l.head; |
| TypeVar tv = (TypeVar)uv.qtype; |
| ListBuffer<Type> hibounds = new ListBuffer<Type>(); |
| for (Type t : that.getConstraints(tv, ConstraintKind.EXTENDS)) { |
| hibounds.append(types.subst(t, that.tvars, undetvars)); |
| } |
| |
| List<Type> inst = that.getConstraints(tv, ConstraintKind.EQUAL); |
| if (inst.nonEmpty() && inst.head.tag != BOT) { |
| uv.inst = inst.head; |
| } |
| uv.hibounds = hibounds.toList(); |
| } |
| Type qtype1 = types.subst(that.qtype, that.tvars, undetvars); |
| if (!types.isSubtype(qtype1, to)) { |
| throw unambiguousNoInstanceException |
| .setMessage("no.conforming.instance.exists", |
| that.tvars, that.qtype, to); |
| } |
| for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail) |
| maximizeInst((UndetVar) l.head, warn); |
| // System.out.println(" = " + qtype1.map(getInstFun));//DEBUG |
| |
| // check bounds |
| List<Type> targs = Type.map(undetvars, getInstFun); |
| if (Type.containsAny(targs, that.tvars)) { |
| //replace uninferred type-vars |
| targs = types.subst(targs, |
| that.tvars, |
| instaniateAsUninferredVars(undetvars, that.tvars)); |
| } |
| return chk.checkType(warn.pos(), that.inst(targs, types), to); |
| } |
| //where |
| private List<Type> instaniateAsUninferredVars(List<Type> undetvars, List<Type> tvars) { |
| ListBuffer<Type> new_targs = ListBuffer.lb(); |
| //step 1 - create syntethic captured vars |
| for (Type t : undetvars) { |
| UndetVar uv = (UndetVar)t; |
| Type newArg = new CapturedType(t.tsym.name, t.tsym, uv.inst, syms.botType, null); |
| new_targs = new_targs.append(newArg); |
| } |
| //step 2 - replace synthetic vars in their bounds |
| for (Type t : new_targs.toList()) { |
| CapturedType ct = (CapturedType)t; |
| ct.bound = types.subst(ct.bound, tvars, new_targs.toList()); |
| WildcardType wt = new WildcardType(ct.bound, BoundKind.EXTENDS, syms.boundClass); |
| ct.wildcard = wt; |
| } |
| return new_targs.toList(); |
| } |
| |
| /** Instantiate method type `mt' by finding instantiations of |
| * `tvars' so that method can be applied to `argtypes'. |
| */ |
| public Type instantiateMethod(final Env<AttrContext> env, |
| List<Type> tvars, |
| MethodType mt, |
| final Symbol msym, |
| final List<Type> argtypes, |
| final boolean allowBoxing, |
| final boolean useVarargs, |
| final Warner warn) throws InferenceException { |
| //-System.err.println("instantiateMethod(" + tvars + ", " + mt + ", " + argtypes + ")"); //DEBUG |
| List<Type> undetvars = Type.map(tvars, fromTypeVarFun); |
| List<Type> formals = mt.argtypes; |
| //need to capture exactly once - otherwise subsequent |
| //applicability checks might fail |
| final List<Type> capturedArgs = types.capture(argtypes); |
| List<Type> actuals = capturedArgs; |
| List<Type> actualsNoCapture = argtypes; |
| // instantiate all polymorphic argument types and |
| // set up lower bounds constraints for undetvars |
| Type varargsFormal = useVarargs ? formals.last() : null; |
| while (actuals.nonEmpty() && formals.head != varargsFormal) { |
| Type formal = formals.head; |
| Type actual = actuals.head.baseType(); |
| Type actualNoCapture = actualsNoCapture.head.baseType(); |
| if (actual.tag == FORALL) |
| actual = instantiateArg((ForAll)actual, formal, tvars, warn); |
| Type undetFormal = types.subst(formal, tvars, undetvars); |
| boolean works = allowBoxing |
| ? types.isConvertible(actual, undetFormal, warn) |
| : types.isSubtypeUnchecked(actual, undetFormal, warn); |
| if (!works) { |
| throw unambiguousNoInstanceException |
| .setMessage("no.conforming.assignment.exists", |
| tvars, actualNoCapture, formal); |
| } |
| formals = formals.tail; |
| actuals = actuals.tail; |
| actualsNoCapture = actualsNoCapture.tail; |
| } |
| if (formals.head != varargsFormal || // not enough args |
| !useVarargs && actuals.nonEmpty()) { // too many args |
| // argument lists differ in length |
| throw unambiguousNoInstanceException |
| .setMessage("arg.length.mismatch"); |
| } |
| |
| // for varargs arguments as well |
| if (useVarargs) { |
| Type elemType = types.elemtype(varargsFormal); |
| Type elemUndet = types.subst(elemType, tvars, undetvars); |
| while (actuals.nonEmpty()) { |
| Type actual = actuals.head.baseType(); |
| Type actualNoCapture = actualsNoCapture.head.baseType(); |
| if (actual.tag == FORALL) |
| actual = instantiateArg((ForAll)actual, elemType, tvars, warn); |
| boolean works = types.isConvertible(actual, elemUndet, warn); |
| if (!works) { |
| throw unambiguousNoInstanceException |
| .setMessage("no.conforming.assignment.exists", |
| tvars, actualNoCapture, elemType); |
| } |
| actuals = actuals.tail; |
| actualsNoCapture = actualsNoCapture.tail; |
| } |
| } |
| |
| // minimize as yet undetermined type variables |
| for (Type t : undetvars) |
| minimizeInst((UndetVar) t, warn); |
| |
| /** Type variables instantiated to bottom */ |
| ListBuffer<Type> restvars = new ListBuffer<Type>(); |
| |
| /** Undet vars instantiated to bottom */ |
| final ListBuffer<Type> restundet = new ListBuffer<Type>(); |
| |
| /** Instantiated types or TypeVars if under-constrained */ |
| ListBuffer<Type> insttypes = new ListBuffer<Type>(); |
| |
| /** Instantiated types or UndetVars if under-constrained */ |
| ListBuffer<Type> undettypes = new ListBuffer<Type>(); |
| |
| for (Type t : undetvars) { |
| UndetVar uv = (UndetVar)t; |
| if (uv.inst.tag == BOT) { |
| restvars.append(uv.qtype); |
| restundet.append(uv); |
| insttypes.append(uv.qtype); |
| undettypes.append(uv); |
| uv.inst = null; |
| } else { |
| insttypes.append(uv.inst); |
| undettypes.append(uv.inst); |
| } |
| } |
| checkWithinBounds(tvars, undettypes.toList(), warn); |
| |
| mt = (MethodType)types.subst(mt, tvars, insttypes.toList()); |
| |
| if (!restvars.isEmpty()) { |
| // if there are uninstantiated variables, |
| // quantify result type with them |
| final List<Type> inferredTypes = insttypes.toList(); |
| final List<Type> all_tvars = tvars; //this is the wrong tvars |
| final MethodType mt2 = new MethodType(mt.argtypes, null, mt.thrown, syms.methodClass); |
| mt2.restype = new ForAll(restvars.toList(), mt.restype) { |
| @Override |
| public List<Type> getConstraints(TypeVar tv, ConstraintKind ck) { |
| for (Type t : restundet.toList()) { |
| UndetVar uv = (UndetVar)t; |
| if (uv.qtype == tv) { |
| switch (ck) { |
| case EXTENDS: return uv.hibounds.appendList(types.subst(types.getBounds(tv), all_tvars, inferredTypes)); |
| case SUPER: return uv.lobounds; |
| case EQUAL: return uv.inst != null ? List.of(uv.inst) : List.<Type>nil(); |
| } |
| } |
| } |
| return List.nil(); |
| } |
| |
| @Override |
| public Type inst(List<Type> inferred, Types types) throws NoInstanceException { |
| List<Type> formals = types.subst(mt2.argtypes, tvars, inferred); |
| if (!rs.argumentsAcceptable(capturedArgs, formals, |
| allowBoxing, useVarargs, warn)) { |
| // inferred method is not applicable |
| throw invalidInstanceException.setMessage("inferred.do.not.conform.to.params", formals, argtypes); |
| } |
| // check that inferred bounds conform to their bounds |
| checkWithinBounds(all_tvars, |
| types.subst(inferredTypes, tvars, inferred), warn); |
| if (useVarargs) { |
| chk.checkVararg(env.tree.pos(), formals, msym, env); |
| } |
| return super.inst(inferred, types); |
| }}; |
| return mt2; |
| } |
| else if (!rs.argumentsAcceptable(capturedArgs, mt.getParameterTypes(), allowBoxing, useVarargs, warn)) { |
| // inferred method is not applicable |
| throw invalidInstanceException.setMessage("inferred.do.not.conform.to.params", mt.getParameterTypes(), argtypes); |
| } |
| else { |
| // return instantiated version of method type |
| return mt; |
| } |
| } |
| //where |
| |
| /** Try to instantiate argument type `that' to given type `to'. |
| * If this fails, try to insantiate `that' to `to' where |
| * every occurrence of a type variable in `tvars' is replaced |
| * by an unknown type. |
| */ |
| private Type instantiateArg(ForAll that, |
| Type to, |
| List<Type> tvars, |
| Warner warn) throws InferenceException { |
| List<Type> targs; |
| try { |
| return instantiateExpr(that, to, warn); |
| } catch (NoInstanceException ex) { |
| Type to1 = to; |
| for (List<Type> l = tvars; l.nonEmpty(); l = l.tail) |
| to1 = types.subst(to1, List.of(l.head), List.of(syms.unknownType)); |
| return instantiateExpr(that, to1, warn); |
| } |
| } |
| |
| /** check that type parameters are within their bounds. |
| */ |
| void checkWithinBounds(List<Type> tvars, |
| List<Type> arguments, |
| Warner warn) |
| throws InvalidInstanceException { |
| for (List<Type> tvs = tvars, args = arguments; |
| tvs.nonEmpty(); |
| tvs = tvs.tail, args = args.tail) { |
| if (args.head instanceof UndetVar) continue; |
| List<Type> bounds = types.subst(types.getBounds((TypeVar)tvs.head), tvars, arguments); |
| if (!types.isSubtypeUnchecked(args.head, bounds, warn)) |
| throw invalidInstanceException |
| .setMessage("inferred.do.not.conform.to.bounds", |
| args.head, bounds); |
| } |
| } |
| |
| /** |
| * Compute a synthetic method type corresponding to the requested polymorphic |
| * method signature. If no explicit return type is supplied, a provisional |
| * return type is computed (just Object in case of non-transitional 292) |
| */ |
| Type instantiatePolymorphicSignatureInstance(Env<AttrContext> env, Type site, |
| Name name, |
| MethodSymbol spMethod, // sig. poly. method or null if none |
| List<Type> argtypes, |
| List<Type> typeargtypes) { |
| final Type restype; |
| if (rs.allowTransitionalJSR292 && typeargtypes.nonEmpty()) { |
| restype = typeargtypes.head; |
| } else { |
| //The return type for a polymorphic signature call is computed from |
| //the enclosing tree E, as follows: if E is a cast, then use the |
| //target type of the cast expression as a return type; if E is an |
| //expression statement, the return type is 'void' - otherwise the |
| //return type is simply 'Object'. |
| switch (env.outer.tree.getTag()) { |
| case JCTree.TYPECAST: |
| restype = ((JCTypeCast)env.outer.tree).clazz.type; break; |
| case JCTree.EXEC: |
| restype = syms.voidType; break; |
| default: |
| restype = syms.objectType; |
| } |
| } |
| |
| List<Type> paramtypes = Type.map(argtypes, implicitArgType); |
| List<Type> exType = spMethod != null ? |
| spMethod.getThrownTypes() : |
| List.of(syms.throwableType); // make it throw all exceptions |
| |
| MethodType mtype = new MethodType(paramtypes, |
| restype, |
| exType, |
| syms.methodClass); |
| return mtype; |
| } |
| //where |
| Mapping implicitArgType = new Mapping ("implicitArgType") { |
| public Type apply(Type t) { |
| t = types.erasure(t); |
| if (t.tag == BOT) |
| // nulls type as the marker type Null (which has no instances) |
| // infer as java.lang.Void for now |
| t = types.boxedClass(syms.voidType).type; |
| return t; |
| } |
| }; |
| } |
