author | mcimadamore |
Wed, 09 Apr 2008 13:41:45 +0100 | |
changeset 508 | 118e500e2e50 |
parent 324 | c4029ac973a2 |
child 735 | 372aa565a221 |
permissions | -rw-r--r-- |
10 | 1 |
/* |
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* Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Sun designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Sun in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
|
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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* CA 95054 USA or visit www.sun.com if you need additional information or |
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* have any questions. |
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*/ |
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package com.sun.tools.javac.comp; |
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import com.sun.tools.javac.util.*; |
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import com.sun.tools.javac.util.List; |
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import com.sun.tools.javac.code.*; |
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import com.sun.tools.javac.code.Type.*; |
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import static com.sun.tools.javac.code.Flags.*; |
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import static com.sun.tools.javac.code.Kinds.*; |
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import static com.sun.tools.javac.code.TypeTags.*; |
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/** Helper class for type parameter inference, used by the attribution phase. |
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* |
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* <p><b>This is NOT part of any API supported by Sun Microsystems. If |
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* you write code that depends on this, you do so at your own risk. |
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* This code and its internal interfaces are subject to change or |
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* deletion without notice.</b> |
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*/ |
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public class Infer { |
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protected static final Context.Key<Infer> inferKey = |
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new Context.Key<Infer>(); |
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47 |
||
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/** A value for prototypes that admit any type, including polymorphic ones. */ |
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public static final Type anyPoly = new Type(NONE, null); |
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Symtab syms; |
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Types types; |
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public static Infer instance(Context context) { |
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Infer instance = context.get(inferKey); |
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if (instance == null) |
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instance = new Infer(context); |
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return instance; |
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} |
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protected Infer(Context context) { |
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context.put(inferKey, this); |
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syms = Symtab.instance(context); |
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types = Types.instance(context); |
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} |
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||
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public static class NoInstanceException extends RuntimeException { |
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private static final long serialVersionUID = 0; |
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boolean isAmbiguous; // exist several incomparable best instances? |
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JCDiagnostic diagnostic; |
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||
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NoInstanceException(boolean isAmbiguous) { |
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this.diagnostic = null; |
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this.isAmbiguous = isAmbiguous; |
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} |
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NoInstanceException setMessage(String key) { |
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this.diagnostic = JCDiagnostic.fragment(key); |
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return this; |
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} |
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NoInstanceException setMessage(String key, Object arg1) { |
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this.diagnostic = JCDiagnostic.fragment(key, arg1); |
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return this; |
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} |
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NoInstanceException setMessage(String key, Object arg1, Object arg2) { |
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this.diagnostic = JCDiagnostic.fragment(key, arg1, arg2); |
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return this; |
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} |
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NoInstanceException setMessage(String key, Object arg1, Object arg2, Object arg3) { |
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this.diagnostic = JCDiagnostic.fragment(key, arg1, arg2, arg3); |
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return this; |
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} |
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public JCDiagnostic getDiagnostic() { |
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return diagnostic; |
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} |
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} |
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private final NoInstanceException ambiguousNoInstanceException = |
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new NoInstanceException(true); |
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private final NoInstanceException unambiguousNoInstanceException = |
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new NoInstanceException(false); |
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/*************************************************************************** |
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* Auxiliary type values and classes |
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***************************************************************************/ |
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/** A mapping that turns type variables into undetermined type variables. |
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*/ |
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Mapping fromTypeVarFun = new Mapping("fromTypeVarFun") { |
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public Type apply(Type t) { |
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if (t.tag == TYPEVAR) return new UndetVar(t); |
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else return t.map(this); |
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} |
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}; |
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/** A mapping that returns its type argument with every UndetVar replaced |
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* by its `inst' field. Throws a NoInstanceException |
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* if this not possible because an `inst' field is null. |
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*/ |
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Mapping getInstFun = new Mapping("getInstFun") { |
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public Type apply(Type t) { |
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switch (t.tag) { |
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case UNKNOWN: |
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throw ambiguousNoInstanceException |
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.setMessage("undetermined.type"); |
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case UNDETVAR: |
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UndetVar that = (UndetVar) t; |
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if (that.inst == null) |
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throw ambiguousNoInstanceException |
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.setMessage("type.variable.has.undetermined.type", |
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that.qtype); |
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return apply(that.inst); |
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default: |
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return t.map(this); |
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} |
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} |
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}; |
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/*************************************************************************** |
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* Mini/Maximization of UndetVars |
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***************************************************************************/ |
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/** Instantiate undetermined type variable to its minimal upper bound. |
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* Throw a NoInstanceException if this not possible. |
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*/ |
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void maximizeInst(UndetVar that, Warner warn) throws NoInstanceException { |
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if (that.inst == null) { |
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if (that.hibounds.isEmpty()) |
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that.inst = syms.objectType; |
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else if (that.hibounds.tail.isEmpty()) |
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that.inst = that.hibounds.head; |
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else { |
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for (List<Type> bs = that.hibounds; |
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bs.nonEmpty() && that.inst == null; |
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bs = bs.tail) { |
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// System.out.println("hibounds = " + that.hibounds);//DEBUG |
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if (isSubClass(bs.head, that.hibounds)) |
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that.inst = types.fromUnknownFun.apply(bs.head); |
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} |
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if (that.inst == null) { |
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int classCount = 0, interfaceCount = 0; |
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for (Type t : that.hibounds) { |
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if (t.tag == CLASS) { |
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if (t.isInterface()) |
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interfaceCount++; |
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else |
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classCount++; |
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} |
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} |
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if ((that.hibounds.size() == classCount + interfaceCount) && classCount == 1) |
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that.inst = types.makeCompoundType(that.hibounds); |
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} |
10 | 173 |
if (that.inst == null || !types.isSubtypeUnchecked(that.inst, that.hibounds, warn)) |
174 |
throw ambiguousNoInstanceException |
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.setMessage("no.unique.maximal.instance.exists", |
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that.qtype, that.hibounds); |
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} |
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} |
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} |
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//where |
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private boolean isSubClass(Type t, final List<Type> ts) { |
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t = t.baseType(); |
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183 |
if (t.tag == TYPEVAR) { |
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List<Type> bounds = types.getBounds((TypeVar)t); |
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for (Type s : ts) { |
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if (!types.isSameType(t, s.baseType())) { |
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for (Type bound : bounds) { |
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if (!isSubClass(bound, List.of(s.baseType()))) |
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return false; |
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} |
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} |
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} |
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} else { |
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for (Type s : ts) { |
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if (!t.tsym.isSubClass(s.baseType().tsym, types)) |
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return false; |
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} |
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198 |
} |
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return true; |
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} |
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201 |
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202 |
/** Instaniate undetermined type variable to the lub of all its lower bounds. |
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203 |
* Throw a NoInstanceException if this not possible. |
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*/ |
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205 |
void minimizeInst(UndetVar that, Warner warn) throws NoInstanceException { |
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206 |
if (that.inst == null) { |
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207 |
if (that.lobounds.isEmpty()) |
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that.inst = syms.botType; |
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209 |
else if (that.lobounds.tail.isEmpty()) |
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210 |
that.inst = that.lobounds.head.isPrimitive() ? syms.errType : that.lobounds.head; |
10 | 211 |
else { |
212 |
that.inst = types.lub(that.lobounds); |
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} |
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214 |
if (that.inst == null || that.inst == syms.errType) |
10 | 215 |
throw ambiguousNoInstanceException |
216 |
.setMessage("no.unique.minimal.instance.exists", |
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217 |
that.qtype, that.lobounds); |
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218 |
// VGJ: sort of inlined maximizeInst() below. Adding |
|
219 |
// bounds can cause lobounds that are above hibounds. |
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220 |
if (that.hibounds.isEmpty()) |
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221 |
return; |
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222 |
Type hb = null; |
|
223 |
if (that.hibounds.tail.isEmpty()) |
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224 |
hb = that.hibounds.head; |
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225 |
else for (List<Type> bs = that.hibounds; |
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226 |
bs.nonEmpty() && hb == null; |
|
227 |
bs = bs.tail) { |
|
228 |
if (isSubClass(bs.head, that.hibounds)) |
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229 |
hb = types.fromUnknownFun.apply(bs.head); |
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230 |
} |
|
231 |
if (hb == null || |
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232 |
!types.isSubtypeUnchecked(hb, that.hibounds, warn) || |
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233 |
!types.isSubtypeUnchecked(that.inst, hb, warn)) |
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234 |
throw ambiguousNoInstanceException; |
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235 |
} |
|
236 |
} |
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237 |
||
238 |
/*************************************************************************** |
|
239 |
* Exported Methods |
|
240 |
***************************************************************************/ |
|
241 |
||
242 |
/** Try to instantiate expression type `that' to given type `to'. |
|
243 |
* If a maximal instantiation exists which makes this type |
|
244 |
* a subtype of type `to', return the instantiated type. |
|
245 |
* If no instantiation exists, or if several incomparable |
|
246 |
* best instantiations exist throw a NoInstanceException. |
|
247 |
*/ |
|
248 |
public Type instantiateExpr(ForAll that, |
|
249 |
Type to, |
|
250 |
Warner warn) throws NoInstanceException { |
|
251 |
List<Type> undetvars = Type.map(that.tvars, fromTypeVarFun); |
|
252 |
for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail) { |
|
253 |
UndetVar v = (UndetVar) l.head; |
|
254 |
ListBuffer<Type> hibounds = new ListBuffer<Type>(); |
|
255 |
for (List<Type> l1 = types.getBounds((TypeVar) v.qtype); l1.nonEmpty(); l1 = l1.tail) { |
|
256 |
if (!l1.head.containsSome(that.tvars)) { |
|
257 |
hibounds.append(l1.head); |
|
258 |
} |
|
259 |
} |
|
260 |
v.hibounds = hibounds.toList(); |
|
261 |
} |
|
262 |
Type qtype1 = types.subst(that.qtype, that.tvars, undetvars); |
|
263 |
if (!types.isSubtype(qtype1, to)) { |
|
264 |
throw unambiguousNoInstanceException |
|
265 |
.setMessage("no.conforming.instance.exists", |
|
266 |
that.tvars, that.qtype, to); |
|
267 |
} |
|
268 |
for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail) |
|
269 |
maximizeInst((UndetVar) l.head, warn); |
|
270 |
// System.out.println(" = " + qtype1.map(getInstFun));//DEBUG |
|
271 |
||
272 |
// check bounds |
|
273 |
List<Type> targs = Type.map(undetvars, getInstFun); |
|
274 |
targs = types.subst(targs, that.tvars, targs); |
|
275 |
checkWithinBounds(that.tvars, targs, warn); |
|
276 |
||
277 |
return getInstFun.apply(qtype1); |
|
278 |
} |
|
279 |
||
280 |
/** Instantiate method type `mt' by finding instantiations of |
|
281 |
* `tvars' so that method can be applied to `argtypes'. |
|
282 |
*/ |
|
283 |
public Type instantiateMethod(List<Type> tvars, |
|
284 |
MethodType mt, |
|
285 |
List<Type> argtypes, |
|
286 |
boolean allowBoxing, |
|
287 |
boolean useVarargs, |
|
288 |
Warner warn) throws NoInstanceException { |
|
289 |
//-System.err.println("instantiateMethod(" + tvars + ", " + mt + ", " + argtypes + ")"); //DEBUG |
|
290 |
List<Type> undetvars = Type.map(tvars, fromTypeVarFun); |
|
291 |
List<Type> formals = mt.argtypes; |
|
292 |
||
293 |
// instantiate all polymorphic argument types and |
|
294 |
// set up lower bounds constraints for undetvars |
|
295 |
Type varargsFormal = useVarargs ? formals.last() : null; |
|
296 |
while (argtypes.nonEmpty() && formals.head != varargsFormal) { |
|
297 |
Type ft = formals.head; |
|
298 |
Type at = argtypes.head.baseType(); |
|
299 |
if (at.tag == FORALL) |
|
300 |
at = instantiateArg((ForAll) at, ft, tvars, warn); |
|
301 |
Type sft = types.subst(ft, tvars, undetvars); |
|
302 |
boolean works = allowBoxing |
|
303 |
? types.isConvertible(at, sft, warn) |
|
304 |
: types.isSubtypeUnchecked(at, sft, warn); |
|
305 |
if (!works) { |
|
306 |
throw unambiguousNoInstanceException |
|
307 |
.setMessage("no.conforming.assignment.exists", |
|
308 |
tvars, at, ft); |
|
309 |
} |
|
310 |
formals = formals.tail; |
|
311 |
argtypes = argtypes.tail; |
|
312 |
} |
|
313 |
if (formals.head != varargsFormal || // not enough args |
|
314 |
!useVarargs && argtypes.nonEmpty()) { // too many args |
|
315 |
// argument lists differ in length |
|
316 |
throw unambiguousNoInstanceException |
|
317 |
.setMessage("arg.length.mismatch"); |
|
318 |
} |
|
319 |
||
320 |
// for varargs arguments as well |
|
321 |
if (useVarargs) { |
|
322 |
Type elt = types.elemtype(varargsFormal); |
|
323 |
Type sft = types.subst(elt, tvars, undetvars); |
|
324 |
while (argtypes.nonEmpty()) { |
|
325 |
Type ft = sft; |
|
326 |
Type at = argtypes.head.baseType(); |
|
327 |
if (at.tag == FORALL) |
|
328 |
at = instantiateArg((ForAll) at, ft, tvars, warn); |
|
329 |
boolean works = types.isConvertible(at, sft, warn); |
|
330 |
if (!works) { |
|
331 |
throw unambiguousNoInstanceException |
|
332 |
.setMessage("no.conforming.assignment.exists", |
|
333 |
tvars, at, ft); |
|
334 |
} |
|
335 |
argtypes = argtypes.tail; |
|
336 |
} |
|
337 |
} |
|
338 |
||
339 |
// minimize as yet undetermined type variables |
|
340 |
for (Type t : undetvars) |
|
341 |
minimizeInst((UndetVar) t, warn); |
|
342 |
||
343 |
/** Type variables instantiated to bottom */ |
|
344 |
ListBuffer<Type> restvars = new ListBuffer<Type>(); |
|
345 |
||
346 |
/** Instantiated types or TypeVars if under-constrained */ |
|
347 |
ListBuffer<Type> insttypes = new ListBuffer<Type>(); |
|
348 |
||
349 |
/** Instantiated types or UndetVars if under-constrained */ |
|
350 |
ListBuffer<Type> undettypes = new ListBuffer<Type>(); |
|
351 |
||
352 |
for (Type t : undetvars) { |
|
353 |
UndetVar uv = (UndetVar)t; |
|
354 |
if (uv.inst.tag == BOT) { |
|
355 |
restvars.append(uv.qtype); |
|
356 |
insttypes.append(uv.qtype); |
|
357 |
undettypes.append(uv); |
|
358 |
uv.inst = null; |
|
359 |
} else { |
|
360 |
insttypes.append(uv.inst); |
|
361 |
undettypes.append(uv.inst); |
|
362 |
} |
|
363 |
} |
|
364 |
checkWithinBounds(tvars, undettypes.toList(), warn); |
|
365 |
||
366 |
if (!restvars.isEmpty()) { |
|
367 |
// if there are uninstantiated variables, |
|
368 |
// quantify result type with them |
|
369 |
mt = new MethodType(mt.argtypes, |
|
370 |
new ForAll(restvars.toList(), mt.restype), |
|
371 |
mt.thrown, syms.methodClass); |
|
372 |
} |
|
373 |
||
374 |
// return instantiated version of method type |
|
375 |
return types.subst(mt, tvars, insttypes.toList()); |
|
376 |
} |
|
377 |
//where |
|
378 |
||
379 |
/** Try to instantiate argument type `that' to given type `to'. |
|
380 |
* If this fails, try to insantiate `that' to `to' where |
|
381 |
* every occurrence of a type variable in `tvars' is replaced |
|
382 |
* by an unknown type. |
|
383 |
*/ |
|
384 |
private Type instantiateArg(ForAll that, |
|
385 |
Type to, |
|
386 |
List<Type> tvars, |
|
387 |
Warner warn) throws NoInstanceException { |
|
388 |
List<Type> targs; |
|
389 |
try { |
|
390 |
return instantiateExpr(that, to, warn); |
|
391 |
} catch (NoInstanceException ex) { |
|
392 |
Type to1 = to; |
|
393 |
for (List<Type> l = tvars; l.nonEmpty(); l = l.tail) |
|
394 |
to1 = types.subst(to1, List.of(l.head), List.of(syms.unknownType)); |
|
395 |
return instantiateExpr(that, to1, warn); |
|
396 |
} |
|
397 |
} |
|
398 |
||
399 |
/** check that type parameters are within their bounds. |
|
400 |
*/ |
|
401 |
private void checkWithinBounds(List<Type> tvars, |
|
402 |
List<Type> arguments, |
|
403 |
Warner warn) |
|
404 |
throws NoInstanceException { |
|
405 |
for (List<Type> tvs = tvars, args = arguments; |
|
406 |
tvs.nonEmpty(); |
|
407 |
tvs = tvs.tail, args = args.tail) { |
|
408 |
if (args.head instanceof UndetVar) continue; |
|
409 |
List<Type> bounds = types.subst(types.getBounds((TypeVar)tvs.head), tvars, arguments); |
|
410 |
if (!types.isSubtypeUnchecked(args.head, bounds, warn)) |
|
411 |
throw unambiguousNoInstanceException |
|
412 |
.setMessage("inferred.do.not.conform.to.bounds", |
|
413 |
arguments, tvars); |
|
414 |
} |
|
415 |
} |
|
416 |
} |