/*******************************************************************************
* Copyright (c) 2013, 2014 GK Software AG.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Stephan Herrmann - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.lookup;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.eclipse.jdt.internal.compiler.ast.Wildcard;
/**
* Implementation of 18.1.3 in JLS8.
* This class is also responsible for incorporation as defined in 18.3.
*/
class BoundSet {
static final BoundSet TRUE = new BoundSet(); // empty set of bounds
static final BoundSet FALSE = new BoundSet(); // pseudo bounds
/**
* For a given inference variable this structure holds all type bounds
* with a relation in { SUPERTYPE, SAME, SUBTYPE }.
* These are internally stored in three sets, one for each of the relations.
*/
private class ThreeSets {
Set<TypeBound> superBounds;
Set<TypeBound> sameBounds;
Set<TypeBound> subBounds;
TypeBinding instantiation;
Map<InferenceVariable,TypeBound> inverseBounds; // from right inference variable to bound
public ThreeSets() {
// empty, the sets are lazily initialized
}
/** Add a type bound to the appropriate set. */
public void addBound(TypeBound bound) {
switch (bound.relation) {
case ReductionResult.SUPERTYPE:
if (this.superBounds == null) this.superBounds = new HashSet<TypeBound>();
this.superBounds.add(bound);
break;
case ReductionResult.SAME:
if (this.sameBounds == null) this.sameBounds = new HashSet<TypeBound>();
this.sameBounds.add(bound);
break;
case ReductionResult.SUBTYPE:
if (this.subBounds == null) this.subBounds = new HashSet<TypeBound>();
this.subBounds.add(bound);
break;
default:
throw new IllegalArgumentException("Unexpected bound relation in : " + bound); //$NON-NLS-1$
}
}
// pre: this.superBounds != null
public TypeBinding[] lowerBounds(boolean onlyProper, InferenceVariable variable) {
TypeBinding[] boundTypes = new TypeBinding[this.superBounds.size()];
Iterator<TypeBound> it = this.superBounds.iterator();
long nullHints = variable.nullHints;
int i = 0;
while(it.hasNext()) {
TypeBound current = it.next();
TypeBinding boundType = current.right;
if (!onlyProper || boundType.isProperType(true)) {
boundTypes[i++] = boundType;
nullHints |= current.nullHints;
}
}
if (i == 0)
return Binding.NO_TYPES;
if (i < boundTypes.length)
System.arraycopy(boundTypes, 0, boundTypes=new TypeBinding[i], 0, i);
useNullHints(nullHints, boundTypes, variable.environment);
InferenceContext18.sortTypes(boundTypes);
return boundTypes;
}
// pre: this.subBounds != null
public TypeBinding[] upperBounds(boolean onlyProper, InferenceVariable variable) {
ReferenceBinding[] rights = new ReferenceBinding[this.subBounds.size()];
TypeBinding simpleUpper = null;
Iterator<TypeBound> it = this.subBounds.iterator();
long nullHints = variable.nullHints;
int i = 0;
while(it.hasNext()) {
TypeBinding right=it.next().right;
if (!onlyProper || right.isProperType(true)) {
if (right instanceof ReferenceBinding) {
rights[i++] = (ReferenceBinding) right;
nullHints |= right.tagBits & TagBits.AnnotationNullMASK;
} else {
if (simpleUpper != null)
return Binding.NO_TYPES; // shouldn't
simpleUpper = right;
}
}
}
if (i == 0)
return Binding.NO_TYPES;
if (i == 1 && simpleUpper != null)
return new TypeBinding[] { simpleUpper }; // no nullHints since not a reference type
if (i < rights.length)
System.arraycopy(rights, 0, rights=new ReferenceBinding[i], 0, i);
useNullHints(nullHints, rights, variable.environment);
InferenceContext18.sortTypes(rights);
return rights;
}
public boolean hasDependency(InferenceVariable beta) {
if (this.superBounds != null && hasDependency(this.superBounds, beta))
return true;
if (this.sameBounds != null && hasDependency(this.sameBounds, beta))
return true;
if (this.subBounds != null && hasDependency(this.subBounds, beta))
return true;
if (this.inverseBounds != null) {
if (this.inverseBounds.containsKey(beta)) {
// TODO: not yet observed in tests
return true;
}
}
return false;
}
private boolean hasDependency(Set<TypeBound> someBounds, InferenceVariable var) {
Iterator<TypeBound> bIt = someBounds.iterator();
while (bIt.hasNext()) {
TypeBound bound = bIt.next();
if (bound.right == var || bound.right.mentionsAny(new TypeBinding[] {var}, -1)) //$IDENTITY-COMPARISON$ InferenceVariable
return true;
}
return false;
}
/** Total number of type bounds in this container. */
public int size() {
int size = 0;
if (this.superBounds != null)
size += this.superBounds.size();
if (this.sameBounds != null)
size += this.sameBounds.size();
if (this.subBounds != null)
size += this.subBounds.size();
return size;
}
public int flattenInto(TypeBound[] collected, int idx) {
if (this.superBounds != null) {
int len = this.superBounds.size();
System.arraycopy(this.superBounds.toArray(), 0, collected, idx, len);
idx += len;
}
if (this.sameBounds != null) {
int len = this.sameBounds.size();
System.arraycopy(this.sameBounds.toArray(), 0, collected, idx, len);
idx += len;
}
if (this.subBounds != null) {
int len = this.subBounds.size();
System.arraycopy(this.subBounds.toArray(), 0, collected, idx, len);
idx += len;
}
return idx;
}
public ThreeSets copy() {
ThreeSets copy = new ThreeSets();
if (this.superBounds != null)
copy.superBounds = new HashSet<TypeBound>(this.superBounds);
if (this.sameBounds != null)
copy.sameBounds = new HashSet<TypeBound>(this.sameBounds);
if (this.subBounds != null)
copy.subBounds = new HashSet<TypeBound>(this.subBounds);
copy.instantiation = this.instantiation;
return copy;
}
public TypeBinding findSingleWrapperType() {
TypeBinding wrapperBound = null;
if (this.subBounds != null) {
Iterator<TypeBound> it = this.subBounds.iterator();
while(it.hasNext()) {
TypeBinding boundType = it.next().right;
if ((boundType).isProperType(true)) {
switch (boundType.id) {
case TypeIds.T_JavaLangByte:
case TypeIds.T_JavaLangShort:
case TypeIds.T_JavaLangCharacter:
case TypeIds.T_JavaLangInteger:
case TypeIds.T_JavaLangLong:
case TypeIds.T_JavaLangFloat:
case TypeIds.T_JavaLangDouble:
case TypeIds.T_JavaLangBoolean:
if (wrapperBound != null)
return null;
wrapperBound = boundType;
}
}
}
}
if (this.superBounds != null) {
Iterator<TypeBound> it = this.superBounds.iterator();
while(it.hasNext()) {
TypeBinding boundType = it.next().right;
if ((boundType).isProperType(true)) {
switch (boundType.id) {
case TypeIds.T_JavaLangByte:
case TypeIds.T_JavaLangShort:
case TypeIds.T_JavaLangCharacter:
case TypeIds.T_JavaLangInteger:
case TypeIds.T_JavaLangLong:
case TypeIds.T_JavaLangFloat:
case TypeIds.T_JavaLangDouble:
case TypeIds.T_JavaLangBoolean:
if (wrapperBound != null)
return null;
wrapperBound = boundType;
}
}
}
}
return wrapperBound;
}
/**
* Not per JLS: enhance the given type bounds using the nullHints, if useful.
* Will only ever be effective if any TypeBounds carry nullHints,
* which only happens if any TypeBindings have non-zero (tagBits & AnnotationNullMASK),
* which only happens if null annotations are enabled in the first place.
*/
private void useNullHints(long nullHints, TypeBinding[] boundTypes, LookupEnvironment environment) {
if (nullHints == TagBits.AnnotationNullMASK) {
// on contradiction remove null type annotations
for (int i = 0; i < boundTypes.length; i++)
boundTypes[i] = boundTypes[i].unannotated();
} else {
AnnotationBinding[] annot = environment.nullAnnotationsFromTagBits(nullHints);
if (annot != null) {
// only get here if exactly one of @NonNull or @Nullable was hinted; now apply this hint:
for (int i = 0; i < boundTypes.length; i++)
boundTypes[i] = environment.createAnnotatedType(boundTypes[i], annot);
}
}
}
TypeBinding combineAndUseNullHints(TypeBinding type, long nullHints, LookupEnvironment environment) {
// precondition: only called when null annotations are enabled.
// TODO(optimization): may want to collect all nullHints in the ThreeSets, which, however,
// needs a reference TypeBound->ThreeSets to propagate the bits as they are added.
if (this.sameBounds != null) {
Iterator<TypeBound> it = this.sameBounds.iterator();
while(it.hasNext())
nullHints |= it.next().nullHints;
}
if (this.superBounds != null) {
Iterator<TypeBound> it = this.superBounds.iterator();
while(it.hasNext())
nullHints |= it.next().nullHints;
}
if (this.subBounds != null) {
Iterator<TypeBound> it = this.subBounds.iterator();
while(it.hasNext())
nullHints |= it.next().nullHints;
}
if (nullHints == TagBits.AnnotationNullMASK) // on contradiction remove null type annotations
return type.unannotated();
AnnotationBinding[] annot = environment.nullAnnotationsFromTagBits(nullHints);
if (annot != null)
// only get here if exactly one of @NonNull or @Nullable was hinted; now apply this hint:
return environment.createAnnotatedType(type, annot);
return type;
}
public void setInstantiation(TypeBinding type, InferenceVariable variable, LookupEnvironment environment) {
if (environment.globalOptions.isAnnotationBasedNullAnalysisEnabled) {
long oldBits = ((this.instantiation != null) ? this.instantiation.tagBits : variable.tagBits)
& TagBits.AnnotationNullMASK;
long requestedBits = type.tagBits & TagBits.AnnotationNullMASK;
long newBits = (oldBits == TagBits.AnnotationNonNull) ? oldBits : requestedBits; // need to preserve @NonNull
if (this.instantiation != null && oldBits == newBits) {
return; // no update needed
}
if (requestedBits != newBits) {
// adjust 'type' to fit the newBits
AnnotationBinding[] annot = environment.nullAnnotationsFromTagBits(newBits);
if (annot != null)
type = environment.createAnnotatedType(type.unannotated(), annot);
}
}
this.instantiation = type;
}
}
// main storage of type bounds:
HashMap<InferenceVariable, ThreeSets> boundsPerVariable = new HashMap<InferenceVariable, ThreeSets>();
/**
* 18.1.3 bullet 4: G<α1, ..., αn> = capture(G<A1, ..., An>)
* On both sides we only enter types with nonnull arguments.
*/
HashMap<ParameterizedTypeBinding,ParameterizedTypeBinding> captures = new HashMap<ParameterizedTypeBinding, ParameterizedTypeBinding>();
/** 18.1.3 bullet 5: throws α */
Set<InferenceVariable> inThrows = new HashSet<InferenceVariable>();
// avoid attempts to incorporate the same pair of type bounds more than once:
Set<TypeBound> incorporatedBounds = new HashSet<TypeBound>();
public BoundSet() {}
// pre: typeParameters != null, variables[i].typeParameter == typeParameters[i]
public void addBoundsFromTypeParameters(InferenceContext18 context, TypeVariableBinding[] typeParameters, InferenceVariable[] variables) {
int length = typeParameters.length;
for (int i = 0; i < length; i++) {
TypeVariableBinding typeParameter = typeParameters[i];
InferenceVariable variable = variables[i];
TypeBound[] someBounds = typeParameter.getTypeBounds(variable, new InferenceSubstitution(context.environment, context.inferenceVariables));
boolean hasProperBound = false;
if (someBounds.length > 0)
hasProperBound = addBounds(someBounds, context.environment);
if (!hasProperBound)
addBound(new TypeBound(variable, context.object, ReductionResult.SUBTYPE), context.environment);
}
}
/** Answer a flat representation of this BoundSet. */
public TypeBound[] flatten() {
int size = 0;
Iterator<ThreeSets> outerIt = this.boundsPerVariable.values().iterator();
while (outerIt.hasNext())
size += outerIt.next().size();
TypeBound[] collected = new TypeBound[size];
if (size == 0) return collected;
outerIt = this.boundsPerVariable.values().iterator();
int idx = 0;
while (outerIt.hasNext())
idx = outerIt.next().flattenInto(collected, idx);
return collected;
}
/**
* For resolution we work with a copy of the bound set, to enable retrying.
* @return the new bound set.
*/
public BoundSet copy() {
BoundSet copy = new BoundSet();
Iterator<Entry<InferenceVariable, ThreeSets>> setsIterator = this.boundsPerVariable.entrySet().iterator();
while (setsIterator.hasNext()) {
Entry<InferenceVariable, ThreeSets> entry = setsIterator.next();
copy.boundsPerVariable.put(entry.getKey(), entry.getValue().copy());
}
copy.inThrows.addAll(this.inThrows);
copy.captures.putAll(this.captures);
return copy;
}
public void addBound(TypeBound bound, LookupEnvironment environment) {
ThreeSets three = this.boundsPerVariable.get(bound.left);
if (three == null)
this.boundsPerVariable.put(bound.left, (three = new ThreeSets()));
three.addBound(bound);
// check if this makes the inference variable instantiated:
TypeBinding typeBinding = bound.right;
if (bound.relation == ReductionResult.SAME && typeBinding.isProperType(true))
three.setInstantiation(typeBinding, bound.left, environment);
if (bound.right instanceof InferenceVariable) {
// for a dependency between two IVs make a note about the inverse bound.
// this should be needed to determine IV dependencies independent of direction.
// TODO: so far no test could be identified which actually needs it ...
InferenceVariable rightIV = (InferenceVariable) bound.right;
three = this.boundsPerVariable.get(rightIV);
if (three == null)
this.boundsPerVariable.put(rightIV, (three = new ThreeSets()));
if (three.inverseBounds == null)
three.inverseBounds = new HashMap<InferenceVariable,TypeBound>();
three.inverseBounds.put(rightIV, bound);
}
}
private boolean addBounds(TypeBound[] newBounds, LookupEnvironment environment) {
boolean hasProperBound = false;
for (int i = 0; i < newBounds.length; i++) {
addBound(newBounds[i], environment);
hasProperBound |= newBounds[i].isBound();
}
return hasProperBound;
}
public boolean isInstantiated(InferenceVariable inferenceVariable) {
ThreeSets three = this.boundsPerVariable.get(inferenceVariable);
if (three != null)
return three.instantiation != null;
return false;
}
public TypeBinding getInstantiation(InferenceVariable inferenceVariable, LookupEnvironment environment) {
ThreeSets three = this.boundsPerVariable.get(inferenceVariable);
if (three != null) {
TypeBinding instantiation = three.instantiation;
if (environment != null && environment.globalOptions.isAnnotationBasedNullAnalysisEnabled
&& instantiation != null && (instantiation.tagBits & TagBits.AnnotationNullMASK) == 0)
return three.combineAndUseNullHints(instantiation, inferenceVariable.nullHints, environment);
return instantiation;
}
return null;
}
public int numUninstantiatedVariables(InferenceVariable[] variables) {
int num = 0;
for (int i = 0; i < variables.length; i++) {
if (!isInstantiated(variables[i]))
num++;
}
return num;
}
/**
* <b>JLS 18.3:</b> Try to infer new constraints from pairs of existing type bounds.
* Each new constraint is first reduced and checked for TRUE or FALSE, which will
* abort the processing.
* @param context the context that manages our inference variables
* @return false if any constraint resolved to false, true otherwise
* @throws InferenceFailureException a compile error has been detected during inference
*/
boolean incorporate(InferenceContext18 context) throws InferenceFailureException {
boolean hasUpdate;
do {
hasUpdate = false;
// using a flattened copy also allows us to insert more bounds during the process
// without disturbing the current round of incorporation:
TypeBound[] bounds = flatten();
int boundsCount = bounds.length;
if (boundsCount < 2)
return true;
// check each pair:
for (int i = 0; i < boundsCount; i++) {
TypeBound boundI = bounds[i];
for (int j = i+1; j < boundsCount; j++) {
TypeBound boundJ = bounds[j];
if (this.incorporatedBounds.contains(boundI) && this.incorporatedBounds.contains(boundJ))
continue;
ConstraintTypeFormula newConstraint = null;
switch (boundI.relation) {
case ReductionResult.SAME:
switch (boundJ.relation) {
case ReductionResult.SAME:
newConstraint = combineSameSame(boundI, boundJ);
break;
case ReductionResult.SUBTYPE:
case ReductionResult.SUPERTYPE:
newConstraint = combineSameSubSuper(boundI, boundJ);
break;
}
break;
case ReductionResult.SUBTYPE:
switch (boundJ.relation) {
case ReductionResult.SAME:
newConstraint = combineSameSubSuper(boundJ, boundI);
break;
case ReductionResult.SUPERTYPE:
newConstraint = combineSuperAndSub(boundJ, boundI);
break;
case ReductionResult.SUBTYPE:
newConstraint = combineEqualSupers(boundI, boundJ);
break;
}
break;
case ReductionResult.SUPERTYPE:
switch (boundJ.relation) {
case ReductionResult.SAME:
newConstraint = combineSameSubSuper(boundJ, boundI);
break;
case ReductionResult.SUBTYPE:
newConstraint = combineSuperAndSub(boundI, boundJ);
break;
case ReductionResult.SUPERTYPE:
newConstraint = combineEqualSupers(boundI, boundJ);
break;
}
}
if (newConstraint != null) {
if (!reduceOneConstraint(context, newConstraint))
return false;
// TODO here and below: better checking if constraint really added to the boundset (optimization)?
hasUpdate = true;
// not per JLS: if the new constraint relates types where at least one has a null annotations,
// record all null tagBits as hints for the final inference solution.
long nullHints = (newConstraint.left.tagBits | newConstraint.right.tagBits) & TagBits.AnnotationNullMASK;
boundI.nullHints |= nullHints;
boundJ.nullHints |= nullHints;
}
ConstraintFormula[] typeArgumentConstraints = deriveTypeArgumentConstraints(boundI, boundJ);
if (typeArgumentConstraints != null) {
for (int k = 0; k < typeArgumentConstraints.length; k++) {
if (!reduceOneConstraint(context, typeArgumentConstraints[k]))
return false;
hasUpdate = true;
}
}
}
this.incorporatedBounds.add(boundI);
}
/* TODO: are we sure this will always terminate? Cf. e.g. (Discussion in 18.3):
*
* "The assertion that incorporation reaches a fixed point oversimplifies the matter slightly. ..."
*/
Iterator<Entry<ParameterizedTypeBinding, ParameterizedTypeBinding>> captIter = this.captures.entrySet().iterator();
while (captIter.hasNext()) {
hasUpdate = true;
Entry<ParameterizedTypeBinding, ParameterizedTypeBinding> capt = captIter.next();
ParameterizedTypeBinding gAlpha = capt.getKey();
ParameterizedTypeBinding gA = capt.getValue();
ReferenceBinding g = (ReferenceBinding) gA.original();
final TypeVariableBinding[] parameters = g.typeVariables();
// construct theta = [P1:=alpha1,...]
final InferenceVariable[] alphas = new InferenceVariable[gAlpha.arguments.length];
System.arraycopy(gAlpha.arguments, 0, alphas, 0, alphas.length);
InferenceSubstitution theta = new InferenceSubstitution(context.environment, alphas) {
@Override
protected TypeBinding getP(int i) {
return parameters[i];
}
};
for (int i = 0; i < parameters.length; i++) {
// A set of bounds on α1, ..., αn, constructed from the declared bounds of P1, ..., Pn as described in 18.1.3, is immediately implied.
TypeVariableBinding pi = parameters[i];
InferenceVariable alpha = (InferenceVariable) gAlpha.arguments[i];
addBounds(pi.getTypeBounds(alpha, theta), context.environment);
TypeBinding ai = gA.arguments[i];
if (ai instanceof WildcardBinding) {
WildcardBinding wildcardBinding = (WildcardBinding)ai;
TypeBinding t = wildcardBinding.bound;
ThreeSets three = this.boundsPerVariable.get(alpha);
if (three != null) {
Iterator<TypeBound> it;
if (three.sameBounds != null) {
// α = R implies false
it = three.sameBounds.iterator();
while (it.hasNext()) {
TypeBound bound = it.next();
if (!(bound.right instanceof InferenceVariable))
return false;
}
}
if (three.subBounds != null && pi.firstBound != null) {
// If Bi is Object, α <: R implies ⟨T <: R⟩ (extends wildcard)
// α <: R implies ⟨θ Bi <: R⟩ (else)
it = three.subBounds.iterator();
while (it.hasNext()) {
TypeBound bound = it.next();
if (!(bound.right instanceof InferenceVariable)) {
TypeBinding r = bound.right;
TypeBinding bi1 = pi.firstBound;
ReferenceBinding[] otherBounds = pi.superInterfaces;
TypeBinding bi;
if (otherBounds == Binding.NO_SUPERINTERFACES) {
bi = bi1;
} else {
int n = otherBounds.length+1;
ReferenceBinding[] allBounds = new ReferenceBinding[n];
allBounds[0] = (ReferenceBinding) bi1; // TODO is this safe?
System.arraycopy(otherBounds, 0, allBounds, 1, n-1);
bi = new IntersectionCastTypeBinding(allBounds, context.environment);
}
addTypeBoundsFromWildcardBound(context, theta, wildcardBinding.boundKind, t, r, bi);
// if (otherBounds != null) {
// for (int j = 0; j < otherBounds.length; j++) {
// TypeBinding tj = otherBounds[j];
// if (TypeBinding.notEquals(tj, t))
// addTypeBoundsFromWildcardBound(context, wildcardBinding, tj, r, bij);
// }
// }
}
}
}
if (three.superBounds != null) {
// R <: α implies ⟨R <: T⟩ (super wildcard)
// R <: α implies false (else)
it = three.superBounds.iterator();
while (it.hasNext()) {
TypeBound bound = it.next();
if (!(bound.right instanceof InferenceVariable)) {
if (wildcardBinding.boundKind == Wildcard.SUPER)
reduceOneConstraint(context, ConstraintTypeFormula.create(bound.right, t, ReductionResult.SUBTYPE));
else
return false;
}
}
}
}
} else {
addBound(new TypeBound(alpha, ai, ReductionResult.SAME), context.environment);
}
}
}
this.captures.clear();
} while (hasUpdate);
return true;
}
void addTypeBoundsFromWildcardBound(InferenceContext18 context, InferenceSubstitution theta, int boundKind, TypeBinding t,
TypeBinding r, TypeBinding bi) throws InferenceFailureException {
ConstraintFormula formula = null;
if (boundKind == Wildcard.EXTENDS) {
if (bi.id == TypeIds.T_JavaLangObject)
formula = ConstraintTypeFormula.create(t, r, ReductionResult.SUBTYPE);
if (t.id == TypeIds.T_JavaLangObject)
formula = ConstraintTypeFormula.create(theta.substitute(theta, bi), r, ReductionResult.SUBTYPE);
} else {
formula = ConstraintTypeFormula.create(theta.substitute(theta, bi), r, ReductionResult.SUBTYPE);
}
if (formula != null)
reduceOneConstraint(context, formula);
}
private ConstraintTypeFormula combineSameSame(TypeBound boundS, TypeBound boundT) {
// α = S and α = T imply ⟨S = T⟩
if (boundS.left == boundT.left) //$IDENTITY-COMPARISON$ InferenceVariable
return ConstraintTypeFormula.create(boundS.right, boundT.right, ReductionResult.SAME, boundS.isSoft||boundT.isSoft);
// match against more shapes:
ConstraintTypeFormula newConstraint;
newConstraint = combineSameSameWithProperType(boundS, boundT);
if (newConstraint != null)
return newConstraint;
newConstraint = combineSameSameWithProperType(boundT, boundS);
if (newConstraint != null)
return newConstraint;
return null;
}
// pre: boundLeft.left != boundRight.left
private ConstraintTypeFormula combineSameSameWithProperType(TypeBound boundLeft, TypeBound boundRight) {
// α = U and S = T imply ⟨S[α:=U] = T[α:=U]⟩
TypeBinding u = boundLeft.right;
if (u.isProperType(true)) {
InferenceVariable alpha = boundLeft.left;
TypeBinding left = boundRight.left; // no substitution since S inference variable and (S != α) per precondition
TypeBinding right = boundRight.right.substituteInferenceVariable(alpha, u);
return ConstraintTypeFormula.create(left, right, ReductionResult.SAME, boundLeft.isSoft||boundRight.isSoft);
}
return null;
}
private ConstraintTypeFormula combineSameSubSuper(TypeBound boundS, TypeBound boundT) {
// α = S and α <: T imply ⟨S <: T⟩
// α = S and T <: α imply ⟨T <: S⟩
InferenceVariable alpha = boundS.left;
TypeBinding s = boundS.right;
if (alpha == boundT.left) //$IDENTITY-COMPARISON$ InferenceVariable
return ConstraintTypeFormula.create(s, boundT.right, boundT.relation, boundT.isSoft||boundS.isSoft);
if (alpha == boundT.right) //$IDENTITY-COMPARISON$ InferenceVariable
return ConstraintTypeFormula.create(boundT.right, s, boundT.relation, boundT.isSoft||boundS.isSoft);
if (boundS.right instanceof InferenceVariable) {
// reverse:
alpha = (InferenceVariable) boundS.right;
s = boundS.left;
if (alpha == boundT.left) //$IDENTITY-COMPARISON$ InferenceVariable
return ConstraintTypeFormula.create(s, boundT.right, boundT.relation, boundT.isSoft||boundS.isSoft);
if (alpha == boundT.right) //$IDENTITY-COMPARISON$ InferenceVariable
return ConstraintTypeFormula.create(boundT.right, s, boundT.relation, boundT.isSoft||boundS.isSoft);
}
// α = U and S <: T imply ⟨S[α:=U] <: T[α:=U]⟩
TypeBinding u = boundS.right;
if (u.isProperType(true)) {
TypeBinding left = (alpha == boundT.left) ? u : boundT.left; //$IDENTITY-COMPARISON$ InferenceVariable
TypeBinding right = boundT.right.substituteInferenceVariable(alpha, u);
return ConstraintTypeFormula.create(left, right, boundT.relation, boundT.isSoft||boundS.isSoft);
}
return null;
}
private ConstraintTypeFormula combineSuperAndSub(TypeBound boundS, TypeBound boundT) {
// permutations of: S <: α and α <: T imply ⟨S <: T⟩
InferenceVariable alpha = boundS.left;
if (alpha == boundT.left) //$IDENTITY-COMPARISON$ InferenceVariable
// α >: S and α <: T imply ⟨S <: T⟩
return ConstraintTypeFormula.create(boundS.right, boundT.right, ReductionResult.SUBTYPE, boundT.isSoft||boundS.isSoft);
if (boundS.right instanceof InferenceVariable) {
// try reverse:
alpha = (InferenceVariable) boundS.right;
if (alpha == boundT.right) //$IDENTITY-COMPARISON$ InferenceVariable
// S :> α and T <: α imply ⟨S :> T⟩
return ConstraintTypeFormula.create(boundS.left, boundT.left, ReductionResult.SUPERTYPE, boundT.isSoft||boundS.isSoft);
}
return null;
}
private ConstraintTypeFormula combineEqualSupers(TypeBound boundS, TypeBound boundT) {
// more permutations of: S <: α and α <: T imply ⟨S <: T⟩
if (boundS.left == boundT.right) //$IDENTITY-COMPARISON$ InferenceVariable
// came in as: α REL S and T REL α imply ⟨T REL S⟩
return ConstraintTypeFormula.create(boundT.left, boundS.right, boundS.relation, boundT.isSoft||boundS.isSoft);
if (boundS.right == boundT.left) //$IDENTITY-COMPARISON$ InferenceVariable
// came in as: S REL α and α REL T imply ⟨S REL T⟩
return ConstraintTypeFormula.create(boundS.left, boundT.right, boundS.relation, boundT.isSoft||boundS.isSoft);
return null;
}
private ConstraintTypeFormula[] deriveTypeArgumentConstraints(TypeBound boundS, TypeBound boundT) {
/* From 18.4:
* If two bounds have the form α <: S and α <: T, and if for some generic class or interface, G,
* there exists a supertype (4.10) of S of the form G<S1, ..., Sn> and a supertype of T of the form G<T1, ..., Tn>,
* then for all i, 1 ≤ i ≤ n, if Si and Ti are types (not wildcards), the constraint ⟨Si = Ti⟩ is implied.
*/
if (boundS.relation != ReductionResult.SUBTYPE || boundT.relation != ReductionResult.SUBTYPE)
return null;
if (boundS.left != boundT.left) //$IDENTITY-COMPARISON$ InferenceVariable
return null;
TypeBinding[] supers = superTypesWithCommonGenericType(boundS.right, boundT.right);
if (supers != null)
return typeArgumentEqualityConstraints(supers[0], supers[1], boundS.isSoft || boundT.isSoft);
return null;
}
private ConstraintTypeFormula[] typeArgumentEqualityConstraints(TypeBinding s, TypeBinding t, boolean isSoft) {
if (s == null || s.kind() != Binding.PARAMETERIZED_TYPE || t == null || t.kind() != Binding.PARAMETERIZED_TYPE)
return null;
if (TypeBinding.equalsEquals(s, t)) // don't create useless constraints
return null;
TypeBinding[] sis = s.typeArguments();
TypeBinding[] tis = t.typeArguments();
if (sis == null || tis == null || sis.length != tis.length)
return null;
List<ConstraintTypeFormula> result = new ArrayList<ConstraintTypeFormula>();
for (int i = 0; i < sis.length; i++) {
TypeBinding si = sis[i];
TypeBinding ti = tis[i];
if (si.isWildcard() || ti.isWildcard() || TypeBinding.equalsEquals(si, ti))
continue;
result.add(ConstraintTypeFormula.create(si, ti, ReductionResult.SAME, isSoft));
}
if (result.size() > 0)
return result.toArray(new ConstraintTypeFormula[result.size()]);
return null;
}
/**
* Try to reduce the one given constraint.
* If a constraint produces further constraints reduce those recursively.
* @throws InferenceFailureException a compile error has been detected during inference
*/
public boolean reduceOneConstraint(InferenceContext18 context, ConstraintFormula currentConstraint) throws InferenceFailureException {
Object result = currentConstraint.reduce(context);
if (result == ReductionResult.FALSE)
return false;
if (result == ReductionResult.TRUE)
return true;
if (result == currentConstraint) {
// not reduceable
throw new IllegalStateException("Failed to reduce constraint formula"); //$NON-NLS-1$
}
if (result != null) {
if (result instanceof ConstraintFormula) {
if (!reduceOneConstraint(context, (ConstraintFormula) result))
return false;
} else if (result instanceof ConstraintFormula[]) {
ConstraintFormula[] resultArray = (ConstraintFormula[]) result;
for (int i = 0; i < resultArray.length; i++)
if (!reduceOneConstraint(context, resultArray[i]))
return false;
} else {
addBound((TypeBound)result, context.environment);
}
}
return true; // no FALSE encountered
}
/**
* Helper for resolution (18.4):
* Does this bound set define a direct dependency between the two given inference variables?
*/
public boolean dependsOnResolutionOf(InferenceVariable alpha, InferenceVariable beta) {
Iterator<Map.Entry<ParameterizedTypeBinding, ParameterizedTypeBinding>> captureIter = this.captures.entrySet().iterator();
boolean betaIsInCaptureLhs = false;
while (captureIter.hasNext()) { // TODO: optimization: consider separate index structure (by IV)
Entry<ParameterizedTypeBinding, ParameterizedTypeBinding> entry = captureIter.next();
ParameterizedTypeBinding g = entry.getKey();
for (int i = 0; i < g.arguments.length; i++) {
if (g.arguments[i] == alpha) { //$IDENTITY-COMPARISON$ InferenceVariable
// An inference variable α appearing on the left-hand side of a bound of the form G<..., α, ...> = capture(G<...>)
// depends on the resolution of every other inference variable mentioned in this bound (on both sides of the = sign).
ParameterizedTypeBinding captured = entry.getValue();
if (captured.mentionsAny(new TypeBinding[]{beta}, -1/*don't care about index*/))
return true;
if (g.mentionsAny(new TypeBinding[]{beta}, i)) // exclude itself
return true;
} else if (g.arguments[i] == beta) { //$IDENTITY-COMPARISON$ InferenceVariable
betaIsInCaptureLhs = true;
}
}
}
if (betaIsInCaptureLhs) { // swap α and β in the rule text to cover "then β depends on the resolution of α"
ThreeSets sets = this.boundsPerVariable.get(beta);
if (sets != null && sets.hasDependency(alpha))
return true;
} else {
ThreeSets sets = this.boundsPerVariable.get(alpha);
if (sets != null && sets.hasDependency(beta))
return true;
}
return false;
}
// helper for 18.4
public boolean hasCaptureBound(Set<InferenceVariable> variableSet) {
Iterator<ParameterizedTypeBinding> captureIter = this.captures.keySet().iterator();
while (captureIter.hasNext()) {
ParameterizedTypeBinding g = captureIter.next();
for (int i = 0; i < g.arguments.length; i++)
if (variableSet.contains(g.arguments[i]))
return true;
}
return false;
}
// helper for 18.4
public boolean hasOnlyTrivialExceptionBounds(InferenceVariable variable, TypeBinding[] upperBounds) {
if (upperBounds != null) {
for (int i = 0; i < upperBounds.length; i++) {
switch (upperBounds[i].id) {
case TypeIds.T_JavaLangException:
case TypeIds.T_JavaLangThrowable:
case TypeIds.T_JavaLangObject:
continue;
}
return false;
}
}
return true;
}
/**
* JLS 18.1.3:
* Answer all upper bounds for the given inference variable as defined by any bounds in this set.
*/
public TypeBinding[] upperBounds(InferenceVariable variable, boolean onlyProper) {
ThreeSets three = this.boundsPerVariable.get(variable);
if (three == null || three.subBounds == null)
return Binding.NO_TYPES;
return three.upperBounds(onlyProper, variable);
// TODO: if !onlyProper: should we also consider ThreeSets.inverseBounds,
// or is it safe to rely on incorporation to produce the required bounds?
}
/**
* JLS 18.1.3:
* Answer all lower bounds for the given inference variable as defined by any bounds in this set.
*/
TypeBinding[] lowerBounds(InferenceVariable variable, boolean onlyProper) {
ThreeSets three = this.boundsPerVariable.get(variable);
if (three == null || three.superBounds == null)
return Binding.NO_TYPES;
return three.lowerBounds(onlyProper, variable);
// bounds where 'variable' appears at the RHS are not relevant because
// we're only interested in bounds with a proper type, but if 'variable'
// appears as RHS the bound is by construction an inference variable,too.
}
// debugging:
public String toString() {
StringBuffer buf = new StringBuffer("Type Bounds:\n"); //$NON-NLS-1$
TypeBound[] flattened = flatten();
for (int i = 0; i < flattened.length; i++) {
buf.append('\t').append(flattened[i].toString()).append('\n');
}
buf.append("Capture Bounds:\n"); //$NON-NLS-1$
Iterator<Map.Entry<ParameterizedTypeBinding,ParameterizedTypeBinding>> captIter = this.captures.entrySet().iterator();
while (captIter.hasNext()) {
Entry<ParameterizedTypeBinding, ParameterizedTypeBinding> capt = captIter.next();
String lhs = String.valueOf(((TypeBinding)capt.getKey()).shortReadableName());
String rhs = String.valueOf(((TypeBinding)capt.getValue()).shortReadableName());
buf.append('\t').append(lhs).append(" = capt(").append(rhs).append(")\n"); //$NON-NLS-1$ //$NON-NLS-2$
}
return buf.toString();
}
public TypeBinding findWrapperTypeBound(InferenceVariable variable) {
ThreeSets three = this.boundsPerVariable.get(variable);
if (three == null) return null;
return three.findSingleWrapperType();
}
// this condition is just way too complex to check it in-line:
public boolean condition18_5_2_bullet_3_3_1(InferenceVariable alpha, TypeBinding targetType) {
// T is a reference type, but is not a wildcard-parameterized type, and either
// i) B2 contains a bound of one of the forms α = S or S <: α, where S is a wildcard-parameterized type, or ...
if (targetType.isBaseType()) return false;
if (InferenceContext18.parameterizedWithWildcard(targetType) != null) return false;
ThreeSets ts = this.boundsPerVariable.get(alpha);
if (ts.sameBounds != null) {
Iterator<TypeBound> bounds = ts.sameBounds.iterator();
while (bounds.hasNext()) {
TypeBound bound = bounds.next();
if (InferenceContext18.parameterizedWithWildcard(bound.right) != null)
return true;
}
}
if (ts.superBounds != null) {
Iterator<TypeBound> bounds = ts.superBounds.iterator();
while (bounds.hasNext()) {
TypeBound bound = bounds.next();
if (InferenceContext18.parameterizedWithWildcard(bound.right) != null)
return true;
}
}
// ii) B2 contains two bounds of the forms S1 <: α and S2 <: α, where
// S1 and S2 have supertypes (4.10) that are two different parameterizations of the same generic class or interface.
if (ts.superBounds != null) {
ArrayList<TypeBound> superBounds = new ArrayList<TypeBound>(ts.superBounds);
int len = superBounds.size();
for (int i=0; i<len; i++) {
TypeBinding s1 = superBounds.get(i).right;
for (int j=i+1; j<len; j++) {
TypeBinding s2 = superBounds.get(j).right;
TypeBinding[] supers = superTypesWithCommonGenericType(s1, s2);
if (supers != null && !TypeBinding.equalsEquals(supers[0], supers[1]))
return true;
}
}
}
return false;
}
public boolean condition18_5_2_bullet_3_3_2(InferenceVariable alpha, TypeBinding targetType, InferenceContext18 ctx18) {
// T is a parameterization of a generic class or interface, G, and
// B2 contains a bound of one of the forms α = S or S <: α,
// where there exists no type of the form G<...> that is a supertype of S, but the raw type G is a supertype of S.
if (!targetType.isParameterizedType()) return false;
TypeBinding g = targetType.original();
ThreeSets ts = this.boundsPerVariable.get(alpha);
Iterator<TypeBound> boundIterator;
if (ts.sameBounds != null) {
boundIterator = ts.sameBounds.iterator();
while (boundIterator.hasNext()) {
TypeBound b = boundIterator.next();
if (superOnlyRaw(g, b.right, ctx18.environment))
return true;
}
}
if (ts.superBounds != null) {
boundIterator = ts.superBounds.iterator();
while (boundIterator.hasNext()) {
TypeBound b = boundIterator.next();
if (superOnlyRaw(g, b.right, ctx18.environment))
return true;
}
}
return false;
}
private boolean superOnlyRaw(TypeBinding g, TypeBinding s, LookupEnvironment env) {
if (s instanceof InferenceVariable)
return false; // inference has no super types
if (s.findSuperTypeOriginatingFrom(g) == null)
return s.isCompatibleWith(env.convertToRawType(g, false));
return false;
}
protected TypeBinding[] superTypesWithCommonGenericType(TypeBinding s, TypeBinding t) {
if (s == null || s.id == TypeIds.T_JavaLangObject || t == null || t.id == TypeIds.T_JavaLangObject)
return null;
if (TypeBinding.equalsEquals(s.original(), t.original())) {
return new TypeBinding[] { s, t };
}
TypeBinding tSuper = t.findSuperTypeOriginatingFrom(s);
if (tSuper != null) {
return new TypeBinding[] {s, tSuper};
}
TypeBinding[] result = superTypesWithCommonGenericType(s.superclass(), t);
if (result != null)
return result;
ReferenceBinding[] superInterfaces = s.superInterfaces();
if (superInterfaces != null) {
for (int i = 0; i < superInterfaces.length; i++) {
result = superTypesWithCommonGenericType(superInterfaces[i], t);
if (result != null)
return result;
}
}
return null;
}
}