JSType meet(JSType that) {
UnionTypeBuilder builder = new UnionTypeBuilder(registry);
for (JSType alternate : alternatesWithoutStucturalTyping) {
if (alternate.isSubtype(that)) {
builder.addAlternate(alternate);
}
}
if (that.isUnionType()) {
for (JSType otherAlternate : that.toMaybeUnionType().alternatesWithoutStucturalTyping) {
if (otherAlternate.isSubtype(this)) {
builder.addAlternate(otherAlternate);
}
}
} else if (that.isSubtype(this)) {
builder.addAlternate(that);
}
JSType result = builder.build();
if (!result.isNoType()) {
return result;
} else if (this.isObject() && (that.isObject() && !that.isNoType())) {
return getNativeType(JSTypeNative.NO_OBJECT_TYPE);
} else {
return getNativeType(JSTypeNative.NO_TYPE);
}
}
/**
* Use UnionTypeBuilder to rebuild the list of alternates and hashcode of the current UnionType.
*/
private void rebuildAlternates() {
UnionTypeBuilder builder = new UnionTypeBuilder(registry);
for (JSType alternate : alternatesWithoutStucturalTyping) {
builder.addAlternate(alternate);
}
alternatesWithoutStucturalTyping = builder.getAlternates();
builder = new UnionTypeBuilder(registry);
for (JSType alternate : alternatesWithoutStucturalTyping) {
builder.addAlternate(alternate, true);
}
alternates = builder.getAlternates();
hashcode = alternatesWithoutStucturalTyping.hashCode();
}
@Override
public TypePair getTypesUnderShallowInequality(JSType that) {
UnionTypeBuilder thisRestricted = new UnionTypeBuilder(registry);
UnionTypeBuilder thatRestricted = new UnionTypeBuilder(registry);
for (JSType element : alternatesWithoutStucturalTyping) {
TypePair p = element.getTypesUnderShallowInequality(that);
if (p.typeA != null) {
thisRestricted.addAlternate(p.typeA);
}
if (p.typeB != null) {
thatRestricted.addAlternate(p.typeB);
}
}
return new TypePair(thisRestricted.build(), thatRestricted.build());
}
@Override
public JSType restrictByNotNullOrUndefined() {
UnionTypeBuilder restricted = new UnionTypeBuilder(registry);
for (JSType t : alternatesWithoutStucturalTyping) {
restricted.addAlternate(t.restrictByNotNullOrUndefined());
}
return restricted.build();
}
@Override
public JSType autobox() {
UnionTypeBuilder restricted = new UnionTypeBuilder(registry);
for (JSType t : alternatesWithoutStucturalTyping) {
restricted.addAlternate(t.autobox());
}
return restricted.build();
}
@Override
public JSType getRestrictedTypeGivenToBooleanOutcome(boolean outcome) {
// gather elements after restriction
UnionTypeBuilder restricted = new UnionTypeBuilder(registry);
for (JSType element : alternatesWithoutStucturalTyping) {
restricted.addAlternate(element.getRestrictedTypeGivenToBooleanOutcome(outcome));
}
return restricted.build();
}
/**
* Returns a more restricted union type than {@code this} one, in which all subtypes of {@code
* type} have been removed.
*
* <p>Examples:
*
* <ul>
* <li>{@code (number,string)} restricted by {@code number} is {@code string}
* <li>{@code (null, EvalError, URIError)} restricted by {@code Error} is {@code null}
* </ul>
*
* @param type the supertype of the types to remove from this union type
*/
public JSType getRestrictedUnion(JSType type) {
UnionTypeBuilder restricted = new UnionTypeBuilder(registry);
for (JSType t : alternatesWithoutStucturalTyping) {
// Keep all unknown/unresolved types.
if (t.isUnknownType() || t.isNoResolvedType() || !t.isSubtype(type)) {
restricted.addAlternate(t);
}
}
return restricted.build();
}
JSType getGreatestSubtypeHelper(JSType that) {
if (that.isRecordType()) {
RecordType thatRecord = that.toMaybeRecordType();
RecordTypeBuilder builder = new RecordTypeBuilder(registry);
builder.setSynthesized(true);
// The greatest subtype consists of those *unique* properties of both
// record types. If any property conflicts, then the NO_TYPE type
// is returned.
for (String property : getOwnPropertyNames()) {
if (thatRecord.hasProperty(property)
&& !thatRecord.getPropertyType(property).isInvariant(getPropertyType(property))) {
return registry.getNativeObjectType(JSTypeNative.NO_TYPE);
}
builder.addProperty(property, getPropertyType(property), getPropertyNode(property));
}
for (String property : thatRecord.getOwnPropertyNames()) {
if (!hasProperty(property)) {
builder.addProperty(
property, thatRecord.getPropertyType(property), thatRecord.getPropertyNode(property));
}
}
return builder.build();
}
JSType greatestSubtype = registry.getNativeType(JSTypeNative.NO_OBJECT_TYPE);
JSType thatRestrictedToObj =
registry.getNativeType(JSTypeNative.OBJECT_TYPE).getGreatestSubtype(that);
if (!thatRestrictedToObj.isEmptyType()) {
// In this branch, the other type is some object type. We find
// the greatest subtype with the following algorithm:
// 1) For each property "x" of this record type, take the union
// of all classes with a property "x" with a compatible property type.
// and which are a subtype of {@code that}.
// 2) Take the intersection of all of these unions.
for (String propName : getOwnPropertyNames()) {
JSType propType = getPropertyType(propName);
UnionTypeBuilder builder = new UnionTypeBuilder(registry);
for (ObjectType alt : registry.getEachReferenceTypeWithProperty(propName)) {
JSType altPropType = alt.getPropertyType(propName);
if (altPropType != null
&& !alt.isEquivalentTo(this)
&& alt.isSubtype(that)
&& propType.isInvariant(altPropType)) {
builder.addAlternate(alt);
}
}
greatestSubtype = greatestSubtype.getLeastSupertype(builder.build());
}
}
return greatestSubtype;
}
/**
* Creates a union type.
*
* @param alternatesWithoutStructuralTyping the alternates of the union without structural typing
* subtype
*/
UnionType(JSTypeRegistry registry, Collection<JSType> alternatesWithoutStructuralTyping) {
super(registry);
this.alternatesWithoutStucturalTyping = alternatesWithoutStructuralTyping;
UnionTypeBuilder builder = new UnionTypeBuilder(registry);
for (JSType alternate : alternatesWithoutStructuralTyping) {
builder.addAlternate(alternate, true);
}
this.alternates = builder.getAlternates();
this.hashcode = this.alternatesWithoutStucturalTyping.hashCode();
}
/** Adds an alternate to the union type under construction. Returns this for easy chaining. */
public UnionTypeBuilder addAlternate(JSType alternate, boolean isStructural) {
// build() returns the bottom type by default, so we can
// just bail out early here.
if (alternate.isNoType()) {
return this;
}
isAllType = isAllType || alternate.isAllType();
containsVoidType = containsVoidType || alternate.isVoidType();
boolean isAlternateUnknown = alternate instanceof UnknownType;
isNativeUnknownType = isNativeUnknownType || isAlternateUnknown;
if (isAlternateUnknown) {
areAllUnknownsChecked = areAllUnknownsChecked && alternate.isCheckedUnknownType();
}
if (!isAllType && !isNativeUnknownType) {
if (alternate.isUnionType()) {
UnionType union = alternate.toMaybeUnionType();
for (JSType unionAlt : union.getAlternatesWithoutStructuralTyping()) {
addAlternate(unionAlt);
}
} else {
if (alternates.size() > maxUnionSize) {
return this;
}
// Function types are special, because they have their
// own bizarre sub-lattice. See the comments on
// FunctionType#supAndInf helper and above at functionTypePosition.
if (alternate.isFunctionType() && functionTypePosition != -1) {
// See the comments on functionTypePosition above.
FunctionType other = alternates.get(functionTypePosition).toMaybeFunctionType();
FunctionType supremum = alternate.toMaybeFunctionType().supAndInfHelper(other, true);
alternates.set(functionTypePosition, supremum);
result = null;
return this;
}
// Look through the alternates we've got so far,
// and check if any of them are duplicates of
// one another.
int currentIndex = 0;
Iterator<JSType> it = alternates.iterator();
while (it.hasNext()) {
boolean removeCurrent = false;
JSType current = it.next();
// Unknown and NoResolved types may just be names that haven't
// been resolved yet. So keep these in the union, and just use
// equality checking for simple de-duping.
if (alternate.isUnknownType()
|| current.isUnknownType()
|| alternate.isNoResolvedType()
|| current.isNoResolvedType()
|| alternate.hasAnyTemplateTypes()
|| current.hasAnyTemplateTypes()) {
if (alternate.isEquivalentTo(current, isStructural)) {
// Alternate is unnecessary.
return this;
}
} else {
// Because "Foo" and "Foo.<?>" are roughly equivalent
// templatized types, special care is needed when building the
// union. For example:
// Object is consider a subtype of Object.<string>
// but we want to leave "Object" not "Object.<string>" when
// building the subtype.
//
if (alternate.isTemplatizedType() || current.isTemplatizedType()) {
// Cases:
// 1) alternate:Array.<string> and current:Object ==> Object
// 2) alternate:Array.<string> and current:Array ==> Array
// 3) alternate:Object.<string> and
// current:Array ==> Array|Object.<string>
// 4) alternate:Object and current:Array.<string> ==> Object
// 5) alternate:Array and current:Array.<string> ==> Array
// 6) alternate:Array and
// current:Object.<string> ==> Array|Object.<string>
// 7) alternate:Array.<string> and
// current:Array.<number> ==> Array.<?>
// 8) alternate:Array.<string> and
// current:Array.<string> ==> Array.<string>
// 9) alternate:Array.<string> and
// current:Object.<string> ==> Object.<string>|Array.<string>
if (!current.isTemplatizedType()) {
if (isSubtype(alternate, current, isStructural)) {
// case 1, 2
return this;
}
// case 3: leave current, add alternate
} else if (!alternate.isTemplatizedType()) {
if (isSubtype(current, alternate, isStructural)) {
// case 4, 5
removeCurrent = true;
}
// case 6: leave current, add alternate
} else {
Preconditions.checkState(
current.isTemplatizedType() && alternate.isTemplatizedType());
TemplatizedType templatizedAlternate = alternate.toMaybeTemplatizedType();
TemplatizedType templatizedCurrent = current.toMaybeTemplatizedType();
if (templatizedCurrent.wrapsSameRawType(templatizedAlternate)) {
if (alternate
.getTemplateTypeMap()
.checkEquivalenceHelper(
current.getTemplateTypeMap(),
EquivalenceMethod.IDENTITY,
SubtypingMode.NORMAL)) {
// case 8
return this;
} else {
// TODO(johnlenz): should we leave both types?
// case 7: add a merged alternate
// We currently merge to the templatized types to "unknown"
// which is equivalent to the raw type.
JSType merged = templatizedCurrent.getReferencedObjTypeInternal();
return addAlternate(merged);
}
}
// case 9: leave current, add alternate
}
// Otherwise leave both templatized types.
} else if (isSubtype(alternate, current, isStructural)) {
// Alternate is unnecessary.
return this;
} else if (isSubtype(current, alternate, isStructural)) {
// Alternate makes current obsolete
removeCurrent = true;
}
}
if (removeCurrent) {
it.remove();
if (currentIndex == functionTypePosition) {
functionTypePosition = -1;
} else if (currentIndex < functionTypePosition) {
functionTypePosition--;
currentIndex--;
}
}
currentIndex++;
}
if (alternate.isFunctionType()) {
// See the comments on functionTypePosition above.
Preconditions.checkState(functionTypePosition == -1);
functionTypePosition = alternates.size();
}
alternates.add(alternate);
result = null; // invalidate the memoized result
}
} else {
result = null;
}
return this;
}