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;
}
/** Try to get the sup/inf of two functions by looking at the piecewise components. */
private FunctionType tryMergeFunctionPiecewise(FunctionType other, boolean leastSuper) {
Node newParamsNode = null;
if (call.hasEqualParameters(other.call, EquivalenceMethod.IDENTITY)) {
newParamsNode = call.parameters;
} else {
// If the parameters are not equal, don't try to merge them.
// Someday, we should try to merge the individual params.
return null;
}
JSType newReturnType =
leastSuper
? call.returnType.getLeastSupertype(other.call.returnType)
: call.returnType.getGreatestSubtype(other.call.returnType);
JSType newTypeOfThis = null;
if (isEquivalent(typeOfThis, other.typeOfThis)) {
newTypeOfThis = typeOfThis;
} else {
JSType maybeNewTypeOfThis =
leastSuper
? typeOfThis.getLeastSupertype(other.typeOfThis)
: typeOfThis.getGreatestSubtype(other.typeOfThis);
newTypeOfThis = maybeNewTypeOfThis;
}
boolean newReturnTypeInferred = call.returnTypeInferred || other.call.returnTypeInferred;
return new FunctionType(
registry,
null,
null,
new ArrowType(registry, newParamsNode, newReturnType, newReturnTypeInferred),
newTypeOfThis,
null,
false,
false);
}
@Override
public JSType findPropertyType(String propertyName) {
JSType propertyType = null;
for (JSType alternate : getAlternates()) {
// Filter out the null/undefined type.
if (alternate.isNullType() || alternate.isVoidType()) {
continue;
}
JSType altPropertyType = alternate.findPropertyType(propertyName);
if (altPropertyType == null) {
continue;
}
if (propertyType == null) {
propertyType = altPropertyType;
} else {
propertyType = propertyType.getLeastSupertype(altPropertyType);
}
}
return propertyType;
}