@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
if (arguments.length < 2) {
throw new UDFArgumentLengthException(
"The function ELT(N,str1,str2,str3,...) needs at least two arguments.");
}
for (int i = 0; i < arguments.length; i++) {
Category category = arguments[i].getCategory();
if (category != Category.PRIMITIVE) {
throw new UDFArgumentTypeException(
i,
"The "
+ GenericUDFUtils.getOrdinal(i + 1)
+ " argument of function ELT is expected to a "
+ Category.PRIMITIVE.toString().toLowerCase()
+ " type, but "
+ category.toString().toLowerCase()
+ " is found");
}
}
converters = new ObjectInspectorConverters.Converter[arguments.length];
for (int i = 0; i < arguments.length; i++) {
if (i == 0) {
converters[i] =
ObjectInspectorConverters.getConverter(
arguments[i], PrimitiveObjectInspectorFactory.writableIntObjectInspector);
} else {
converters[i] =
ObjectInspectorConverters.getConverter(
arguments[i], PrimitiveObjectInspectorFactory.writableStringObjectInspector);
}
}
return PrimitiveObjectInspectorFactory.writableStringObjectInspector;
}
/**
* Compares two types identified by the given object inspectors. This method compares the types as
* follows:
*
* <ol>
* <li>If the given inspectors do not belong to same category, the result is negative.
* <li>If the given inspectors are for <code>PRIMITIVE</code> type, the result is the comparison
* of their type names.
* <li>If the given inspectors are for <code>LIST</code> type, then the result is recursive call
* to compare the type of list elements.
* <li>If the given inspectors are <code>MAP</code> type, then the result is a recursive call to
* compare the map key and value types.
* <li>If the given inspectors are <code>STRUCT</code> type, then the result is negative if they
* do not have the same number of fields. If they do have the same number of fields, the
* result is a recursive call to compare each of the field types.
* <li>If none of the above, the result is negative.
* </ol>
*
* @param o1
* @param o2
* @return true if the given object inspectors represent the same types.
*/
public static boolean compareTypes(ObjectInspector o1, ObjectInspector o2) {
Category c1 = o1.getCategory();
Category c2 = o2.getCategory();
// Return false if categories are not equal
if (!c1.equals(c2)) {
return false;
}
// If both categories are primitive return the comparison of type names.
if (c1.equals(Category.PRIMITIVE)) {
return o1.getTypeName().equals(o2.getTypeName());
}
// If lists, recursively compare the list element types
if (c1.equals(Category.LIST)) {
ObjectInspector child1 = ((ListObjectInspector) o1).getListElementObjectInspector();
ObjectInspector child2 = ((ListObjectInspector) o2).getListElementObjectInspector();
return compareTypes(child1, child2);
}
// If maps, recursively compare the key and value types
if (c1.equals(Category.MAP)) {
MapObjectInspector mapOI1 = (MapObjectInspector) o1;
MapObjectInspector mapOI2 = (MapObjectInspector) o2;
ObjectInspector childKey1 = mapOI1.getMapKeyObjectInspector();
ObjectInspector childKey2 = mapOI2.getMapKeyObjectInspector();
if (compareTypes(childKey1, childKey2)) {
ObjectInspector childVal1 = mapOI1.getMapValueObjectInspector();
ObjectInspector childVal2 = mapOI2.getMapValueObjectInspector();
if (compareTypes(childVal1, childVal2)) {
return true;
}
}
return false;
}
// If structs, recursively compare the fields
if (c1.equals(Category.STRUCT)) {
StructObjectInspector structOI1 = (StructObjectInspector) o1;
StructObjectInspector structOI2 = (StructObjectInspector) o2;
List<? extends StructField> childFieldsList1 = structOI1.getAllStructFieldRefs();
List<? extends StructField> childFieldsList2 = structOI2.getAllStructFieldRefs();
if (childFieldsList1 == null && childFieldsList2 == null) {
return true;
} else if (childFieldsList1 == null || childFieldsList2 == null) {
return false;
} else if (childFieldsList1.size() != childFieldsList2.size()) {
return false;
}
Iterator<? extends StructField> it1 = childFieldsList1.iterator();
Iterator<? extends StructField> it2 = childFieldsList2.iterator();
while (it1.hasNext()) {
StructField field1 = it1.next();
StructField field2 = it2.next();
if (!compareTypes(field1.getFieldObjectInspector(), field2.getFieldObjectInspector())) {
return false;
}
}
return true;
}
if (c1.equals(Category.UNION)) {
UnionObjectInspector uoi1 = (UnionObjectInspector) o1;
UnionObjectInspector uoi2 = (UnionObjectInspector) o2;
List<ObjectInspector> ois1 = uoi1.getObjectInspectors();
List<ObjectInspector> ois2 = uoi2.getObjectInspectors();
if (ois1 == null && ois2 == null) {
return true;
} else if (ois1 == null || ois2 == null) {
return false;
} else if (ois1.size() != ois2.size()) {
return false;
}
Iterator<? extends ObjectInspector> it1 = ois1.iterator();
Iterator<? extends ObjectInspector> it2 = ois2.iterator();
while (it1.hasNext()) {
if (!compareTypes(it1.next(), it2.next())) {
return false;
}
}
return true;
}
// Unknown category
throw new RuntimeException("Unknown category encountered: " + c1);
}