package backtype.storm;
import java.util.Map;
/**
* Provides functionality for validating configuration fields.
*/
public class ConfigValidation {
/**
* Declares methods for validating configuration values.
*/
public static interface FieldValidator {
/**
* Validates the given field.
*
* @param name
* the name of the field.
* @param field
* The field to be validated.
* @throws IllegalArgumentException
* if the field fails validation.
*/
public void validateField(String name, Object field)
throws IllegalArgumentException;
}
/**
* Returns a new FieldValidator for a List of the given Class.
*
* @param cls
* the Class of elements composing the list
* @return a FieldValidator for a list of the given class
*/
static FieldValidator FieldListValidatorFactory(final Class cls) {
return new FieldValidator() {
@Override
public void validateField(String name, Object field)
throws IllegalArgumentException {
if (field == null) {
// A null value is acceptable.
return;
}
if (field instanceof Iterable) {
for (Object e : (Iterable) field) {
if (!cls.isInstance(e)) {
throw new IllegalArgumentException(
"Each element of the list " + name
+ " must be a " + cls.getName()
+ ".");
}
}
return;
}
throw new IllegalArgumentException("Field " + name
+ " must be an Iterable of " + cls.getName());
}
};
}
/**
* Validates a list of Numbers.
*/
public static Object NumbersValidator = FieldListValidatorFactory(Number.class);
/**
* Validates is a list of Strings.
*/
public static Object StringsValidator = FieldListValidatorFactory(String.class);
/**
* Validates is a list of Maps.
*/
public static Object MapsValidator = FieldListValidatorFactory(Map.class);
/**
* Validates a power of 2.
*/
public static Object PowerOf2Validator = new FieldValidator() {
@Override
public void validateField(String name, Object o)
throws IllegalArgumentException {
if (o == null) {
// A null value is acceptable.
return;
}
final long i;
if (o instanceof Number
&& (i = ((Number) o).longValue()) == ((Number) o)
.doubleValue()) {
// Test whether the integer is a power of 2.
if (i > 0 && (i & (i - 1)) == 0) {
return;
}
}
throw new IllegalArgumentException("Field " + name
+ " must be a power of 2.");
}
};
}