/*
* Copyright 2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.hadoop.store.expression;
import java.util.List;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.MethodExecutor;
import org.springframework.expression.TypedValue;
/**
* A {@link MethodExecutor} using an first argument as key
* to be matched from second argument which is expected to be
* a List of List of Objects.
*
* <p>Use case is to use spel expression
* "list(region,{{'nordic','fin','swe'},{'britain','eng','sco'}})" to partition
* value in 'region' so that resolved partition value is 'nordic' if any of a
* 'nordic','fin', or 'swe' is matched. Resolved value will be suffixed with
* '_list' and default value if there are no matches is 'list'.
*
* @author Janne Valkealahti
*
*/
public class HashListMethodExecutor implements MethodExecutor {
@Override
public TypedValue execute(EvaluationContext context, Object target, Object... arguments) throws AccessException {
if (arguments[1] instanceof List) {
List<?> list = (List<?>)arguments[1];
for (Object object : list) {
if (object instanceof List) {
List<?> sublist = ((List<?>)object);
if (sublist.contains(arguments[0])) {
return new TypedValue(sublist.get(0) + "_list");
}
}
}
} else {
throw new AccessException("Argument " + arguments[1] + " not a List");
}
// we didn't match anything, return default partition as 'list'
return new TypedValue("list");
}
}