org.teiid.language.LanguageUtil Maven / Gradle / Ivy
/*
* Copyright Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags and
* the COPYRIGHT.txt file distributed with this work.
*
* 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.teiid.language;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.teiid.language.AndOr.Operator;
/**
* Helpful utility methods to work with language interfaces.
*/
public final class LanguageUtil {
/**
* Can't construct - this contains only static utility methods
*/
private LanguageUtil() {
}
/**
* Take a criteria, which may be null, a single IPredicateCriteria or a
* complex criteria built using ICompoundCriteria and breaks it apart
* at ANDs such that a List of ICriteria conjuncts are returned. For
* example, ((a=1 OR b=2) AND (c=3 AND d=4)) would return the list
* (a=1 OR b=2), c=3, d=4. If criteria is null, an empty list is
* returned.
* @param criteria Criteria to break, may be null
* @return List of ICriteria, never null
*/
public static final List separateCriteriaByAnd(Condition criteria) {
if(criteria == null) {
return Collections.emptyList();
}
List parts = new ArrayList();
separateCriteria(criteria, parts);
return parts;
}
/**
* Helper method for {@link #separateCriteriaByAnd(Condition)} that
* can be called recursively to collect parts.
* @param crit Crit to break apart
* @param parts List to add parts to
*/
private static void separateCriteria(Condition crit, List parts) {
if(crit instanceof AndOr) {
AndOr compCrit = (AndOr) crit;
if(compCrit.getOperator() == Operator.AND) {
separateCriteria(compCrit.getLeftCondition(), parts);
separateCriteria(compCrit.getRightCondition(), parts);
} else {
parts.add(crit);
}
} else {
parts.add(crit);
}
}
/**
* This utility method can be used to combine two criteria using an AND.
* If both criteria are null, then null will be returned. If either is null,
* then the other will be returned.
* @param primaryCrit Primary criteria - may be modified
* @param additionalCrit Won't be modified, but will likely be attached to the returned crit
* @param languageFactory Will be used to construct new ICompoundCriteria if necessary
* @return Combined criteria
*/
public static Condition combineCriteria(Condition primaryCrit, Condition additionalCrit, LanguageFactory languageFactory) {
if(primaryCrit == null) {
return additionalCrit;
} else if(additionalCrit == null) {
return primaryCrit;
} else {
return languageFactory.createAndOr(Operator.AND, primaryCrit, additionalCrit);
}
}
/**
* Combines a list of conditions under a single AndOr
* @param crits
* @return
*/
public static Condition combineCriteria(List crits) {
if(crits == null || crits.isEmpty()) {
return null;
}
if (crits.size() == 1) {
return crits.get(0);
}
Condition result = null;
for (Condition crit : crits) {
if (result == null) {
result = crit;
} else {
result = new AndOr(result, crit, Operator.AND);
}
}
return result;
}
}