ch.rasc.edsutil.PropertyComparator.java Source code

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Here is the source code for ch.rasc.edsutil.PropertyComparator.java

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/**
 * Copyright 2013-2015 Ralph Schaer <ralphschaer@gmail.com>
 *
 * 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 ch.rasc.edsutil;

import java.util.Comparator;

import org.springframework.expression.Expression;
import org.springframework.expression.spel.SpelCompilerMode;
import org.springframework.expression.spel.SpelParserConfiguration;
import org.springframework.expression.spel.standard.SpelExpressionParser;

public class PropertyComparator<T> implements Comparator<T> {
    private final static SpelExpressionParser parser = new SpelExpressionParser(
            new SpelParserConfiguration(SpelCompilerMode.IMMEDIATE, null));

    private final Expression readPropertyExpression;
    private final boolean ignoreCase;

    public PropertyComparator(String property) {
        this.readPropertyExpression = parser.parseExpression(property);
        this.ignoreCase = false;
    }

    public PropertyComparator(String property, boolean ignoreCase) {
        this.readPropertyExpression = parser.parseExpression(property);
        this.ignoreCase = ignoreCase;
    }

    @SuppressWarnings("unchecked")
    @Override
    public int compare(T o1, T o2) {
        Object left = this.readPropertyExpression.getValue(o1);
        Object right = this.readPropertyExpression.getValue(o2);

        if (left == right) {
            return 0;
        }
        if (left == null) {
            return -1;
        }
        if (right == null) {
            return 1;
        }

        if (left instanceof String && ignoreCase) {
            return ((String) left).compareToIgnoreCase((String) right);
        }

        return ((Comparable<Object>) left).compareTo(right);
    }

}