org.pentaho.metadata.query.model.util.BooleanComparator.java Source code

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Here is the source code for org.pentaho.metadata.query.model.util.BooleanComparator.java

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/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * Copyright (c) 2016 Pentaho Corporation.  All rights reserved.
 */
package org.pentaho.metadata.query.model.util;

import java.util.Comparator;

import org.apache.commons.math.MathException;
import org.apache.commons.math.util.DefaultTransformer;
import org.pentaho.metadata.messages.Messages;

public class BooleanComparator implements Comparator<Object> {

    private static BooleanComparator _instance = new BooleanComparator();

    private BooleanComparator() {
    }

    public static Comparator<Object> getComparator() {
        return _instance;
    }

    public static Comparable<Object> getComparable(Object object) {
        final Boolean b = toBoolean(object);
        return new Comparable<Object>() {

            public int compareTo(Object o) {
                return _instance.compare(b, o);
            }

            @Override
            public String toString() {
                return "BooleanComparable[boolean=" + b + "]"; //$NON-NLS-1$ //$NON-NLS-2$
            }
        };
    }

    public int compare(Object o1, Object o2) {
        Boolean b1 = toBoolean(o1);
        Boolean b2 = toBoolean(o2);
        return b1.compareTo(b2);
    }

    private static Boolean toBoolean(Object o) {
        if (o != null) {
            if (o instanceof Boolean) {
                return (Boolean) o;
            }
            if (o instanceof String) {
                try {
                    return parseBoolean((String) o);
                } catch (IllegalArgumentException e) {
                    return false;
                }
            }
            if (o instanceof Number) {
                try {
                    double number = new DefaultTransformer().transform(o);
                    if (number >= 1.0) {
                        return true;
                    }
                } catch (MathException e) {
                    // ignore
                }
            }
        }
        return false;
    }

    /**
     * Parses a string and returns a boolean representation of it. To parse the string the following values will be
     * accepted, irrespective of case.
     * <ul>
     * <li>true</li>
     * <li>false</li>
     * <li>1</li>
     * <li>0</li>
     * <li>yes</li>
     * <li>no</li>
     * <li>y</li>
     * <li>n</li>
     * </ul>
     * 
     * @param string
     *          the string to parse
     * @return a boolean
     * @throws IllegalArgumentException
     *           if the string provided cannot be parsed as a boolean
     */
    public static boolean parseBoolean(String string) throws IllegalArgumentException {
        string = string.trim();
        if ("true".equalsIgnoreCase(string) || "1".equals(string) //$NON-NLS-1$ //$NON-NLS-2$
                || "y".equalsIgnoreCase(string) //$NON-NLS-1$
                || "yes".equalsIgnoreCase(string)) { //$NON-NLS-1$
            return true;
        } else if ("false".equalsIgnoreCase(string) || "0".equals(string) //$NON-NLS-1$ //$NON-NLS-2$
                || "n".equalsIgnoreCase(string) //$NON-NLS-1$
                || "no".equalsIgnoreCase(string)) { //$NON-NLS-1$
            return false;
        } else {
            throw new IllegalArgumentException(
                    Messages.getErrorString("BooleanComparator.ERROR_0001_UNABLE_TO_DETECT_BOOLEAN_VAL", string)); //$NON-NLS-1$
        }
    }

}