Commons JXPath example source code file (InfoSetUtil.java)

This example Commons JXPath source code file (InfoSetUtil.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons JXPath tags/keywords

boolean, boolean, double, evalcontext, evalcontext, nodepointer, not_a_number, number, number, one, pointer, string, string, zero

The Commons JXPath InfoSetUtil.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.jxpath.ri;

import org.apache.commons.jxpath.Pointer;
import org.apache.commons.jxpath.ri.model.NodePointer;
import org.apache.commons.jxpath.ri.model.VariablePointer;

/**
 * Type conversions, XPath style.
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
 */
public class InfoSetUtil {

    private static final Double ZERO = new Double(0);
    private static final Double ONE = new Double(1);
    private static final Double NOT_A_NUMBER = new Double(Double.NaN);

    /**
     * Converts the supplied object to String.
     * @param object to convert
     * @return String value
     */
    public static String stringValue(Object object) {
        if (object instanceof String) {
            return (String) object;
        }
        if (object instanceof Number) {
            double d = ((Number) object).doubleValue();
            long l = ((Number) object).longValue();
            return d == l ? String.valueOf(l) : String.valueOf(d);
        }
        if (object instanceof Boolean) {
            return ((Boolean) object).booleanValue() ? "true" : "false";
        }
        if (object == null) {
            return "";
        }
        if (object instanceof NodePointer) {
            return stringValue(((NodePointer) object).getValue());
        }
        if (object instanceof EvalContext) {
            EvalContext ctx = (EvalContext) object;
            Pointer ptr = ctx.getSingleNodePointer();
            return ptr == null ? "" : stringValue(ptr);
        }
        return String.valueOf(object);
    }

    /**
     * Converts the supplied object to Number.
     * @param object to convert
     * @return Number result
     */
    public static Number number(Object object) {
        if (object instanceof Number) {
            return (Number) object;
        }
        if (object instanceof Boolean) {
            return ((Boolean) object).booleanValue() ? ONE : ZERO;
        }
        if (object instanceof String) {
            try {
                return new Double((String) object);
            }
            catch (NumberFormatException ex) {
                return NOT_A_NUMBER;
            }
        }
        if (object instanceof EvalContext) {
            EvalContext ctx = (EvalContext) object;
            Pointer ptr = ctx.getSingleNodePointer();
            return ptr == null ? NOT_A_NUMBER : number(ptr);
        }
        if (object instanceof NodePointer) {
            return number(((NodePointer) object).getValue());
        }
        return number(stringValue(object));
    }

    /**
     * Converts the supplied object to double.
     * @param object to convert
     * @return double
     */
    public static double doubleValue(Object object) {
        if (object instanceof Number) {
            return ((Number) object).doubleValue();
        }
        if (object instanceof Boolean) {
            return ((Boolean) object).booleanValue() ? 0.0 : 1.0;
        }
        if (object instanceof String) {
            if (object.equals("")) {
                return 0.0;
            }
            try {
                return Double.parseDouble((String) object);
            }
            catch (NumberFormatException ex) {
                return Double.NaN;
            }
        }
        if (object instanceof NodePointer) {
            return doubleValue(((NodePointer) object).getValue());
        }
        if (object instanceof EvalContext) {
            EvalContext ctx = (EvalContext) object;
            Pointer ptr = ctx.getSingleNodePointer();
            return ptr == null ? Double.NaN : doubleValue(ptr);
        }
        return doubleValue(stringValue(object));
    }

    /**
     * Converts the supplied object to boolean.
     * @param object to convert
     * @return boolean
     */
    public static boolean booleanValue(Object object) {
        if (object instanceof Number) {
            double value = ((Number) object).doubleValue();
            final int negZero = -0;
            return value != 0 && value != negZero && !Double.isNaN(value);
        }
        if (object instanceof Boolean) {
            return ((Boolean) object).booleanValue();
        }
        if (object instanceof EvalContext) {
            EvalContext ctx = (EvalContext) object;
            Pointer ptr = ctx.getSingleNodePointer();
            return ptr == null ? false : booleanValue(ptr);
        }
        if (object instanceof String) {
            return ((String) object).length() != 0;
        }
        if (object instanceof NodePointer) {
            NodePointer pointer = (NodePointer) object;
            if (pointer instanceof VariablePointer) {
                return booleanValue(pointer.getNode());
            }
            pointer = pointer.getValuePointer();
            return pointer.isActual();
        }
        return object != null;
    }
}