/*
 * 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;

import java.io.Serializable;

/**
 * Pointers represent locations of objects and their properties in Java object graphs. JXPathContext has methods
 * ({@link JXPathContext#getPointer(java.lang.String) getPointer()} and ({@link JXPathContext#iteratePointers(java.lang.String) iteratePointers()}, which, given
 * an XPath, produce Pointers for the objects or properties described the path. For example, {@code ctx.getPointer
 * ("foo/bar")} will produce a Pointer that can get and set the property "bar" of the object which is the value of the property "foo" of the root object. The
 * value of {@code ctx.getPointer("aMap/aKey[3]")} will be a pointer to the 3'rd element of the array, which is the value for the key "aKey" of the map, which
 * is the value of the property "aMap" of the root object.
 */
public interface Pointer extends Cloneable, Comparable, Serializable {

    /**
     * Returns a string that is a proper "canonical" XPath that corresponds to this pointer. Consider this example:
     * <p>
     * {@code Pointer  ptr = ctx.getPointer("//employees[firstName = 'John']")
     * }
     * </p>
     * <p>
     * The value of {@code ptr.asPath()} will look something like {@code "/departments[2]/employees[3]"}, so, basically, it represents the concrete location(s)
     * of the result of a search performed by JXPath. If an object in the pointer's path is a Dynamic Property object (like a Map), the asPath method generates
     * an XPath that looks like this: {@code "
     * /departments[@name = 'HR']/employees[3]"}.
     *
     * @return String path
     */
    String asPath();

    /**
     * Pointers are cloneable.
     *
     * @return cloned Object
     */
    Object clone();

    /**
     * Returns the raw value of the object, property or collection element this pointer represents. Never converts the object to a canonical type: returns it as
     * is.
     * <p>
     * For example, for an XML element, getNode() will return the element itself rather than the text it contains.
     * </p>
     *
     * @return Object node
     */
    Object getNode();

    /**
     * Returns the node this pointer is based on.
     *
     * @return Object
     */
    Object getRootNode();

    /**
     * Returns the value of the object, property or collection element this pointer represents. May convert the value to one of the canonical InfoSet types:
     * String, Number, Boolean, Set.
     * <p>
     * For example, in the case of an XML element, getValue() will return the text contained by the element rather than the element itself.
     * </p>
     *
     * @return Object value
     */
    Object getValue();

    /**
     * Modifies the value of the object, property or collection element this pointer represents.
     *
     * @param value value to set
     */
    void setValue(Object value);
}
