AbstractJsonProvider.java

/*
 * Copyright 2011 the original author or authors.
 * 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 com.jayway.jsonpath.spi.json;

import com.jayway.jsonpath.JsonPathException;

import java.util.Collection;
import java.util.List;
import java.util.Map;

public abstract class AbstractJsonProvider implements JsonProvider {

    /**
     * checks if object is an array
     *
     * @param obj object to check
     * @return true if obj is an array
     */
    public boolean isArray(Object obj) {
        return (obj instanceof List);
    }

    /**
     * Extracts a value from an array
     *
     * @param obj an array
     * @param idx index
     * @return the entry at the given index
     */
    public Object getArrayIndex(Object obj, int idx) {
        return ((List) obj).get(idx);
    }

    public final Object getArrayIndex(Object obj, int idx, boolean unwrap){
        return getArrayIndex(obj, idx);
    }

    public void setArrayIndex(Object array, int index, Object newValue) {
        if (!isArray(array)) {
            throw new UnsupportedOperationException();
        } else {
            List l = (List) array;
            if (index == l.size()){
                l.add(newValue);
            }else {
                l.set(index, newValue);
            }
        }
    }


    /**
     * Extracts a value from an map
     *
     * @param obj a map
     * @param key property key
     * @return the map entry or {@link com.jayway.jsonpath.spi.json.JsonProvider#UNDEFINED} for missing properties
     */
    public Object getMapValue(Object obj, String key){
        Map m = (Map) obj;
        if(!m.containsKey(key)){
            return JsonProvider.UNDEFINED;
        } else {
            return m.get(key);
        }
    }

    /**
     * Sets a value in an object
     *
     * @param obj   an object
     * @param key   a String key
     * @param value the value to set
     */
    @SuppressWarnings("unchecked")
    public void setProperty(Object obj, Object key, Object value) {
        if (isMap(obj))
            ((Map) obj).put(key.toString(), value);
        else {
            throw new JsonPathException("setProperty operation cannot be used with " + obj!=null?obj.getClass().getName():"null");
        }
    }



    /**
     * Removes a value in an object or array
     *
     * @param obj   an array or an object
     * @param key   a String key or a numerical index to remove
     */
    @SuppressWarnings("unchecked")
    public void removeProperty(Object obj, Object key) {
        if (isMap(obj))
            ((Map) obj).remove(key.toString());
        else {
            List list = (List) obj;
            int index = key instanceof Integer ? (Integer) key : Integer.parseInt(key.toString());
            list.remove(index);
        }
    }


    /**
     * checks if object is a map (i.e. no array)
     *
     * @param obj object to check
     * @return true if the object is a map
     */
    public boolean isMap(Object obj) {
        return (obj instanceof Map);
    }

    /**
     * Returns the keys from the given object
     *
     * @param obj an object
     * @return the keys for an object
     */
    @SuppressWarnings("unchecked")
    public Collection<String> getPropertyKeys(Object obj) {
        if (isArray(obj)) {
          throw new UnsupportedOperationException();
        } else {
            return ((Map) obj).keySet();
        }
    }

    /**
     * Get the length of an array or object
     *
     * @param obj an array or an object
     * @return the number of entries in the array or object
     */
    public int length(Object obj) {
        if (isArray(obj)) {
            return ((List) obj).size();
        } else if (isMap(obj)){
            return getPropertyKeys(obj).size();
        } else if(obj instanceof String){
            return ((String)obj).length();
        }
        throw new JsonPathException("length operation cannot be applied to " + obj!=null?obj.getClass().getName():"null");
    }

    /**
     * Converts given array to an {@link Iterable}
     *
     * @param obj an array
     * @return an Iterable that iterates over the entries of an array
     */
    @SuppressWarnings("unchecked")
    public Iterable<? extends Object> toIterable(Object obj) {
        if (isArray(obj))
            return ((Iterable) obj);
        else
            throw new JsonPathException("Cannot iterate over " + obj!=null?obj.getClass().getName():"null");
    }

    @Override
    public Object unwrap(Object obj) {
        return obj;
    }

}