    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.jxpath;
    019
    020import java.util.HashMap;
    021
    022/**
    023 * A basic implementation of the Variables interface that uses a HashMap.
    024 */
    025public class BasicVariables implements Variables {
    026
    027    private static final long serialVersionUID = 2708263960832062725L;
    028
    029    /**
    030     * Contains the values of declared variables
    031     */
    032    private final HashMap vars = new HashMap();
    033
    034    /**
    035     * Constructs a new instance.
    036     */
    037    public BasicVariables() {
    038        // empty
    039    }
    040
    041    /**
    042     * Defines a new variable with the specified value or modifies the value of an existing variable.
    043     *
    044     * @param varName is a variable name without the "$" sign
    045     * @param value   is the new value for the variable, which can be null
    046     */
    047    @Override
    048    public void declareVariable(final String varName, final Object value) {
    049        vars.put(varName, value);
    050    }
    051
    052    /**
    053     * Returns the value of the variable if it is defined, otherwise, throws IllegalArgumentException
    054     *
    055     * @param varName is a variable name without the "$" sign
    056     * @return the value of the variable
    057     */
    058    @Override
    059    public Object getVariable(final String varName) {
    060        // Note that a variable may be defined with a null value
    061        if (vars.containsKey(varName)) {
    062            return vars.get(varName);
    063        }
    064        throw new IllegalArgumentException("No such variable: '" + varName + "'");
    065    }
    066
    067    /**
    068     * Returns true if the variable has been defined, even if the value of the variable is null.
    069     *
    070     * @param varName is a variable name without the "$" sign
    071     * @return true if the variable is declared
    072     */
    073    @Override
    074    public boolean isDeclaredVariable(final String varName) {
    075        return vars.containsKey(varName);
    076    }
    077
    078    @Override
    079    public String toString() {
    080        return vars.toString();
    081    }
    082
    083    /**
    084     * Removes an existing variable. May throw UnsupportedOperationException.
    085     *
    086     * @param varName is a variable name without the "$" sign
    087     */
    088    @Override
    089    public void undeclareVariable(final String varName) {
    090        vars.remove(varName);
    091    }
    092}