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 package org.apache.commons.betwixt.expression; 018 019 /** <p><code>ConstantExpression</code> represents a constant expression.</p> 020 * 021 * <p> In other words, {@link #evaluate} returns a value independent of the context. </p> 022 * 023 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a> 024 * @version $Revision: 438373 $ 025 */ 026 public class ConstantExpression implements Expression { 027 028 /** The value of this expression */ 029 private Object value; 030 031 /** Base constructor 032 */ 033 public ConstantExpression() { 034 } 035 036 /** 037 * Convenience constructor sets <code>value</code> property. 038 * @param value the Object which is the constant value for this expression 039 */ 040 public ConstantExpression(Object value) { 041 this.value = value; 042 } 043 044 /** 045 * Evaluate expression against given context. 046 * 047 * @param context evaluate expression against this context 048 * @return current value of <code>value</code> property 049 */ 050 public Object evaluate(Context context) { 051 return value; 052 } 053 054 /** 055 * Do nothing 056 * @see org.apache.commons.betwixt.expression.Expression 057 */ 058 public void update(Context context, String newValue) { 059 // do nothing 060 } 061 062 /** 063 * Gets the constant value of this expression 064 * @return this expression's constant value 065 */ 066 public Object getValue() { 067 return value; 068 } 069 070 /** 071 * Sets the constant value of this expression 072 * @param value the constant value for this expression 073 */ 074 public void setValue(Object value) { 075 this.value = value; 076 } 077 078 /** 079 * Returns something useful for logging 080 * @return something useful for logging 081 */ 082 public String toString() { 083 return "ConstantExpression [value=" + value + "]"; 084 } 085 }