/*
* $Id: Expression.java 788032 2009-06-24 14:08:32Z apetrelli $
*
* 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.tiles;
import static org.apache.tiles.
CompareUtil.*;
/**
* It is an expression, along with the expression language (e.g. EL, MVEL, OGNL)
* it is expressed with.
*
* @version $Rev: 788032 $ $Date: 2009-06-25 00:08:32 +1000 (Thu, 25 Jun 2009) $
* @since 2.2.0
*/
public class
Expression {
/**
* The expression itself.
*/
private
String expression;
/**
* The language of the expression.
*/
private
String language;
/**
* Constructor.
*
* @param expression The expression itself.
* @param language The language of the expression.
* @since 2.2.0
*/
public
Expression(
String expression,
String language) {
this.
expression =
expression;
this.
language =
language;
}
/**
* Constructor, using the default (i.e. <code>null</code>) language.
*
* @param expression The expression itself.
* @since 2.2.0
*/
public
Expression(
String expression) {
this(
expression, null);
}
/**
* Copy constructor.
*
* @param toCopy The expression to copy.
* @since 2.2.0
*/
public
Expression(
Expression toCopy) {
this.
expression =
toCopy.
expression;
this.
language =
toCopy.
language;
}
/**
* Creates an Expression object from a string in the form
* <code>LANGUAGE:EXPRESSION</code>.
*
* @param describedExpression The expression in the form
* <code>LANGUAGE:EXPRESSION</code>. The LANGUAGE part should be expressed
* only with letters and numbers.
* @return The created object, or <code>null</code> if the expression is null.
* @since 2.2.0
*/
public static
Expression createExpressionFromDescribedExpression(
String describedExpression) {
if (
describedExpression != null) {
String language = null;
String expression =
describedExpression;
if (
describedExpression.
matches("[a-zA-Z0-9]+:.+")) {
language =
describedExpression.
substring(0,
describedExpression.
indexOf(':'));
expression =
describedExpression.
substring(
describedExpression.
indexOf(':') + 1);
}
return new
Expression(
expression,
language);
}
return null;
}
/**
* Creates an Expression object from the expression and its language.
*
* @param expression The expression itself.
* @param language The language of the expression.
* @return The created object, or <code>null</code> if the expression is null.
* @since 2.2.0
*/
public static
Expression createExpression(
String expression,
String language) {
if (
expression != null) {
return new
Expression(
expression,
language);
}
return null;
}
/**
* Returns the expression string.
*
* @return The expression itself.
* @since 2.2.0
*/
public
String getExpression() {
return
expression;
}
/**
* Returns the language in which the expression is expressed.
*
* @return The expression language.
* @since 2.2.0
*/
public
String getLanguage() {
return
language;
}
/** {@inheritDoc} */
@
Override
public boolean
equals(
Object obj) {
Expression exp = (
Expression)
obj;
return
nullSafeEquals(
expression,
exp.
expression)
&&
nullSafeEquals(
language,
exp.
language);
}
/** {@inheritDoc} */
@
Override
public int
hashCode() {
return
nullSafeHashCode(
expression) +
nullSafeHashCode(
language);
}
/** {@inheritDoc} */
@
Override
public
String toString() {
return (
language == null ? "DEFAULT" :
language) + ":" +
expression;
}
}