org.apache.tiles.api.Expression Maven / Gradle / Ivy
/*
* 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.api;
import java.util.Objects;
/**
* It is an expression, along with the expression language (e.g. EL, MVEL, OGNL)
* it is expressed with.
*
* @since 2.2.0
*/
public class Expression {
/**
* The expression itself.
*/
private final String expression;
/**
* The language of the expression.
*/
private final 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. null) 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
* LANGUAGE:EXPRESSION.
*
* @param describedExpression The expression in the form
* LANGUAGE:EXPRESSION. The LANGUAGE part should be expressed
* only with letters and numbers.
* @return The created object, or null 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 null 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) {
if (obj == null) {
return false;
}
if (!(obj instanceof Expression)) {
return false;
}
Expression exp = (Expression) obj;
return Objects.equals(expression, exp.expression) && Objects.equals(language, exp.language);
}
/**
* {@inheritDoc}
*/
@Override
public int hashCode() {
return Objects.hashCode(expression) + Objects.hashCode(language);
}
/**
* {@inheritDoc}
*/
@Override
public String toString() {
return (language == null ? "DEFAULT" : language) + ":" + expression;
}
}