/*
* Copyright 2000-2010 JetBrains s.r.o.
*
* 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.intellij.util.xml;
/**
* Visitor is a very common design pattern. DOM model also has a visitor and it's called
* DomElementVisitor. The {@link DomElement} interface has methods {@link DomElement#accept(DomElementVisitor)}
* and {@link DomElement#acceptChildren(DomElementVisitor)}
* taking this visitor as a parameter.
* <p>
* DomElementVisitor has only one method: {@link #visitDomElement(DomElement)}.
* Where is the Visitor pattern? Where are all those methods with names like {@code visitT(T)} that
* are usually found in it? There are no such methods, because the actual interfaces ({@code T}'s)
* aren't known to anyone except you. But when you instantiate the DomElementVisitor
* interface, you may add your own {@code visitT()} methods and they will be called! You may
* even name them just {@code visit()}, specify the type of the parameter and everything will be
* fine.
* <p>
* For example, if you have two DOM element classes - {@code Foo} and {@code Bar}- your visitor
* may look like this:
* <pre>
* class MyVisitor implements DomElementVisitor {
* void visitDomElement(DomElement element) {}
* void visitFoo(Foo foo) {}
* void visitBar(Bar bar) {}
* }
* </pre>
* @author peter
*/
public interface DomElementVisitor {
void visitDomElement(DomElement element);
}