Behavior mode-Visitor Mode

Using System;
Using System. Collections. Generic;
Using System. text;
Using System. collections;

NamespaceVisitor Mode
{

/*
* Access Mode intent: indicates an operation that acts on each element in an object structure. It can define new operations that act on these elements without changing the classes of each element.
* Key Points of access mode implementation: 1. Use a stable management container to manage the elements to be accessed
* Applicable scenarios of access mode: 1. When there is an effect sealing class level
* 2. perform a variety of different operations on the class level
* 3. These operations follow the class level core functions are orthogonal
* 4. Flexibility for defining new operations in the future
*/

///

/// declares a visitor operation for each subclass of element in the object structure.
//
Public abstract class visitor
{< br> Public abstract void visitconcreteelementa (concreteelementa A);

Public abstract void visitconcreteelementb (concreteelementb);
}

///

/// specific Category
//
Public class concretevisitor1: Visitor
{< br> Public override void visitconcreteelementa (concreteelementa A1)
{< br> /// access data related to element a
}

PublicOverrideVoidVisitconcreteelementb (concreteelementb B1)
{
//Access Data of Element B
}
}

PublicClassConcretevisitor2: visitor
{
PublicOverrideVoidVisitconcreteelementa (concreteelementa A2)
{
//Access specific A2 Element Data
}

Public Override Void Visitconcreteelementb (concreteelementb B2)
{
// Access data related to specific B2 Elements
}
}
/// <Summary>
/// Defines an accept operation, which takes a visitor as the parameter.
/// </Summary>
Public Abstract Class Element
{
Public Abstract Void Accept (visitor );
}

PublicClassConcreteelementa: Element
{
PublicOverrideVoidAccept (visitor)
{
Visitor. visitconcreteelementa (This);

}
PublicVoidOperationa ()
{
//Operations on Element
}
}

Public Class Concreteelementb: Element
{
Public Override Void Accept (visitor)
{
Visitor. visitconcreteelementb ( This );
}
}
/// <Summary>
/// Enumeration of its elements provides a high-level interface to allow visitors to access its elements
/// </Summary>
Public Class Objectstructure
{
Ilist < Element > Elements = New List < Element > ();
Public Void Add (Element E)
{
Elements. Add (E );
}

PublicVoidRemove (Element E)
{
Elements. Remove (E );

}

Public void Accept (visitor)
{< br> foreach (Element E in elements)
{< br> E. accept (visitor);
}< BR >}

Public class appclient
{< br> Public static void main ( string [] ARGs)
{< br> objectstructure OS = New objectstructure ();
OS. add ( New concreteelementa ());
OS. add ( New concreteelementb ());

Concretevisitor1 visitor1=NewConcretevisitor1 ();
Concretevisitor2 visitor2=NewConcretevisitor2 ();

OS. Accept (visitor1 );

OS. Accept (visitor2 );

}

}
}