Use Cases of the Visitor Design Pattern

Below are the use cases of visitor design pattern:

• Document Processing:
  • In document processing applications you regularly operate with complicated structures of objects representing different types of elements like paragraphs, headings, lists, images, etc.
  • The Visitor Method can be applied to these objects to perform various operations without their classes.
  • For instance, you could determine an interface for visitors consisting of techniques for creating HTML or PDF representations of document elements.
  • User format whatsoever is sure to encompass a particular action for each element type thus cleanly separating the concerns and keeping the processes modular in the documents processing systems.
• Compiler Design:
  • In the Visitor Method of compiler design, traversing through the abstract syntax trees (ASTs) and performing several compiler tasks like type checking, optimization, and code generation are done.
  • Every node in the AST demonstrates an expression, statement, or function, and the Visitor Method helps you act on these nodes by defining different operations without modifying the classes.
  • For example, you could define a visitor interface with methods for performing type-checking on expressions and statements, and concrete implementations sourcing specific type-checking logic for each node type.
• GUI Component Frameworks:
  • In graphical user interface (GUI) component frameworks, the Visitor Method can perform various operations on the components of the GUI hierarchy like rendering, event handling, or layout.
  • Every element of the GUI hierarchy signifies a different type of visual component (for instance, the buttons, panels, and text fields), so the Visitor Method enables one to specify different operations on these components without needing to change their classes. For example, there could be interfaces for the visitor that can be used to render components and concrete visitors which will include concrete rendering logic for each component type.

The Visitor Design Pattern is a behavioral design pattern that allows you to separate algorithms or operations from the objects on which they operate. It enables you to add new operations to objects without modifying their structure.