解释器模式

Give a language, the Interpreter design pattern defines a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language.

The Interpreter Design Pattern provides a way to evaluate language grammar or expression. This pattern is used in SQL Parsing, Symbol Processing Enginee, etc.

UML Class Diagram

 Context: This is a class that contains information that is going to be used by the interpreter ot interpret.

  AbstractExpression: This is an interface that defines the interpret method which should be impletmented by the subclasses. This method takes the context object as a parameter. This context object holds the data we want to interpret.

  TerminalExpression: This is a concrete class that implements the AbstractExpression interface. The TerminalExpression represents elements in the grammar that do not get replaced such as symbols.

   NonTerminalExpression: This is also a concrete class that implements the AbstractExpression interface. The NonTerminalExpression represents elements in the grammar that do not get replaced such as symbols.

   Client: This is a class that builds the abstract syntax tree for a set of instructions in the given grammar.This tree builds with the help of instances of NonTerminalExpression and TerminalExpression classes.

 

When to use the Interpreter Design Pattern in C#?

• Grammar is simple
• Efficiency is not a critical concern