An introduction to the Interpreter pattern of the Java design pattern

Interpreter definition: defines the grammar of a language and sets up an Interpreter to interpret the sentences in that language.

Interpreter does not seem to be widely used. It describes how a language Interpreter is constructed. In practice, we may seldom construct the grammar of a language. So let's take a quick look.

The first step is to create an interface to describe common operations.

    public interface AbstractExpression {

　　 void interpret( Context context );

    }

Now let's look at some global information that contains outside of the interpreter

public interface Context { }
AbstractExpression There are two kinds of realization: terminal expression and non-terminal expression. 

    public class TerminalExpression implements AbstractExpression {

　　 public void interpret( Context context ) { }

    }
 For no rule in grammar, non-terminal expressions are required: 

public class NonterminalExpression implements AbstractExpression {

　　 private AbstractExpression successor;

　　

　　 public void setSuccessor( AbstractExpression successor ) {

　　　　 this.successor = successor;

　　 }
　　 public AbstractExpression getSuccessor() {

　　　　 return successor;

　　 }
　　 public void interpret( Context context ) { }

}