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This article introduces the knowledge of "what are the advantages and disadvantages of web interpreter mode". Many people will encounter this dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Effect.

Advantages of interpreter mode

1) easy to implement grammar

All kinds of settings in the interpreter mode correspond to each node in the grammar book one by one, and have similar functions and the same structure, which is very easy to implement.

2) easy to change and extend grammar

The interpreter pattern uses classes to represent grammars, and the functions of each grammar element are concentrated in the corresponding class. the advantage of this natural functional partition is that it is very easy to maintain. Whether adding new features or maintaining existing features will have little impact on existing features.

3) it is easy to "evaluate" the new expression.

Of course, the calculation here may be a real calculation, or it may be to implement some function. The method of implementation is also very simple, as long as the so-called computing function is implemented for the class corresponding to each grammar element.

Shortcomings of interpreter mode

As the saying goes, there are advantages and disadvantages, and so is the interpreter mode. If the grammatical structure that needs to be expressed is very complex, preparing the corresponding class for each grammatical element can be a great burden.

Realize

The interpreter pattern is one of the more magical design patterns. The so-called magic means that as long as it is realized in accordance with the specified steps, there is a high probability of getting the ideal result. When using the interpreter mode, you usually follow these steps.

1) build the syntax tree

The interpreter pattern does not specify how to create the syntax tree. The syntax tree can be generated by an advanced parser, created by a handwritten recursive descending parser, or provided directly by the customer.

2) define interpretation operation

For simple cases, you can simply generate a "calculate" action for the class corresponding to each syntax element. However, in some cases, users may want to implement different "calculation" behaviors on the same syntax tree. For example, for a simple four-item operation syntax tree, when debugging, users may want to get the operation results directly, but they also hope to generate code in different languages in practical application. It might be better to use the visitor pattern that will be described later.

That's all for "what are the pros and cons of the web interpreter pattern?" Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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