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📐 DESIGN PATTERN: Interpreter

· pattern

The _____ Pattern is a design pattern for defining and evaluating expressions or commands in a custom language.

It involves abstract expressions, terminal and non-terminal expressions, and a context for evaluation.

* Visitor

* Null object

* Interpreter

* Memento

Answer: Interpreter

The Interpreter Pattern is a behavioral design pattern in software development that is used to define a language grammar or syntax and provide a way to evaluate expressions written in that language.

It's typically used for tasks like interpreting and processing textual commands or expressions.

Key components of the Interpreter Pattern:

1) Abstract Expression:

The Abstract Expression is an abstract class or interface that defines the common interface for all terminal and non-terminal expressions in the language.

It typically includes an interpret() method.

2) Terminal Expression:

Terminal expressions represent the smallest units of the language and usually implement the interpret() method.

They do not have sub-expressions.

3) Non-terminal Expression:

Non-terminal expressions represent higher-level constructs that consist of multiple sub-expressions.

They also implement the interpret() method and can recursively evaluate their sub-expressions.


The Context contains information and state that is shared among expressions during evaluation.

t provides the necessary context for interpreting expressions.


The Client is responsible for constructing and assembling expressions based on the language's grammar and providing input to be evaluated.

The Interpreter Pattern is well-suited for scenarios where you need to process and evaluate expressions or commands specified in a custom language.

It enables the creation of interpreters that can handle complex expressions by breaking them down into simpler parts and recursively evaluating them.