Revision Notes/Design Patterns
Field Entry - Design Patterns
Interpreter Pattern
Defines a grammar for a simple language and provides an interpreter to evaluate sentences in that language by representing each grammar rule as a class.
Field Note - Real-world Analogy
“Like a music sheet and a musician. The music notation is the language (grammar). Each symbol — a note, a rest, a chord — is an expression. The musician (interpreter) reads each symbol recursively and produces sound. The same sheet produces consistent output no matter which musician plays it, because they all follow the same interpretation rules.”
Field Observations - Key Topics Covered
The Interpreter pattern is used when you have a simple language or expression that you need to evaluate repeatedly. You define grammar rules, and each rule becomes a class. To evaluate an expression, you build a tree of these rule objects (an Abstract Syntax Tree, or AST) and call interpret() on the root.
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