The interpreter pattern evaluates textual inputs. It does it by turning it into separated lexical terms (lexing) and interpreting each sequence (parsing). You can think of programming languages, or languages meant to carry information such as XML.
For example, we want to calculate the result of this formula: 1+3+5*7
First, we need to find the terms: [1,3,5,7] and the operations: [+, +, *]
Second, we interpret them into a logical sequence: add(add(1,3),multiply(5,7)).
The idea is to single out terms and operations in order to simplify and make the design flexible to different inputs (ex: term order, etc.)
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