January 2026
Intermediate to advanced
372 pages
8h 14m
English
Content preview from Building Programming Language Interpreters
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13
Lexing: Turning Text into a Stream of Tokens
Now that I have an interpreter runtime capable of executing the instructions that my programming language needs, it is time to start the process of transforming source code into those instructions.
The first step in this process transforms the sequence of characters into a sequence of typed tokens. This allows the subsequent steps to work at a higher level of abstraction than plain text, simplifying the process of specifying the language grammar.
In this chapter, I will do the following:
- Identify the different types of tokens in the language and the data each needs to store
- Specify the rules for how those tokens are matched
- Evaluate different libraries that can be used to implement a lexer and ...
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