Lookahead

Definitions

1. A parsing technique that examines upcoming tokens or characters in the input stream without consuming them, used to make decisions about which grammar rule to apply. In regular expressions, lookahead assertions match a position based on what follows without including it in the match.

   In plain English: Peeking ahead at what comes next in the input to decide how to handle what you're looking at now, without actually moving forward.

   Example: "The parser needs two tokens of lookahead to disambiguate between a function call and a variable declaration."

Related Terms

• Formal Grammar
• JIT Compiler
• Parse Tree
• Parser Combinator
• Parser Generator
• Regex Engine
• Scope Resolution
• Capture Group
• Custom Parser