Intuiting Pratt Parsing
2 days ago
- #parsing
- #algorithms
- #compilers
- Explains Pratt parsing as a method to parse expressions with mixed operator precedence using left-leaning and right-leaning abstract syntax trees.
- Highlights that left-leaning trees represent decreasing or equal precedence (left-associative operators), while right-leaning trees represent strictly increasing precedence.
- Describes how to handle transitions from increasing to decreasing precedence by walking back up the spine of the tree to find where the new operator belongs.
- Provides pseudocode for a Pratt parser that uses left binding power (LBP) and right binding power (RBP) to manage associativity, with left-associative operators having equal LBP and RBP, and right-associative ones having RBP lower than LBP.
- Emphasizes the geometric intuition behind Pratt parsing, simplifying it as a walk-back procedure based on precedence changes, rather than presenting it as a complex trick.