hogql-parser-rs 1.3.59

Hand-rolled Rust HogQL parser with C++-parity AST output

hogql_parser_rs

ALL(*) variant of the rust HogQL parser. Loads the same serialized ATN that ANTLR generates for cpp and implements the runtime simulator (lexer ATN sim, DFA cache, SLL/LL prediction, semantic predicates).

Why a separate crate

hogql_parser_rs is a hand-rolled Pratt + recursive-descent parser, fast but ~99.88% cpp grammar parity (36 cpp-accept rust-reject divergences per 30 000 Hypothesis examples). hogql_parser_backtrack_rs is its sibling exploring sequential backtracking on top of the same Pratt core.

This crate explores the third path: implement the same algorithm class that cpp uses (adaptive ALL(*)). Grammar parity by construction; perf TBD vs the Pratt parser.

See PARSER_BENCHMARK_BASELINE.md for the perf baseline this variant will be measured against.

Status

Scaffold only. Every entry point returns a NotImplementedError envelope.

Implementation roadmap:

• M1: ATN deserializer (parse .interp byte format)
• M2: Lexer ATN simulator + mode stack
• M3: Parser with SLL prediction
• M4: LL fallback for full-context decisions
• M5: Semantic predicates + HogQLX modes
• M6: Visitor parity (matches cpp's emit JSON shape)

Selecting in Python

Exposed via the rust-json backend in posthog/hogql/parser.py.

Building locally

maturin develop --release -m rust/hogql/parser/Cargo.toml

Coexists with hogql_parser_rs and hogql_parser_backtrack_rs — all three wheels install side by side under distinct Python module names.