LPG2

LPG2 (Lookahead Parser Generator v2) compiles .g / .lpg grammars into parse tables and semantic-action code for your target language.

Current version: 2.3.0 (lpg-v2.3.0)

中文文档 · Documentation index

Documentation

Docs are layered by audience. New to LPG? Start with the Quick Start.

Document	Audience	Contents
Quick Start (5 min)	Beginners	Download/build generator → run calculator
Concepts	Beginners	How generator / templates / runtime fit together
Tutorial	Beginners	Step-by-step calculator grammar
User guide	Grammar authors, integrators	Tooling, CLI, languages, runtimes, FAQ
Developer guide	Generator maintainers	Build, layout, bootstrap, tests, backends
AI / Agent playbook	AI coding agents	Workflow, CLI, language matrix, anti-patterns (AGENTS.md)
Chinese docs	中文读者	上手 / 概念 / 教程 / USER / AI 等
Contributing	Contributors	Build, goldens, PR process
Doc index	—	Pick a path by role
Ecosystem	Integrators / release	Runtime versions, package coords, release checklist

Topics:

• Grammar reference (EN summary) · full Chinese
• Bootstrap policy — regenerating jikespg_* parsers
• Machine-readable matrix: ecosystem/compat.json

Repository layout

Path	Role
lpg2/	Generator sources
runtime/	Language runtimes (git submodules)
tool/	VS Code extension and language server (submodules)
grammars-example/	Example grammars (submodule)
examples/calculator/	Runnable calculator starter
docs/	Documentation (docs/en/ default; Chinese alongside)

Quick try

Fastest: npm

npx lpg2 --help
npx lpg2 -programming_language=java -table your.g

Browser playground (WASM, built by CI): playground/.

The C++ runtime provides token-level re-lex + statement-level re-parse (not tree-sitter subtree reuse); see USER.md / ECOSYSTEM.md.

Recommended: Release binary + calculator

1. Download a platform archive from GitHub Releases and verify SHA256SUMS
2. Init the runtime submodule for your language (e.g. Java):

git submodule update --init runtime/lpg-runtime
export LPG_BIN=/path/to/bin/lpg-v2.3.0
./examples/calculator/scripts/run.sh java

Full steps: docs/en/QUICKSTART.md.

Or build the generator from source:

cd lpg2
cmake -S . -B build && cmake --build build -j
export LPG_BIN="$PWD/build/lpg-v2.3.0"
cd ..
./examples/calculator/scripts/run.sh java

Integration and CLI details: user guide.

Related projects

• LPG-rust-runtime — Rust parse runtime
• LPG2-grammars-example — grammar examples
• LPG-VScode — VS Code extension