Awesome

ll1pg

Yet another parser generation tool. It can generate either a parser class or a LL prediction table in Java. The input specification file must specify a LL(1) grammar.

This tool is now a part of the decaf project for the undergraduate course Principles of Compilation in Tsinghua University.

Build

Prebuilt jars will be updated in the release page.

To build from source, simply type ./gradlew build. To assemble a standalone jar with all dependencies, type ./gradlew assembly and you'll find it at build/libs/.

Usage

java -jar ll1pg.jar [-parser | -table | -check] <spec file> <output dir>

where <output dir> is the destination folder for the generated parser, and <spec file> is the path of the specification file. The options mean:

• -parser: generate a Java parser
• -table: generate a LL predication table
• -check: simply check if a grammar is LL(1), or else warnings will be reported

See here for the definition of specification file. And here for how we resolve conflicts even when your grammar is not LL(1).

We strongly recommend you to read our wiki first.

Demo Projects

To integrate our tool with your project better, please take a closer look at our demo project arith, which implements a simple calculator. Also, the decaf project is a good practice.