LR(0) Parser Generator. Grammar to NFA, DFA, Table

Overview

Given a grammar in (limited) EBNF, this tool will draw the NFA and DFA used in the producing a corresponding LR(0) parser. It also generates the LR(0) parse table, in a pretty, human-readable format, and as JSON so that you can conveniently read the table in for driving your own code.

Feed me your delicious grammar, mortal.

Grammar Specification Requirements

Productions use the following format:

• Goal -> A
• A -> ( A ) | Two
• Two -> a
• Two -> b

• "->" separates the non-terminal on the left-hand-side from what it produces.
• x -> y | z is EBNF short-hand for
  • x -> y
  • x -> z

Be certain to place spaces between things you don't want read as one symbol. ( A ) ≠ (A)

About This Tool

Intended Audience

Computer science students & autodidacts studying compilers or parsing.

Purpose

This tool provides rapid feedback loop for learning about grammars. How?

• Rapid visualization of grammars enables convenient tweaking. Botched a production? No problem; tweak it and everything's spit back out.
• Ability to dump LR(0) and SLR(1) tables. Helps with manual parse tracing and hand-writing parsers.
• Assisting with coursework.

Underlying Theory

How to draw NFAs for SLR(0) and LR(1) grammars. Want to learn how it works or how to do it by hand? Read that.