Question 1

How do I generate random test data with bnf?

Accepted Answer

Parse your BNF grammar using Grammar::parse, then call grammar.generate() to produce a random sentence. Ensure your grammar avoids infinite loops, as the library detects and errors on recursive productions like ::= .

Question 2

bnf vs pest or nom for Rust parsing?

Accepted Answer

bnf is specifically for parsing BNF grammar definitions, while pest and nom are general-purpose parsing libraries for building custom parsers. Use bnf if you need to manipulate BNF grammars directly; for other parsing tasks, pest or nom might be better.

Question 3

Can bnf parse EBNF grammars?

Accepted Answer

bnf supports some EBNF-like extensions like groups and optionals, but not all EBNF features. It normalizes these into standard BNF, so it's suitable for basic use but not full EBNF compatibility.

Question 4

How to validate a string against a grammar using bnf?

Accepted Answer

Parse the grammar with Grammar::parse, create a parser using grammar.build_parser(), then call parser.parse_input(your_string) to check if it matches. This returns parse trees for valid inputs.

Question 5

Does bnf handle left-recursive grammars?

Accepted Answer

The README doesn't specify, but since it uses standard BNF parsing, it might handle left recursion. However, infinite loop detection could flag it, so test with your specific grammar to ensure compatibility.

Question 6

Is bnf efficient for large or complex grammars?

Accepted Answer

Performance details aren't provided, but as a Rust library, it should be reasonably efficient. For very large grammars, normalization overhead might impact performance, so benchmark if scale is a concern.

bnf

What is bnf?

Overview

Use Cases

Best For

Found a gem we're missing?

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions