Crate fn_bnf

fn-bnf

This crate contains a no_std compatible, low-allocation parsing library that uses a BNF-like syntax with the define! macro to allow for using arbitrary Rust items as grammar rules, and for parsing both strs and any [T] (for example, [u8] or [Token]).

If you just want to skip to writing grammars, look at the documentation for define!.

Feature flags

This crate has two feature flags:

• more_tuple_impls, raising the amount of elements Rule is implemented for on tuples of Rules from 16 to 256 - however, enabling this will raise compilation times dramatically
• error_in_core, enabling use of this library before Rust 1.81.0 on nightly compilers - however, continued support for versions below 1.81.0 is not guaranteed

A note about the stack

This library’s very lifeblood is deep - and likely recursive - function calls. You may run into stack overflow issues if you have an overly complex grammar, or are blindly parsing malicious input.

Licensing

This crate is dual-licensed under the Apache 2.0 or MIT licenses.

Modules

• errors
  Contains some common error types.

Macros

• define
  Allows defining multiple custom rules using a PEG-like syntax.
• err
  Convenience macro for quickly defining errors with static messages for use in your grammars.

Structs

• Any
  Matches one of any character or slice member. Fails on empty input.
• Attempt
  Attempts to parse a rule, returning its result. See Rule::attempt.
• Consume
  Matches a rule forever, failing if it does. See Rule::consume_all.
• Fail
  Always fails with a given error.
• Many
  Matches a rule an arbitrary amount of times. See Rule::take.
• Map
  Maps a function over the output of a rule. See Rule::map_parsed.
• Not
  Errors if a rule matches. See Rule::prevent.
• ParseError
  Holds data about something that went wrong while parsing a rule.
• Repeat
  Matches a rule a set amount of times. See Rule::repeat
• RepeatFor
  Repeatedly matches a rule a known amount of times. See Rule::repeat_for.
• Span
  Struct returned by Rule::spanned to store the span and source of a given parsed rule.
• Spanned
  Records the span of a given rule. See Rule::spanned.
• TryMap
  Attempts to map a function over the output of a rule. See Rule::try_map_parsed.
• While
  Takes input until a given function fails.

Traits

• NamedRule
  Defines a rule’s name separate from the Rule trait.
• Rule
  Trait dictating that something can be used as a rule within a parsing grammar.

Type Aliases

• AnyRule
  Alias for a refernce to a dyn Rule object of a given type and output.
• Never
  The ! type.

Derive Macros

• NamedRule
  Derive macro generating an impl of the trait NamedRule.