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

Action

Runs a function when parsed. Parses nothing, and returns the function’s output.

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.

Separated

Parses similar to Many, but with an separator rule between each parse. See [Rule::separated].

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.