Crate granit_parser 

YAML 1.2 parser implementation in pure Rust.

granit-parser is a low-level event parser. It reads YAML input and yields a stream of Event values paired with their source Span. Comments are emitted as Event::Comment. They are presentation metadata, not YAML data nodes, so consumers building YAML value trees should ignore them.

Add it to your project:

cargo add granit-parser

Usage

use granit_parser::{Event, Parser, Placement};

let yaml = r#"# header
items: # inline
  - milk
  - bread
"#;
let mut comments = Vec::new();

for next in Parser::new_from_str(yaml) {
    let (event, span) = next?;
    if let Event::Comment(text, placement) = event {
        comments.push((
            text.into_owned(),
            placement,
            span.slice(yaml).unwrap().to_owned(),
        ));
    }
}

assert_eq!(
    comments,
    [
        (" header".to_owned(), Placement::Above, "# header".to_owned()),
        (" inline".to_owned(), Placement::Right, "# inline".to_owned()),
    ]
);

For comment events, the companion Span covers the whole source comment, including # and excluding the line break. With Parser::new_from_str, Span::slice returns that source comment text.

Features

Note: This crate’s MSRV is 1.81.0.

debug_prints

Enables the debug module and usage of debug prints in the scanner and the parser. Do not enable if you are consuming the crate rather than working on it as this can significantly decrease performance. Output remains opt-in behind a local compile-time toggle in src/debug.rs.

This feature does not raise the MSRV further.

This feature is not no_std compatible.

Re-exports

pub use crate::input::BorrowedInput;

pub use crate::input::BufferedInput;

pub use crate::input::Input;

Modules

input

Utilities to create a source of input to the parser.

parser_stack

A stack-based parser implementation.

Structs

Comment

A YAML comment captured from the source.

Marker

A location in a YAML document.

Parser

A YAML parser.

ScanError

An error that occurred while scanning.

Scanner

The YAML scanner.

Span

A range of locations in a YAML document.

StrInput

A parser input backed by a &str.

Tag

A YAML tag.

Token

A scanner token.

Enums

Event

An event generated by the YAML parser.

Placement

A positional hint for a YAML source comment.

ScalarStyle

The source style used for a YAML scalar.

StructureStyle

The notation style used for a YAML sequence or mapping.

TokenType

The contents of a scanner token.

TryLoadError

Error returned by Parser::try_load and ParserTrait::try_load.

Traits

EventReceiver

Trait to be implemented in order to use the low-level parsing API.

ParserTrait

Trait extracted from Parser to support mocking and alternative implementations.

SpannedEventReceiver

Trait to be implemented for using the low-level parsing API.

TryEventReceiver

Trait to be implemented for fallible event handling without source spans.

TrySpannedEventReceiver

Trait to be implemented for fallible event handling with source spans.