Crates.io | peg |
lib.rs | peg |
version | 0.8.3 |
source | src |
created_at | 2014-11-23 21:01:43.578924 |
updated_at | 2024-04-27 17:35:12.36921 |
description | A simple Parsing Expression Grammar (PEG) parser generator. |
homepage | |
repository | https://github.com/kevinmehall/rust-peg |
max_upload_size | |
id | 374 |
size | 58,290 |
rust-peg
is a simple yet flexible parser generator that makes it easy to write robust parsers. Based on the Parsing Expression Grammar formalism, it provides a Rust macro that builds a recursive descent parser from a concise definition of the grammar.
&str
, &[u8]
, &[T]
or custom types implementing traitsrustc
error messages for errors in the grammar definition or the Rust
code embedded within itParse a comma-separated list of numbers surrounded by brackets into a Vec<u32>
:
peg::parser!{
grammar list_parser() for str {
rule number() -> u32
= n:$(['0'..='9']+) {? n.parse().or(Err("u32")) }
pub rule list() -> Vec<u32>
= "[" l:(number() ** ",") "]" { l }
}
}
pub fn main() {
assert_eq!(list_parser::list("[1,1,2,3,5,8]"), Ok(vec![1, 1, 2, 3, 5, 8]));
}
See the tests for more examples
Grammar rule syntax reference in rustdoc
crate | parser type | action code | integration | input type | precedence climbing | parameterized rules | streaming input |
---|---|---|---|---|---|---|---|
peg | PEG | in grammar | proc macro (block) | &str , &[T] , custom |
Yes | Yes | No |
pest | PEG | external | proc macro (file) | &str |
Yes | No | No |
nom | combinators | in source | library | &[u8] , custom |
No | Yes | Yes |
lalrpop | LR(1) | in grammar | build script | &str |
No | Yes | No |
The rust-peg
grammar is written in rust-peg
: peg-macros/grammar.rustpeg
. To avoid the circular dependency, a precompiled grammar is checked in as peg-macros/grammar.rs
. To regenerate this, run the ./bootstrap.sh
script.
There is a large test suite which uses trybuild
to test both functionality (tests/run-pass
) and error messages for incorrect grammars (tests/compile-fail
). Because rustc
error messages change, the compile-fail
tests are only run on the minimum supported Rust version to avoid spurious failures.
Use cargo test
to run the entire suite,
or cargo test -- trybuild trybuild=lifetimes.rs
to test just the indicated file.
Add --features trace
to trace these tests.