promql-parser 0.6.0

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# PromQL Lexer and Parser

The goal of this project is to build a PromQL lexer and parser capable of
parsing PromQL that conforms with [Prometheus Query][querying-prometheus].

## Example

To parse a simple instant vector selector expression:

``` rust
use promql_parser::parser;

let promql = r#"
    http_requests_total{
        environment=~"staging|testing|development",
        method!="GET"
    } offset 5m
"#;

match parser::parse(promql) {
    Ok(expr) => {
        println!("Prettify:\n{}\n", expr.prettify());
        println!("AST:\n{expr:?}");
    }
    Err(info) => println!("Err: {info:?}"),
}
```

or you can directly run examples under this repo:

``` shell
cargo run --example parser
```

This outputs:

```rust
Prettify:
http_requests_total{environment=~"staging|testing|development",method!="GET"} offset 5m

AST:
VectorSelector(VectorSelector { name: Some("http_requests_total"), matchers: Matchers { matchers: [Matcher { op: Re(staging|testing|development), name: "environment", value: "staging|testing|development" }, Matcher { op: NotEqual, name: "method", value: "GET" }] }, offset: Some(Pos(300s)), at: None })
```

## PromQL compliance

This crate declares compatible with [prometheus v2.45.0][prom-v2.45.0], which is
released at 2023-06-23. Any revision on PromQL after this commit is not guaranteed.

## Community Extensions

There are a number of community projects that extend promql-parser or
provide integrations with other systems.

### Language Bindings

- [py-promql-parser](https://github.com/messense/py-promql-parser) Python.
- [lua-promql-parser](https://github.com/mtrbpr/lua-promql-parser) Lua.

## Known Uses

Here are some of the projects known to use promql-parser:

- [GreptimeDB](https://github.com/GreptimeTeam/greptimedb) Open Source & Cloud Native Distributed Time Series Database
- [OpenObserve](https://github.com/openobserve/openobserve) High performance, petabyte scale Elasticsearch/Splunk/Datadog alternative for (logs, metrics, traces, RUM, Error tracking, Session replay)

If your project is using promql-parser, feel free to make a PR to add it to this list.

## Contributing

Contributions are highly encouraged!

Pull requests that add support for or fix a bug in a feature in the PromQL will
likely be accepted after review.

## Licensing

All code in this repository is licensed under the [Apache License 2.0](LICENSE).

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
licensed as above, without any additional terms or conditions.

[prom-v2.45.0]: https://github.com/prometheus/prometheus/blob/v2.45.0/promql/
[querying-prometheus]: https://prometheus.io/docs/prometheus/latest/querying/basics/