# yang2-rs

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Rust bindings for the [libyang2] library.

For raw FFI bindings for libyang2, see [libyang2-sys].

[libyang2]: https://github.com/CESNET/libyang/tree/libyang2
[libyang2-sys]: https://github.com/holo-routing/yang2-rs/tree/master/libyang2-sys

#### Cargo.toml

```toml
[dependencies]
yang2 = "0.15"
```
## Design Goals
* Provide high-level bindings for libyang2 using idiomatic Rust
* Leverage Rust's ownership system to detect API misuse problems at compile time
* Automatic resource management
* Zero-cost abstractions

## Feature flags
By default, yang2-rs uses pre-generated FFI bindings and uses dynamic linking to load libyang2. The following feature flags, however, can be used to change that behavior:
* **bundled**: instructs cargo to download and build libyang2 from the sources. The resulting objects are grouped into a static archive linked to this crate. This feature can be used when having a libyang2 dynamic link dependency isn't desirable.
  * Additional build requirements: *cc 1.0*, *cmake 0.1*, a C compiler and CMake.
* **use_bindgen**: generate new C FFI bindings dynamically instead of using the pre-generated ones. Useful when updating this crate to use newer libyang2 versions.
  * Additional build requirements: *bindgen 0.68.0*

## Example

A basic example that parses and validates JSON instance data, and then converts
it to the XML format:
```rust,no_run
use std::sync::Arc;
use std::fs::File;
use yang2::context::{Context, ContextFlags};
use yang2::data::{
    Data, DataFormat, DataParserFlags, DataPrinterFlags, DataTree,
    DataValidationFlags,
};

static SEARCH_DIR: &str = "./assets/yang/";

fn main() -> std::io::Result<()> {
    // Initialize context.
    let mut ctx = Context::new(ContextFlags::NO_YANGLIBRARY)
        .expect("Failed to create context");
    ctx.set_searchdir(SEARCH_DIR)
        .expect("Failed to set YANG search directory");

    // Load YANG modules.
    for module_name in &["ietf-interfaces", "iana-if-type"] {
        ctx.load_module(module_name, None, &[])
            .expect("Failed to load module");
    }
    let ctx = Arc::new(ctx);

    // Parse and validate data tree in the JSON format.
    let dtree = DataTree::parse_file(
        &ctx,
        File::open("./assets/data/interfaces.json")?,
        DataFormat::JSON,
        DataParserFlags::empty(),
        DataValidationFlags::NO_STATE,
    )
    .expect("Failed to parse data tree");

    // Print data tree in the XML format.
    dtree
        .print_file(
            std::io::stdout(),
            DataFormat::XML,
            DataPrinterFlags::WD_ALL | DataPrinterFlags::WITH_SIBLINGS,
        )
        .expect("Failed to print data tree");

    Ok(())
}
```

Note the `NO_STATE` flag passed to `parse_file` since the example json file does not contain state data.
More examples can be found [here][examples].

[examples]: https://github.com/holo-routing/yang2-rs/tree/master/examples

## License

This project is licensed under the [MIT license].

[MIT license]: https://github.com/holo-routing/yang2-rs/blob/master/LICENSE

### Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/holo-routing/yang2-rs.