# enum_macro_gen   [![Build Status]][actions] [![Latest Version]][crates.io] [![Docs badge]][Docs link] [![License badge]][License link]

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[Docs link]: https://docs.rs/enum_macro_gen

This crate provides the `EnumMacroGen` derive proc macro for Rust, which
simplifies handling variants of an enum. It generates declartive macros
according to a given template.

## Example

```rust
use enum_macro_gen::EnumMacroGen;

#[derive(EnumMacroGen)]
#[enum_macro[handle_test={match: $self.handle_$variant($fields);}]]
enum Test {
    Foo(Item),
    Double(Item, Box<Test>),
    Bar,
}
```

Instead of writing a `match` statement to handle each variant of `Test`, you
can use the `handle_test!` a macro generated by `EnumMacroGen`.

```rust
// <**GENERATED**>
macro_rules! handle_test {
    ($self:ident, $test:ident) => {
        match $test {
            Test::Foo(a_0) => {
                $self.handle_foo(a_0);
            }
            Test::Double(a_0, a_1) => {
                $self.handle_double(a_0, a_1);
            }
            Test::Bar => {
                $self.handle_bar();
            }
        }
    };
}
// </**GENERATED**>
```

## Deriving EnumMacroGen

To use `EnumMacroGen`, simply add `#[derive(EnumMacroGen)]` above your enum
declaration.

You can also specify the format of the generated macro with the `enum_macro`
attribute. The attribute value should be a token list containing `$variant`
and `$fields`, which will be replaced with the variant name and fields,
respectively.

## License

`enum_macro_gen` is licensed under either of

 * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
   http://www.apache.org/licenses/LICENSE-2.0)
 * MIT license ([LICENSE-MIT](LICENSE-MIT) or
   http://opensource.org/licenses/MIT)

at your option.


### Contribution

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