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# nest_struct

Nest struct and enum definitions with minimal syntax changes in Rust

### Example

```rust
use nest_struct::nest_struct;

#[nest_struct]
struct Post {
    title: String,
    summary: String,
    author: nest! {
        name: String,
        handle: String,
    },
}
```

<details>
  <summary>See expanded code</summary>

```rust
struct Post {
    title: String,
    summary: String,
    author: PostAuthor,
}

struct PostAuthor {
    name: String,
    handle: String,
}
```

</details>
<br>

You can also overwrite inner struct name, by passing the name itself as macro instead of `nest!`:

```rust
use nest_struct::nest_struct;

#[nest_struct]
struct Post {
    title: String,
    summary: String,
    author: Author! {
        name: String,
        handle: String,
    },
}
```

<details>
 <summary>See expanded code</summary>

```rust
struct Post {
    title: String,
    summary: String,
    author: Author,
}

struct Author {
    name: String,
    handle: String,
}
```

</details>
<br>

Or, you can open a block and define struct like normal Rust code for full flexibility:

```rust
use nest_struct::nest_struct;

#[nest_struct]
struct Post {
    title: String,
    summary: String,
    author: nest! {
        /// doc comment for Author struct
        #[derive(Debug)]
        struct Author {
            name: String,
            handle: String,
        }
    },
}
```

<details>
 <summary>See expanded code</summary>

```rust
struct Post {
    title: String,
    summary: String,
    author: Author,
}

/// doc comment for Author struct
#[derive(Debug)]
struct Author {
    name: String,
    handle: String,
}
```

</details>
<br>

<details>
 <summary>Another example calling Pokemon API</summary>

```rust
use nest_struct::nest_struct;

// Define a struct with nested struct definitions all in one place
// with minimal syntax changes.
#[nest_struct]
#[derive(serde::Deserialize)]
struct APIResponse {
    id: u32,
    name: String,
    abilities: Vec<nest! {
            ability: nest! { name: String, url: String },
            is_hidden: bool,
            slot: u32,
        },
    >,
}

let body = reqwest::blocking::get("https://pokeapi.co/api/v2/pokemon/ditto").unwrap().text().unwrap();
let api_response: APIResponse = serde_json::from_str(&body).unwrap();

assert_eq!(api_response.name, "ditto");
// Access nested struct fields
assert_eq!(api_response.abilities.first().unwrap().ability.name, "limber");
```

</details>
<br>

For more examples, see the [`./tests/cases`](https://github.com/ZibanPirate/nest_struct/tree/main/tests/cases) directory.

### Features

-   [x] deep nesting (no theoretical limit).
-   [x] nest `struct` inside another `struct`.
-   [x] nest `enum` inside another `enum`.
-   [x] nest `enum` inside a `struct` and vice-versa.
-   [x] inherit `derive` and other attribute macros from root `struct`.
-   [x] auto-generate inner `struct` names.
-   [x] overwrite the auto-generated inner struct name.

Feature parity with native Rust code:

-   [x] `impl` block on inner `struct`s.
-   [x] define `derive` and other attribute macros individually per inner `struct`.
-   [x] define doc comments individually per inner `struct`.
-   [ ] useful compiler error messages.
-   [x] support generic types.
-   [x] support lifetimes.

## Contributing

Contributions are welcome, please read [`CONTRIBUTING.md`](https://github.com/ZibanPirate/nest_struct/blob/main/CONTRIBUTING.md) to get started.

## License

Licensed under MIT (twitter: [@zibanpirate](https://twitter.com/zibanpirate)).