Hide Internal Rules in `macro_rules!` Docs
==========================================
When generating docs for `macro_rules!` macros, `rustdoc` will include every
rule, including internal rules that are only supposed to be called from within
your macro. The `clean_docs` attribute will hide your internal rules from
`rustdoc`.
## Example:
```rust
#[macro_export]
macro_rules! messy {
(@impl $e:expr) => {
format!("{}", $e)
};
($e:expr) => {
messy!(@impl $e)
};
}
#[clean_docs]
#[macro_export]
macro_rules! clean {
(@impl $e:expr) => {
format!("{}", $e)
};
($e:expr) => {
clean!(@impl $e)
};
}
```
would be documented as
```rust
macro_rules! messy {
(@impl $e:expr) => { ... };
($e:expr) => { ... };
}
macro_rules! clean {
($e:expr) => { ... };
}
```
## How does it work?
The `clean!` macro above is transformed into
```rust
#[macro_export]
macro_rules! clean {
($e:expr) => {
$crate::__clean!(@impl $e)
};
}
#[macro_export]
macro_rules! __clean {
(@impl $e:expr) => {
format!("{}", $e)
};
}
macro_rules! clean {
(@impl $e:expr) => {
format!("{}", $e)
};
($e:expr) => {
clean!(@impl $e)
};
}
```
The last, non-`macro_export`ed macro is there becuase Rust doesn't allow
macro-expanded macros to be invoked by absolute path (i.e. `$crate::__clean`).
The solution is to shadow the `macro_export`ed macro with a local version
that doesn't use absolute paths.
## Arguments
You can use these optional arguments to configure `clean_macro`.
```rust
#[clean_docs(impl = "#internal", internal = "__internal_mac")]
```
### `impl`
A string representing the "flag" at the begining of an internal rule. Defaults to `"@"`.
```rust
#[clean_docs(impl = "#internal")]
#[macro_export]
macro_rules! mac {
(#internal $e:expr) => {
format!("{}", $e)
};
($e:expr) => {
mac!(#internal $e)
};
}
```
### `internal`
A string representing the identifier to use for the internal version of your macro.
By default `clean_docs` prepends `__` (two underscores) to the main macro's identifier.
```rust
#[clean_docs(internal = "__internal_mac")]
#[macro_export]
macro_rules! mac {
(@impl $e:expr) => {
format!("{}", $e)
};
($e:expr) => {
mac!(@impl $e)
};
}
```