54 lines
2.1 KiB
Markdown
54 lines
2.1 KiB
Markdown
|
# proc-macro-crate
|
||
|
|
|
||
|
|
|
||
|
|
[](https://docs.rs/proc-macro-crate/) [](https://crates.io/crates/proc-macro-crate) [](https://crates.io/crates/proc-macro-crate) [](https://travis-ci.org/bkchr/proc-macro-crate)
|
||
|
|
|
||
|
|
Providing support for `$crate` in procedural macros.
|
||
|
|
|
||
|
|
* [Introduction](#introduction)
|
||
|
|
* [Example](#example)
|
||
|
|
* [License](#license)
|
||
|
|
|
||
|
|
### Introduction
|
||
|
|
|
||
|
|
In `macro_rules!` `$crate` is used to get the path of the crate where a macro is declared in. In
|
||
|
|
procedural macros there is currently no easy way to get this path. A common hack is to import the
|
||
|
|
desired crate with a know name and use this. However, with rust edition 2018 and dropping
|
||
|
|
`extern crate` declarations from `lib.rs`, people start to rename crates in `Cargo.toml` directly.
|
||
|
|
However, this breaks importing the crate, as the proc-macro developer does not know the renamed
|
||
|
|
name of the crate that should be imported.
|
||
|
|
|
||
|
|
This crate provides a way to get the name of a crate, even if it renamed in `Cargo.toml`. For this
|
||
|
|
purpose a single function `crate_name` is provided. This function needs to be called in the context
|
||
|
|
of a proc-macro with the name of the desired crate. `CARGO_MANIFEST_DIR` will be used to find the
|
||
|
|
current active `Cargo.toml` and this `Cargo.toml` is searched for the desired crate. The returned
|
||
|
|
name of `crate_name` is either the given original rename (crate not renamed) or the renamed name.
|
||
|
|
|
||
|
|
### Example
|
||
|
|
|
||
|
|
```rust
|
||
|
|
use quote::quote;
|
||
|
|
use syn::Ident;
|
||
|
|
use proc_macro2::Span;
|
||
|
|
use proc_macro_crate::crate_name;
|
||
|
|
|
||
|
|
fn import_my_crate() {
|
||
|
|
let name = crate_name("my-crate").expect("my-crate is present in `Cargo.toml`");
|
||
|
|
let ident = Ident::new(&name, Span::call_site());
|
||
|
|
quote!( extern crate #ident as my_crate_known_name );
|
||
|
|
}
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
### License
|
||
|
|
|
||
|
|
Licensed under either of
|
||
|
|
|
||
|
|
* [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
|
||
|
|
|
||
|
|
* [MIT license](http://opensource.org/licenses/MIT)
|
||
|
|
|
||
|
|
at your option.
|
||
|
|
|
||
|
|
License: Apache-2.0/MIT
|