find-crate

Find the crate name from the current Cargo.toml ($crate for proc-macro).

When writing declarative macros, $crate representing the current crate is very useful, but procedural macros do not have this. To do the same thing as $crate with procedural macros, you need to know the current name of the crate you want to use as $crate. This crate provides the features to make it easy.

Documentation

Usage

Add this to your Cargo.toml:

[dependencies]
find-crate = "0.1"

Now, you can use find-crate:

use find_crate::find_crate;

The current version of find-crate requires Rust 1.30 or later.

Examples

find_crate() gets the crate name from the current Cargo.toml.

use find_crate::find_crate;
use proc_macro2::{Ident, Span, TokenStream};
use quote::quote;

fn import() -> TokenStream {
    let name = find_crate(|s| s == "foo").unwrap();
    let name = Ident::new(&name, Span::call_site());
    quote!(extern crate #name as _foo;)
}

As in this example, it is easy to handle cases where proc-macro is exported from multiple crates.

use find_crate::find_crate;
use proc_macro2::{Ident, Span, TokenStream};
use quote::quote;

fn import() -> TokenStream {
    let name = find_crate(|s| s == "foo" || s == "foo-core").unwrap();
    let name = Ident::new(&name, Span::call_site());
    quote!(extern crate #name as _foo;)
}

Search for multiple crates. It is much more efficient than using find_crate() for each crate.

use find_crate::Manifest;
use proc_macro2::{Ident, Span, TokenStream};
use quote::quote;

const CRATE_NAMES: &[&[&str]] = &[
    &["foo", "foo-core"],
    &["bar", "bar-util", "bar-core"],
    &["baz"],
];

fn imports() -> TokenStream {
    let mut tts = TokenStream::new();
    let manifest = Manifest::new().unwrap();
    let manifest = manifest.lock();

    for names in CRATE_NAMES {
        let name = manifest.find_name(|s| names.iter().any(|x| s == *x)).unwrap();
        let name = Ident::new(&name, Span::call_site());
        let import_name = Ident::new(&format!("_{}", names[0]), Span::call_site());
        tts.extend(quote!(extern crate #name as #import_name;));
    }
    tts
}

By default it will be searched from dependencies, dev-dependencies and build-dependencies. Also, find_crate() and Manifest::new() read Cargo.toml in CARGO_MANIFEST_DIR as manifest.

License

Licensed under either of

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

at your option.

Contribution

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