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