[−][src]Crate 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. If you know the current
name of the crate you want to use, you can do the same thing as $crate
.
This crate provides the features to make it easy.
Examples
find_crate()
gets the crate name from 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()); // If your proc-macro crate is 2018 edition, use `quote!(use #name as _foo;)` instead. 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()); // If your proc-macro crate is 2018 edition, use `quote!(use #name as _foo;)` instead. 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()); // If your proc-macro crate is 2018 edition, use `quote!(use #name as #import_name;)` instead. 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.
Structs
Manifest | The manifest of cargo. |
ManifestLock | A locked reference to the dependencies tables of |
Package | The package data. This has information on the current package name, original package name, and specified version. |
Enums
Error | An error that occurred when getting manifest. |
Constants
DEFAULT_DEPENDENCIES | The kinds of dependencies searched by default. |
Functions
find_crate | Find the crate name from the current |