proc_macro_crate/lib.rs
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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)
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.
## Example
```
use quote::quote;
use syn::Ident;
use proc_macro2::Span;
use proc_macro_crate::{crate_name, FoundCrate};
fn import_my_crate() {
let found_crate = crate_name("my-crate").expect("my-crate is present in `Cargo.toml`");
match found_crate {
FoundCrate::Itself => quote!( crate::Something ),
FoundCrate::Name(name) => {
let ident = Ident::new(&name, Span::call_site());
quote!( #ident::Something )
}
};
}
# fn main() {}
```
## Edge cases
There are multiple edge cases when it comes to determining the correct crate. If you for example
import a crate as its own dependency, like this:
```toml
[package]
name = "my_crate"
[dev-dependencies]
my_crate = { version = "0.1", features = [ "test-feature" ] }
```
The crate will return `FoundCrate::Itself` and you will not be able to find the other instance
of your crate in `dev-dependencies`. Other similar cases are when one crate is imported multiple
times:
```toml
[package]
name = "my_crate"
[dependencies]
some-crate = { version = "0.5" }
some-crate-old = { package = "some-crate", version = "0.1" }
```
When searching for `some-crate` in this `Cargo.toml` it will return `FoundCrate::Name("some_old_crate")`,
aka the last definition of the crate in the `Cargo.toml`.
## License
Licensed under either of
* [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0)
* [MIT license](https://opensource.org/licenses/MIT)
at your option.
*/
use std::{
collections::btree_map::{self, BTreeMap},
env, fmt, fs, io,
path::{Path, PathBuf},
process::Command,
sync::Mutex,
time::SystemTime,
};
use toml_edit::{DocumentMut, Item, Table, TomlError};
/// Error type used by this crate.
pub enum Error {
NotFound(PathBuf),
CargoManifestDirNotSet,
CargoEnvVariableNotSet,
FailedGettingWorkspaceManifestPath,
CouldNotRead { path: PathBuf, source: io::Error },
InvalidToml { source: TomlError },
CrateNotFound { crate_name: String, path: PathBuf },
}
impl std::error::Error for Error {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
match self {
Error::CouldNotRead { source, .. } => Some(source),
Error::InvalidToml { source } => Some(source),
_ => None,
}
}
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(self, f)
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
Error::NotFound(path) =>
write!(f, "Could not find `Cargo.toml` in manifest dir: `{}`.", path.display()),
Error::CargoManifestDirNotSet =>
f.write_str("`CARGO_MANIFEST_DIR` env variable not set."),
Error::CouldNotRead { path, .. } => write!(f, "Could not read `{}`.", path.display()),
Error::InvalidToml { .. } => f.write_str("Invalid toml file."),
Error::CrateNotFound { crate_name, path } => write!(
f,
"Could not find `{}` in `dependencies` or `dev-dependencies` in `{}`!",
crate_name,
path.display(),
),
Error::CargoEnvVariableNotSet => f.write_str("`CARGO` env variable not set."),
Error::FailedGettingWorkspaceManifestPath =>
f.write_str("Failed to get the path of the workspace manifest path."),
}
}
}
/// The crate as found by [`crate_name`].
#[derive(Debug, PartialEq, Clone, Eq)]
pub enum FoundCrate {
/// The searched crate is this crate itself.
Itself,
/// The searched crate was found with this name.
Name(String),
}
// In a rustc invocation, there will only ever be one entry in this map, since every crate is
// compiled with its own rustc process. However, the same is not (currently) the case for
// rust-analyzer.
type Cache = BTreeMap<String, CacheEntry>;
struct CacheEntry {
manifest_ts: SystemTime,
workspace_manifest_ts: SystemTime,
workspace_manifest_path: PathBuf,
crate_names: CrateNames,
}
type CrateNames = BTreeMap<String, FoundCrate>;
/// Find the crate name for the given `orig_name` in the current `Cargo.toml`.
///
/// `orig_name` should be the original name of the searched crate.
///
/// The current `Cargo.toml` is determined by taking `CARGO_MANIFEST_DIR/Cargo.toml`.
///
/// # Returns
///
/// - `Ok(orig_name)` if the crate was found, but not renamed in the `Cargo.toml`.
/// - `Ok(RENAMED)` if the crate was found, but is renamed in the `Cargo.toml`. `RENAMED` will be
/// the renamed name.
/// - `Err` if an error occurred.
///
/// The returned crate name is sanitized in such a way that it is a valid rust identifier. Thus,
/// it is ready to be used in `extern crate` as identifier.
pub fn crate_name(orig_name: &str) -> Result<FoundCrate, Error> {
let manifest_dir = env::var("CARGO_MANIFEST_DIR").map_err(|_| Error::CargoManifestDirNotSet)?;
let manifest_path = Path::new(&manifest_dir).join("Cargo.toml");
let manifest_ts = cargo_toml_timestamp(&manifest_path)?;
static CACHE: Mutex<Cache> = Mutex::new(BTreeMap::new());
let mut cache = CACHE.lock().unwrap();
let crate_names = match cache.entry(manifest_dir) {
btree_map::Entry::Occupied(entry) => {
let cache_entry = entry.into_mut();
let workspace_manifest_path = cache_entry.workspace_manifest_path.as_path();
let workspace_manifest_ts = cargo_toml_timestamp(&workspace_manifest_path)?;
// Timestamp changed, rebuild this cache entry.
if manifest_ts != cache_entry.manifest_ts ||
workspace_manifest_ts != cache_entry.workspace_manifest_ts
{
*cache_entry = read_cargo_toml(
&manifest_path,
&workspace_manifest_path,
manifest_ts,
workspace_manifest_ts,
)?;
}
&cache_entry.crate_names
},
btree_map::Entry::Vacant(entry) => {
// If `workspace_manifest_path` returns `None`, we are probably in a vendored deps
// folder and cargo complaining that we have some package inside a workspace, that isn't
// part of the workspace. In this case we just use the `manifest_path` as the
// `workspace_manifest_path`.
let workspace_manifest_path =
workspace_manifest_path(&manifest_path)?.unwrap_or_else(|| manifest_path.clone());
let workspace_manifest_ts = cargo_toml_timestamp(&workspace_manifest_path)?;
let cache_entry = entry.insert(read_cargo_toml(
&manifest_path,
&workspace_manifest_path,
manifest_ts,
workspace_manifest_ts,
)?);
&cache_entry.crate_names
},
};
Ok(crate_names
.get(orig_name)
.ok_or_else(|| Error::CrateNotFound {
crate_name: orig_name.to_owned(),
path: manifest_path,
})?
.clone())
}
fn workspace_manifest_path(cargo_toml_manifest: &Path) -> Result<Option<PathBuf>, Error> {
let stdout = Command::new(env::var("CARGO").map_err(|_| Error::CargoEnvVariableNotSet)?)
.arg("locate-project")
.args(&["--workspace", "--message-format=plain"])
.arg(format!("--manifest-path={}", cargo_toml_manifest.display()))
.output()
.map_err(|_| Error::FailedGettingWorkspaceManifestPath)?
.stdout;
String::from_utf8(stdout)
.map_err(|_| Error::FailedGettingWorkspaceManifestPath)
.map(|s| {
let path = s.trim();
if path.is_empty() {
None
} else {
Some(path.into())
}
})
}
fn cargo_toml_timestamp(manifest_path: &Path) -> Result<SystemTime, Error> {
fs::metadata(manifest_path).and_then(|meta| meta.modified()).map_err(|source| {
if source.kind() == io::ErrorKind::NotFound {
Error::NotFound(manifest_path.to_owned())
} else {
Error::CouldNotRead { path: manifest_path.to_owned(), source }
}
})
}
fn read_cargo_toml(
manifest_path: &Path,
workspace_manifest_path: &Path,
manifest_ts: SystemTime,
workspace_manifest_ts: SystemTime,
) -> Result<CacheEntry, Error> {
let manifest = open_cargo_toml(manifest_path)?;
let workspace_dependencies = if manifest_path != workspace_manifest_path {
let workspace_manifest = open_cargo_toml(workspace_manifest_path)?;
extract_workspace_dependencies(&workspace_manifest)?
} else {
extract_workspace_dependencies(&manifest)?
};
let crate_names = extract_crate_names(&manifest, workspace_dependencies)?;
Ok(CacheEntry {
manifest_ts,
workspace_manifest_ts,
crate_names,
workspace_manifest_path: workspace_manifest_path.to_path_buf(),
})
}
/// Extract all `[workspace.dependencies]`.
///
/// Returns a hash map that maps from dep name to the package name. Dep name
/// and package name can be the same if there doesn't exist any rename.
fn extract_workspace_dependencies(
workspace_toml: &DocumentMut,
) -> Result<BTreeMap<String, String>, Error> {
Ok(workspace_dep_tables(&workspace_toml)
.into_iter()
.flatten()
.map(move |(dep_name, dep_value)| {
let pkg_name = dep_value.get("package").and_then(|i| i.as_str()).unwrap_or(dep_name);
(dep_name.to_owned(), pkg_name.to_owned())
})
.collect())
}
/// Return an iterator over all `[workspace.dependencies]`
fn workspace_dep_tables(cargo_toml: &DocumentMut) -> Option<&Table> {
cargo_toml
.get("workspace")
.and_then(|w| w.as_table()?.get("dependencies")?.as_table())
}
/// Make sure that the given crate name is a valid rust identifier.
fn sanitize_crate_name<S: AsRef<str>>(name: S) -> String {
name.as_ref().replace('-', "_")
}
/// Open the given `Cargo.toml` and parse it into a hashmap.
fn open_cargo_toml(path: &Path) -> Result<DocumentMut, Error> {
let content = fs::read_to_string(path)
.map_err(|e| Error::CouldNotRead { source: e, path: path.into() })?;
content.parse::<DocumentMut>().map_err(|e| Error::InvalidToml { source: e })
}
/// Extract all crate names from the given `Cargo.toml` by checking the `dependencies` and
/// `dev-dependencies`.
fn extract_crate_names(
cargo_toml: &DocumentMut,
workspace_dependencies: BTreeMap<String, String>,
) -> Result<CrateNames, Error> {
let package_name = extract_package_name(cargo_toml);
let root_pkg = package_name.as_ref().map(|name| {
let cr = match env::var_os("CARGO_TARGET_TMPDIR") {
// We're running for a library/binary crate
None => FoundCrate::Itself,
// We're running for an integration test
Some(_) => FoundCrate::Name(sanitize_crate_name(name)),
};
(name.to_string(), cr)
});
let dep_tables = dep_tables(cargo_toml).chain(target_dep_tables(cargo_toml));
let dep_pkgs = dep_tables.flatten().filter_map(move |(dep_name, dep_value)| {
let pkg_name = dep_value.get("package").and_then(|i| i.as_str()).unwrap_or(dep_name);
// We already handle this via `root_pkg` above.
if package_name.as_ref().map_or(false, |n| *n == pkg_name) {
return None
}
// Check if this is a workspace dependency.
let workspace = dep_value.get("workspace").and_then(|w| w.as_bool()).unwrap_or_default();
let pkg_name = workspace
.then(|| workspace_dependencies.get(pkg_name).map(|p| p.as_ref()))
.flatten()
.unwrap_or(pkg_name);
let cr = FoundCrate::Name(sanitize_crate_name(dep_name));
Some((pkg_name.to_owned(), cr))
});
Ok(root_pkg.into_iter().chain(dep_pkgs).collect())
}
fn extract_package_name(cargo_toml: &DocumentMut) -> Option<&str> {
cargo_toml.get("package")?.get("name")?.as_str()
}
fn target_dep_tables(cargo_toml: &DocumentMut) -> impl Iterator<Item = &Table> {
cargo_toml.get("target").into_iter().filter_map(Item::as_table).flat_map(|t| {
t.iter().map(|(_, value)| value).filter_map(Item::as_table).flat_map(dep_tables)
})
}
fn dep_tables(table: &Table) -> impl Iterator<Item = &Table> {
table
.get("dependencies")
.into_iter()
.chain(table.get("dev-dependencies"))
.filter_map(Item::as_table)
}
#[cfg(test)]
mod tests {
use super::*;
macro_rules! create_test {
(
$name:ident,
$cargo_toml:expr,
$workspace_toml:expr,
$( $result:tt )*
) => {
#[test]
fn $name() {
let cargo_toml = $cargo_toml.parse::<DocumentMut>()
.expect("Parses `Cargo.toml`");
let workspace_cargo_toml = $workspace_toml.parse::<DocumentMut>()
.expect("Parses workspace `Cargo.toml`");
let workspace_deps = extract_workspace_dependencies(&workspace_cargo_toml)
.expect("Extracts workspace dependencies");
match extract_crate_names(&cargo_toml, workspace_deps)
.map(|mut map| map.remove("my_crate"))
{
$( $result )* => (),
o => panic!("Invalid result: {:?}", o),
}
}
};
}
create_test! {
deps_with_crate,
r#"
[dependencies]
my_crate = "0.1"
"#,
"",
Ok(Some(FoundCrate::Name(name))) if name == "my_crate"
}
create_test! {
dev_deps_with_crate,
r#"
[dev-dependencies]
my_crate = "0.1"
"#,
"",
Ok(Some(FoundCrate::Name(name))) if name == "my_crate"
}
create_test! {
deps_with_crate_renamed,
r#"
[dependencies]
cool = { package = "my_crate", version = "0.1" }
"#,
"",
Ok(Some(FoundCrate::Name(name))) if name == "cool"
}
create_test! {
deps_with_crate_renamed_second,
r#"
[dependencies.cool]
package = "my_crate"
version = "0.1"
"#,
"",
Ok(Some(FoundCrate::Name(name))) if name == "cool"
}
create_test! {
deps_empty,
r#"
[dependencies]
"#,
"",
Ok(None)
}
create_test! {
crate_not_found,
r#"
[dependencies]
serde = "1.0"
"#,
"",
Ok(None)
}
create_test! {
target_dependency,
r#"
[target.'cfg(target_os="android")'.dependencies]
my_crate = "0.1"
"#,
"",
Ok(Some(FoundCrate::Name(name))) if name == "my_crate"
}
create_test! {
target_dependency2,
r#"
[target.x86_64-pc-windows-gnu.dependencies]
my_crate = "0.1"
"#,
"",
Ok(Some(FoundCrate::Name(name))) if name == "my_crate"
}
create_test! {
own_crate,
r#"
[package]
name = "my_crate"
"#,
"",
Ok(Some(FoundCrate::Itself))
}
create_test! {
own_crate_and_in_deps,
r#"
[package]
name = "my_crate"
[dev-dependencies]
my_crate = "0.1"
"#,
"",
Ok(Some(FoundCrate::Itself))
}
create_test! {
multiple_times,
r#"
[dependencies]
my_crate = { version = "0.5" }
my-crate-old = { package = "my_crate", version = "0.1" }
"#,
"",
Ok(Some(FoundCrate::Name(name))) if name == "my_crate_old"
}
create_test! {
workspace_deps,
r#"
[dependencies]
my_crate_cool = { workspace = true }
"#,
r#"
[workspace.dependencies]
my_crate_cool = { package = "my_crate" }
"#,
Ok(Some(FoundCrate::Name(name))) if name == "my_crate_cool"
}
}