rust-analyzer/crates/proc_macro_srv/src/lib.rs

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//! RA Proc Macro Server
//!
//! This library is able to call compiled Rust custom derive dynamic libraries on arbitrary code.
//! The general idea here is based on <https://github.com/fedochet/rust-proc-macro-expander>.
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//!
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//! But we adapt it to better fit RA needs:
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//!
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//! * We use `tt` for proc-macro `TokenStream` server, it is easier to manipulate and interact with
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//! RA than `proc-macro2` token stream.
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//! * By **copying** the whole rustc `lib_proc_macro` code, we are able to build this with `stable`
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//! rustc rather than `unstable`. (Although in general ABI compatibility is still an issue)…
#![allow(unreachable_pub)]
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mod dylib;
mod abis;
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use proc_macro_api::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask};
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use std::{
collections::{hash_map::Entry, HashMap},
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env, fs,
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path::{Path, PathBuf},
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time::SystemTime,
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};
#[derive(Default)]
pub(crate) struct ProcMacroSrv {
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expanders: HashMap<(PathBuf, SystemTime), dylib::Expander>,
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}
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impl ProcMacroSrv {
pub fn expand(&mut self, task: &ExpansionTask) -> Result<ExpansionResult, String> {
let expander = self.expander(task.lib.as_ref())?;
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let mut prev_env = HashMap::new();
for (k, v) in &task.env {
prev_env.insert(k.as_str(), env::var_os(k));
env::set_var(k, v);
}
let result = expander.expand(&task.macro_name, &task.macro_body, task.attributes.as_ref());
for (k, _) in &task.env {
match &prev_env[k.as_str()] {
Some(v) => env::set_var(k, v),
None => env::remove_var(k),
}
}
match result {
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Ok(expansion) => Ok(ExpansionResult { expansion }),
Err(msg) => Err(format!("proc-macro panicked: {}", msg)),
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}
}
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pub fn list_macros(&mut self, task: &ListMacrosTask) -> Result<ListMacrosResult, String> {
let expander = self.expander(task.lib.as_ref())?;
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Ok(ListMacrosResult { macros: expander.list_macros() })
}
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fn expander(&mut self, path: &Path) -> Result<&dylib::Expander, String> {
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let time = fs::metadata(path).and_then(|it| it.modified()).map_err(|err| {
format!("Failed to get file metadata for {}: {:?}", path.display(), err)
})?;
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Ok(match self.expanders.entry((path.to_path_buf(), time)) {
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Entry::Vacant(v) => v.insert(dylib::Expander::new(path).map_err(|err| {
format!("Cannot create expander for {}: {:?}", path.display(), err)
})?),
Entry::Occupied(e) => e.into_mut(),
})
}
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}
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pub mod cli;
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#[cfg(test)]
mod tests;