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/// This module specifies the input to rust-analyzer. In some sense, this is
/// **the** most important module, because all other fancy stuff is strictly
/// derived from this input.
///
/// Note that neither this module, nor any other part of the analyzer's core do
/// actual IO. See `vfs` and `project_model` in the `ra_lsp_server` crate for how
/// actual IO is done and lowered to input.
use relative_path::RelativePathBuf;
use rustc_hash::FxHashMap;
use ra_syntax::SmolStr;
use rustc_hash::FxHashSet;
/// `FileId` is an integer which uniquely identifies a file. File paths are
/// messy and system-dependent, so most of the code should work directly with
/// `FileId`, without inspecting the path. The mapping between `FileId` and path
/// and `SourceRoot` is constant. A file rename is represented as a pair of
/// deletion/creation.
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct FileId(pub u32);
/// Files are grouped into source roots. A source root is a directory on the
/// file systems which is watched for changes. Typically it corresponds to a
/// Rust crate. Source roots *might* be nested: in this case, a file belongs to
/// the nearest enclosing source root. Paths to files are always relative to a
/// source root, and the analyzer does not know the root path of the source root at
/// all. So, a file from one source root can't refer to a file in another source
/// root by path.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct SourceRootId(pub u32);
#[derive(Default, Clone, Debug, PartialEq, Eq)]
pub struct SourceRoot {
pub files: FxHashMap<RelativePathBuf, FileId>,
}
/// `CrateGraph` is a bit of information which turns a set of text files into a
/// number of Rust crates. Each crate is defined by the `FileId` of its root module,
/// the set of cfg flags (not yet implemented) and the set of dependencies. Note
/// that, due to cfg's, there might be several crates for a single `FileId`! As
/// in the rust-lang proper, a crate does not have a name. Instead, names are
/// specified on dependency edges. That is, a crate might be known under
/// different names in different dependent crates.
///
/// Note that `CrateGraph` is build-system agnostic: it's a concept of the Rust
/// language proper, not a concept of the build system. In practice, we get
/// `CrateGraph` by lowering `cargo metadata` output.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct CrateGraph {
arena: FxHashMap<CrateId, CrateData>,
}
#[derive(Debug)]
pub struct CyclicDependencies;
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct CrateId(pub u32);
#[derive(Debug, Clone, PartialEq, Eq)]
struct CrateData {
file_id: FileId,
dependencies: Vec<Dependency>,
}
impl CrateData {
fn new(file_id: FileId) -> CrateData {
CrateData { file_id, dependencies: Vec::new() }
}
fn add_dep(&mut self, name: SmolStr, crate_id: CrateId) {
self.dependencies.push(Dependency { name, crate_id })
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Dependency {
pub crate_id: CrateId,
pub name: SmolStr,
}
impl Dependency {
pub fn crate_id(&self) -> CrateId {
self.crate_id
}
}
impl CrateGraph {
pub fn add_crate_root(&mut self, file_id: FileId) -> CrateId {
let crate_id = CrateId(self.arena.len() as u32);
let prev = self.arena.insert(crate_id, CrateData::new(file_id));
assert!(prev.is_none());
crate_id
}
pub fn add_dep(
&mut self,
from: CrateId,
name: SmolStr,
to: CrateId,
) -> Result<(), CyclicDependencies> {
if self.dfs_find(from, to, &mut FxHashSet::default()) {
return Err(CyclicDependencies);
}
Ok(self.arena.get_mut(&from).unwrap().add_dep(name, to))
}
pub fn is_empty(&self) -> bool {
self.arena.is_empty()
}
pub fn crate_root(&self, crate_id: CrateId) -> FileId {
self.arena[&crate_id].file_id
}
pub fn crate_id_for_crate_root(&self, file_id: FileId) -> Option<CrateId> {
let (&crate_id, _) = self.arena.iter().find(|(_crate_id, data)| data.file_id == file_id)?;
Some(crate_id)
}
pub fn dependencies<'a>(
&'a self,
crate_id: CrateId,
) -> impl Iterator<Item = &'a Dependency> + 'a {
self.arena[&crate_id].dependencies.iter()
}
/// Extends this crate graph by adding a complete disjoint second crate
/// graph.
pub fn extend(&mut self, other: CrateGraph) {
let start = self.arena.len() as u32;
self.arena.extend(other.arena.into_iter().map(|(id, mut data)| {
let new_id = CrateId(id.0 + start);
for dep in &mut data.dependencies {
dep.crate_id = CrateId(dep.crate_id.0 + start);
}
(new_id, data)
}));
}
fn dfs_find(&self, target: CrateId, from: CrateId, visited: &mut FxHashSet<CrateId>) -> bool {
if !visited.insert(from) {
return false;
}
for dep in self.dependencies(from) {
let crate_id = dep.crate_id();
if crate_id == target {
return true;
}
if self.dfs_find(target, crate_id, visited) {
return true;
}
}
return false;
}
}
#[cfg(test)]
mod tests {
use super::{CrateGraph, FileId, SmolStr};
#[test]
fn it_should_painc_because_of_cycle_dependencies() {
let mut graph = CrateGraph::default();
let crate1 = graph.add_crate_root(FileId(1u32));
let crate2 = graph.add_crate_root(FileId(2u32));
let crate3 = graph.add_crate_root(FileId(3u32));
assert!(graph.add_dep(crate1, SmolStr::new("crate2"), crate2).is_ok());
assert!(graph.add_dep(crate2, SmolStr::new("crate3"), crate3).is_ok());
assert!(graph.add_dep(crate3, SmolStr::new("crate1"), crate1).is_err());
}
#[test]
fn it_works() {
let mut graph = CrateGraph::default();
let crate1 = graph.add_crate_root(FileId(1u32));
let crate2 = graph.add_crate_root(FileId(2u32));
let crate3 = graph.add_crate_root(FileId(3u32));
assert!(graph.add_dep(crate1, SmolStr::new("crate2"), crate2).is_ok());
assert!(graph.add_dep(crate2, SmolStr::new("crate3"), crate3).is_ok());
}
}
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