1 files changed, 453 insertions, 0 deletions

diff --git a/crates/base_db/src/input.rs b/crates/base_db/src/input.rs
new file mode 100644
index 000000000..f3d65cdf0
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+++ b/crates/base_db/src/input.rs
@@ -0,0 +1,453 @@
+//! 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 `rust-analyzer` crate for how
+//! actual IO is done and lowered to input.
+
+use std::{fmt, iter::FromIterator, ops, str::FromStr, sync::Arc};
+
+use cfg::CfgOptions;
+use rustc_hash::{FxHashMap, FxHashSet};
+use syntax::SmolStr;
+use tt::TokenExpander;
+use vfs::file_set::FileSet;
+
+pub use vfs::FileId;
+
+/// 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(Clone, Debug, PartialEq, Eq)]
+pub struct SourceRoot {
+    /// Sysroot or crates.io library.
+    ///
+    /// Libraries are considered mostly immutable, this assumption is used to
+    /// optimize salsa's query structure
+    pub is_library: bool,
+    pub(crate) file_set: FileSet,
+}
+
+impl SourceRoot {
+    pub fn new_local(file_set: FileSet) -> SourceRoot {
+        SourceRoot { is_library: false, file_set }
+    }
+    pub fn new_library(file_set: FileSet) -> SourceRoot {
+        SourceRoot { is_library: true, file_set }
+    }
+    pub fn iter(&self) -> impl Iterator<Item = FileId> + '_ {
+        self.file_set.iter()
+    }
+}
+
+/// `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, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct CrateId(pub u32);
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct CrateName(SmolStr);
+
+impl CrateName {
+    /// Creates a crate name, checking for dashes in the string provided.
+    /// Dashes are not allowed in the crate names,
+    /// hence the input string is returned as `Err` for those cases.
+    pub fn new(name: &str) -> Result<CrateName, &str> {
+        if name.contains('-') {
+            Err(name)
+        } else {
+            Ok(Self(SmolStr::new(name)))
+        }
+    }
+
+    /// Creates a crate name, unconditionally replacing the dashes with underscores.
+    pub fn normalize_dashes(name: &str) -> CrateName {
+        Self(SmolStr::new(name.replace('-', "_")))
+    }
+}
+
+impl fmt::Display for CrateName {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl ops::Deref for CrateName {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        &*self.0
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub struct ProcMacroId(pub u32);
+
+#[derive(Debug, Clone)]
+pub struct ProcMacro {
+    pub name: SmolStr,
+    pub expander: Arc<dyn TokenExpander>,
+}
+
+impl Eq for ProcMacro {}
+impl PartialEq for ProcMacro {
+    fn eq(&self, other: &ProcMacro) -> bool {
+        self.name == other.name && Arc::ptr_eq(&self.expander, &other.expander)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct CrateData {
+    pub root_file_id: FileId,
+    pub edition: Edition,
+    /// The name to display to the end user.
+    /// This actual crate name can be different in a particular dependent crate
+    /// or may even be missing for some cases, such as a dummy crate for the code snippet.
+    pub display_name: Option<String>,
+    pub cfg_options: CfgOptions,
+    pub env: Env,
+    pub dependencies: Vec<Dependency>,
+    pub proc_macro: Vec<ProcMacro>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Edition {
+    Edition2018,
+    Edition2015,
+}
+
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
+pub struct Env {
+    entries: FxHashMap<String, String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Dependency {
+    pub crate_id: CrateId,
+    pub name: CrateName,
+}
+
+impl CrateGraph {
+    pub fn add_crate_root(
+        &mut self,
+        file_id: FileId,
+        edition: Edition,
+        display_name: Option<String>,
+        cfg_options: CfgOptions,
+        env: Env,
+        proc_macro: Vec<(SmolStr, Arc<dyn tt::TokenExpander>)>,
+    ) -> CrateId {
+        let proc_macro =
+            proc_macro.into_iter().map(|(name, it)| ProcMacro { name, expander: it }).collect();
+
+        let data = CrateData {
+            root_file_id: file_id,
+            edition,
+            display_name,
+            cfg_options,
+            env,
+            proc_macro,
+            dependencies: Vec::new(),
+        };
+        let crate_id = CrateId(self.arena.len() as u32);
+        let prev = self.arena.insert(crate_id, data);
+        assert!(prev.is_none());
+        crate_id
+    }
+
+    pub fn add_dep(
+        &mut self,
+        from: CrateId,
+        name: CrateName,
+        to: CrateId,
+    ) -> Result<(), CyclicDependenciesError> {
+        if self.dfs_find(from, to, &mut FxHashSet::default()) {
+            return Err(CyclicDependenciesError);
+        }
+        self.arena.get_mut(&from).unwrap().add_dep(name, to);
+        Ok(())
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.arena.is_empty()
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = CrateId> + '_ {
+        self.arena.keys().copied()
+    }
+
+    /// Returns an iterator over all transitive dependencies of the given crate.
+    pub fn transitive_deps(&self, of: CrateId) -> impl Iterator<Item = CrateId> + '_ {
+        let mut worklist = vec![of];
+        let mut deps = FxHashSet::default();
+
+        while let Some(krate) = worklist.pop() {
+            if !deps.insert(krate) {
+                continue;
+            }
+
+            worklist.extend(self[krate].dependencies.iter().map(|dep| dep.crate_id));
+        }
+
+        deps.remove(&of);
+        deps.into_iter()
+    }
+
+    // FIXME: this only finds one crate with the given root; we could have multiple
+    pub fn crate_id_for_crate_root(&self, file_id: FileId) -> Option<CrateId> {
+        let (&crate_id, _) =
+            self.arena.iter().find(|(_crate_id, data)| data.root_file_id == file_id)?;
+        Some(crate_id)
+    }
+
+    /// Extends this crate graph by adding a complete disjoint second crate
+    /// graph.
+    ///
+    /// The ids of the crates in the `other` graph are shifted by the return
+    /// amount.
+    pub fn extend(&mut self, other: CrateGraph) -> u32 {
+        let start = self.arena.len() as u32;
+        self.arena.extend(other.arena.into_iter().map(|(id, mut data)| {
+            let new_id = id.shift(start);
+            for dep in &mut data.dependencies {
+                dep.crate_id = dep.crate_id.shift(start);
+            }
+            (new_id, data)
+        }));
+        start
+    }
+
+    fn dfs_find(&self, target: CrateId, from: CrateId, visited: &mut FxHashSet<CrateId>) -> bool {
+        if !visited.insert(from) {
+            return false;
+        }
+
+        if target == from {
+            return true;
+        }
+
+        for dep in &self[from].dependencies {
+            let crate_id = dep.crate_id;
+            if self.dfs_find(target, crate_id, visited) {
+                return true;
+            }
+        }
+        false
+    }
+}
+
+impl ops::Index<CrateId> for CrateGraph {
+    type Output = CrateData;
+    fn index(&self, crate_id: CrateId) -> &CrateData {
+        &self.arena[&crate_id]
+    }
+}
+
+impl CrateId {
+    pub fn shift(self, amount: u32) -> CrateId {
+        CrateId(self.0 + amount)
+    }
+}
+
+impl CrateData {
+    fn add_dep(&mut self, name: CrateName, crate_id: CrateId) {
+        self.dependencies.push(Dependency { name, crate_id })
+    }
+}
+
+impl FromStr for Edition {
+    type Err = ParseEditionError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let res = match s {
+            "2015" => Edition::Edition2015,
+            "2018" => Edition::Edition2018,
+            _ => return Err(ParseEditionError { invalid_input: s.to_string() }),
+        };
+        Ok(res)
+    }
+}
+
+impl fmt::Display for Edition {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(match self {
+            Edition::Edition2015 => "2015",
+            Edition::Edition2018 => "2018",
+        })
+    }
+}
+
+impl FromIterator<(String, String)> for Env {
+    fn from_iter<T: IntoIterator<Item = (String, String)>>(iter: T) -> Self {
+        Env { entries: FromIterator::from_iter(iter) }
+    }
+}
+
+impl Env {
+    pub fn set(&mut self, env: &str, value: String) {
+        self.entries.insert(env.to_owned(), value);
+    }
+
+    pub fn get(&self, env: &str) -> Option<String> {
+        self.entries.get(env).cloned()
+    }
+}
+
+#[derive(Debug)]
+pub struct ParseEditionError {
+    invalid_input: String,
+}
+
+impl fmt::Display for ParseEditionError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "invalid edition: {:?}", self.invalid_input)
+    }
+}
+
+impl std::error::Error for ParseEditionError {}
+
+#[derive(Debug)]
+pub struct CyclicDependenciesError;
+
+#[cfg(test)]
+mod tests {
+    use super::{CfgOptions, CrateGraph, CrateName, Dependency, Edition::Edition2018, Env, FileId};
+
+    #[test]
+    fn detect_cyclic_dependency_indirect() {
+        let mut graph = CrateGraph::default();
+        let crate1 = graph.add_crate_root(
+            FileId(1u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        let crate2 = graph.add_crate_root(
+            FileId(2u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        let crate3 = graph.add_crate_root(
+            FileId(3u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        assert!(graph.add_dep(crate1, CrateName::new("crate2").unwrap(), crate2).is_ok());
+        assert!(graph.add_dep(crate2, CrateName::new("crate3").unwrap(), crate3).is_ok());
+        assert!(graph.add_dep(crate3, CrateName::new("crate1").unwrap(), crate1).is_err());
+    }
+
+    #[test]
+    fn detect_cyclic_dependency_direct() {
+        let mut graph = CrateGraph::default();
+        let crate1 = graph.add_crate_root(
+            FileId(1u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        let crate2 = graph.add_crate_root(
+            FileId(2u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        assert!(graph.add_dep(crate1, CrateName::new("crate2").unwrap(), crate2).is_ok());
+        assert!(graph.add_dep(crate2, CrateName::new("crate2").unwrap(), crate2).is_err());
+    }
+
+    #[test]
+    fn it_works() {
+        let mut graph = CrateGraph::default();
+        let crate1 = graph.add_crate_root(
+            FileId(1u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        let crate2 = graph.add_crate_root(
+            FileId(2u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        let crate3 = graph.add_crate_root(
+            FileId(3u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        assert!(graph.add_dep(crate1, CrateName::new("crate2").unwrap(), crate2).is_ok());
+        assert!(graph.add_dep(crate2, CrateName::new("crate3").unwrap(), crate3).is_ok());
+    }
+
+    #[test]
+    fn dashes_are_normalized() {
+        let mut graph = CrateGraph::default();
+        let crate1 = graph.add_crate_root(
+            FileId(1u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        let crate2 = graph.add_crate_root(
+            FileId(2u32),
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        assert!(graph
+            .add_dep(crate1, CrateName::normalize_dashes("crate-name-with-dashes"), crate2)
+            .is_ok());
+        assert_eq!(
+            graph[crate1].dependencies,
+            vec![Dependency {
+                crate_id: crate2,
+                name: CrateName::new("crate_name_with_dashes").unwrap()
+            }]
+        );
+    }
+}