1 files changed, 368 insertions, 0 deletions

diff --git a/crates/ra_hir/src/module_tree.rs b/crates/ra_hir/src/module_tree.rs
new file mode 100644
index 000000000..c7a442319
--- /dev/null
+++ b/crates/ra_hir/src/module_tree.rs
@@ -0,0 +1,368 @@
+use std::sync::Arc;
+
+use rustc_hash::{FxHashMap, FxHashSet};
+use arrayvec::ArrayVec;
+use relative_path::RelativePathBuf;
+use ra_db::{FileId, SourceRootId, Cancelable, SourceRoot};
+use ra_syntax::{
+    algo::generate,
+    ast::{self, AstNode, NameOwner},
+    SyntaxNode,
+};
+use ra_arena::{Arena, RawId, impl_arena_id};
+
+use crate::{Name, AsName, HirDatabase, SourceItemId, HirFileId, Problem, SourceFileItems, ModuleSource};
+
+impl ModuleSource {
+    pub fn from_source_item_id(
+        db: &impl HirDatabase,
+        source_item_id: SourceItemId,
+    ) -> ModuleSource {
+        let module_syntax = db.file_item(source_item_id);
+        let module_syntax = module_syntax.borrowed();
+        if let Some(source_file) = ast::SourceFile::cast(module_syntax) {
+            ModuleSource::SourceFile(source_file.owned())
+        } else if let Some(module) = ast::Module::cast(module_syntax) {
+            assert!(module.item_list().is_some(), "expected inline module");
+            ModuleSource::Module(module.owned())
+        } else {
+            panic!("expected file or inline module")
+        }
+    }
+}
+
+#[derive(Clone, Hash, PartialEq, Eq, Debug)]
+pub struct Submodule {
+    name: Name,
+    is_declaration: bool,
+    source: SourceItemId,
+}
+
+impl Submodule {
+    pub(crate) fn submodules_query(
+        db: &impl HirDatabase,
+        source: SourceItemId,
+    ) -> Cancelable<Arc<Vec<Submodule>>> {
+        db.check_canceled()?;
+        let file_id = source.file_id;
+        let file_items = db.file_items(file_id);
+        let module_source = ModuleSource::from_source_item_id(db, source);
+        let submodules = match module_source {
+            ModuleSource::SourceFile(source_file) => {
+                collect_submodules(file_id, &file_items, source_file.borrowed())
+            }
+            ModuleSource::Module(module) => {
+                let module = module.borrowed();
+                collect_submodules(file_id, &file_items, module.item_list().unwrap())
+            }
+        };
+        return Ok(Arc::new(submodules));
+
+        fn collect_submodules<'a>(
+            file_id: HirFileId,
+            file_items: &SourceFileItems,
+            root: impl ast::ModuleItemOwner<'a>,
+        ) -> Vec<Submodule> {
+            modules(root)
+                .map(|(name, m)| Submodule {
+                    name,
+                    is_declaration: m.has_semi(),
+                    source: SourceItemId {
+                        file_id,
+                        item_id: Some(file_items.id_of(file_id, m.syntax())),
+                    },
+                })
+                .collect()
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ModuleId(RawId);
+impl_arena_id!(ModuleId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct LinkId(RawId);
+impl_arena_id!(LinkId);
+
+/// Physically, rust source is organized as a set of files, but logically it is
+/// organized as a tree of modules. Usually, a single file corresponds to a
+/// single module, but it is not nessary the case.
+///
+/// Module encapsulate the logic of transitioning from the fuzzy world of files
+/// (which can have multiple parents) to the precise world of modules (which
+/// always have one parent).
+#[derive(Default, Debug, PartialEq, Eq)]
+pub struct ModuleTree {
+    mods: Arena<ModuleId, ModuleData>,
+    links: Arena<LinkId, LinkData>,
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct ModuleData {
+    source: SourceItemId,
+    parent: Option<LinkId>,
+    children: Vec<LinkId>,
+}
+
+#[derive(Hash, Debug, PartialEq, Eq)]
+struct LinkData {
+    source: SourceItemId,
+    owner: ModuleId,
+    name: Name,
+    points_to: Vec<ModuleId>,
+    problem: Option<Problem>,
+}
+
+impl ModuleTree {
+    pub(crate) fn module_tree_query(
+        db: &impl HirDatabase,
+        source_root: SourceRootId,
+    ) -> Cancelable<Arc<ModuleTree>> {
+        db.check_canceled()?;
+        let res = create_module_tree(db, source_root)?;
+        Ok(Arc::new(res))
+    }
+
+    pub(crate) fn modules<'a>(&'a self) -> impl Iterator<Item = ModuleId> + 'a {
+        self.mods.iter().map(|(id, _)| id)
+    }
+
+    pub(crate) fn find_module_by_source(&self, source: SourceItemId) -> Option<ModuleId> {
+        let (res, _) = self.mods.iter().find(|(_, m)| m.source == source)?;
+        Some(res)
+    }
+}
+
+impl ModuleId {
+    pub(crate) fn source(self, tree: &ModuleTree) -> SourceItemId {
+        tree.mods[self].source
+    }
+    pub(crate) fn parent_link(self, tree: &ModuleTree) -> Option<LinkId> {
+        tree.mods[self].parent
+    }
+    pub(crate) fn parent(self, tree: &ModuleTree) -> Option<ModuleId> {
+        let link = self.parent_link(tree)?;
+        Some(tree.links[link].owner)
+    }
+    pub(crate) fn crate_root(self, tree: &ModuleTree) -> ModuleId {
+        generate(Some(self), move |it| it.parent(tree))
+            .last()
+            .unwrap()
+    }
+    pub(crate) fn child(self, tree: &ModuleTree, name: &Name) -> Option<ModuleId> {
+        let link = tree.mods[self]
+            .children
+            .iter()
+            .map(|&it| &tree.links[it])
+            .find(|it| it.name == *name)?;
+        Some(*link.points_to.first()?)
+    }
+    pub(crate) fn children<'a>(
+        self,
+        tree: &'a ModuleTree,
+    ) -> impl Iterator<Item = (Name, ModuleId)> + 'a {
+        tree.mods[self].children.iter().filter_map(move |&it| {
+            let link = &tree.links[it];
+            let module = *link.points_to.first()?;
+            Some((link.name.clone(), module))
+        })
+    }
+    pub(crate) fn problems(
+        self,
+        tree: &ModuleTree,
+        db: &impl HirDatabase,
+    ) -> Vec<(SyntaxNode, Problem)> {
+        tree.mods[self]
+            .children
+            .iter()
+            .filter_map(|&link| {
+                let p = tree.links[link].problem.clone()?;
+                let s = link.source(tree, db);
+                let s = s.borrowed().name().unwrap().syntax().owned();
+                Some((s, p))
+            })
+            .collect()
+    }
+}
+
+impl LinkId {
+    pub(crate) fn owner(self, tree: &ModuleTree) -> ModuleId {
+        tree.links[self].owner
+    }
+    pub(crate) fn name(self, tree: &ModuleTree) -> &Name {
+        &tree.links[self].name
+    }
+    pub(crate) fn source(self, tree: &ModuleTree, db: &impl HirDatabase) -> ast::ModuleNode {
+        let syntax_node = db.file_item(tree.links[self].source);
+        ast::ModuleNode::cast(syntax_node.borrowed())
+            .unwrap()
+            .owned()
+    }
+}
+
+impl ModuleTree {
+    fn push_mod(&mut self, data: ModuleData) -> ModuleId {
+        self.mods.alloc(data)
+    }
+    fn push_link(&mut self, data: LinkData) -> LinkId {
+        let owner = data.owner;
+        let id = self.links.alloc(data);
+        self.mods[owner].children.push(id);
+        id
+    }
+}
+
+fn modules<'a>(
+    root: impl ast::ModuleItemOwner<'a>,
+) -> impl Iterator<Item = (Name, ast::Module<'a>)> {
+    root.items()
+        .filter_map(|item| match item {
+            ast::ModuleItem::Module(m) => Some(m),
+            _ => None,
+        })
+        .filter_map(|module| {
+            let name = module.name()?.as_name();
+            Some((name, module))
+        })
+}
+
+fn create_module_tree<'a>(
+    db: &impl HirDatabase,
+    source_root: SourceRootId,
+) -> Cancelable<ModuleTree> {
+    let mut tree = ModuleTree::default();
+
+    let mut roots = FxHashMap::default();
+    let mut visited = FxHashSet::default();
+
+    let source_root = db.source_root(source_root);
+    for &file_id in source_root.files.values() {
+        let source = SourceItemId {
+            file_id: file_id.into(),
+            item_id: None,
+        };
+        if visited.contains(&source) {
+            continue; // TODO: use explicit crate_roots here
+        }
+        assert!(!roots.contains_key(&file_id));
+        let module_id = build_subtree(
+            db,
+            &source_root,
+            &mut tree,
+            &mut visited,
+            &mut roots,
+            None,
+            source,
+        )?;
+        roots.insert(file_id, module_id);
+    }
+    Ok(tree)
+}
+
+fn build_subtree(
+    db: &impl HirDatabase,
+    source_root: &SourceRoot,
+    tree: &mut ModuleTree,
+    visited: &mut FxHashSet<SourceItemId>,
+    roots: &mut FxHashMap<FileId, ModuleId>,
+    parent: Option<LinkId>,
+    source: SourceItemId,
+) -> Cancelable<ModuleId> {
+    visited.insert(source);
+    let id = tree.push_mod(ModuleData {
+        source,
+        parent,
+        children: Vec::new(),
+    });
+    for sub in db.submodules(source)?.iter() {
+        let link = tree.push_link(LinkData {
+            source: sub.source,
+            name: sub.name.clone(),
+            owner: id,
+            points_to: Vec::new(),
+            problem: None,
+        });
+
+        let (points_to, problem) = if sub.is_declaration {
+            let (points_to, problem) = resolve_submodule(db, source.file_id, &sub.name);
+            let points_to = points_to
+                .into_iter()
+                .map(|file_id| match roots.remove(&file_id) {
+                    Some(module_id) => {
+                        tree.mods[module_id].parent = Some(link);
+                        Ok(module_id)
+                    }
+                    None => build_subtree(
+                        db,
+                        source_root,
+                        tree,
+                        visited,
+                        roots,
+                        Some(link),
+                        SourceItemId {
+                            file_id: file_id.into(),
+                            item_id: None,
+                        },
+                    ),
+                })
+                .collect::<Cancelable<Vec<_>>>()?;
+            (points_to, problem)
+        } else {
+            let points_to = build_subtree(
+                db,
+                source_root,
+                tree,
+                visited,
+                roots,
+                Some(link),
+                sub.source,
+            )?;
+            (vec![points_to], None)
+        };
+
+        tree.links[link].points_to = points_to;
+        tree.links[link].problem = problem;
+    }
+    Ok(id)
+}
+
+fn resolve_submodule(
+    db: &impl HirDatabase,
+    file_id: HirFileId,
+    name: &Name,
+) -> (Vec<FileId>, Option<Problem>) {
+    // FIXME: handle submodules of inline modules properly
+    let file_id = file_id.original_file(db);
+    let source_root_id = db.file_source_root(file_id);
+    let path = db.file_relative_path(file_id);
+    let root = RelativePathBuf::default();
+    let dir_path = path.parent().unwrap_or(&root);
+    let mod_name = path.file_stem().unwrap_or("unknown");
+    let is_dir_owner = mod_name == "mod" || mod_name == "lib" || mod_name == "main";
+
+    let file_mod = dir_path.join(format!("{}.rs", name));
+    let dir_mod = dir_path.join(format!("{}/mod.rs", name));
+    let file_dir_mod = dir_path.join(format!("{}/{}.rs", mod_name, name));
+    let mut candidates = ArrayVec::<[_; 2]>::new();
+    if is_dir_owner {
+        candidates.push(file_mod.clone());
+        candidates.push(dir_mod);
+    } else {
+        candidates.push(file_dir_mod.clone());
+    };
+    let sr = db.source_root(source_root_id);
+    let points_to = candidates
+        .into_iter()
+        .filter_map(|path| sr.files.get(&path))
+        .map(|&it| it)
+        .collect::<Vec<_>>();
+    let problem = if points_to.is_empty() {
+        Some(Problem::UnresolvedModule {
+            candidate: if is_dir_owner { file_mod } else { file_dir_mod },
+        })
+    } else {
+        None
+    };
+    (points_to, problem)
+}