1 files changed, 117 insertions, 0 deletions

diff --git a/crates/libanalysis/src/module_map.rs b/crates/libanalysis/src/module_map.rs
new file mode 100644
index 000000000..9b4c778b6
--- /dev/null
+++ b/crates/libanalysis/src/module_map.rs
@@ -0,0 +1,117 @@
+use std::{
+    path::{PathBuf},
+};
+
+use libsyntax2::{
+    ast::{self, AstNode, NameOwner},
+    SyntaxNode, ParsedFile, SmolStr,
+};
+use {FileId, FileResolver};
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
+pub struct ModuleId(FileId);
+
+#[derive(Clone, Debug, Default)]
+pub struct ModuleMap {
+    links: Vec<Link>,
+}
+
+#[derive(Clone, Debug)]
+struct Link {
+    owner: ModuleId,
+    syntax: SyntaxNode,
+    points_to: Vec<ModuleId>,
+}
+
+impl ModuleMap {
+    pub fn update_file(
+        &mut self,
+        file_id: FileId,
+        syntax: Option<&ParsedFile>,
+        file_resolver: &FileResolver,
+    ) {
+        let mod_id = ModuleId(file_id);
+        self.links.retain(|link| link.owner != mod_id);
+        match syntax {
+            None => {
+                for link in self.links.iter_mut() {
+                    link.points_to.retain(|&x| x != mod_id);
+                }
+            }
+            Some(syntax) => {
+                self.links.extend(
+                    syntax.ast().modules().filter_map(|it| {
+                        Link::new(mod_id, it)
+                    })
+                )
+            }
+        }
+        self.links.iter_mut().for_each(|link| {
+            link.resolve(file_resolver)
+        })
+    }
+
+    pub fn module2file(&self, m: ModuleId) -> FileId {
+        m.0
+    }
+
+    pub fn file2module(&self, file_id: FileId) -> ModuleId {
+        ModuleId(file_id)
+    }
+
+    pub fn child_module_by_name(&self, parent_mod: ModuleId, child_mod: &str) -> Vec<ModuleId> {
+        self.links
+            .iter()
+            .filter(|link| link.owner == parent_mod)
+            .filter(|link| link.name() == child_mod)
+            .filter_map(|it| it.points_to.first())
+            .map(|&it| it)
+            .collect()
+    }
+
+    pub fn parent_modules<'a>(&'a self, m: ModuleId) -> impl Iterator<Item=(ModuleId, ast::Module<'a>)> + 'a {
+        self.links
+            .iter()
+            .filter(move |link| link.points_to.iter().any(|&it| it == m))
+            .map(|link| {
+                (link.owner, link.ast())
+            })
+    }
+}
+
+impl Link {
+    fn new(owner: ModuleId, module: ast::Module) -> Option<Link> {
+        if module.name().is_none() {
+            return None;
+        }
+        let link = Link {
+            owner,
+            syntax: module.syntax().owned(),
+            points_to: Vec::new(),
+        };
+        Some(link)
+    }
+
+    fn name(&self) -> SmolStr {
+        self.ast().name()
+            .unwrap()
+            .text()
+    }
+
+    fn ast(&self) -> ast::Module {
+        ast::Module::cast(self.syntax.borrowed())
+            .unwrap()
+    }
+
+    fn resolve(&mut self, file_resolver: &FileResolver) {
+        let name = self.name();
+        let paths = &[
+            PathBuf::from(format!("../{}.rs", name)),
+            PathBuf::from(format!("../{}/mod.rs", name)),
+        ];
+        self.points_to = paths.iter()
+            .filter_map(|path| file_resolver(self.owner.0, path))
+            .map(ModuleId)
+            .collect();
+    }
+}