Add ModuleScope as a query

This is a first step towards queryifing completion and resolve.

Some code currently duplicates ra_editor: the plan is to move all
completion from ra_editor, but it'll take more than one commit.

1 files changed, 128 insertions, 0 deletions

diff --git a/crates/ra_analysis/src/descriptors/module/scope.rs b/crates/ra_analysis/src/descriptors/module/scope.rs
new file mode 100644
index 000000000..da58ddce0
--- /dev/null
+++ b/crates/ra_analysis/src/descriptors/module/scope.rs
@@ -0,0 +1,128 @@
+//! Backend for module-level scope resolution & completion
+
+
+use ra_syntax::{
+    ast::{self, AstChildren, ModuleItemOwner},
+    File, AstNode, SmolStr, SyntaxNode, SyntaxNodeRef,
+};
+
+use crate::syntax_ptr::LocalSyntaxPtr;
+
+/// `ModuleScope` contains all named items declared in the scope.
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) struct ModuleScope {
+    entries: Vec<Entry>,
+}
+
+/// `Entry` is a single named declaration iside a module.
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) struct Entry {
+    ptr: LocalSyntaxPtr,
+    kind: EntryKind,
+    name: SmolStr,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+enum EntryKind {
+    Item,
+    Import,
+}
+
+impl ModuleScope {
+    pub fn new(file: &File) -> ModuleScope {
+        let mut entries = Vec::new();
+        for item in file.ast().items() {
+            let entry = match item {
+                ast::ModuleItem::StructDef(item) => Entry::new(item),
+                ast::ModuleItem::EnumDef(item) => Entry::new(item),
+                ast::ModuleItem::FnDef(item) => Entry::new(item),
+                ast::ModuleItem::ConstDef(item) => Entry::new(item),
+                ast::ModuleItem::StaticDef(item) => Entry::new(item),
+                ast::ModuleItem::TraitDef(item) => Entry::new(item),
+                ast::ModuleItem::TypeDef(item) => Entry::new(item),
+                ast::ModuleItem::Module(item) => Entry::new(item),
+                ast::ModuleItem::UseItem(item) => {
+                    if let Some(tree) = item.use_tree() {
+                        collect_imports(tree, &mut entries);
+                    }
+                    continue;
+                }
+                ast::ModuleItem::ExternCrateItem(_) | ast::ModuleItem::ImplItem(_) => continue,
+            };
+            entries.extend(entry)
+        }
+
+        ModuleScope { entries }
+    }
+
+    pub fn entries(&self) -> &[Entry] {
+        self.entries.as_slice()
+    }
+}
+
+impl Entry {
+    fn new<'a>(item: impl ast::NameOwner<'a>) -> Option<Entry> {
+        let name = item.name()?;
+        Some(Entry {
+            name: name.text(),
+            ptr: LocalSyntaxPtr::new(name.syntax()),
+            kind: EntryKind::Item,
+        })
+    }
+    fn new_import(path: ast::Path) -> Option<Entry> {
+        let name_ref = path.segment()?.name_ref()?;
+        Some(Entry {
+            name: name_ref.text(),
+            ptr: LocalSyntaxPtr::new(name_ref.syntax()),
+            kind: EntryKind::Import,
+        })
+    }
+    pub fn name(&self) -> &SmolStr {
+        &self.name
+    }
+    pub fn ptr(&self) -> LocalSyntaxPtr {
+        self.ptr
+    }
+}
+
+fn collect_imports(tree: ast::UseTree, acc: &mut Vec<Entry>) {
+    if let Some(use_tree_list) = tree.use_tree_list() {
+        return use_tree_list
+            .use_trees()
+            .for_each(|it| collect_imports(it, acc));
+    }
+    if let Some(path) = tree.path() {
+        acc.extend(Entry::new_import(path));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ra_syntax::{ast::ModuleItemOwner, File};
+
+    fn do_check(code: &str, expected: &[&str]) {
+        let file = File::parse(&code);
+        let scope = ModuleScope::new(&file);
+        let actual = scope.entries.iter().map(|it| it.name()).collect::<Vec<_>>();
+        assert_eq!(expected, actual.as_slice());
+    }
+
+    #[test]
+    fn test_module_scope() {
+        do_check(
+            "
+            struct Foo;
+            enum Bar {}
+            mod baz {}
+            fn quux() {}
+            use x::{
+                y::z,
+                t,
+            };
+            type T = ();
+        ",
+            &["Foo", "Bar", "baz", "quux", "z", "t", "T"],
+        )
+    }
+}