Move FnDescriptors to analyzer

12 files changed, 610 insertions, 97 deletions

diff --git a/crates/ra_analysis/src/completion.rs b/crates/ra_analysis/src/completion.rs
index 0141d132e..869ab5afb 100644
--- a/crates/ra_analysis/src/completion.rs
+++ b/crates/ra_analysis/src/completion.rs
@@ -1,14 +1,15 @@
 use ra_editor::{CompletionItem, find_node_at_offset};
 use ra_syntax::{
     AtomEdit, File, TextUnit, AstNode,
-    ast::{self, ModuleItemOwner, AstChildren},
+    ast,
 };
 
 use crate::{
     FileId, Cancelable,
     input::FilesDatabase,
     db::{self, SyntaxDatabase},
-    descriptors::module::{ModulesDatabase, ModuleTree, ModuleId, scope::ModuleScope},
+    descriptors::DescriptorDatabase,
+    descriptors::module::{ModuleTree, ModuleId},
 };
 
 pub(crate) fn resolve_based_completion(db: &db::RootDatabase, file_id: FileId, offset: TextUnit) -> Cancelable<Option<Vec<CompletionItem>>> {
diff --git a/crates/ra_analysis/src/db.rs b/crates/ra_analysis/src/db.rs
index e7a5d5e2f..fe6587f20 100644
--- a/crates/ra_analysis/src/db.rs
+++ b/crates/ra_analysis/src/db.rs
@@ -9,7 +9,10 @@ use salsa;
 use crate::{
     db,
     Cancelable, Canceled,
-    descriptors::module::{SubmodulesQuery, ModuleTreeQuery, ModulesDatabase, ModuleScopeQuery},
+    descriptors::{
+        DescriptorDatabase, SubmodulesQuery, ModuleTreeQuery, ModuleScopeQuery,
+        FnSyntaxQuery, FnScopesQuery
+    },
     symbol_index::SymbolIndex,
     syntax_ptr::{SyntaxPtrDatabase, ResolveSyntaxPtrQuery},
     FileId,
@@ -63,10 +66,12 @@ salsa::database_storage! {
             fn file_lines() for FileLinesQuery;
             fn file_symbols() for FileSymbolsQuery;
         }
-        impl ModulesDatabase {
+        impl DescriptorDatabase {
             fn module_tree() for ModuleTreeQuery;
             fn module_descriptor() for SubmodulesQuery;
             fn module_scope() for ModuleScopeQuery;
+            fn fn_syntax() for FnSyntaxQuery;
+            fn fn_scopes() for FnScopesQuery;
         }
         impl SyntaxPtrDatabase {
             fn resolve_syntax_ptr() for ResolveSyntaxPtrQuery;
diff --git a/crates/ra_analysis/src/descriptors/function/imp.rs b/crates/ra_analysis/src/descriptors/function/imp.rs
new file mode 100644
index 000000000..0a006f733
--- /dev/null
+++ b/crates/ra_analysis/src/descriptors/function/imp.rs
@@ -0,0 +1,26 @@
+use std::sync::Arc;
+
+use ra_syntax::{
+    ast::{AstNode, FnDef, FnDefNode},
+};
+
+use crate::{
+    descriptors::{
+        DescriptorDatabase,
+        function::{FnId, FnScopes},
+    },
+};
+
+/// Resolve `FnId` to the corresponding `SyntaxNode`
+/// TODO: this should return something more type-safe then `SyntaxNode`
+pub(crate) fn fn_syntax(db: &impl DescriptorDatabase, fn_id: FnId) -> FnDefNode {
+    let syntax = db.resolve_syntax_ptr(fn_id.0);
+    let fn_def = FnDef::cast(syntax.borrowed()).unwrap();
+    FnDefNode::new(fn_def)
+}
+
+pub(crate) fn fn_scopes(db: &impl DescriptorDatabase, fn_id: FnId) -> Arc<FnScopes> {
+    let syntax = db.fn_syntax(fn_id);
+    let res = FnScopes::new(syntax.ast());
+    Arc::new(res)
+}
diff --git a/crates/ra_analysis/src/descriptors/function/mod.rs b/crates/ra_analysis/src/descriptors/function/mod.rs
new file mode 100644
index 000000000..687413ddc
--- /dev/null
+++ b/crates/ra_analysis/src/descriptors/function/mod.rs
@@ -0,0 +1,83 @@
+pub(super) mod imp;
+mod scope;
+
+use ra_syntax::{
+    ast::{self, AstNode, NameOwner}
+};
+
+use crate::{
+    FileId,
+    syntax_ptr::SyntaxPtr
+};
+
+pub(crate) use self::scope::FnScopes;
+
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub(crate) struct FnId(SyntaxPtr);
+
+impl FnId {
+    pub(crate) fn new(file_id: FileId, fn_def: ast::FnDef) -> FnId {
+        let ptr = SyntaxPtr::new(file_id, fn_def.syntax());
+        FnId(ptr)
+    }
+}
+
+
+#[derive(Debug, Clone)]
+pub struct FnDescriptor {
+    pub name: String,
+    pub label: String,
+    pub ret_type: Option<String>,
+    pub params: Vec<String>,
+}
+
+impl FnDescriptor {
+    pub fn new(node: ast::FnDef) -> Option<Self> {
+        let name = node.name()?.text().to_string();
+
+        // Strip the body out for the label.
+        let label: String = if let Some(body) = node.body() {
+            let body_range = body.syntax().range();
+            let label: String = node
+                .syntax()
+                .children()
+                .filter(|child| !child.range().is_subrange(&body_range))
+                .map(|node| node.text().to_string())
+                .collect();
+            label
+        } else {
+            node.syntax().text().to_string()
+        };
+
+        let params = FnDescriptor::param_list(node);
+        let ret_type = node.ret_type().map(|r| r.syntax().text().to_string());
+
+        Some(FnDescriptor {
+            name,
+            ret_type,
+            params,
+            label,
+        })
+    }
+
+    fn param_list(node: ast::FnDef) -> Vec<String> {
+        let mut res = vec![];
+        if let Some(param_list) = node.param_list() {
+            if let Some(self_param) = param_list.self_param() {
+                res.push(self_param.syntax().text().to_string())
+            }
+
+            // Maybe use param.pat here? See if we can just extract the name?
+            //res.extend(param_list.params().map(|p| p.syntax().text().to_string()));
+            res.extend(
+                param_list
+                    .params()
+                    .filter_map(|p| p.pat())
+                    .map(|pat| pat.syntax().text().to_string()),
+            );
+        }
+        res
+    }
+}
+
diff --git a/crates/ra_analysis/src/descriptors/function/scope.rs b/crates/ra_analysis/src/descriptors/function/scope.rs
new file mode 100644
index 000000000..5333a0a3b
--- /dev/null
+++ b/crates/ra_analysis/src/descriptors/function/scope.rs
@@ -0,0 +1,435 @@
+use rustc_hash::FxHashMap;
+
+use ra_syntax::{
+    algo::generate,
+    ast::{self, ArgListOwner, LoopBodyOwner, NameOwner},
+    AstNode, SmolStr, SyntaxNodeRef,
+};
+
+use crate::syntax_ptr::LocalSyntaxPtr;
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub(crate) struct ScopeId(u32);
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct FnScopes {
+    pub(crate) self_param: Option<LocalSyntaxPtr>,
+    scopes: Vec<ScopeData>,
+    scope_for: FxHashMap<LocalSyntaxPtr, ScopeId>,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ScopeEntry {
+    name: SmolStr,
+    ptr: LocalSyntaxPtr,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+struct ScopeData {
+    parent: Option<ScopeId>,
+    entries: Vec<ScopeEntry>,
+}
+
+impl FnScopes {
+    pub(crate) fn new(fn_def: ast::FnDef) -> FnScopes {
+        let mut scopes = FnScopes {
+            self_param: fn_def
+                .param_list()
+                .and_then(|it| it.self_param())
+                .map(|it| LocalSyntaxPtr::new(it.syntax())),
+            scopes: Vec::new(),
+            scope_for: FxHashMap::default(),
+        };
+        let root = scopes.root_scope();
+        scopes.add_params_bindings(root, fn_def.param_list());
+        if let Some(body) = fn_def.body() {
+            compute_block_scopes(body, &mut scopes, root)
+        }
+        scopes
+    }
+    pub(crate) fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
+        &self.get(scope).entries
+    }
+    pub fn scope_chain<'a>(&'a self, node: SyntaxNodeRef) -> impl Iterator<Item = ScopeId> + 'a {
+        generate(self.scope_for(node), move |&scope| {
+            self.get(scope).parent
+        })
+    }
+    fn root_scope(&mut self) -> ScopeId {
+        let res = ScopeId(self.scopes.len() as u32);
+        self.scopes.push(ScopeData {
+            parent: None,
+            entries: vec![],
+        });
+        res
+    }
+    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
+        let res = ScopeId(self.scopes.len() as u32);
+        self.scopes.push(ScopeData {
+            parent: Some(parent),
+            entries: vec![],
+        });
+        res
+    }
+    fn add_bindings(&mut self, scope: ScopeId, pat: ast::Pat) {
+        let entries = pat
+            .syntax()
+            .descendants()
+            .filter_map(ast::BindPat::cast)
+            .filter_map(ScopeEntry::new);
+        self.get_mut(scope).entries.extend(entries);
+    }
+    fn add_params_bindings(&mut self, scope: ScopeId, params: Option<ast::ParamList>) {
+        params
+            .into_iter()
+            .flat_map(|it| it.params())
+            .filter_map(|it| it.pat())
+            .for_each(|it| self.add_bindings(scope, it));
+    }
+    fn set_scope(&mut self, node: SyntaxNodeRef, scope: ScopeId) {
+        self.scope_for.insert(LocalSyntaxPtr::new(node), scope);
+    }
+    fn scope_for(&self, node: SyntaxNodeRef) -> Option<ScopeId> {
+        node.ancestors()
+            .map(LocalSyntaxPtr::new)
+            .filter_map(|it| self.scope_for.get(&it).map(|&scope| scope))
+            .next()
+    }
+    fn get(&self, scope: ScopeId) -> &ScopeData {
+        &self.scopes[scope.0 as usize]
+    }
+    fn get_mut(&mut self, scope: ScopeId) -> &mut ScopeData {
+        &mut self.scopes[scope.0 as usize]
+    }
+}
+
+impl ScopeEntry {
+    fn new(pat: ast::BindPat) -> Option<ScopeEntry> {
+        let name = pat.name()?;
+        let res = ScopeEntry {
+            name: name.text(),
+            ptr: LocalSyntaxPtr::new(pat.syntax()),
+        };
+        Some(res)
+    }
+    pub(crate) fn name(&self) -> &SmolStr {
+        &self.name
+    }
+    pub(crate) fn ptr(&self) -> LocalSyntaxPtr {
+        self.ptr
+    }
+}
+
+fn compute_block_scopes(block: ast::Block, scopes: &mut FnScopes, mut scope: ScopeId) {
+    for stmt in block.statements() {
+        match stmt {
+            ast::Stmt::LetStmt(stmt) => {
+                if let Some(expr) = stmt.initializer() {
+                    scopes.set_scope(expr.syntax(), scope);
+                    compute_expr_scopes(expr, scopes, scope);
+                }
+                scope = scopes.new_scope(scope);
+                if let Some(pat) = stmt.pat() {
+                    scopes.add_bindings(scope, pat);
+                }
+            }
+            ast::Stmt::ExprStmt(expr_stmt) => {
+                if let Some(expr) = expr_stmt.expr() {
+                    scopes.set_scope(expr.syntax(), scope);
+                    compute_expr_scopes(expr, scopes, scope);
+                }
+            }
+        }
+    }
+    if let Some(expr) = block.expr() {
+        scopes.set_scope(expr.syntax(), scope);
+        compute_expr_scopes(expr, scopes, scope);
+    }
+}
+
+fn compute_expr_scopes(expr: ast::Expr, scopes: &mut FnScopes, scope: ScopeId) {
+    match expr {
+        ast::Expr::IfExpr(e) => {
+            let cond_scope = e
+                .condition()
+                .and_then(|cond| compute_cond_scopes(cond, scopes, scope));
+            if let Some(block) = e.then_branch() {
+                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
+            }
+            if let Some(block) = e.else_branch() {
+                compute_block_scopes(block, scopes, scope);
+            }
+        }
+        ast::Expr::BlockExpr(e) => {
+            if let Some(block) = e.block() {
+                compute_block_scopes(block, scopes, scope);
+            }
+        }
+        ast::Expr::LoopExpr(e) => {
+            if let Some(block) = e.loop_body() {
+                compute_block_scopes(block, scopes, scope);
+            }
+        }
+        ast::Expr::WhileExpr(e) => {
+            let cond_scope = e
+                .condition()
+                .and_then(|cond| compute_cond_scopes(cond, scopes, scope));
+            if let Some(block) = e.loop_body() {
+                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
+            }
+        }
+        ast::Expr::ForExpr(e) => {
+            if let Some(expr) = e.iterable() {
+                compute_expr_scopes(expr, scopes, scope);
+            }
+            let mut scope = scope;
+            if let Some(pat) = e.pat() {
+                scope = scopes.new_scope(scope);
+                scopes.add_bindings(scope, pat);
+            }
+            if let Some(block) = e.loop_body() {
+                compute_block_scopes(block, scopes, scope);
+            }
+        }
+        ast::Expr::LambdaExpr(e) => {
+            let scope = scopes.new_scope(scope);
+            scopes.add_params_bindings(scope, e.param_list());
+            if let Some(body) = e.body() {
+                scopes.set_scope(body.syntax(), scope);
+                compute_expr_scopes(body, scopes, scope);
+            }
+        }
+        ast::Expr::CallExpr(e) => {
+            compute_call_scopes(e.expr(), e.arg_list(), scopes, scope);
+        }
+        ast::Expr::MethodCallExpr(e) => {
+            compute_call_scopes(e.expr(), e.arg_list(), scopes, scope);
+        }
+        ast::Expr::MatchExpr(e) => {
+            if let Some(expr) = e.expr() {
+                compute_expr_scopes(expr, scopes, scope);
+            }
+            for arm in e.match_arm_list().into_iter().flat_map(|it| it.arms()) {
+                let scope = scopes.new_scope(scope);
+                for pat in arm.pats() {
+                    scopes.add_bindings(scope, pat);
+                }
+                if let Some(expr) = arm.expr() {
+                    compute_expr_scopes(expr, scopes, scope);
+                }
+            }
+        }
+        _ => expr
+            .syntax()
+            .children()
+            .filter_map(ast::Expr::cast)
+            .for_each(|expr| compute_expr_scopes(expr, scopes, scope)),
+    };
+
+    fn compute_call_scopes(
+        receiver: Option<ast::Expr>,
+        arg_list: Option<ast::ArgList>,
+        scopes: &mut FnScopes,
+        scope: ScopeId,
+    ) {
+        arg_list
+            .into_iter()
+            .flat_map(|it| it.args())
+            .chain(receiver)
+            .for_each(|expr| compute_expr_scopes(expr, scopes, scope));
+    }
+
+    fn compute_cond_scopes(
+        cond: ast::Condition,
+        scopes: &mut FnScopes,
+        scope: ScopeId,
+    ) -> Option<ScopeId> {
+        if let Some(expr) = cond.expr() {
+            compute_expr_scopes(expr, scopes, scope);
+        }
+        if let Some(pat) = cond.pat() {
+            let s = scopes.new_scope(scope);
+            scopes.add_bindings(s, pat);
+            Some(s)
+        } else {
+            None
+        }
+    }
+}
+
+pub fn resolve_local_name<'a>(
+    name_ref: ast::NameRef,
+    scopes: &'a FnScopes,
+) -> Option<&'a ScopeEntry> {
+    use rustc_hash::FxHashSet;
+
+    let mut shadowed = FxHashSet::default();
+    let ret = scopes
+        .scope_chain(name_ref.syntax())
+        .flat_map(|scope| scopes.entries(scope).iter())
+        .filter(|entry| shadowed.insert(entry.name()))
+        .filter(|entry| entry.name() == &name_ref.text())
+        .nth(0);
+    ret
+}
+
+#[cfg(test)]
+mod tests {
+    use ra_syntax::File;
+    use test_utils::extract_offset;
+    use ra_editor::{find_node_at_offset};
+
+    use super::*;
+
+
+    fn do_check(code: &str, expected: &[&str]) {
+        let (off, code) = extract_offset(code);
+        let code = {
+            let mut buf = String::new();
+            let off = u32::from(off) as usize;
+            buf.push_str(&code[..off]);
+            buf.push_str("marker");
+            buf.push_str(&code[off..]);
+            buf
+        };
+        let file = File::parse(&code);
+        let marker: ast::PathExpr = find_node_at_offset(file.syntax(), off).unwrap();
+        let fn_def: ast::FnDef = find_node_at_offset(file.syntax(), off).unwrap();
+        let scopes = FnScopes::new(fn_def);
+        let actual = scopes
+            .scope_chain(marker.syntax())
+            .flat_map(|scope| scopes.entries(scope))
+            .map(|it| it.name())
+            .collect::<Vec<_>>();
+        assert_eq!(actual.as_slice(), expected);
+    }
+
+    #[test]
+    fn test_lambda_scope() {
+        do_check(
+            r"
+            fn quux(foo: i32) {
+                let f = |bar, baz: i32| {
+                    <|>
+                };
+            }",
+            &["bar", "baz", "foo"],
+        );
+    }
+
+    #[test]
+    fn test_call_scope() {
+        do_check(
+            r"
+            fn quux() {
+                f(|x| <|> );
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_metod_call_scope() {
+        do_check(
+            r"
+            fn quux() {
+                z.f(|x| <|> );
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_loop_scope() {
+        do_check(
+            r"
+            fn quux() {
+                loop {
+                    let x = ();
+                    <|>
+                };
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_match() {
+        do_check(
+            r"
+            fn quux() {
+                match () {
+                    Some(x) => {
+                        <|>
+                    }
+                };
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_shadow_variable() {
+        do_check(
+            r"
+            fn foo(x: String) {
+                let x : &str = &x<|>;
+            }",
+            &["x"],
+        );
+    }
+
+    fn do_check_local_name(code: &str, expected_offset: u32) {
+        let (off, code) = extract_offset(code);
+        let file = File::parse(&code);
+        let fn_def: ast::FnDef = find_node_at_offset(file.syntax(), off).unwrap();
+        let name_ref: ast::NameRef = find_node_at_offset(file.syntax(), off).unwrap();
+
+        let scopes = FnScopes::new(fn_def);
+
+        let local_name_entry = resolve_local_name(name_ref, &scopes).unwrap();
+        let local_name = local_name_entry.ptr().resolve(&file);
+        let expected_name =
+            find_node_at_offset::<ast::Name>(file.syntax(), expected_offset.into()).unwrap();
+        assert_eq!(local_name.range(), expected_name.syntax().range());
+    }
+
+    #[test]
+    fn test_resolve_local_name() {
+        do_check_local_name(
+            r#"
+            fn foo(x: i32, y: u32) {
+                {
+                    let z = x * 2;
+                }
+                {
+                    let t = x<|> * 3;
+                }
+            }"#,
+            21,
+        );
+    }
+
+    #[test]
+    fn test_resolve_local_name_declaration() {
+        do_check_local_name(
+            r#"
+            fn foo(x: String) {
+                let x : &str = &x<|>;
+            }"#,
+            21,
+        );
+    }
+
+    #[test]
+    fn test_resolve_local_name_shadow() {
+        do_check_local_name(
+            r"
+        fn foo(x: String) {
+            let x : &str = &x;
+            x<|>
+        }",
+            46,
+        );
+    }
+}
diff --git a/crates/ra_analysis/src/descriptors/mod.rs b/crates/ra_analysis/src/descriptors/mod.rs
index 0220f7d5d..0c4991757 100644
--- a/crates/ra_analysis/src/descriptors/mod.rs
+++ b/crates/ra_analysis/src/descriptors/mod.rs
@@ -1,62 +1,46 @@
 pub(crate) mod module;
+pub(crate) mod function;
+
+use std::sync::Arc;
 
 use ra_syntax::{
-    ast::{self, AstNode, NameOwner},
+    SmolStr,
+    ast::{FnDefNode},
 };
 
-#[derive(Debug, Clone)]
-pub struct FnDescriptor {
-    pub name: String,
-    pub label: String,
-    pub ret_type: Option<String>,
-    pub params: Vec<String>,
-}
-
-impl FnDescriptor {
-    pub fn new(node: ast::FnDef) -> Option<Self> {
-        let name = node.name()?.text().to_string();
-
-        // Strip the body out for the label.
-        let label: String = if let Some(body) = node.body() {
-            let body_range = body.syntax().range();
-            let label: String = node
-                .syntax()
-                .children()
-                .filter(|child| !child.range().is_subrange(&body_range))
-                .map(|node| node.text().to_string())
-                .collect();
-            label
-        } else {
-            node.syntax().text().to_string()
-        };
-
-        let params = FnDescriptor::param_list(node);
-        let ret_type = node.ret_type().map(|r| r.syntax().text().to_string());
-
-        Some(FnDescriptor {
-            name,
-            ret_type,
-            params,
-            label,
-        })
-    }
+use crate::{
+    FileId, Cancelable,
+    db::SyntaxDatabase,
+    descriptors::module::{ModuleTree, ModuleId, ModuleScope},
+    descriptors::function::{FnId, FnScopes},
+    input::SourceRootId,
+    syntax_ptr::SyntaxPtrDatabase,
+};
 
-    fn param_list(node: ast::FnDef) -> Vec<String> {
-        let mut res = vec![];
-        if let Some(param_list) = node.param_list() {
-            if let Some(self_param) = param_list.self_param() {
-                res.push(self_param.syntax().text().to_string())
-            }
 
-            // Maybe use param.pat here? See if we can just extract the name?
-            //res.extend(param_list.params().map(|p| p.syntax().text().to_string()));
-            res.extend(
-                param_list
-                    .params()
-                    .filter_map(|p| p.pat())
-                    .map(|pat| pat.syntax().text().to_string()),
-            );
+salsa::query_group! {
+    pub(crate) trait DescriptorDatabase: SyntaxDatabase + SyntaxPtrDatabase {
+        fn module_tree(source_root_id: SourceRootId) -> Cancelable<Arc<ModuleTree>> {
+            type ModuleTreeQuery;
+            use fn module::imp::module_tree;
+        }
+        fn submodules(file_id: FileId) -> Cancelable<Arc<Vec<SmolStr>>> {
+            type SubmodulesQuery;
+            use fn module::imp::submodules;
+        }
+        fn module_scope(source_root_id: SourceRootId, module_id: ModuleId) -> Cancelable<Arc<ModuleScope>> {
+            type ModuleScopeQuery;
+            use fn module::imp::module_scope;
+        }
+        fn fn_syntax(fn_id: FnId) -> FnDefNode {
+            type FnSyntaxQuery;
+            // Don't retain syntax trees in memory
+            storage volatile;
+            use fn function::imp::fn_syntax;
+        }
+        fn fn_scopes(fn_id: FnId) -> Arc<FnScopes> {
+            type FnScopesQuery;
+            use fn function::imp::fn_scopes;
         }
-        res
     }
 }
diff --git a/crates/ra_analysis/src/descriptors/module/imp.rs b/crates/ra_analysis/src/descriptors/module/imp.rs
index 5fdaad137..dae3a356d 100644
--- a/crates/ra_analysis/src/descriptors/module/imp.rs
+++ b/crates/ra_analysis/src/descriptors/module/imp.rs
@@ -10,14 +10,15 @@ use ra_syntax::{
 use crate::{
     FileId, Cancelable, FileResolverImp, db,
     input::{SourceRoot, SourceRootId},
+    descriptors::DescriptorDatabase,
 };
 
 use super::{
-    ModuleData, ModuleTree, ModuleId, LinkId, LinkData, Problem, ModulesDatabase, ModuleScope
+    ModuleData, ModuleTree, ModuleId, LinkId, LinkData, Problem, ModuleScope
 };
 
 
-pub(super) fn submodules(db: &impl ModulesDatabase, file_id: FileId) -> Cancelable<Arc<Vec<SmolStr>>> {
+pub(crate) fn submodules(db: &impl DescriptorDatabase, file_id: FileId) -> Cancelable<Arc<Vec<SmolStr>>> {
     db::check_canceled(db)?;
     let file = db.file_syntax(file_id);
     let root = file.ast();
@@ -25,7 +26,7 @@ pub(super) fn submodules(db: &impl ModulesDatabase, file_id: FileId) -> Cancelab
     Ok(Arc::new(submodules))
 }
 
-pub(super) fn modules(root: ast::Root<'_>) -> impl Iterator<Item = (SmolStr, ast::Module<'_>)> {
+pub(crate) fn modules(root: ast::Root<'_>) -> impl Iterator<Item = (SmolStr, ast::Module<'_>)> {
     root.modules().filter_map(|module| {
         let name = module.name()?.text();
         if !module.has_semi() {
@@ -35,8 +36,8 @@ pub(super) fn modules(root: ast::Root<'_>) -> impl Iterator<Item = (SmolStr, ast
     })
 }
 
-pub(super) fn module_scope(
-    db: &impl ModulesDatabase,
+pub(crate) fn module_scope(
+    db: &impl DescriptorDatabase,
     source_root_id: SourceRootId,
     module_id: ModuleId,
 ) -> Cancelable<Arc<ModuleScope>> {
@@ -47,8 +48,8 @@ pub(super) fn module_scope(
     Ok(Arc::new(res))
 }
 
-pub(super) fn module_tree(
-    db: &impl ModulesDatabase,
+pub(crate) fn module_tree(
+    db: &impl DescriptorDatabase,
     source_root: SourceRootId,
 ) -> Cancelable<Arc<ModuleTree>> {
     db::check_canceled(db)?;
@@ -64,7 +65,7 @@ pub struct Submodule {
 
 
 fn create_module_tree<'a>(
-    db: &impl ModulesDatabase,
+    db: &impl DescriptorDatabase,
     source_root: SourceRootId,
 ) -> Cancelable<ModuleTree> {
     let mut tree = ModuleTree {
@@ -88,7 +89,7 @@ fn create_module_tree<'a>(
 }
 
 fn build_subtree(
-    db: &impl ModulesDatabase,
+    db: &impl DescriptorDatabase,
     source_root: &SourceRoot,
     tree: &mut ModuleTree,
     visited: &mut FxHashSet<FileId>,
diff --git a/crates/ra_analysis/src/descriptors/module/mod.rs b/crates/ra_analysis/src/descriptors/module/mod.rs
index 9e5d73f94..667553f74 100644
--- a/crates/ra_analysis/src/descriptors/module/mod.rs
+++ b/crates/ra_analysis/src/descriptors/module/mod.rs
@@ -1,37 +1,13 @@
-mod imp;
+pub(super) mod imp;
 pub(crate) mod scope;
 
-use std::sync::Arc;
-
 use relative_path::RelativePathBuf;
 use ra_syntax::{ast::{self, NameOwner, AstNode}, SmolStr, SyntaxNode};
 
-use crate::{
-    FileId, Cancelable,
-    db::SyntaxDatabase,
-    input::SourceRootId,
-};
+use crate::FileId;
 
 pub(crate) use self::scope::ModuleScope;
 
-salsa::query_group! {
-    pub(crate) trait ModulesDatabase: SyntaxDatabase {
-        fn module_tree(source_root_id: SourceRootId) -> Cancelable<Arc<ModuleTree>> {
-            type ModuleTreeQuery;
-            use fn imp::module_tree;
-        }
-        fn submodules(file_id: FileId) -> Cancelable<Arc<Vec<SmolStr>>> {
-            type SubmodulesQuery;
-            use fn imp::submodules;
-        }
-        fn module_scope(source_root_id: SourceRootId, module_id: ModuleId) -> Cancelable<Arc<ModuleScope>> {
-            type ModuleScopeQuery;
-            use fn imp::module_scope;
-        }
-    }
-}
-
-
 #[derive(Debug, PartialEq, Eq, Hash)]
 pub(crate) struct ModuleTree {
     mods: Vec<ModuleData>,
diff --git a/crates/ra_analysis/src/descriptors/module/scope.rs b/crates/ra_analysis/src/descriptors/module/scope.rs
index da58ddce0..0f8f325ab 100644
--- a/crates/ra_analysis/src/descriptors/module/scope.rs
+++ b/crates/ra_analysis/src/descriptors/module/scope.rs
@@ -2,8 +2,8 @@
 
 
 use ra_syntax::{
-    ast::{self, AstChildren, ModuleItemOwner},
-    File, AstNode, SmolStr, SyntaxNode, SyntaxNodeRef,
+    ast::{self, ModuleItemOwner},
+    File, AstNode, SmolStr,
 };
 
 use crate::syntax_ptr::LocalSyntaxPtr;
@@ -99,7 +99,7 @@ fn collect_imports(tree: ast::UseTree, acc: &mut Vec<Entry>) {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use ra_syntax::{ast::ModuleItemOwner, File};
+    use ra_syntax::{File};
 
     fn do_check(code: &str, expected: &[&str]) {
         let file = File::parse(&code);
diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index efb3182a6..49b693ae8 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -21,8 +21,9 @@ use crate::{
         self, SyntaxDatabase, FileSyntaxQuery,
     },
     input::{SourceRootId, FilesDatabase, SourceRoot, WORKSPACE},
-    descriptors::module::{ModulesDatabase, ModuleTree, Problem},
-    descriptors::{FnDescriptor},
+    descriptors::DescriptorDatabase,
+    descriptors::module::{ModuleTree, Problem},
+    descriptors::function::{FnDescriptor},
     symbol_index::SymbolIndex,
     CrateGraph, CrateId, Diagnostic, FileId, FileResolver, FileSystemEdit, Position,
     Query, SourceChange, SourceFileEdit, Cancelable,
diff --git a/crates/ra_analysis/src/lib.rs b/crates/ra_analysis/src/lib.rs
index 363c72c0b..a77c9a5fa 100644
--- a/crates/ra_analysis/src/lib.rs
+++ b/crates/ra_analysis/src/lib.rs
@@ -29,7 +29,7 @@ use crate::{
 };
 
 pub use crate::{
-    descriptors::FnDescriptor,
+    descriptors::function::FnDescriptor,
     input::{FileId, FileResolver, CrateGraph, CrateId}
 };
 pub use ra_editor::{
diff --git a/crates/ra_analysis/src/syntax_ptr.rs b/crates/ra_analysis/src/syntax_ptr.rs
index adbff4806..aee214318 100644
--- a/crates/ra_analysis/src/syntax_ptr.rs
+++ b/crates/ra_analysis/src/syntax_ptr.rs
@@ -12,6 +12,7 @@ salsa::query_group! {
     pub(crate) trait SyntaxPtrDatabase: SyntaxDatabase {
         fn resolve_syntax_ptr(ptr: SyntaxPtr) -> SyntaxNode {
             type ResolveSyntaxPtrQuery;
+            // Don't retain syntax trees in memory
             storage volatile;
         }
     }