5 files changed, 328 insertions, 85 deletions

diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index ac8f8261b..85dc4feb0 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -1,11 +1,15 @@
 //! FIXME: write short doc here
 mod lower;
+pub mod scope;
 
 use std::{ops::Index, sync::Arc};
 
-use hir_expand::{either::Either, HirFileId, MacroDefId, Source};
+use hir_expand::{
+    either::Either, hygiene::Hygiene, AstId, HirFileId, MacroCallLoc, MacroDefId, MacroFileKind,
+    Source,
+};
 use ra_arena::{map::ArenaMap, Arena};
-use ra_syntax::{ast, AstPtr};
+use ra_syntax::{ast, AstNode, AstPtr};
 use rustc_hash::FxHashMap;
 
 use crate::{
@@ -13,28 +17,87 @@ use crate::{
     expr::{Expr, ExprId, Pat, PatId},
     nameres::CrateDefMap,
     path::Path,
-    ModuleId,
+    AstItemDef, DefWithBodyId, ModuleId,
 };
 
-pub struct MacroResolver {
+pub struct Expander {
     crate_def_map: Arc<CrateDefMap>,
+    current_file_id: HirFileId,
+    hygiene: Hygiene,
     module: ModuleId,
 }
 
-impl MacroResolver {
-    pub fn new(db: &impl DefDatabase2, module: ModuleId) -> MacroResolver {
-        MacroResolver { crate_def_map: db.crate_def_map(module.krate), module }
+impl Expander {
+    pub fn new(db: &impl DefDatabase2, current_file_id: HirFileId, module: ModuleId) -> Expander {
+        let crate_def_map = db.crate_def_map(module.krate);
+        let hygiene = Hygiene::new(db, current_file_id);
+        Expander { crate_def_map, current_file_id, hygiene, module }
     }
 
-    pub(crate) fn resolve_path_as_macro(
-        &self,
+    fn enter_expand(
+        &mut self,
         db: &impl DefDatabase2,
-        path: &Path,
-    ) -> Option<MacroDefId> {
+        macro_call: ast::MacroCall,
+    ) -> Option<(Mark, ast::Expr)> {
+        let ast_id = AstId::new(
+            self.current_file_id,
+            db.ast_id_map(self.current_file_id).ast_id(&macro_call),
+        );
+
+        if let Some(path) = macro_call.path().and_then(|path| self.parse_path(path)) {
+            if let Some(def) = self.resolve_path_as_macro(db, &path) {
+                let call_id = db.intern_macro(MacroCallLoc { def, ast_id });
+                let file_id = call_id.as_file(MacroFileKind::Expr);
+                if let Some(node) = db.parse_or_expand(file_id) {
+                    if let Some(expr) = ast::Expr::cast(node) {
+                        log::debug!("macro expansion {:#?}", expr.syntax());
+
+                        let mark = Mark { file_id: self.current_file_id };
+                        self.hygiene = Hygiene::new(db, file_id);
+                        self.current_file_id = file_id;
+
+                        return Some((mark, expr));
+                    }
+                }
+            }
+        }
+
+        // FIXME: Instead of just dropping the error from expansion
+        // report it
+        None
+    }
+
+    fn exit(&mut self, db: &impl DefDatabase2, mark: Mark) {
+        self.hygiene = Hygiene::new(db, mark.file_id);
+        self.current_file_id = mark.file_id;
+        std::mem::forget(mark);
+    }
+
+    fn to_source<T>(&self, ast: T) -> Source<T> {
+        Source { file_id: self.current_file_id, ast }
+    }
+
+    fn parse_path(&mut self, path: ast::Path) -> Option<Path> {
+        Path::from_src(path, &self.hygiene)
+    }
+
+    fn resolve_path_as_macro(&self, db: &impl DefDatabase2, path: &Path) -> Option<MacroDefId> {
         self.crate_def_map.resolve_path(db, self.module.module_id, path).0.get_macros()
     }
 }
 
+struct Mark {
+    file_id: HirFileId,
+}
+
+impl Drop for Mark {
+    fn drop(&mut self) {
+        if !std::thread::panicking() {
+            panic!("dropped mark")
+        }
+    }
+}
+
 /// The body of an item (function, const etc.).
 #[derive(Debug, Eq, PartialEq)]
 pub struct Body {
@@ -70,22 +133,51 @@ pub type PatSource = Source<PatPtr>;
 /// this properly for macros.
 #[derive(Default, Debug, Eq, PartialEq)]
 pub struct BodySourceMap {
-    expr_map: FxHashMap<ExprPtr, ExprId>,
+    expr_map: FxHashMap<ExprSource, ExprId>,
     expr_map_back: ArenaMap<ExprId, ExprSource>,
-    pat_map: FxHashMap<PatPtr, PatId>,
+    pat_map: FxHashMap<PatSource, PatId>,
     pat_map_back: ArenaMap<PatId, PatSource>,
     field_map: FxHashMap<(ExprId, usize), AstPtr<ast::RecordField>>,
 }
 
 impl Body {
-    pub fn new(
+    pub(crate) fn body_with_source_map_query(
+        db: &impl DefDatabase2,
+        def: DefWithBodyId,
+    ) -> (Arc<Body>, Arc<BodySourceMap>) {
+        let mut params = None;
+
+        let (file_id, module, body) = match def {
+            DefWithBodyId::FunctionId(f) => {
+                let src = f.source(db);
+                params = src.ast.param_list();
+                (src.file_id, f.module(db), src.ast.body().map(ast::Expr::from))
+            }
+            DefWithBodyId::ConstId(c) => {
+                let src = c.source(db);
+                (src.file_id, c.module(db), src.ast.body())
+            }
+            DefWithBodyId::StaticId(s) => {
+                let src = s.source(db);
+                (src.file_id, s.module(db), src.ast.body())
+            }
+        };
+        let expander = Expander::new(db, file_id, module);
+        let (body, source_map) = Body::new(db, expander, params, body);
+        (Arc::new(body), Arc::new(source_map))
+    }
+
+    pub(crate) fn body_query(db: &impl DefDatabase2, def: DefWithBodyId) -> Arc<Body> {
+        db.body_with_source_map(def).0
+    }
+
+    fn new(
         db: &impl DefDatabase2,
-        resolver: MacroResolver,
-        file_id: HirFileId,
+        expander: Expander,
         params: Option<ast::ParamList>,
         body: Option<ast::Expr>,
     ) -> (Body, BodySourceMap) {
-        lower::lower(db, resolver, file_id, params, body)
+        lower::lower(db, expander, params, body)
     }
 
     pub fn params(&self) -> &[PatId] {
@@ -126,16 +218,18 @@ impl BodySourceMap {
         self.expr_map_back.get(expr).copied()
     }
 
-    pub fn node_expr(&self, node: &ast::Expr) -> Option<ExprId> {
-        self.expr_map.get(&Either::A(AstPtr::new(node))).cloned()
+    pub fn node_expr(&self, node: Source<&ast::Expr>) -> Option<ExprId> {
+        let src = node.map(|it| Either::A(AstPtr::new(it)));
+        self.expr_map.get(&src).cloned()
     }
 
     pub fn pat_syntax(&self, pat: PatId) -> Option<PatSource> {
         self.pat_map_back.get(pat).copied()
     }
 
-    pub fn node_pat(&self, node: &ast::Pat) -> Option<PatId> {
-        self.pat_map.get(&Either::A(AstPtr::new(node))).cloned()
+    pub fn node_pat(&self, node: Source<&ast::Pat>) -> Option<PatId> {
+        let src = node.map(|it| Either::A(AstPtr::new(it)));
+        self.pat_map.get(&src).cloned()
     }
 
     pub fn field_syntax(&self, expr: ExprId, field: usize) -> AstPtr<ast::RecordField> {
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 2aa863c9e..a5bb60e85 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -2,9 +2,7 @@
 
 use hir_expand::{
     either::Either,
-    hygiene::Hygiene,
     name::{self, AsName, Name},
-    AstId, HirFileId, MacroCallLoc, MacroFileKind, Source,
 };
 use ra_arena::Arena;
 use ra_syntax::{
@@ -16,7 +14,7 @@ use ra_syntax::{
 };
 
 use crate::{
-    body::{Body, BodySourceMap, MacroResolver, PatPtr},
+    body::{Body, BodySourceMap, Expander, PatPtr},
     builtin_type::{BuiltinFloat, BuiltinInt},
     db::DefDatabase2,
     expr::{
@@ -30,16 +28,13 @@ use crate::{
 
 pub(super) fn lower(
     db: &impl DefDatabase2,
-    resolver: MacroResolver,
-    file_id: HirFileId,
+    expander: Expander,
     params: Option<ast::ParamList>,
     body: Option<ast::Expr>,
 ) -> (Body, BodySourceMap) {
     ExprCollector {
-        resolver,
+        expander,
         db,
-        original_file_id: file_id,
-        current_file_id: file_id,
         source_map: BodySourceMap::default(),
         body: Body {
             exprs: Arena::default(),
@@ -53,9 +48,7 @@ pub(super) fn lower(
 
 struct ExprCollector<DB> {
     db: DB,
-    resolver: MacroResolver,
-    original_file_id: HirFileId,
-    current_file_id: HirFileId,
+    expander: Expander,
 
     body: Body,
     source_map: BodySourceMap,
@@ -101,12 +94,9 @@ where
     fn alloc_expr(&mut self, expr: Expr, ptr: AstPtr<ast::Expr>) -> ExprId {
         let ptr = Either::A(ptr);
         let id = self.body.exprs.alloc(expr);
-        if self.current_file_id == self.original_file_id {
-            self.source_map.expr_map.insert(ptr, id);
-        }
-        self.source_map
-            .expr_map_back
-            .insert(id, Source { file_id: self.current_file_id, ast: ptr });
+        let src = self.expander.to_source(ptr);
+        self.source_map.expr_map.insert(src, id);
+        self.source_map.expr_map_back.insert(id, src);
         id
     }
     // desugared exprs don't have ptr, that's wrong and should be fixed
@@ -117,20 +107,16 @@ where
     fn alloc_expr_field_shorthand(&mut self, expr: Expr, ptr: AstPtr<ast::RecordField>) -> ExprId {
         let ptr = Either::B(ptr);
         let id = self.body.exprs.alloc(expr);
-        if self.current_file_id == self.original_file_id {
-            self.source_map.expr_map.insert(ptr, id);
-        }
-        self.source_map
-            .expr_map_back
-            .insert(id, Source { file_id: self.current_file_id, ast: ptr });
+        let src = self.expander.to_source(ptr);
+        self.source_map.expr_map.insert(src, id);
+        self.source_map.expr_map_back.insert(id, src);
         id
     }
     fn alloc_pat(&mut self, pat: Pat, ptr: PatPtr) -> PatId {
         let id = self.body.pats.alloc(pat);
-        if self.current_file_id == self.original_file_id {
-            self.source_map.pat_map.insert(ptr, id);
-        }
-        self.source_map.pat_map_back.insert(id, Source { file_id: self.current_file_id, ast: ptr });
+        let src = self.expander.to_source(ptr);
+        self.source_map.pat_map.insert(src, id);
+        self.source_map.pat_map_back.insert(id, src);
         id
     }
 
@@ -272,7 +258,7 @@ where
             ast::Expr::PathExpr(e) => {
                 let path = e
                     .path()
-                    .and_then(|path| self.parse_path(path))
+                    .and_then(|path| self.expander.parse_path(path))
                     .map(Expr::Path)
                     .unwrap_or(Expr::Missing);
                 self.alloc_expr(path, syntax_ptr)
@@ -288,7 +274,8 @@ where
             ast::Expr::ParenExpr(e) => {
                 let inner = self.collect_expr_opt(e.expr());
                 // make the paren expr point to the inner expression as well
-                self.source_map.expr_map.insert(Either::A(syntax_ptr), inner);
+                let src = self.expander.to_source(Either::A(syntax_ptr));
+                self.source_map.expr_map.insert(src, inner);
                 inner
             }
             ast::Expr::ReturnExpr(e) => {
@@ -296,7 +283,7 @@ where
                 self.alloc_expr(Expr::Return { expr }, syntax_ptr)
             }
             ast::Expr::RecordLit(e) => {
-                let path = e.path().and_then(|path| self.parse_path(path));
+                let path = e.path().and_then(|path| self.expander.parse_path(path));
                 let mut field_ptrs = Vec::new();
                 let record_lit = if let Some(nfl) = e.record_field_list() {
                     let fields = nfl
@@ -443,32 +430,14 @@ where
             // FIXME implement HIR for these:
             ast::Expr::Label(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
             ast::Expr::RangeExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
-            ast::Expr::MacroCall(e) => {
-                let ast_id = AstId::new(
-                    self.current_file_id,
-                    self.db.ast_id_map(self.current_file_id).ast_id(&e),
-                );
-
-                if let Some(path) = e.path().and_then(|path| self.parse_path(path)) {
-                    if let Some(def) = self.resolver.resolve_path_as_macro(self.db, &path) {
-                        let call_id = self.db.intern_macro(MacroCallLoc { def, ast_id });
-                        let file_id = call_id.as_file(MacroFileKind::Expr);
-                        if let Some(node) = self.db.parse_or_expand(file_id) {
-                            if let Some(expr) = ast::Expr::cast(node) {
-                                log::debug!("macro expansion {:#?}", expr.syntax());
-                                let old_file_id =
-                                    std::mem::replace(&mut self.current_file_id, file_id);
-                                let id = self.collect_expr(expr);
-                                self.current_file_id = old_file_id;
-                                return id;
-                            }
-                        }
-                    }
+            ast::Expr::MacroCall(e) => match self.expander.enter_expand(self.db, e) {
+                Some((mark, expansion)) => {
+                    let id = self.collect_expr(expansion);
+                    self.expander.exit(self.db, mark);
+                    id
                 }
-                // FIXME: Instead of just dropping the error from expansion
-                // report it
-                self.alloc_expr(Expr::Missing, syntax_ptr)
-            }
+                None => self.alloc_expr(Expr::Missing, syntax_ptr),
+            },
         }
     }
 
@@ -519,7 +488,7 @@ where
                 Pat::Bind { name, mode: annotation, subpat }
             }
             ast::Pat::TupleStructPat(p) => {
-                let path = p.path().and_then(|path| self.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path));
                 let args = p.args().map(|p| self.collect_pat(p)).collect();
                 Pat::TupleStruct { path, args }
             }
@@ -529,7 +498,7 @@ where
                 Pat::Ref { pat, mutability }
             }
             ast::Pat::PathPat(p) => {
-                let path = p.path().and_then(|path| self.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path));
                 path.map(Pat::Path).unwrap_or(Pat::Missing)
             }
             ast::Pat::TuplePat(p) => {
@@ -538,7 +507,7 @@ where
             }
             ast::Pat::PlaceholderPat(_) => Pat::Wild,
             ast::Pat::RecordPat(p) => {
-                let path = p.path().and_then(|path| self.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path));
                 let record_field_pat_list =
                     p.record_field_pat_list().expect("every struct should have a field list");
                 let mut fields: Vec<_> = record_field_pat_list
@@ -579,11 +548,6 @@ where
             self.missing_pat()
         }
     }
-
-    fn parse_path(&mut self, path: ast::Path) -> Option<Path> {
-        let hygiene = Hygiene::new(self.db, self.current_file_id);
-        Path::from_src(path, &hygiene)
-    }
 }
 
 impl From<ast::BinOp> for BinaryOp {
diff --git a/crates/ra_hir_def/src/body/scope.rs b/crates/ra_hir_def/src/body/scope.rs
new file mode 100644
index 000000000..09a39e721
--- /dev/null
+++ b/crates/ra_hir_def/src/body/scope.rs
@@ -0,0 +1,165 @@
+//! FIXME: write short doc here
+use std::sync::Arc;
+
+use hir_expand::name::Name;
+use ra_arena::{impl_arena_id, Arena, RawId};
+use rustc_hash::FxHashMap;
+
+use crate::{
+    body::Body,
+    db::DefDatabase2,
+    expr::{Expr, ExprId, Pat, PatId, Statement},
+    DefWithBodyId,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ScopeId(RawId);
+impl_arena_id!(ScopeId);
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ExprScopes {
+    scopes: Arena<ScopeId, ScopeData>,
+    scope_by_expr: FxHashMap<ExprId, ScopeId>,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ScopeEntry {
+    name: Name,
+    pat: PatId,
+}
+
+impl ScopeEntry {
+    pub fn name(&self) -> &Name {
+        &self.name
+    }
+
+    pub fn pat(&self) -> PatId {
+        self.pat
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ScopeData {
+    parent: Option<ScopeId>,
+    entries: Vec<ScopeEntry>,
+}
+
+impl ExprScopes {
+    pub(crate) fn expr_scopes_query(db: &impl DefDatabase2, def: DefWithBodyId) -> Arc<ExprScopes> {
+        let body = db.body(def);
+        Arc::new(ExprScopes::new(&*body))
+    }
+
+    fn new(body: &Body) -> ExprScopes {
+        let mut scopes =
+            ExprScopes { scopes: Arena::default(), scope_by_expr: FxHashMap::default() };
+        let root = scopes.root_scope();
+        scopes.add_params_bindings(body, root, body.params());
+        compute_expr_scopes(body.body_expr(), body, &mut scopes, root);
+        scopes
+    }
+
+    pub fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
+        &self.scopes[scope].entries
+    }
+
+    pub fn scope_chain(&self, scope: Option<ScopeId>) -> impl Iterator<Item = ScopeId> + '_ {
+        std::iter::successors(scope, move |&scope| self.scopes[scope].parent)
+    }
+
+    pub fn scope_for(&self, expr: ExprId) -> Option<ScopeId> {
+        self.scope_by_expr.get(&expr).copied()
+    }
+
+    pub fn scope_by_expr(&self) -> &FxHashMap<ExprId, ScopeId> {
+        &self.scope_by_expr
+    }
+
+    fn root_scope(&mut self) -> ScopeId {
+        self.scopes.alloc(ScopeData { parent: None, entries: vec![] })
+    }
+
+    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
+        self.scopes.alloc(ScopeData { parent: Some(parent), entries: vec![] })
+    }
+
+    fn add_bindings(&mut self, body: &Body, scope: ScopeId, pat: PatId) {
+        match &body[pat] {
+            Pat::Bind { name, .. } => {
+                // bind can have a sub pattern, but it's actually not allowed
+                // to bind to things in there
+                let entry = ScopeEntry { name: name.clone(), pat };
+                self.scopes[scope].entries.push(entry)
+            }
+            p => p.walk_child_pats(|pat| self.add_bindings(body, scope, pat)),
+        }
+    }
+
+    fn add_params_bindings(&mut self, body: &Body, scope: ScopeId, params: &[PatId]) {
+        params.iter().for_each(|pat| self.add_bindings(body, scope, *pat));
+    }
+
+    fn set_scope(&mut self, node: ExprId, scope: ScopeId) {
+        self.scope_by_expr.insert(node, scope);
+    }
+}
+
+fn compute_block_scopes(
+    statements: &[Statement],
+    tail: Option<ExprId>,
+    body: &Body,
+    scopes: &mut ExprScopes,
+    mut scope: ScopeId,
+) {
+    for stmt in statements {
+        match stmt {
+            Statement::Let { pat, initializer, .. } => {
+                if let Some(expr) = initializer {
+                    scopes.set_scope(*expr, scope);
+                    compute_expr_scopes(*expr, body, scopes, scope);
+                }
+                scope = scopes.new_scope(scope);
+                scopes.add_bindings(body, scope, *pat);
+            }
+            Statement::Expr(expr) => {
+                scopes.set_scope(*expr, scope);
+                compute_expr_scopes(*expr, body, scopes, scope);
+            }
+        }
+    }
+    if let Some(expr) = tail {
+        compute_expr_scopes(expr, body, scopes, scope);
+    }
+}
+
+fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope: ScopeId) {
+    scopes.set_scope(expr, scope);
+    match &body[expr] {
+        Expr::Block { statements, tail } => {
+            compute_block_scopes(&statements, *tail, body, scopes, scope);
+        }
+        Expr::For { iterable, pat, body: body_expr } => {
+            compute_expr_scopes(*iterable, body, scopes, scope);
+            let scope = scopes.new_scope(scope);
+            scopes.add_bindings(body, scope, *pat);
+            compute_expr_scopes(*body_expr, body, scopes, scope);
+        }
+        Expr::Lambda { args, body: body_expr, .. } => {
+            let scope = scopes.new_scope(scope);
+            scopes.add_params_bindings(body, scope, &args);
+            compute_expr_scopes(*body_expr, body, scopes, scope);
+        }
+        Expr::Match { expr, arms } => {
+            compute_expr_scopes(*expr, body, scopes, scope);
+            for arm in arms {
+                let scope = scopes.new_scope(scope);
+                for pat in &arm.pats {
+                    scopes.add_bindings(body, scope, *pat);
+                }
+                scopes.set_scope(arm.expr, scope);
+                compute_expr_scopes(arm.expr, body, scopes, scope);
+            }
+        }
+        e => e.walk_child_exprs(|e| compute_expr_scopes(e, body, scopes, scope)),
+    };
+}
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index 29cf71a59..40b5920d9 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -7,11 +7,12 @@ use ra_syntax::ast;
 
 use crate::{
     adt::{EnumData, StructData},
+    body::{scope::ExprScopes, Body, BodySourceMap},
     nameres::{
         raw::{ImportSourceMap, RawItems},
         CrateDefMap,
     },
-    EnumId, StructOrUnionId,
+    DefWithBodyId, EnumId, StructOrUnionId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -52,4 +53,13 @@ pub trait DefDatabase2: InternDatabase + AstDatabase {
 
     #[salsa::invoke(EnumData::enum_data_query)]
     fn enum_data(&self, e: EnumId) -> Arc<EnumData>;
+
+    #[salsa::invoke(Body::body_with_source_map_query)]
+    fn body_with_source_map(&self, def: DefWithBodyId) -> (Arc<Body>, Arc<BodySourceMap>);
+
+    #[salsa::invoke(Body::body_query)]
+    fn body(&self, def: DefWithBodyId) -> Arc<Body>;
+
+    #[salsa::invoke(ExprScopes::expr_scopes_query)]
+    fn expr_scopes(&self, def: DefWithBodyId) -> Arc<ExprScopes>;
 }
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index 4a758bb83..3fab7965c 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -374,3 +374,13 @@ impl_froms!(
     TypeAliasId,
     BuiltinType
 );
+
+/// The defs which have a body.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum DefWithBodyId {
+    FunctionId(FunctionId),
+    StaticId(StaticId),
+    ConstId(ConstId),
+}
+
+impl_froms!(DefWithBodyId: FunctionId, ConstId, StaticId);