6 files changed, 97 insertions, 17 deletions

diff --git a/crates/ra_hir/src/code_model_impl/function/scope.rs b/crates/ra_hir/src/code_model_impl/function/scope.rs
index afca1e9f8..c551e445a 100644
--- a/crates/ra_hir/src/code_model_impl/function/scope.rs
+++ b/crates/ra_hir/src/code_model_impl/function/scope.rs
@@ -47,9 +47,11 @@ impl FnScopes {
         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_for<'a>(&'a self, expr: ExprId) -> impl Iterator<Item = ScopeId> + 'a {
         generate(self.scope_for(expr), move |&scope| {
             self.scopes[scope].parent
@@ -76,12 +78,14 @@ impl FnScopes {
             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 } => self.scopes[scope].entries.push(ScopeEntry {
@@ -91,15 +95,18 @@ impl FnScopes {
             p => p.walk_child_pats(|pat| self.add_bindings(body, scope, pat)),
         }
     }
+
     fn add_params_bindings(&mut self, scope: ScopeId, params: &[PatId]) {
         let body = Arc::clone(&self.body);
         params
             .into_iter()
             .for_each(|pat| self.add_bindings(&body, scope, *pat));
     }
+
     fn set_scope(&mut self, node: ExprId, scope: ScopeId) {
         self.scope_for.insert(node, scope);
     }
+
     fn scope_for(&self, expr: ExprId) -> Option<ScopeId> {
         self.scope_for.get(&expr).map(|&scope| scope)
     }
@@ -121,6 +128,7 @@ impl ScopeEntryWithSyntax {
     pub fn name(&self) -> &Name {
         &self.name
     }
+
     pub fn ptr(&self) -> LocalSyntaxPtr {
         self.ptr
     }
@@ -132,6 +140,7 @@ impl ScopesWithSyntaxMapping {
             self.scopes.scopes[scope].parent
         })
     }
+
     pub fn scope_chain_for_offset<'a>(
         &'a self,
         offset: TextUnit,
@@ -152,6 +161,7 @@ impl ScopesWithSyntaxMapping {
 
         generate(scope, move |&scope| self.scopes.scopes[scope].parent)
     }
+
     // XXX: during completion, cursor might be outside of any particular
     // expression. Try to figure out the correct scope...
     fn adjust(&self, ptr: LocalSyntaxPtr, original_scope: ScopeId, offset: TextUnit) -> ScopeId {
@@ -225,6 +235,7 @@ impl ScopeEntry {
     pub fn name(&self) -> &Name {
         &self.name
     }
+
     pub fn pat(&self) -> PatId {
         self.pat
     }
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 6e98ebc69..8f7e75309 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -329,9 +329,25 @@ impl Expr {
 pub struct PatId(RawId);
 impl_arena_id!(PatId);
 
+/// Close relative to rustc's hir::PatKind
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Pat {
-    Missing,
+    Missing, // do we need this?
+    Wild,
+    Tuple(Vec<PatId>),
+    Struct, // TODO
+    Range {
+        start: ExprId,
+        end: ExprId,
+    },
+    Box(PatId),
+    Slice {
+        prefix: Vec<PatId>,
+        rest: Option<PatId>,
+        suffix: Vec<PatId>,
+    },
+    Path(Path),
+    Lit(ExprId),
     Bind {
         name: Name,
     },
@@ -348,11 +364,25 @@ pub enum Pat {
 impl Pat {
     pub fn walk_child_pats(&self, mut f: impl FnMut(PatId)) {
         match self {
-            Pat::Missing | Pat::Bind { .. } => {}
-            Pat::TupleStruct { args, .. } => {
+            Pat::Range { .. }
+            | Pat::Lit(..)
+            | Pat::Path(..)
+            | Pat::Wild
+            | Pat::Missing
+            | Pat::Bind { .. } => {}
+            Pat::Tuple(args) | Pat::TupleStruct { args, .. } => {
                 args.iter().map(|pat| *pat).for_each(f);
             }
-            Pat::Ref { pat, .. } => f(*pat),
+            Pat::Ref { pat, .. } | Pat::Box(pat) => f(*pat),
+            Pat::Slice {
+                prefix,
+                rest,
+                suffix,
+            } => {
+                let total_iter = prefix.iter().chain(rest.iter()).chain(suffix.iter());
+                total_iter.map(|pat| *pat).for_each(f);
+            }
+            Pat::Struct { .. } => {} // TODO
         }
     }
 }
@@ -745,30 +775,41 @@ impl ExprCollector {
     }
 
     fn collect_pat(&mut self, pat: &ast::Pat) -> PatId {
-        let syntax_ptr = LocalSyntaxPtr::new(pat.syntax());
-        match pat.kind() {
+        let pattern = match pat.kind() {
             ast::PatKind::BindPat(bp) => {
                 let name = bp
                     .name()
                     .map(|nr| nr.as_name())
                     .unwrap_or_else(Name::missing);
-                self.alloc_pat(Pat::Bind { name }, syntax_ptr)
+                Pat::Bind { name }
             }
             ast::PatKind::TupleStructPat(p) => {
                 let path = p.path().and_then(Path::from_ast);
                 let args = p.args().map(|p| self.collect_pat(p)).collect();
-                self.alloc_pat(Pat::TupleStruct { path, args }, syntax_ptr)
+                Pat::TupleStruct { path, args }
             }
             ast::PatKind::RefPat(p) => {
                 let pat = self.collect_pat_opt(p.pat());
                 let mutability = Mutability::from_mutable(p.is_mut());
-                self.alloc_pat(Pat::Ref { pat, mutability }, syntax_ptr)
+                Pat::Ref { pat, mutability }
             }
-            _ => {
-                // TODO
-                self.alloc_pat(Pat::Missing, syntax_ptr)
+            ast::PatKind::PathPat(p) => {
+                let path = p.path().and_then(Path::from_ast);
+                path.map(|path| Pat::Path(path)).unwrap_or(Pat::Missing)
             }
-        }
+            ast::PatKind::TuplePat(p) => {
+                let args = p.args().map(|p| self.collect_pat(p)).collect();
+                Pat::Tuple(args)
+            }
+            ast::PatKind::PlaceholderPat(_) => Pat::Wild,
+            // TODO: implement
+            ast::PatKind::FieldPatList(_)
+            | ast::PatKind::SlicePat(_)
+            | ast::PatKind::StructPat(_)
+            | ast::PatKind::RangePat(_) => Pat::Missing,
+        };
+        let syntax_ptr = LocalSyntaxPtr::new(pat.syntax());
+        self.alloc_pat(pattern, syntax_ptr)
     }
 
     fn collect_pat_opt(&mut self, pat: Option<&ast::Pat>) -> PatId {
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index c7c063601..854d3e3d9 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -1168,6 +1168,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                         decl_ty
                     };
 
+                    // TODO: walk the pattern here?
+
                     self.write_pat_ty(*pat, ty);
                 }
                 Statement::Expr(expr) => {
@@ -1188,6 +1190,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         for (type_ref, pat) in signature.params().iter().zip(body.params()) {
             let ty = self.make_ty(type_ref);
             let ty = self.insert_type_vars(ty);
+
+            // TODO: walk pattern?
+
             self.write_pat_ty(*pat, ty);
         }
         self.return_ty = {
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index a430cbe88..fc1e5b09c 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -358,6 +358,21 @@ fn test(x: &str, y: isize) {
     );
 }
 
+#[test]
+fn infer_pattern() {
+    check_inference(
+        r#"
+fn test(x: &i32) {
+    let y = x;
+    let &z = x;
+    let a = z;
+    let (c, d) = (1, "hello");
+}
+"#,
+        "pattern.txt",
+    );
+}
+
 fn infer(content: &str) -> String {
     let (db, _, file_id) = MockDatabase::with_single_file(content);
     let source_file = db.source_file(file_id);
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index 2d9603d90..2fd146bf1 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -2285,7 +2285,11 @@ impl AstNode for PathPat {
 }
 
 
-impl PathPat {}
+impl PathPat {
+    pub fn path(&self) -> Option<&Path> {
+        super::child_opt(self)
+    }
+}
 
 // PathSegment
 #[derive(Debug, PartialEq, Eq, Hash)]
@@ -3219,7 +3223,11 @@ impl AstNode for TuplePat {
 }
 
 
-impl TuplePat {}
+impl TuplePat {
+    pub fn args(&self) -> impl Iterator<Item = &Pat> {
+        super::children(self)
+    }
+}
 
 // TupleStructPat
 #[derive(Debug, PartialEq, Eq, Hash)]
diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index 2aaad46b1..b524c8aaf 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -490,14 +490,14 @@ Grammar(
         "RefPat": ( options: [ "Pat" ]),
         "BindPat": ( traits: ["NameOwner"] ),
         "PlaceholderPat": (),
-        "PathPat": (),
+        "PathPat": ( options: ["Path"] ),
         "StructPat": (),
         "FieldPatList": (),
         "TupleStructPat": (
             options: ["Path"],
             collections: [["args", "Pat"]],
         ),
-        "TuplePat": (),
+        "TuplePat": ( collections: [["args", "Pat"]] ),
         "SlicePat": (),
         "RangePat": (),