4 files changed, 169 insertions, 21 deletions

diff --git a/crates/ra_analysis/src/completion/complete_dot.rs b/crates/ra_analysis/src/completion/complete_dot.rs
new file mode 100644
index 000000000..93d657576
--- /dev/null
+++ b/crates/ra_analysis/src/completion/complete_dot.rs
@@ -0,0 +1,98 @@
+use ra_syntax::ast::AstNode;
+use hir::{Ty, Def};
+
+use crate::Cancelable;
+use crate::completion::{CompletionContext, Completions, CompletionKind, CompletionItem, CompletionItemKind};
+
+/// Complete dot accesses, i.e. fields or methods (currently only fields).
+pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) -> Cancelable<()> {
+    let module = if let Some(module) = &ctx.module {
+        module
+    } else {
+        return Ok(());
+    };
+    let function = if let Some(fn_def) = ctx.enclosing_fn {
+        hir::source_binder::function_from_module(ctx.db, module, fn_def)
+    } else {
+        return Ok(());
+    };
+    let receiver = if let Some(receiver) = ctx.dot_receiver {
+        receiver
+    } else {
+        return Ok(());
+    };
+    let infer_result = function.infer(ctx.db)?;
+    let receiver_ty = if let Some(ty) = infer_result.type_of_node(receiver.syntax()) {
+        ty
+    } else {
+        return Ok(());
+    };
+    if !ctx.is_method_call {
+        complete_fields(acc, ctx, receiver_ty)?;
+    }
+    Ok(())
+}
+
+fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty) -> Cancelable<()> {
+    // TODO: autoderef etc.
+    match receiver {
+        Ty::Adt { def_id, .. } => {
+            match def_id.resolve(ctx.db)? {
+                Def::Struct(s) => {
+                    let variant_data = s.variant_data(ctx.db)?;
+                    for field in variant_data.fields() {
+                        CompletionItem::new(CompletionKind::Reference, field.name().to_string())
+                            .kind(CompletionItemKind::Field)
+                            .add_to(acc);
+                    }
+                }
+                // TODO unions
+                _ => {}
+            }
+        }
+        Ty::Tuple(fields) => {
+            for (i, _ty) in fields.iter().enumerate() {
+                CompletionItem::new(CompletionKind::Reference, i.to_string())
+                    .kind(CompletionItemKind::Field)
+                    .add_to(acc);
+            }
+        }
+        _ => {}
+    };
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::*;
+
+    fn check_ref_completion(code: &str, expected_completions: &str) {
+        check_completion(code, expected_completions, CompletionKind::Reference);
+    }
+
+    #[test]
+    fn test_struct_field_completion() {
+        check_ref_completion(
+            r"
+            struct A { the_field: u32 }
+            fn foo(a: A) {
+               a.<|>
+            }
+            ",
+            r#"the_field"#,
+        );
+    }
+
+    #[test]
+    fn test_no_struct_field_completion_for_method_call() {
+        check_ref_completion(
+            r"
+            struct A { the_field: u32 }
+            fn foo(a: A) {
+               a.<|>()
+            }
+            ",
+            r#""#,
+        );
+    }
+}
diff --git a/crates/ra_analysis/src/completion/complete_path.rs b/crates/ra_analysis/src/completion/complete_path.rs
index ad4d68a33..aaa2c7cee 100644
--- a/crates/ra_analysis/src/completion/complete_path.rs
+++ b/crates/ra_analysis/src/completion/complete_path.rs
@@ -8,7 +8,7 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) -> C
         (Some(path), Some(module)) => (path.clone(), module),
         _ => return Ok(()),
     };
-    let def_id = match module.resolve_path(ctx.db, path)? {
+    let def_id = match module.resolve_path(ctx.db, &path)?.take_types() {
         Some(it) => it,
         None => return Ok(()),
     };
diff --git a/crates/ra_analysis/src/completion/completion_context.rs b/crates/ra_analysis/src/completion/completion_context.rs
index 064fbc6f7..978772fd4 100644
--- a/crates/ra_analysis/src/completion/completion_context.rs
+++ b/crates/ra_analysis/src/completion/completion_context.rs
@@ -1,12 +1,13 @@
 use ra_editor::find_node_at_offset;
 use ra_text_edit::AtomTextEdit;
 use ra_syntax::{
-    algo::find_leaf_at_offset,
+    algo::{find_leaf_at_offset, find_covering_node},
     ast,
     AstNode,
     SyntaxNodeRef,
     SourceFileNode,
     TextUnit,
+    TextRange,
     SyntaxKind::*,
 };
 use hir::source_binder;
@@ -31,6 +32,10 @@ pub(super) struct CompletionContext<'a> {
     pub(super) is_stmt: bool,
     /// Something is typed at the "top" level, in module or impl/trait.
     pub(super) is_new_item: bool,
+    /// The receiver if this is a field or method access, i.e. writing something.<|>
+    pub(super) dot_receiver: Option<ast::Expr<'a>>,
+    /// If this is a method call in particular, i.e. the () are already there.
+    pub(super) is_method_call: bool,
 }
 
 impl<'a> CompletionContext<'a> {
@@ -54,12 +59,14 @@ impl<'a> CompletionContext<'a> {
             after_if: false,
             is_stmt: false,
             is_new_item: false,
+            dot_receiver: None,
+            is_method_call: false,
         };
         ctx.fill(original_file, position.offset);
         Ok(Some(ctx))
     }
 
-    fn fill(&mut self, original_file: &SourceFileNode, offset: TextUnit) {
+    fn fill(&mut self, original_file: &'a SourceFileNode, offset: TextUnit) {
         // Insert a fake ident to get a valid parse tree. We will use this file
         // to determine context, though the original_file will be used for
         // actual completion.
@@ -76,7 +83,7 @@ impl<'a> CompletionContext<'a> {
                 self.is_param = true;
                 return;
             }
-            self.classify_name_ref(&file, name_ref);
+            self.classify_name_ref(original_file, name_ref);
         }
 
         // Otherwise, see if this is a declaration. We can use heuristics to
@@ -88,7 +95,7 @@ impl<'a> CompletionContext<'a> {
             }
         }
     }
-    fn classify_name_ref(&mut self, file: &SourceFileNode, name_ref: ast::NameRef) {
+    fn classify_name_ref(&mut self, original_file: &'a SourceFileNode, name_ref: ast::NameRef) {
         let name_range = name_ref.syntax().range();
         let top_node = name_ref
             .syntax()
@@ -105,6 +112,12 @@ impl<'a> CompletionContext<'a> {
             _ => (),
         }
 
+        self.enclosing_fn = self
+            .leaf
+            .ancestors()
+            .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
+            .find_map(ast::FnDef::cast);
+
         let parent = match name_ref.syntax().parent() {
             Some(it) => it,
             None => return,
@@ -120,11 +133,6 @@ impl<'a> CompletionContext<'a> {
             }
             if path.qualifier().is_none() {
                 self.is_trivial_path = true;
-                self.enclosing_fn = self
-                    .leaf
-                    .ancestors()
-                    .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
-                    .find_map(ast::FnDef::cast);
 
                 self.is_stmt = match name_ref
                     .syntax()
@@ -137,7 +145,9 @@ impl<'a> CompletionContext<'a> {
                 };
 
                 if let Some(off) = name_ref.syntax().range().start().checked_sub(2.into()) {
-                    if let Some(if_expr) = find_node_at_offset::<ast::IfExpr>(file.syntax(), off) {
+                    if let Some(if_expr) =
+                        find_node_at_offset::<ast::IfExpr>(original_file.syntax(), off)
+                    {
                         if if_expr.syntax().range().end() < name_ref.syntax().range().start() {
                             self.after_if = true;
                         }
@@ -145,9 +155,33 @@ impl<'a> CompletionContext<'a> {
                 }
             }
         }
+        if let Some(field_expr) = ast::FieldExpr::cast(parent) {
+            // The receiver comes before the point of insertion of the fake
+            // ident, so it should have the same range in the non-modified file
+            self.dot_receiver = field_expr
+                .expr()
+                .map(|e| e.syntax().range())
+                .and_then(|r| find_node_with_range(original_file.syntax(), r));
+        }
+        if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
+            // As above
+            self.dot_receiver = method_call_expr
+                .expr()
+                .map(|e| e.syntax().range())
+                .and_then(|r| find_node_with_range(original_file.syntax(), r));
+            self.is_method_call = true;
+        }
     }
 }
 
+fn find_node_with_range<'a, N: AstNode<'a>>(
+    syntax: SyntaxNodeRef<'a>,
+    range: TextRange,
+) -> Option<N> {
+    let node = find_covering_node(syntax, range);
+    node.ancestors().find_map(N::cast)
+}
+
 fn is_node<'a, N: AstNode<'a>>(node: SyntaxNodeRef<'a>) -> bool {
     match node.ancestors().filter_map(N::cast).next() {
         None => false,
diff --git a/crates/ra_analysis/src/completion/completion_item.rs b/crates/ra_analysis/src/completion/completion_item.rs
index 911f08468..c9f9f495d 100644
--- a/crates/ra_analysis/src/completion/completion_item.rs
+++ b/crates/ra_analysis/src/completion/completion_item.rs
@@ -1,5 +1,7 @@
 use crate::db;
 
+use hir::PerNs;
+
 /// `CompletionItem` describes a single completion variant in the editor pop-up.
 /// It is basically a POD with various properties. To construct a
 /// `CompletionItem`, use `new` method and the `Builder` struct.
@@ -25,7 +27,10 @@ pub enum CompletionItemKind {
     Keyword,
     Module,
     Function,
+    Struct,
+    Enum,
     Binding,
+    Field,
 }
 
 #[derive(Debug, PartialEq, Eq)]
@@ -117,16 +122,27 @@ impl Builder {
         db: &db::RootDatabase,
         resolution: &hir::Resolution,
     ) -> Builder {
-        if let Some(def_id) = resolution.def_id {
-            if let Ok(def) = def_id.resolve(db) {
-                let kind = match def {
-                    hir::Def::Module(..) => CompletionItemKind::Module,
-                    hir::Def::Function(..) => CompletionItemKind::Function,
-                    _ => return self,
-                };
-                self.kind = Some(kind);
-            }
-        }
+        let resolved = resolution.def_id.and_then(|d| d.resolve(db).ok());
+        let kind = match resolved {
+            PerNs {
+                types: Some(hir::Def::Module(..)),
+                ..
+            } => CompletionItemKind::Module,
+            PerNs {
+                types: Some(hir::Def::Struct(..)),
+                ..
+            } => CompletionItemKind::Struct,
+            PerNs {
+                types: Some(hir::Def::Enum(..)),
+                ..
+            } => CompletionItemKind::Enum,
+            PerNs {
+                values: Some(hir::Def::Function(..)),
+                ..
+            } => CompletionItemKind::Function,
+            _ => return self,
+        };
+        self.kind = Some(kind);
         self
     }
 }