complete struct literals

crates/ra_ide_api/src/completion.rs

@@ -2,6 +2,7 @@ mod completion_item;
 mod completion_context;
 
 mod complete_dot;
+mod complete_struct_literal;
 mod complete_fn_param;
 mod complete_keyword;
 mod complete_snippet;
@@ -59,6 +60,7 @@ pub(crate) fn completions(db: &db::RootDatabase, position: FilePosition) -> Opti
     complete_path::complete_path(&mut acc, &ctx);
     complete_scope::complete_scope(&mut acc, &ctx);
     complete_dot::complete_dot(&mut acc, &ctx);
+    complete_struct_literal::complete_struct_literal(&mut acc, &ctx);
     complete_postfix::complete_postfix(&mut acc, &ctx);
     Some(acc)
 }

crates/ra_ide_api/src/completion/complete_struct_literal.rs

@@ -0,0 +1,64 @@
+use hir::{Ty, AdtDef, Docs};
+
+use crate::completion::{CompletionContext, Completions, CompletionItem, CompletionItemKind};
+use crate::completion::completion_item::CompletionKind;
+
+/// Complete dot accesses, i.e. fields or methods (currently only fields).
+pub(super) fn complete_struct_literal(acc: &mut Completions, ctx: &CompletionContext) {
+    let (function, struct_lit) = match (&ctx.function, ctx.struct_lit_syntax) {
+        (Some(function), Some(struct_lit)) => (function, struct_lit),
+        _ => return,
+    };
+    let infer_result = function.infer(ctx.db);
+    let syntax_mapping = function.body_syntax_mapping(ctx.db);
+    let expr = match syntax_mapping.node_expr(struct_lit.into()) {
+        Some(expr) => expr,
+        None => return,
+    };
+    let ty = infer_result[expr].clone();
+    let (adt, substs) = match ty {
+        Ty::Adt { def_id, ref substs, .. } => (def_id, substs),
+        _ => return,
+    };
+    match adt {
+        AdtDef::Struct(s) => {
+            for field in s.fields(ctx.db) {
+                CompletionItem::new(
+                    CompletionKind::Reference,
+                    ctx.source_range(),
+                    field.name(ctx.db).to_string(),
+                )
+                .kind(CompletionItemKind::Field)
+                .detail(field.ty(ctx.db).subst(substs).to_string())
+                .set_documentation(field.docs(ctx.db))
+                .add_to(acc);
+            }
+        }
+
+        // TODO unions
+        AdtDef::Enum(_) => (),
+    };
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::*;
+    use crate::completion::completion_item::check_completion;
+
+    fn check_ref_completion(name: &str, code: &str) {
+        check_completion(name, code, CompletionKind::Reference);
+    }
+
+    #[test]
+    fn test_struct_literal_field() {
+        check_ref_completion(
+            "test_struct_literal_field",
+            r"
+            struct A { the_field: u32 }
+            fn foo() {
+               A { the<|> }
+            }
+            ",
+        );
+    }
+}

crates/ra_ide_api/src/completion/completion_context.rs

@@ -21,6 +21,7 @@ pub(crate) struct CompletionContext<'a> {
     pub(super) function: Option<hir::Function>,
     pub(super) function_syntax: Option<&'a ast::FnDef>,
     pub(super) use_item_syntax: Option<&'a ast::UseItem>,
+    pub(super) struct_lit_syntax: Option<&'a ast::StructLit>,
     pub(super) is_param: bool,
     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
     pub(super) is_trivial_path: bool,
@@ -55,6 +56,7 @@ impl<'a> CompletionContext<'a> {
             function: None,
             function_syntax: None,
             use_item_syntax: None,
+            struct_lit_syntax: None,
             is_param: false,
             is_trivial_path: false,
             path_prefix: None,
@@ -108,6 +110,10 @@ impl<'a> CompletionContext<'a> {
     }
     fn classify_name_ref(&mut self, original_file: &'a SourceFile, name_ref: &ast::NameRef) {
         let name_range = name_ref.syntax().range();
+        if name_ref.syntax().parent().and_then(ast::NamedField::cast).is_some() {
+            self.struct_lit_syntax = find_node_at_offset(original_file.syntax(), self.offset);
+        }
+
         let top_node =
             name_ref.syntax().ancestors().take_while(|it| it.range() == name_range).last().unwrap();
 

crates/ra_syntax/src/ast.rs

@@ -724,6 +724,12 @@ impl LiteralExpr {
     }
 }
 
+impl NamedField {
+    pub fn parent_struct_lit(&self) -> &StructLit {
+        self.syntax().ancestors().find_map(StructLit::cast).unwrap()
+    }
+}
+
 impl BindPat {
     pub fn is_mutable(&self) -> bool {
         self.syntax().children().any(|n| n.kind() == MUT_KW)