1 //! FIXME: write short doc here
5 use hir::{db::HirDatabase, Adt, HasSource};
6 use ra_syntax::ast::{self, edit::IndentLevel, make, AstNode, NameOwner};
8 use crate::{Assist, AssistCtx, AssistId};
10 // Assist: fill_match_arms
12 // Adds missing clauses to a `match` expression.
15 // enum Action { Move { distance: u32 }, Stop }
17 // fn handle(action: Action) {
25 // enum Action { Move { distance: u32 }, Stop }
27 // fn handle(action: Action) {
29 // Action::Move{ distance } => (),
30 // Action::Stop => (),
34 pub(crate) fn fill_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
35 let match_expr = ctx.node_at_offset::<ast::MatchExpr>()?;
36 let match_arm_list = match_expr.match_arm_list()?;
38 // We already have some match arms, so we don't provide any assists.
39 // Unless if there is only one trivial match arm possibly created
40 // by match postfix complete. Trivial match arm is the catch all arm.
41 let mut existing_arms = match_arm_list.arms();
42 if let Some(arm) = existing_arms.next() {
43 if !is_trivial(&arm) || existing_arms.next().is_some() {
48 let expr = match_expr.expr()?;
50 let file_id = ctx.frange.file_id;
51 let analyzer = hir::SourceAnalyzer::new(ctx.db, file_id, expr.syntax(), None);
52 resolve_enum_def(ctx.db, &analyzer, &expr)?
54 let variant_list = enum_def.variant_list()?;
56 ctx.add_action(AssistId("fill_match_arms"), "fill match arms", |edit| {
57 let indent_level = IndentLevel::from_node(match_arm_list.syntax());
60 let variants = variant_list.variants();
62 .filter_map(build_pat)
63 .map(|pat| make::match_arm(iter::once(pat), make::expr_unit()));
64 indent_level.increase_indent(make::match_arm_list(arms))
67 edit.target(match_expr.syntax().text_range());
68 edit.set_cursor(expr.syntax().text_range().start());
69 edit.replace_ast(match_arm_list, new_arm_list);
75 fn is_trivial(arm: &ast::MatchArm) -> bool {
76 arm.pats().any(|pat| match pat {
77 ast::Pat::PlaceholderPat(..) => true,
83 db: &impl HirDatabase,
84 analyzer: &hir::SourceAnalyzer,
86 ) -> Option<ast::EnumDef> {
87 let expr_ty = analyzer.type_of(db, &expr)?;
89 analyzer.autoderef(db, expr_ty).find_map(|ty| match ty.as_adt() {
90 Some((Adt::Enum(e), _)) => Some(e.source(db).ast),
95 fn build_pat(var: ast::EnumVariant) -> Option<ast::Pat> {
96 let path = make::path_qualified(
97 make::path_from_name_ref(make::name_ref(&var.parent_enum().name()?.syntax().to_string())),
98 make::name_ref(&var.name()?.syntax().to_string()),
101 let pat: ast::Pat = match var.kind() {
102 ast::StructKind::Tuple(field_list) => {
104 iter::repeat(make::placeholder_pat().into()).take(field_list.fields().count());
105 make::tuple_struct_pat(path, pats).into()
107 ast::StructKind::Named(field_list) => {
108 let pats = field_list.fields().map(|f| make::bind_pat(f.name().unwrap()).into());
109 make::record_pat(path, pats).into()
111 ast::StructKind::Unit => make::path_pat(path).into(),
119 use crate::helpers::{check_assist, check_assist_target};
121 use super::fill_match_arms;
124 fn fill_match_arms_empty_body() {
133 Es{ x: usize, y: usize }
147 Es{ x: usize, y: usize }
165 fn test_fill_match_arm_refs() {
195 Es{ x: usize, y: usize }
205 Es{ x: usize, y: usize }
218 fn fill_match_arms_target() {
233 fn fill_match_arms_trivial_arm() {