crates/ide_completion/src/context.rs

   1 //! See `CompletionContext` structure.
   2
   3 use base_db::SourceDatabaseExt;
   4 use hir::{Local, Name, ScopeDef, Semantics, SemanticsScope, Type};
   5 use ide_db::{
   6     base_db::{FilePosition, SourceDatabase},
   7     call_info::ActiveParameter,
   8     RootDatabase,
   9 };
  10 use syntax::{
  11     algo::find_node_at_offset,
  12     ast::{self, NameOrNameRef, NameOwner},
  13     match_ast, AstNode, NodeOrToken,
  14     SyntaxKind::{self, *},
  15     SyntaxNode, SyntaxToken, TextRange, TextSize, T,
  16 };
  17 use text_edit::Indel;
  18
  19 use crate::{
  20     patterns::{
  21         determine_location, determine_prev_sibling, for_is_prev2, inside_impl_trait_block,
  22         is_in_loop_body, previous_token, ImmediateLocation, ImmediatePrevSibling,
  23     },
  24     CompletionConfig,
  25 };
  26
  27 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  28 pub(crate) enum PatternRefutability {
  29     Refutable,
  30     Irrefutable,
  31 }
  32
  33 #[derive(Debug)]
  34 pub(super) enum PathKind {
  35     Expr,
  36     Type,
  37 }
  38
  39 #[derive(Debug)]
  40 pub(crate) struct PathCompletionContext {
  41     /// If this is a call with () already there
  42     call_kind: Option<CallKind>,
  43     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  44     pub(super) is_trivial_path: bool,
  45     /// If not a trivial path, the prefix (qualifier).
  46     pub(super) qualifier: Option<ast::Path>,
  47     /// Whether the qualifier comes from a use tree parent or not
  48     pub(super) use_tree_parent: bool,
  49     pub(super) kind: Option<PathKind>,
  50     /// Whether the path segment has type args or not.
  51     pub(super) has_type_args: bool,
  52     /// `true` if we are a statement or a last expr in the block.
  53     pub(super) can_be_stmt: bool,
  54     pub(super) in_loop_body: bool,
  55 }
  56
  57 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  58 pub(crate) enum CallKind {
  59     Pat,
  60     Mac,
  61     Expr,
  62 }
  63 /// `CompletionContext` is created early during completion to figure out, where
  64 /// exactly is the cursor, syntax-wise.
  65 #[derive(Debug)]
  66 pub(crate) struct CompletionContext<'a> {
  67     pub(super) sema: Semantics<'a, RootDatabase>,
  68     pub(super) scope: SemanticsScope<'a>,
  69     pub(super) db: &'a RootDatabase,
  70     pub(super) config: &'a CompletionConfig,
  71     pub(super) position: FilePosition,
  72     /// The token before the cursor, in the original file.
  73     pub(super) original_token: SyntaxToken,
  74     /// The token before the cursor, in the macro-expanded file.
  75     pub(super) token: SyntaxToken,
  76     pub(super) krate: Option<hir::Crate>,
  77     pub(super) expected_name: Option<NameOrNameRef>,
  78     pub(super) expected_type: Option<Type>,
  79
  80     /// The parent function of the cursor position if it exists.
  81     pub(super) function_def: Option<ast::Fn>,
  82     /// The parent impl of the cursor position if it exists.
  83     pub(super) impl_def: Option<ast::Impl>,
  84     pub(super) name_ref_syntax: Option<ast::NameRef>,
  85
  86     // potentially set if we are completing a lifetime
  87     pub(super) lifetime_syntax: Option<ast::Lifetime>,
  88     pub(super) lifetime_param_syntax: Option<ast::LifetimeParam>,
  89     pub(super) lifetime_allowed: bool,
  90     pub(super) is_label_ref: bool,
  91
  92     // potentially set if we are completing a name
  93     pub(super) is_pat_or_const: Option<PatternRefutability>,
  94     pub(super) is_param: bool,
  95
  96     pub(super) completion_location: Option<ImmediateLocation>,
  97     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
  98     pub(super) attribute_under_caret: Option<ast::Attr>,
  99     pub(super) previous_token: Option<SyntaxToken>,
 100
 101     pub(super) path_context: Option<PathCompletionContext>,
 102     pub(super) active_parameter: Option<ActiveParameter>,
 103     pub(super) locals: Vec<(String, Local)>,
 104
 105     pub(super) incomplete_let: bool,
 106
 107     no_completion_required: bool,
 108 }
 109
 110 impl<'a> CompletionContext<'a> {
 111     pub(super) fn new(
 112         db: &'a RootDatabase,
 113         position: FilePosition,
 114         config: &'a CompletionConfig,
 115     ) -> Option<CompletionContext<'a>> {
 116         let sema = Semantics::new(db);
 117
 118         let original_file = sema.parse(position.file_id);
 119
 120         // Insert a fake ident to get a valid parse tree. We will use this file
 121         // to determine context, though the original_file will be used for
 122         // actual completion.
 123         let file_with_fake_ident = {
 124             let parse = db.parse(position.file_id);
 125             let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
 126             parse.reparse(&edit).tree()
 127         };
 128         let fake_ident_token =
 129             file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 130
 131         let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
 132         let original_token =
 133             original_file.syntax().token_at_offset(position.offset).left_biased()?;
 134         let token = sema.descend_into_macros(original_token.clone());
 135         let scope = sema.scope_at_offset(&token, position.offset);
 136         let mut locals = vec![];
 137         scope.process_all_names(&mut |name, scope| {
 138             if let ScopeDef::Local(local) = scope {
 139                 locals.push((name.to_string(), local));
 140             }
 141         });
 142         let mut ctx = CompletionContext {
 143             sema,
 144             scope,
 145             db,
 146             config,
 147             position,
 148             original_token,
 149             token,
 150             krate,
 151             expected_name: None,
 152             expected_type: None,
 153             function_def: None,
 154             impl_def: None,
 155             name_ref_syntax: None,
 156             lifetime_syntax: None,
 157             lifetime_param_syntax: None,
 158             lifetime_allowed: false,
 159             is_label_ref: false,
 160             is_pat_or_const: None,
 161             is_param: false,
 162             completion_location: None,
 163             prev_sibling: None,
 164             attribute_under_caret: None,
 165             previous_token: None,
 166             path_context: None,
 167             active_parameter: ActiveParameter::at(db, position),
 168             locals,
 169             incomplete_let: false,
 170             no_completion_required: false,
 171         };
 172
 173         let mut original_file = original_file.syntax().clone();
 174         let mut speculative_file = file_with_fake_ident.syntax().clone();
 175         let mut offset = position.offset;
 176         let mut fake_ident_token = fake_ident_token;
 177
 178         // Are we inside a macro call?
 179         while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 180             find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 181             find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 182         ) {
 183             if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
 184                 != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
 185             {
 186                 break;
 187             }
 188             let speculative_args = match macro_call_with_fake_ident.token_tree() {
 189                 Some(tt) => tt,
 190                 None => break,
 191             };
 192             if let (Some(actual_expansion), Some(speculative_expansion)) = (
 193                 ctx.sema.expand(&actual_macro_call),
 194                 ctx.sema.speculative_expand(
 195                     &actual_macro_call,
 196                     &speculative_args,
 197                     fake_ident_token,
 198                 ),
 199             ) {
 200                 let new_offset = speculative_expansion.1.text_range().start();
 201                 if new_offset > actual_expansion.text_range().end() {
 202                     break;
 203                 }
 204                 original_file = actual_expansion;
 205                 speculative_file = speculative_expansion.0;
 206                 fake_ident_token = speculative_expansion.1;
 207                 offset = new_offset;
 208             } else {
 209                 break;
 210             }
 211         }
 212         ctx.fill(&original_file, speculative_file, offset);
 213         Some(ctx)
 214     }
 215
 216     /// Checks whether completions in that particular case don't make much sense.
 217     /// Examples:
 218     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 219     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 220     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 221     pub(crate) fn no_completion_required(&self) -> bool {
 222         self.no_completion_required
 223     }
 224
 225     /// The range of the identifier that is being completed.
 226     pub(crate) fn source_range(&self) -> TextRange {
 227         // check kind of macro-expanded token, but use range of original token
 228         let kind = self.token.kind();
 229         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 230             cov_mark::hit!(completes_if_prefix_is_keyword);
 231             self.original_token.text_range()
 232         } else if kind == CHAR {
 233             // assume we are completing a lifetime but the user has only typed the '
 234             cov_mark::hit!(completes_if_lifetime_without_idents);
 235             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 236         } else {
 237             TextRange::empty(self.position.offset)
 238         }
 239     }
 240
 241     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 242         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 243     }
 244
 245     pub(crate) fn expects_assoc_item(&self) -> bool {
 246         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 247     }
 248
 249     pub(crate) fn has_dot_receiver(&self) -> bool {
 250         matches!(
 251             &self.completion_location,
 252             Some(ImmediateLocation::FieldAccess { receiver, .. } | ImmediateLocation::MethodCall { receiver,.. })
 253                 if receiver.is_some()
 254         )
 255     }
 256
 257     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 258         match &self.completion_location {
 259             Some(
 260                 ImmediateLocation::MethodCall { receiver, .. }
 261                 | ImmediateLocation::FieldAccess { receiver, .. },
 262             ) => receiver.as_ref(),
 263             _ => None,
 264         }
 265     }
 266
 267     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 268         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 269     }
 270
 271     pub(crate) fn expects_item(&self) -> bool {
 272         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 273     }
 274
 275     pub(crate) fn expects_generic_arg(&self) -> bool {
 276         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 277     }
 278
 279     pub(crate) fn has_block_expr_parent(&self) -> bool {
 280         matches!(self.completion_location, Some(ImmediateLocation::BlockExpr))
 281     }
 282
 283     pub(crate) fn expects_ident_pat_or_ref_expr(&self) -> bool {
 284         matches!(
 285             self.completion_location,
 286             Some(ImmediateLocation::IdentPat | ImmediateLocation::RefExpr)
 287         )
 288     }
 289
 290     pub(crate) fn expect_field(&self) -> bool {
 291         matches!(
 292             self.completion_location,
 293             Some(ImmediateLocation::RecordField | ImmediateLocation::TupleField)
 294         )
 295     }
 296
 297     pub(crate) fn in_use_tree(&self) -> bool {
 298         matches!(
 299             self.completion_location,
 300             Some(ImmediateLocation::Use | ImmediateLocation::UseTree)
 301         )
 302     }
 303
 304     pub(crate) fn has_impl_or_trait_prev_sibling(&self) -> bool {
 305         matches!(
 306             self.prev_sibling,
 307             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 308         )
 309     }
 310
 311     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 312         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 313     }
 314
 315     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 316         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 317     }
 318
 319     pub(crate) fn after_if(&self) -> bool {
 320         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 321     }
 322
 323     pub(crate) fn is_path_disallowed(&self) -> bool {
 324         self.attribute_under_caret.is_some()
 325             || self.previous_token_is(T![unsafe])
 326             || matches!(
 327                 self.prev_sibling,
 328                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 329             )
 330             || matches!(
 331                 self.completion_location,
 332                 Some(
 333                     ImmediateLocation::Attribute(_)
 334                         | ImmediateLocation::ModDeclaration(_)
 335                         | ImmediateLocation::RecordPat(_)
 336                         | ImmediateLocation::RecordExpr(_)
 337                 )
 338             )
 339     }
 340
 341     pub(crate) fn expects_expression(&self) -> bool {
 342         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Expr), .. }))
 343     }
 344
 345     pub(crate) fn expects_type(&self) -> bool {
 346         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Type), .. }))
 347     }
 348
 349     pub(crate) fn path_call_kind(&self) -> Option<CallKind> {
 350         self.path_context.as_ref().and_then(|it| it.call_kind)
 351     }
 352
 353     pub(crate) fn is_trivial_path(&self) -> bool {
 354         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: true, .. }))
 355     }
 356
 357     pub(crate) fn is_non_trivial_path(&self) -> bool {
 358         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: false, .. }))
 359     }
 360
 361     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 362         self.path_context.as_ref().and_then(|it| it.qualifier.as_ref())
 363     }
 364
 365     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 366     pub(crate) fn is_visible<I>(&self, item: &I) -> bool
 367     where
 368         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 369     {
 370         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 371     }
 372
 373     pub(crate) fn is_scope_def_hidden(&self, scope_def: &ScopeDef) -> bool {
 374         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 375             return self.is_doc_hidden(&attrs, krate);
 376         }
 377
 378         false
 379     }
 380
 381     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
 382         let attrs = item.attrs(self.db);
 383         let krate = item.krate(self.db);
 384         match (attrs, krate) {
 385             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
 386             _ => false,
 387         }
 388     }
 389
 390     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 391     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 392         self.scope.process_all_names(&mut |name, def| {
 393             if self.is_scope_def_hidden(&def) {
 394                 return;
 395             }
 396
 397             f(name, def);
 398         })
 399     }
 400
 401     fn is_visible_impl(
 402         &self,
 403         vis: &hir::Visibility,
 404         attrs: &hir::Attrs,
 405         defining_crate: hir::Crate,
 406     ) -> bool {
 407         let module = match self.scope.module() {
 408             Some(it) => it,
 409             None => return false,
 410         };
 411         if !vis.is_visible_from(self.db, module.into()) {
 412             // If the definition location is editable, also show private items
 413             let root_file = defining_crate.root_file(self.db);
 414             let source_root_id = self.db.file_source_root(root_file);
 415             let is_editable = !self.db.source_root(source_root_id).is_library;
 416             return is_editable;
 417         }
 418
 419         !self.is_doc_hidden(attrs, defining_crate)
 420     }
 421
 422     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 423         let module = match self.scope.module() {
 424             Some(it) => it,
 425             None => return true,
 426         };
 427         if module.krate() != defining_crate && attrs.has_doc_hidden() {
 428             // `doc(hidden)` items are only completed within the defining crate.
 429             return true;
 430         }
 431
 432         false
 433     }
 434
 435     fn fill_impl_def(&mut self) {
 436         self.impl_def = self
 437             .sema
 438             .token_ancestors_with_macros(self.token.clone())
 439             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 440             .find_map(ast::Impl::cast);
 441     }
 442
 443     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 444         let mut node = match self.token.parent() {
 445             Some(it) => it,
 446             None => return (None, None),
 447         };
 448         loop {
 449             break match_ast! {
 450                 match node {
 451                     ast::LetStmt(it) => {
 452                         cov_mark::hit!(expected_type_let_with_leading_char);
 453                         cov_mark::hit!(expected_type_let_without_leading_char);
 454                         let ty = it.pat()
 455                             .and_then(|pat| self.sema.type_of_pat(&pat))
 456                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)));
 457                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 458                             ident.name().map(NameOrNameRef::Name)
 459                         } else {
 460                             None
 461                         };
 462
 463                         (ty, name)
 464                     },
 465                     ast::ArgList(_it) => {
 466                         cov_mark::hit!(expected_type_fn_param);
 467                         ActiveParameter::at_token(
 468                             &self.sema,
 469                             self.token.clone(),
 470                         ).map(|ap| {
 471                             let name = ap.ident().map(NameOrNameRef::Name);
 472                             let ty = if has_ref(&self.token) {
 473                                 cov_mark::hit!(expected_type_fn_param_ref);
 474                                 ap.ty.remove_ref()
 475                             } else {
 476                                 Some(ap.ty)
 477                             };
 478                             (ty, name)
 479                         })
 480                         .unwrap_or((None, None))
 481                     },
 482                     ast::RecordExprFieldList(_it) => {
 483                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
 484                         // wouldn't try {} be nice...
 485                         (|| {
 486                             let expr_field = self.token.prev_sibling_or_token()?
 487                                       .into_node()
 488                                       .and_then(ast::RecordExprField::cast)?;
 489                             let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 490                             Some((
 491                                 Some(ty),
 492                                 expr_field.field_name().map(NameOrNameRef::NameRef),
 493                             ))
 494                         })().unwrap_or((None, None))
 495                     },
 496                     ast::RecordExprField(it) => {
 497                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 498                         (
 499                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)),
 500                             it.field_name().map(NameOrNameRef::NameRef),
 501                         )
 502                     },
 503                     ast::MatchExpr(it) => {
 504                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 505                         let ty = it.expr()
 506                             .and_then(|e| self.sema.type_of_expr(&e));
 507                         (ty, None)
 508                     },
 509                     ast::IfExpr(it) => {
 510                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 511                         let ty = it.condition()
 512                             .and_then(|cond| cond.expr())
 513                             .and_then(|e| self.sema.type_of_expr(&e));
 514                         (ty, None)
 515                     },
 516                     ast::IdentPat(it) => {
 517                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 518                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 519                         let ty = self.sema.type_of_pat(&ast::Pat::from(it));
 520                         (ty, None)
 521                     },
 522                     ast::Fn(it) => {
 523                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 524                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 525                         let def = self.sema.to_def(&it);
 526                         (def.map(|def| def.ret_type(self.db)), None)
 527                     },
 528                     ast::ClosureExpr(it) => {
 529                         let ty = self.sema.type_of_expr(&it.into());
 530                         ty.and_then(|ty| ty.as_callable(self.db))
 531                             .map(|c| (Some(c.return_type()), None))
 532                             .unwrap_or((None, None))
 533                     },
 534                     ast::Stmt(_it) => (None, None),
 535                     _ => {
 536                         match node.parent() {
 537                             Some(n) => {
 538                                 node = n;
 539                                 continue;
 540                             },
 541                             None => (None, None),
 542                         }
 543                     },
 544                 }
 545             };
 546         }
 547     }
 548
 549     fn fill(
 550         &mut self,
 551         original_file: &SyntaxNode,
 552         file_with_fake_ident: SyntaxNode,
 553         offset: TextSize,
 554     ) {
 555         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 556         let syntax_element = NodeOrToken::Token(fake_ident_token);
 557         self.previous_token = previous_token(syntax_element.clone());
 558         self.attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
 559         self.no_completion_required = {
 560             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 561             let fn_is_prev = self.previous_token_is(T![fn]);
 562             let for_is_prev2 = for_is_prev2(syntax_element.clone());
 563             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
 564         };
 565
 566         self.incomplete_let =
 567             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 568                 it.syntax().text_range().end() == syntax_element.text_range().end()
 569             });
 570
 571         let (expected_type, expected_name) = self.expected_type_and_name();
 572         self.expected_type = expected_type;
 573         self.expected_name = expected_name;
 574
 575         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 576             Some(it) => it,
 577             None => return,
 578         };
 579         self.completion_location =
 580             determine_location(&self.sema, original_file, offset, &name_like);
 581         self.prev_sibling = determine_prev_sibling(&name_like);
 582         match name_like {
 583             ast::NameLike::Lifetime(lifetime) => {
 584                 self.classify_lifetime(original_file, lifetime, offset);
 585             }
 586             ast::NameLike::NameRef(name_ref) => {
 587                 self.classify_name_ref(original_file, name_ref);
 588             }
 589             ast::NameLike::Name(name) => {
 590                 self.classify_name(name);
 591             }
 592         }
 593     }
 594
 595     fn classify_lifetime(
 596         &mut self,
 597         original_file: &SyntaxNode,
 598         lifetime: ast::Lifetime,
 599         offset: TextSize,
 600     ) {
 601         self.lifetime_syntax =
 602             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 603         if let Some(parent) = lifetime.syntax().parent() {
 604             if parent.kind() == ERROR {
 605                 return;
 606             }
 607
 608             match_ast! {
 609                 match parent {
 610                     ast::LifetimeParam(_it) => {
 611                         self.lifetime_allowed = true;
 612                         self.lifetime_param_syntax =
 613                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 614                     },
 615                     ast::BreakExpr(_it) => self.is_label_ref = true,
 616                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 617                     ast::Label(_it) => (),
 618                     _ => self.lifetime_allowed = true,
 619                 }
 620             }
 621         }
 622     }
 623
 624     fn classify_name(&mut self, name: ast::Name) {
 625         if let Some(bind_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
 626             self.is_pat_or_const = Some(PatternRefutability::Refutable);
 627             if !bind_pat.is_simple_ident() {
 628                 self.is_pat_or_const = None;
 629             } else {
 630                 let irrefutable_pat = bind_pat.syntax().ancestors().find_map(|node| {
 631                     match_ast! {
 632                         match node {
 633                             ast::LetStmt(it) => Some(it.pat()),
 634                             ast::Param(it) => Some(it.pat()),
 635                             _ => None,
 636                         }
 637                     }
 638                 });
 639                 if let Some(Some(pat)) = irrefutable_pat {
 640                     // This check is here since we could be inside a pattern in the initializer expression of the let statement.
 641                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 642                         self.is_pat_or_const = Some(PatternRefutability::Irrefutable);
 643                     }
 644                 }
 645
 646                 let is_name_in_field_pat = bind_pat
 647                     .syntax()
 648                     .parent()
 649                     .and_then(ast::RecordPatField::cast)
 650                     .map_or(false, |pat_field| pat_field.name_ref().is_none());
 651                 if is_name_in_field_pat {
 652                     self.is_pat_or_const = None;
 653                 }
 654             }
 655
 656             self.fill_impl_def();
 657         }
 658
 659         self.is_param |= is_node::<ast::Param>(name.syntax());
 660     }
 661
 662     fn classify_name_ref(&mut self, original_file: &SyntaxNode, name_ref: ast::NameRef) {
 663         self.fill_impl_def();
 664
 665         self.name_ref_syntax =
 666             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 667
 668         self.function_def = self
 669             .sema
 670             .token_ancestors_with_macros(self.token.clone())
 671             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 672             .find_map(ast::Fn::cast);
 673
 674         let parent = match name_ref.syntax().parent() {
 675             Some(it) => it,
 676             None => return,
 677         };
 678
 679         if let Some(segment) = ast::PathSegment::cast(parent) {
 680             let path_ctx = self.path_context.get_or_insert(PathCompletionContext {
 681                 call_kind: None,
 682                 is_trivial_path: false,
 683                 qualifier: None,
 684                 has_type_args: false,
 685                 can_be_stmt: false,
 686                 in_loop_body: false,
 687                 use_tree_parent: false,
 688                 kind: None,
 689             });
 690             path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
 691             let path = segment.parent_path();
 692
 693             if let Some(p) = path.syntax().parent() {
 694                 path_ctx.call_kind = match_ast! {
 695                     match p {
 696                         ast::PathExpr(it) => it.syntax().parent().and_then(ast::CallExpr::cast).map(|_| CallKind::Expr),
 697                         ast::MacroCall(it) => it.excl_token().and(Some(CallKind::Mac)),
 698                         ast::TupleStructPat(_it) => Some(CallKind::Pat),
 699                         _ => None
 700                     }
 701                 };
 702             }
 703
 704             if let Some(parent) = path.syntax().parent() {
 705                 path_ctx.kind = match_ast! {
 706                     match parent {
 707                         ast::PathType(_it) => Some(PathKind::Type),
 708                         ast::PathExpr(_it) => Some(PathKind::Expr),
 709                         _ => None,
 710                     }
 711                 };
 712             }
 713             path_ctx.has_type_args = segment.generic_arg_list().is_some();
 714
 715             if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
 716                 path_ctx.use_tree_parent = use_tree_parent;
 717                 path_ctx.qualifier = path
 718                     .segment()
 719                     .and_then(|it| {
 720                         find_node_with_range::<ast::PathSegment>(
 721                             original_file,
 722                             it.syntax().text_range(),
 723                         )
 724                     })
 725                     .map(|it| it.parent_path());
 726                 return;
 727             }
 728
 729             if let Some(segment) = path.segment() {
 730                 if segment.coloncolon_token().is_some() {
 731                     return;
 732                 }
 733             }
 734
 735             path_ctx.is_trivial_path = true;
 736
 737             // Find either enclosing expr statement (thing with `;`) or a
 738             // block. If block, check that we are the last expr.
 739             path_ctx.can_be_stmt = name_ref
 740                 .syntax()
 741                 .ancestors()
 742                 .find_map(|node| {
 743                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 744                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 745                     }
 746                     if let Some(block) = ast::BlockExpr::cast(node) {
 747                         return Some(
 748                             block.tail_expr().map(|e| e.syntax().text_range())
 749                                 == Some(name_ref.syntax().text_range()),
 750                         );
 751                     }
 752                     None
 753                 })
 754                 .unwrap_or(false);
 755         }
 756     }
 757 }
 758
 759 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 760     syntax.covering_element(range).ancestors().find_map(N::cast)
 761 }
 762
 763 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 764     match node.ancestors().find_map(N::cast) {
 765         None => false,
 766         Some(n) => n.syntax().text_range() == node.text_range(),
 767     }
 768 }
 769
 770 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
 771     if let Some(qual) = path.qualifier() {
 772         return Some((qual, false));
 773     }
 774     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 775     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 776     use_tree.path().zip(Some(true))
 777 }
 778
 779 fn has_ref(token: &SyntaxToken) -> bool {
 780     let mut token = token.clone();
 781     for skip in [WHITESPACE, IDENT, T![mut]] {
 782         if token.kind() == skip {
 783             token = match token.prev_token() {
 784                 Some(it) => it,
 785                 None => return false,
 786             }
 787         }
 788     }
 789     token.kind() == T![&]
 790 }
 791
 792 #[cfg(test)]
 793 mod tests {
 794     use expect_test::{expect, Expect};
 795     use hir::HirDisplay;
 796
 797     use crate::tests::{position, TEST_CONFIG};
 798
 799     use super::CompletionContext;
 800
 801     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 802         let (db, pos) = position(ra_fixture);
 803         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 804
 805         let ty = completion_context
 806             .expected_type
 807             .map(|t| t.display_test(&db).to_string())
 808             .unwrap_or("?".to_owned());
 809
 810         let name = completion_context
 811             .expected_name
 812             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 813
 814         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 815     }
 816
 817     #[test]
 818     fn expected_type_let_without_leading_char() {
 819         cov_mark::check!(expected_type_let_without_leading_char);
 820         check_expected_type_and_name(
 821             r#"
 822 fn foo() {
 823     let x: u32 = $0;
 824 }
 825 "#,
 826             expect![[r#"ty: u32, name: x"#]],
 827         );
 828     }
 829
 830     #[test]
 831     fn expected_type_let_with_leading_char() {
 832         cov_mark::check!(expected_type_let_with_leading_char);
 833         check_expected_type_and_name(
 834             r#"
 835 fn foo() {
 836     let x: u32 = c$0;
 837 }
 838 "#,
 839             expect![[r#"ty: u32, name: x"#]],
 840         );
 841     }
 842
 843     #[test]
 844     fn expected_type_let_pat() {
 845         check_expected_type_and_name(
 846             r#"
 847 fn foo() {
 848     let x$0 = 0u32;
 849 }
 850 "#,
 851             expect![[r#"ty: u32, name: ?"#]],
 852         );
 853         check_expected_type_and_name(
 854             r#"
 855 fn foo() {
 856     let $0 = 0u32;
 857 }
 858 "#,
 859             expect![[r#"ty: u32, name: ?"#]],
 860         );
 861     }
 862
 863     #[test]
 864     fn expected_type_fn_param() {
 865         cov_mark::check!(expected_type_fn_param);
 866         check_expected_type_and_name(
 867             r#"
 868 fn foo() { bar($0); }
 869 fn bar(x: u32) {}
 870 "#,
 871             expect![[r#"ty: u32, name: x"#]],
 872         );
 873         check_expected_type_and_name(
 874             r#"
 875 fn foo() { bar(c$0); }
 876 fn bar(x: u32) {}
 877 "#,
 878             expect![[r#"ty: u32, name: x"#]],
 879         );
 880     }
 881
 882     #[test]
 883     fn expected_type_fn_param_ref() {
 884         cov_mark::check!(expected_type_fn_param_ref);
 885         check_expected_type_and_name(
 886             r#"
 887 fn foo() { bar(&$0); }
 888 fn bar(x: &u32) {}
 889 "#,
 890             expect![[r#"ty: u32, name: x"#]],
 891         );
 892         check_expected_type_and_name(
 893             r#"
 894 fn foo() { bar(&mut $0); }
 895 fn bar(x: &mut u32) {}
 896 "#,
 897             expect![[r#"ty: u32, name: x"#]],
 898         );
 899         check_expected_type_and_name(
 900             r#"
 901 fn foo() { bar(&c$0); }
 902 fn bar(x: &u32) {}
 903         "#,
 904             expect![[r#"ty: u32, name: x"#]],
 905         );
 906     }
 907
 908     #[test]
 909     fn expected_type_struct_field_without_leading_char() {
 910         cov_mark::check!(expected_type_struct_field_without_leading_char);
 911         check_expected_type_and_name(
 912             r#"
 913 struct Foo { a: u32 }
 914 fn foo() {
 915     Foo { a: $0 };
 916 }
 917 "#,
 918             expect![[r#"ty: u32, name: a"#]],
 919         )
 920     }
 921
 922     #[test]
 923     fn expected_type_generic_struct_field() {
 924         check_expected_type_and_name(
 925             r#"
 926 struct Foo<T> { a: T }
 927 fn foo() -> Foo<u32> {
 928     Foo { a: $0 }
 929 }
 930 "#,
 931             expect![[r#"ty: u32, name: a"#]],
 932         )
 933     }
 934
 935     #[test]
 936     fn expected_type_struct_field_with_leading_char() {
 937         cov_mark::check!(expected_type_struct_field_with_leading_char);
 938         check_expected_type_and_name(
 939             r#"
 940 struct Foo { a: u32 }
 941 fn foo() {
 942     Foo { a: c$0 };
 943 }
 944 "#,
 945             expect![[r#"ty: u32, name: a"#]],
 946         );
 947     }
 948
 949     #[test]
 950     fn expected_type_match_arm_without_leading_char() {
 951         cov_mark::check!(expected_type_match_arm_without_leading_char);
 952         check_expected_type_and_name(
 953             r#"
 954 enum E { X }
 955 fn foo() {
 956    match E::X { $0 }
 957 }
 958 "#,
 959             expect![[r#"ty: E, name: ?"#]],
 960         );
 961     }
 962
 963     #[test]
 964     fn expected_type_match_arm_with_leading_char() {
 965         cov_mark::check!(expected_type_match_arm_with_leading_char);
 966         check_expected_type_and_name(
 967             r#"
 968 enum E { X }
 969 fn foo() {
 970    match E::X { c$0 }
 971 }
 972 "#,
 973             expect![[r#"ty: E, name: ?"#]],
 974         );
 975     }
 976
 977     #[test]
 978     fn expected_type_if_let_without_leading_char() {
 979         cov_mark::check!(expected_type_if_let_without_leading_char);
 980         check_expected_type_and_name(
 981             r#"
 982 enum Foo { Bar, Baz, Quux }
 983
 984 fn foo() {
 985     let f = Foo::Quux;
 986     if let $0 = f { }
 987 }
 988 "#,
 989             expect![[r#"ty: Foo, name: ?"#]],
 990         )
 991     }
 992
 993     #[test]
 994     fn expected_type_if_let_with_leading_char() {
 995         cov_mark::check!(expected_type_if_let_with_leading_char);
 996         check_expected_type_and_name(
 997             r#"
 998 enum Foo { Bar, Baz, Quux }
 999
1000 fn foo() {
1001     let f = Foo::Quux;
1002     if let c$0 = f { }
1003 }
1004 "#,
1005             expect![[r#"ty: Foo, name: ?"#]],
1006         )
1007     }
1008
1009     #[test]
1010     fn expected_type_fn_ret_without_leading_char() {
1011         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1012         check_expected_type_and_name(
1013             r#"
1014 fn foo() -> u32 {
1015     $0
1016 }
1017 "#,
1018             expect![[r#"ty: u32, name: ?"#]],
1019         )
1020     }
1021
1022     #[test]
1023     fn expected_type_fn_ret_with_leading_char() {
1024         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1025         check_expected_type_and_name(
1026             r#"
1027 fn foo() -> u32 {
1028     c$0
1029 }
1030 "#,
1031             expect![[r#"ty: u32, name: ?"#]],
1032         )
1033     }
1034
1035     #[test]
1036     fn expected_type_fn_ret_fn_ref_fully_typed() {
1037         check_expected_type_and_name(
1038             r#"
1039 fn foo() -> u32 {
1040     foo$0
1041 }
1042 "#,
1043             expect![[r#"ty: u32, name: ?"#]],
1044         )
1045     }
1046
1047     #[test]
1048     fn expected_type_closure_param_return() {
1049         // FIXME: make this work with `|| $0`
1050         check_expected_type_and_name(
1051             r#"
1052 //- minicore: fn
1053 fn foo() {
1054     bar(|| a$0);
1055 }
1056
1057 fn bar(f: impl FnOnce() -> u32) {}
1058 "#,
1059             expect![[r#"ty: u32, name: ?"#]],
1060         );
1061     }
1062
1063     #[test]
1064     fn expected_type_generic_function() {
1065         check_expected_type_and_name(
1066             r#"
1067 fn foo() {
1068     bar::<u32>($0);
1069 }
1070
1071 fn bar<T>(t: T) {}
1072 "#,
1073             expect![[r#"ty: u32, name: t"#]],
1074         );
1075     }
1076
1077     #[test]
1078     fn expected_type_generic_method() {
1079         check_expected_type_and_name(
1080             r#"
1081 fn foo() {
1082     S(1u32).bar($0);
1083 }
1084
1085 struct S<T>(T);
1086 impl<T> S<T> {
1087     fn bar(self, t: T) {}
1088 }
1089 "#,
1090             expect![[r#"ty: u32, name: t"#]],
1091         );
1092     }
1093 }