crates/ide_completion/src/context.rs

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