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, TypeInfo};
   5 use ide_db::{
   6     active_parameter::ActiveParameter,
   7     base_db::{FilePosition, SourceDatabase},
   8     helpers::FamousDefs,
   9     RootDatabase,
  10 };
  11 use syntax::{
  12     algo::find_node_at_offset,
  13     ast::{self, HasName, NameOrNameRef},
  14     match_ast, AstNode, NodeOrToken,
  15     SyntaxKind::{self, *},
  16     SyntaxNode, SyntaxToken, TextRange, TextSize, T,
  17 };
  18 use text_edit::Indel;
  19
  20 use crate::{
  21     patterns::{
  22         determine_location, determine_prev_sibling, for_is_prev2, inside_impl_trait_block,
  23         is_in_loop_body, previous_token, ImmediateLocation, ImmediatePrevSibling,
  24     },
  25     CompletionConfig,
  26 };
  27
  28 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  29 pub(crate) enum PatternRefutability {
  30     Refutable,
  31     Irrefutable,
  32 }
  33
  34 #[derive(Copy, Clone, Debug)]
  35 pub(super) enum PathKind {
  36     Expr,
  37     Type,
  38     Attr,
  39     Mac,
  40     Pat,
  41     Vis { has_in_token: bool },
  42     Use,
  43 }
  44
  45 #[derive(Debug)]
  46 pub(crate) struct PathCompletionContext {
  47     /// If this is a call with () already there
  48     has_call_parens: bool,
  49     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  50     pub(super) is_trivial_path: bool,
  51     /// If not a trivial path, the prefix (qualifier).
  52     pub(super) qualifier: Option<ast::Path>,
  53     #[allow(dead_code)]
  54     /// If not a trivial path, the suffix (parent).
  55     pub(super) parent: Option<ast::Path>,
  56     /// Whether the qualifier comes from a use tree parent or not
  57     pub(super) use_tree_parent: bool,
  58     pub(super) kind: Option<PathKind>,
  59     /// Whether the path segment has type args or not.
  60     pub(super) has_type_args: bool,
  61     /// `true` if we are a statement or a last expr in the block.
  62     pub(super) can_be_stmt: bool,
  63     pub(super) in_loop_body: bool,
  64 }
  65
  66 #[derive(Debug)]
  67 pub(super) struct PatternContext {
  68     pub(super) refutability: PatternRefutability,
  69     pub(super) is_param: Option<ParamKind>,
  70     pub(super) has_type_ascription: bool,
  71 }
  72
  73 #[derive(Debug)]
  74 pub(super) enum LifetimeContext {
  75     LifetimeParam(Option<ast::LifetimeParam>),
  76     Lifetime,
  77     LabelRef,
  78     LabelDef,
  79 }
  80
  81 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  82 pub(crate) enum ParamKind {
  83     Function,
  84     Closure,
  85 }
  86 /// `CompletionContext` is created early during completion to figure out, where
  87 /// exactly is the cursor, syntax-wise.
  88 #[derive(Debug)]
  89 pub(crate) struct CompletionContext<'a> {
  90     pub(super) sema: Semantics<'a, RootDatabase>,
  91     pub(super) scope: SemanticsScope<'a>,
  92     pub(super) db: &'a RootDatabase,
  93     pub(super) config: &'a CompletionConfig,
  94     pub(super) position: FilePosition,
  95     /// The token before the cursor, in the original file.
  96     pub(super) original_token: SyntaxToken,
  97     /// The token before the cursor, in the macro-expanded file.
  98     pub(super) token: SyntaxToken,
  99     /// The crate of the current file.
 100     pub(super) krate: Option<hir::Crate>,
 101     pub(super) expected_name: Option<NameOrNameRef>,
 102     pub(super) expected_type: Option<Type>,
 103
 104     /// The parent function of the cursor position if it exists.
 105     pub(super) function_def: Option<ast::Fn>,
 106     pub(super) attr: Option<ast::Attr>,
 107     /// The parent impl of the cursor position if it exists.
 108     pub(super) impl_def: Option<ast::Impl>,
 109     /// The NameLike under the cursor in the original file if it exists.
 110     pub(super) name_syntax: Option<ast::NameLike>,
 111     pub(super) incomplete_let: bool,
 112
 113     pub(super) completion_location: Option<ImmediateLocation>,
 114     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
 115     pub(super) fake_attribute_under_caret: Option<ast::Attr>,
 116     pub(super) previous_token: Option<SyntaxToken>,
 117
 118     pub(super) lifetime_ctx: Option<LifetimeContext>,
 119     pub(super) pattern_ctx: Option<PatternContext>,
 120     pub(super) path_context: Option<PathCompletionContext>,
 121     pub(super) locals: Vec<(Name, Local)>,
 122
 123     no_completion_required: bool,
 124 }
 125
 126 impl<'a> CompletionContext<'a> {
 127     /// Checks whether completions in that particular case don't make much sense.
 128     /// Examples:
 129     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 130     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 131     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 132     pub(crate) fn no_completion_required(&self) -> bool {
 133         self.no_completion_required
 134     }
 135
 136     /// The range of the identifier that is being completed.
 137     pub(crate) fn source_range(&self) -> TextRange {
 138         // check kind of macro-expanded token, but use range of original token
 139         let kind = self.token.kind();
 140         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 141             self.original_token.text_range()
 142         } else if kind == CHAR {
 143             // assume we are completing a lifetime but the user has only typed the '
 144             cov_mark::hit!(completes_if_lifetime_without_idents);
 145             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 146         } else {
 147             TextRange::empty(self.position.offset)
 148         }
 149     }
 150
 151     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 152         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 153     }
 154
 155     pub(crate) fn famous_defs(&self) -> FamousDefs {
 156         FamousDefs(&self.sema, self.krate)
 157     }
 158
 159     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 160         match &self.completion_location {
 161             Some(
 162                 ImmediateLocation::MethodCall { receiver, .. }
 163                 | ImmediateLocation::FieldAccess { receiver, .. },
 164             ) => receiver.as_ref(),
 165             _ => None,
 166         }
 167     }
 168
 169     pub(crate) fn has_dot_receiver(&self) -> bool {
 170         matches!(
 171             &self.completion_location,
 172             Some(ImmediateLocation::FieldAccess { receiver, .. } | ImmediateLocation::MethodCall { receiver,.. })
 173                 if receiver.is_some()
 174         )
 175     }
 176
 177     pub(crate) fn expects_assoc_item(&self) -> bool {
 178         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 179     }
 180
 181     pub(crate) fn expects_variant(&self) -> bool {
 182         matches!(self.completion_location, Some(ImmediateLocation::Variant))
 183     }
 184
 185     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 186         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 187     }
 188
 189     pub(crate) fn expects_item(&self) -> bool {
 190         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 191     }
 192
 193     pub(crate) fn expects_generic_arg(&self) -> bool {
 194         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 195     }
 196
 197     pub(crate) fn has_block_expr_parent(&self) -> bool {
 198         matches!(self.completion_location, Some(ImmediateLocation::StmtList))
 199     }
 200
 201     pub(crate) fn expects_ident_pat_or_ref_expr(&self) -> bool {
 202         matches!(
 203             self.completion_location,
 204             Some(ImmediateLocation::IdentPat | ImmediateLocation::RefExpr)
 205         )
 206     }
 207
 208     pub(crate) fn expect_field(&self) -> bool {
 209         matches!(
 210             self.completion_location,
 211             Some(ImmediateLocation::RecordField | ImmediateLocation::TupleField)
 212         )
 213     }
 214
 215     pub(crate) fn has_impl_or_trait_prev_sibling(&self) -> bool {
 216         matches!(
 217             self.prev_sibling,
 218             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 219         )
 220     }
 221
 222     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 223         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 224     }
 225
 226     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 227         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 228     }
 229
 230     pub(crate) fn after_if(&self) -> bool {
 231         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 232     }
 233
 234     pub(crate) fn is_path_disallowed(&self) -> bool {
 235         self.previous_token_is(T![unsafe])
 236             || matches!(
 237                 self.prev_sibling,
 238                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 239             )
 240             || matches!(
 241                 self.completion_location,
 242                 Some(
 243                     ImmediateLocation::ModDeclaration(_)
 244                         | ImmediateLocation::RecordPat(_)
 245                         | ImmediateLocation::RecordExpr(_)
 246                         | ImmediateLocation::Rename
 247                 )
 248             )
 249     }
 250
 251     pub(crate) fn expects_expression(&self) -> bool {
 252         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Expr), .. }))
 253     }
 254
 255     pub(crate) fn expects_type(&self) -> bool {
 256         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Type), .. }))
 257     }
 258
 259     pub(crate) fn path_is_call(&self) -> bool {
 260         self.path_context.as_ref().map_or(false, |it| it.has_call_parens)
 261     }
 262
 263     pub(crate) fn is_trivial_path(&self) -> bool {
 264         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: true, .. }))
 265     }
 266
 267     pub(crate) fn is_non_trivial_path(&self) -> bool {
 268         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: false, .. }))
 269     }
 270
 271     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 272         self.path_context.as_ref().and_then(|it| it.qualifier.as_ref())
 273     }
 274
 275     pub(crate) fn path_kind(&self) -> Option<PathKind> {
 276         self.path_context.as_ref().and_then(|it| it.kind)
 277     }
 278
 279     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 280     pub(crate) fn is_visible<I>(&self, item: &I) -> bool
 281     where
 282         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 283     {
 284         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 285     }
 286
 287     pub(crate) fn is_scope_def_hidden(&self, scope_def: ScopeDef) -> bool {
 288         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 289             return self.is_doc_hidden(&attrs, krate);
 290         }
 291
 292         false
 293     }
 294
 295     /// Check if an item is `#[doc(hidden)]`.
 296     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
 297         let attrs = item.attrs(self.db);
 298         let krate = item.krate(self.db);
 299         match (attrs, krate) {
 300             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
 301             _ => false,
 302         }
 303     }
 304
 305     pub(crate) fn is_immediately_after_macro_bang(&self) -> bool {
 306         self.token.kind() == BANG && self.token.parent().map_or(false, |it| it.kind() == MACRO_CALL)
 307     }
 308
 309     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 310     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 311         let _p = profile::span("CompletionContext::process_all_names");
 312         self.scope.process_all_names(&mut |name, def| {
 313             if self.is_scope_def_hidden(def) {
 314                 return;
 315             }
 316
 317             f(name, def);
 318         })
 319     }
 320
 321     fn is_visible_impl(
 322         &self,
 323         vis: &hir::Visibility,
 324         attrs: &hir::Attrs,
 325         defining_crate: hir::Crate,
 326     ) -> bool {
 327         let module = match self.scope.module() {
 328             Some(it) => it,
 329             None => return false,
 330         };
 331         if !vis.is_visible_from(self.db, module.into()) {
 332             // If the definition location is editable, also show private items
 333             let root_file = defining_crate.root_file(self.db);
 334             let source_root_id = self.db.file_source_root(root_file);
 335             let is_editable = !self.db.source_root(source_root_id).is_library;
 336             return is_editable;
 337         }
 338
 339         !self.is_doc_hidden(attrs, defining_crate)
 340     }
 341
 342     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 343         let krate = match self.krate {
 344             Some(it) => it,
 345             None => return true,
 346         };
 347         if krate != defining_crate && attrs.has_doc_hidden() {
 348             // `doc(hidden)` items are only completed within the defining crate.
 349             return true;
 350         }
 351
 352         false
 353     }
 354 }
 355
 356 // CompletionContext construction
 357 impl<'a> CompletionContext<'a> {
 358     pub(super) fn new(
 359         db: &'a RootDatabase,
 360         position @ FilePosition { file_id, offset }: FilePosition,
 361         config: &'a CompletionConfig,
 362     ) -> Option<CompletionContext<'a>> {
 363         let _p = profile::span("CompletionContext::new");
 364         let sema = Semantics::new(db);
 365
 366         let original_file = sema.parse(file_id);
 367
 368         // Insert a fake ident to get a valid parse tree. We will use this file
 369         // to determine context, though the original_file will be used for
 370         // actual completion.
 371         let file_with_fake_ident = {
 372             let parse = db.parse(file_id);
 373             let edit = Indel::insert(offset, "intellijRulezz".to_string());
 374             parse.reparse(&edit).tree()
 375         };
 376         let fake_ident_token =
 377             file_with_fake_ident.syntax().token_at_offset(offset).right_biased()?;
 378
 379         let original_token = original_file.syntax().token_at_offset(offset).left_biased()?;
 380         let token = sema.descend_into_macros_single(original_token.clone());
 381         let scope = sema.scope_at_offset(&token, offset);
 382         let krate = scope.krate();
 383         let mut locals = vec![];
 384         scope.process_all_names(&mut |name, scope| {
 385             if let ScopeDef::Local(local) = scope {
 386                 locals.push((name, local));
 387             }
 388         });
 389         let mut ctx = CompletionContext {
 390             sema,
 391             scope,
 392             db,
 393             config,
 394             position,
 395             original_token,
 396             token,
 397             krate,
 398             expected_name: None,
 399             expected_type: None,
 400             function_def: None,
 401             attr: None,
 402             impl_def: None,
 403             name_syntax: None,
 404             lifetime_ctx: None,
 405             pattern_ctx: None,
 406             completion_location: None,
 407             prev_sibling: None,
 408             fake_attribute_under_caret: None,
 409             previous_token: None,
 410             path_context: None,
 411             locals,
 412             incomplete_let: false,
 413             no_completion_required: false,
 414         };
 415         ctx.expand_and_fill(
 416             original_file.syntax().clone(),
 417             file_with_fake_ident.syntax().clone(),
 418             offset,
 419             fake_ident_token,
 420         );
 421         Some(ctx)
 422     }
 423
 424     /// Do the attribute expansion at the current cursor position for both original file and fake file
 425     /// as long as possible. As soon as one of the two expansions fail we stop to stay in sync.
 426     fn expand_and_fill(
 427         &mut self,
 428         mut original_file: SyntaxNode,
 429         mut speculative_file: SyntaxNode,
 430         mut offset: TextSize,
 431         mut fake_ident_token: SyntaxToken,
 432     ) {
 433         let _p = profile::span("CompletionContext::expand_and_fill");
 434         loop {
 435             // Expand attributes
 436             if let (Some(actual_item), Some(item_with_fake_ident)) = (
 437                 find_node_at_offset::<ast::Item>(&original_file, offset),
 438                 find_node_at_offset::<ast::Item>(&speculative_file, offset),
 439             ) {
 440                 match (
 441                     self.sema.expand_attr_macro(&actual_item),
 442                     self.sema.speculative_expand_attr_macro(
 443                         &actual_item,
 444                         &item_with_fake_ident,
 445                         fake_ident_token.clone(),
 446                     ),
 447                 ) {
 448                     (Some(actual_expansion), Some(speculative_expansion)) => {
 449                         let new_offset = speculative_expansion.1.text_range().start();
 450                         if new_offset > actual_expansion.text_range().end() {
 451                             break;
 452                         }
 453                         original_file = actual_expansion;
 454                         speculative_file = speculative_expansion.0;
 455                         fake_ident_token = speculative_expansion.1;
 456                         offset = new_offset;
 457                         continue;
 458                     }
 459                     (None, None) => (),
 460                     _ => break,
 461                 }
 462             }
 463
 464             // Expand fn-like macro calls
 465             if let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 466                 find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 467                 find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 468             ) {
 469                 let mac_call_path0 = actual_macro_call.path().as_ref().map(|s| s.syntax().text());
 470                 let mac_call_path1 =
 471                     macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text());
 472                 if mac_call_path0 != mac_call_path1 {
 473                     break;
 474                 }
 475                 let speculative_args = match macro_call_with_fake_ident.token_tree() {
 476                     Some(tt) => tt,
 477                     None => break,
 478                 };
 479
 480                 if let (Some(actual_expansion), Some(speculative_expansion)) = (
 481                     self.sema.expand(&actual_macro_call),
 482                     self.sema.speculative_expand(
 483                         &actual_macro_call,
 484                         &speculative_args,
 485                         fake_ident_token,
 486                     ),
 487                 ) {
 488                     let new_offset = speculative_expansion.1.text_range().start();
 489                     if new_offset > actual_expansion.text_range().end() {
 490                         break;
 491                     }
 492                     original_file = actual_expansion;
 493                     speculative_file = speculative_expansion.0;
 494                     fake_ident_token = speculative_expansion.1;
 495                     offset = new_offset;
 496                 } else {
 497                     break;
 498                 }
 499             } else {
 500                 break;
 501             }
 502         }
 503
 504         self.fill(&original_file, speculative_file, offset);
 505     }
 506
 507     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 508         let mut node = match self.token.parent() {
 509             Some(it) => it,
 510             None => return (None, None),
 511         };
 512         loop {
 513             break match_ast! {
 514                 match node {
 515                     ast::LetStmt(it) => {
 516                         cov_mark::hit!(expected_type_let_with_leading_char);
 517                         cov_mark::hit!(expected_type_let_without_leading_char);
 518                         let ty = it.pat()
 519                             .and_then(|pat| self.sema.type_of_pat(&pat))
 520                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)))
 521                             .map(TypeInfo::original);
 522                         let name = match it.pat() {
 523                             Some(ast::Pat::IdentPat(ident)) => ident.name().map(NameOrNameRef::Name),
 524                             Some(_) | None => None,
 525                         };
 526
 527                         (ty, name)
 528                     },
 529                     ast::ArgList(_) => {
 530                         cov_mark::hit!(expected_type_fn_param);
 531                         ActiveParameter::at_token(
 532                             &self.sema,
 533                             self.token.clone(),
 534                         ).map(|ap| {
 535                             let name = ap.ident().map(NameOrNameRef::Name);
 536                             let ty = if has_ref(&self.token) {
 537                                 cov_mark::hit!(expected_type_fn_param_ref);
 538                                 ap.ty.remove_ref()
 539                             } else {
 540                                 Some(ap.ty)
 541                             };
 542                             (ty, name)
 543                         })
 544                         .unwrap_or((None, None))
 545                     },
 546                     ast::RecordExprFieldList(it) => {
 547                         // wouldn't try {} be nice...
 548                         (|| {
 549                             if self.token.kind() == T![..]
 550                                 || self.token.prev_token().map(|t| t.kind()) == Some(T![..])
 551                             {
 552                                 cov_mark::hit!(expected_type_struct_func_update);
 553                                 let record_expr = it.syntax().parent().and_then(ast::RecordExpr::cast)?;
 554                                 let ty = self.sema.type_of_expr(&record_expr.into())?;
 555                                 Some((
 556                                     Some(ty.original),
 557                                     None
 558                                 ))
 559                             } else {
 560                                 cov_mark::hit!(expected_type_struct_field_without_leading_char);
 561                                 let expr_field = self.token.prev_sibling_or_token()?
 562                                     .into_node()
 563                                     .and_then(ast::RecordExprField::cast)?;
 564                                 let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 565                                 Some((
 566                                     Some(ty),
 567                                     expr_field.field_name().map(NameOrNameRef::NameRef),
 568                                 ))
 569                             }
 570                         })().unwrap_or((None, None))
 571                     },
 572                     ast::RecordExprField(it) => {
 573                         if let Some(expr) = it.expr() {
 574                             cov_mark::hit!(expected_type_struct_field_with_leading_char);
 575                             (
 576                                 self.sema.type_of_expr(&expr).map(TypeInfo::original),
 577                                 it.field_name().map(NameOrNameRef::NameRef),
 578                             )
 579                         } else {
 580                             cov_mark::hit!(expected_type_struct_field_followed_by_comma);
 581                             let ty = self.sema.resolve_record_field(&it)
 582                                 .map(|(_, _, ty)| ty);
 583                             (
 584                                 ty,
 585                                 it.field_name().map(NameOrNameRef::NameRef),
 586                             )
 587                         }
 588                     },
 589                     ast::MatchExpr(it) => {
 590                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 591                         let ty = it.expr().and_then(|e| self.sema.type_of_expr(&e)).map(TypeInfo::original);
 592                         (ty, None)
 593                     },
 594                     ast::IfExpr(it) => {
 595                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 596                         let ty = it.condition()
 597                             .and_then(|cond| cond.expr())
 598                             .and_then(|e| self.sema.type_of_expr(&e))
 599                             .map(TypeInfo::original);
 600                         (ty, None)
 601                     },
 602                     ast::IdentPat(it) => {
 603                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 604                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 605                         let ty = self.sema.type_of_pat(&ast::Pat::from(it)).map(TypeInfo::original);
 606                         (ty, None)
 607                     },
 608                     ast::Fn(it) => {
 609                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 610                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 611                         let def = self.sema.to_def(&it);
 612                         (def.map(|def| def.ret_type(self.db)), None)
 613                     },
 614                     ast::ClosureExpr(it) => {
 615                         let ty = self.sema.type_of_expr(&it.into());
 616                         ty.and_then(|ty| ty.original.as_callable(self.db))
 617                             .map(|c| (Some(c.return_type()), None))
 618                             .unwrap_or((None, None))
 619                     },
 620                     ast::ParamList(_) => (None, None),
 621                     ast::Stmt(_) => (None, None),
 622                     ast::Item(_) => (None, None),
 623                     _ => {
 624                         match node.parent() {
 625                             Some(n) => {
 626                                 node = n;
 627                                 continue;
 628                             },
 629                             None => (None, None),
 630                         }
 631                     },
 632                 }
 633             };
 634         }
 635     }
 636
 637     fn fill(
 638         &mut self,
 639         original_file: &SyntaxNode,
 640         file_with_fake_ident: SyntaxNode,
 641         offset: TextSize,
 642     ) {
 643         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 644         let syntax_element = NodeOrToken::Token(fake_ident_token);
 645         self.previous_token = previous_token(syntax_element.clone());
 646         self.no_completion_required = {
 647             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 648             let fn_is_prev = self.previous_token_is(T![fn]);
 649             let for_is_prev2 = for_is_prev2(syntax_element.clone());
 650             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
 651         };
 652
 653         self.attr = self
 654             .sema
 655             .token_ancestors_with_macros(self.token.clone())
 656             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 657             .find_map(ast::Attr::cast);
 658         self.fake_attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
 659
 660         self.incomplete_let =
 661             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 662                 it.syntax().text_range().end() == syntax_element.text_range().end()
 663             });
 664
 665         let (expected_type, expected_name) = self.expected_type_and_name();
 666         self.expected_type = expected_type;
 667         self.expected_name = expected_name;
 668
 669         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 670             Some(it) => it,
 671             None => return,
 672         };
 673         self.completion_location =
 674             determine_location(&self.sema, original_file, offset, &name_like);
 675         self.prev_sibling = determine_prev_sibling(&name_like);
 676         self.name_syntax =
 677             find_node_at_offset(original_file, name_like.syntax().text_range().start());
 678         self.impl_def = self
 679             .sema
 680             .token_ancestors_with_macros(self.token.clone())
 681             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 682             .find_map(ast::Impl::cast);
 683         self.function_def = self
 684             .sema
 685             .token_ancestors_with_macros(self.token.clone())
 686             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 687             .find_map(ast::Fn::cast);
 688         match name_like {
 689             ast::NameLike::Lifetime(lifetime) => {
 690                 self.lifetime_ctx =
 691                     Self::classify_lifetime(&self.sema, original_file, lifetime, offset);
 692             }
 693             ast::NameLike::NameRef(name_ref) => {
 694                 if let Some((path_ctx, pat_ctx)) =
 695                     Self::classify_name_ref(&self.sema, original_file, name_ref)
 696                 {
 697                     self.path_context = Some(path_ctx);
 698                     self.pattern_ctx = pat_ctx;
 699                 }
 700             }
 701             ast::NameLike::Name(name) => {
 702                 self.pattern_ctx = Self::classify_name(&self.sema, name);
 703             }
 704         }
 705     }
 706
 707     fn classify_lifetime(
 708         sema: &Semantics<RootDatabase>,
 709         original_file: &SyntaxNode,
 710         lifetime: ast::Lifetime,
 711         offset: TextSize,
 712     ) -> Option<LifetimeContext> {
 713         let parent = lifetime.syntax().parent()?;
 714         if parent.kind() == ERROR {
 715             return None;
 716         }
 717
 718         Some(match_ast! {
 719             match parent {
 720                 ast::LifetimeParam(_) => LifetimeContext::LifetimeParam(sema.find_node_at_offset_with_macros(original_file, offset)),
 721                 ast::BreakExpr(_) => LifetimeContext::LabelRef,
 722                 ast::ContinueExpr(_) => LifetimeContext::LabelRef,
 723                 ast::Label(_) => LifetimeContext::LabelDef,
 724                 _ => LifetimeContext::Lifetime,
 725             }
 726         })
 727     }
 728
 729     fn classify_name(_sema: &Semantics<RootDatabase>, name: ast::Name) -> Option<PatternContext> {
 730         let bind_pat = name.syntax().parent().and_then(ast::IdentPat::cast)?;
 731         let is_name_in_field_pat = bind_pat
 732             .syntax()
 733             .parent()
 734             .and_then(ast::RecordPatField::cast)
 735             .map_or(false, |pat_field| pat_field.name_ref().is_none());
 736         if is_name_in_field_pat {
 737             return None;
 738         }
 739         if !bind_pat.is_simple_ident() {
 740             return None;
 741         }
 742         Some(pattern_context_for(bind_pat.into()))
 743     }
 744
 745     fn classify_name_ref(
 746         _sema: &Semantics<RootDatabase>,
 747         original_file: &SyntaxNode,
 748         name_ref: ast::NameRef,
 749     ) -> Option<(PathCompletionContext, Option<PatternContext>)> {
 750         let parent = name_ref.syntax().parent()?;
 751         let segment = ast::PathSegment::cast(parent)?;
 752         let path = segment.parent_path();
 753
 754         let mut path_ctx = PathCompletionContext {
 755             has_call_parens: false,
 756             is_trivial_path: false,
 757             qualifier: None,
 758             parent: None,
 759             has_type_args: false,
 760             can_be_stmt: false,
 761             in_loop_body: false,
 762             use_tree_parent: false,
 763             kind: None,
 764         };
 765         let mut pat_ctx = None;
 766         path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
 767
 768         path_ctx.kind  = path.syntax().ancestors().find_map(|it| {
 769             match_ast! {
 770                 match it {
 771                     ast::PathType(_) => Some(PathKind::Type),
 772                     ast::PathExpr(it) => {
 773                         path_ctx.has_call_parens = it.syntax().parent().map_or(false, |it| ast::CallExpr::can_cast(it.kind()));
 774                         Some(PathKind::Expr)
 775                     },
 776                     ast::TupleStructPat(it) => {
 777                         path_ctx.has_call_parens = true;
 778                         pat_ctx = Some(pattern_context_for(it.into()));
 779                         Some(PathKind::Pat)
 780                     },
 781                     ast::RecordPat(it) => {
 782                         pat_ctx = Some(pattern_context_for(it.into()));
 783                         Some(PathKind::Pat)
 784                     },
 785                     ast::PathPat(it) => {
 786                         pat_ctx = Some(pattern_context_for(it.into()));
 787                         Some(PathKind::Pat)
 788                     },
 789                     ast::MacroCall(it) => it.excl_token().and(Some(PathKind::Mac)),
 790                     ast::Meta(_) => Some(PathKind::Attr),
 791                     ast::Visibility(it) => Some(PathKind::Vis { has_in_token: it.in_token().is_some() }),
 792                     ast::UseTree(_) => Some(PathKind::Use),
 793                     _ => None,
 794                 }
 795             }
 796         });
 797         path_ctx.has_type_args = segment.generic_arg_list().is_some();
 798
 799         if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
 800             path_ctx.use_tree_parent = use_tree_parent;
 801             path_ctx.qualifier = path
 802                 .segment()
 803                 .and_then(|it| {
 804                     find_node_with_range::<ast::PathSegment>(
 805                         original_file,
 806                         it.syntax().text_range(),
 807                     )
 808                 })
 809                 .map(|it| it.parent_path());
 810             return Some((path_ctx, pat_ctx));
 811         }
 812
 813         if let Some(segment) = path.segment() {
 814             if segment.coloncolon_token().is_some() {
 815                 return Some((path_ctx, pat_ctx));
 816             }
 817         }
 818
 819         path_ctx.is_trivial_path = true;
 820
 821         // Find either enclosing expr statement (thing with `;`) or a
 822         // block. If block, check that we are the last expr.
 823         path_ctx.can_be_stmt = name_ref
 824             .syntax()
 825             .ancestors()
 826             .find_map(|node| {
 827                 if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 828                     return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 829                 }
 830                 if let Some(stmt_list) = ast::StmtList::cast(node) {
 831                     return Some(
 832                         stmt_list.tail_expr().map(|e| e.syntax().text_range())
 833                             == Some(name_ref.syntax().text_range()),
 834                     );
 835                 }
 836                 None
 837             })
 838             .unwrap_or(false);
 839         Some((path_ctx, pat_ctx))
 840     }
 841 }
 842
 843 fn pattern_context_for(pat: ast::Pat) -> PatternContext {
 844     let mut is_param = None;
 845     let (refutability, has_type_ascription) =
 846     pat
 847         .syntax()
 848         .ancestors()
 849         .skip_while(|it| ast::Pat::can_cast(it.kind()))
 850         .next()
 851         .map_or((PatternRefutability::Irrefutable, false), |node| {
 852             let refutability = match_ast! {
 853                 match node {
 854                     ast::LetStmt(let_) => return (PatternRefutability::Irrefutable, let_.ty().is_some()),
 855                     ast::Param(param) => {
 856                         let is_closure_param = param
 857                             .syntax()
 858                             .ancestors()
 859                             .nth(2)
 860                             .and_then(ast::ClosureExpr::cast)
 861                             .is_some();
 862                         is_param = Some(if is_closure_param {
 863                             ParamKind::Closure
 864                         } else {
 865                             ParamKind::Function
 866                         });
 867                         return (PatternRefutability::Irrefutable, param.ty().is_some())
 868                     },
 869                     ast::MatchArm(_) => PatternRefutability::Refutable,
 870                     ast::Condition(_) => PatternRefutability::Refutable,
 871                     ast::ForExpr(_) => PatternRefutability::Irrefutable,
 872                     _ => PatternRefutability::Irrefutable,
 873                 }
 874             };
 875             (refutability, false)
 876         });
 877     PatternContext { refutability, is_param, has_type_ascription }
 878 }
 879 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 880     syntax.covering_element(range).ancestors().find_map(N::cast)
 881 }
 882
 883 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
 884     if let Some(qual) = path.qualifier() {
 885         return Some((qual, false));
 886     }
 887     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 888     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 889     use_tree.path().zip(Some(true))
 890 }
 891
 892 fn has_ref(token: &SyntaxToken) -> bool {
 893     let mut token = token.clone();
 894     for skip in [WHITESPACE, IDENT, T![mut]] {
 895         if token.kind() == skip {
 896             token = match token.prev_token() {
 897                 Some(it) => it,
 898                 None => return false,
 899             }
 900         }
 901     }
 902     token.kind() == T![&]
 903 }
 904
 905 #[cfg(test)]
 906 mod tests {
 907     use expect_test::{expect, Expect};
 908     use hir::HirDisplay;
 909
 910     use crate::tests::{position, TEST_CONFIG};
 911
 912     use super::CompletionContext;
 913
 914     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 915         let (db, pos) = position(ra_fixture);
 916         let config = TEST_CONFIG;
 917         let completion_context = CompletionContext::new(&db, pos, &config).unwrap();
 918
 919         let ty = completion_context
 920             .expected_type
 921             .map(|t| t.display_test(&db).to_string())
 922             .unwrap_or("?".to_owned());
 923
 924         let name = completion_context
 925             .expected_name
 926             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 927
 928         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 929     }
 930
 931     #[test]
 932     fn expected_type_let_without_leading_char() {
 933         cov_mark::check!(expected_type_let_without_leading_char);
 934         check_expected_type_and_name(
 935             r#"
 936 fn foo() {
 937     let x: u32 = $0;
 938 }
 939 "#,
 940             expect![[r#"ty: u32, name: x"#]],
 941         );
 942     }
 943
 944     #[test]
 945     fn expected_type_let_with_leading_char() {
 946         cov_mark::check!(expected_type_let_with_leading_char);
 947         check_expected_type_and_name(
 948             r#"
 949 fn foo() {
 950     let x: u32 = c$0;
 951 }
 952 "#,
 953             expect![[r#"ty: u32, name: x"#]],
 954         );
 955     }
 956
 957     #[test]
 958     fn expected_type_let_pat() {
 959         check_expected_type_and_name(
 960             r#"
 961 fn foo() {
 962     let x$0 = 0u32;
 963 }
 964 "#,
 965             expect![[r#"ty: u32, name: ?"#]],
 966         );
 967         check_expected_type_and_name(
 968             r#"
 969 fn foo() {
 970     let $0 = 0u32;
 971 }
 972 "#,
 973             expect![[r#"ty: u32, name: ?"#]],
 974         );
 975     }
 976
 977     #[test]
 978     fn expected_type_fn_param() {
 979         cov_mark::check!(expected_type_fn_param);
 980         check_expected_type_and_name(
 981             r#"
 982 fn foo() { bar($0); }
 983 fn bar(x: u32) {}
 984 "#,
 985             expect![[r#"ty: u32, name: x"#]],
 986         );
 987         check_expected_type_and_name(
 988             r#"
 989 fn foo() { bar(c$0); }
 990 fn bar(x: u32) {}
 991 "#,
 992             expect![[r#"ty: u32, name: x"#]],
 993         );
 994     }
 995
 996     #[test]
 997     fn expected_type_fn_param_ref() {
 998         cov_mark::check!(expected_type_fn_param_ref);
 999         check_expected_type_and_name(
1000             r#"
1001 fn foo() { bar(&$0); }
1002 fn bar(x: &u32) {}
1003 "#,
1004             expect![[r#"ty: u32, name: x"#]],
1005         );
1006         check_expected_type_and_name(
1007             r#"
1008 fn foo() { bar(&mut $0); }
1009 fn bar(x: &mut u32) {}
1010 "#,
1011             expect![[r#"ty: u32, name: x"#]],
1012         );
1013         check_expected_type_and_name(
1014             r#"
1015 fn foo() { bar(&c$0); }
1016 fn bar(x: &u32) {}
1017         "#,
1018             expect![[r#"ty: u32, name: x"#]],
1019         );
1020     }
1021
1022     #[test]
1023     fn expected_type_struct_field_without_leading_char() {
1024         cov_mark::check!(expected_type_struct_field_without_leading_char);
1025         check_expected_type_and_name(
1026             r#"
1027 struct Foo { a: u32 }
1028 fn foo() {
1029     Foo { a: $0 };
1030 }
1031 "#,
1032             expect![[r#"ty: u32, name: a"#]],
1033         )
1034     }
1035
1036     #[test]
1037     fn expected_type_struct_field_followed_by_comma() {
1038         cov_mark::check!(expected_type_struct_field_followed_by_comma);
1039         check_expected_type_and_name(
1040             r#"
1041 struct Foo { a: u32 }
1042 fn foo() {
1043     Foo { a: $0, };
1044 }
1045 "#,
1046             expect![[r#"ty: u32, name: a"#]],
1047         )
1048     }
1049
1050     #[test]
1051     fn expected_type_generic_struct_field() {
1052         check_expected_type_and_name(
1053             r#"
1054 struct Foo<T> { a: T }
1055 fn foo() -> Foo<u32> {
1056     Foo { a: $0 }
1057 }
1058 "#,
1059             expect![[r#"ty: u32, name: a"#]],
1060         )
1061     }
1062
1063     #[test]
1064     fn expected_type_struct_field_with_leading_char() {
1065         cov_mark::check!(expected_type_struct_field_with_leading_char);
1066         check_expected_type_and_name(
1067             r#"
1068 struct Foo { a: u32 }
1069 fn foo() {
1070     Foo { a: c$0 };
1071 }
1072 "#,
1073             expect![[r#"ty: u32, name: a"#]],
1074         );
1075     }
1076
1077     #[test]
1078     fn expected_type_match_arm_without_leading_char() {
1079         cov_mark::check!(expected_type_match_arm_without_leading_char);
1080         check_expected_type_and_name(
1081             r#"
1082 enum E { X }
1083 fn foo() {
1084    match E::X { $0 }
1085 }
1086 "#,
1087             expect![[r#"ty: E, name: ?"#]],
1088         );
1089     }
1090
1091     #[test]
1092     fn expected_type_match_arm_with_leading_char() {
1093         cov_mark::check!(expected_type_match_arm_with_leading_char);
1094         check_expected_type_and_name(
1095             r#"
1096 enum E { X }
1097 fn foo() {
1098    match E::X { c$0 }
1099 }
1100 "#,
1101             expect![[r#"ty: E, name: ?"#]],
1102         );
1103     }
1104
1105     #[test]
1106     fn expected_type_if_let_without_leading_char() {
1107         cov_mark::check!(expected_type_if_let_without_leading_char);
1108         check_expected_type_and_name(
1109             r#"
1110 enum Foo { Bar, Baz, Quux }
1111
1112 fn foo() {
1113     let f = Foo::Quux;
1114     if let $0 = f { }
1115 }
1116 "#,
1117             expect![[r#"ty: Foo, name: ?"#]],
1118         )
1119     }
1120
1121     #[test]
1122     fn expected_type_if_let_with_leading_char() {
1123         cov_mark::check!(expected_type_if_let_with_leading_char);
1124         check_expected_type_and_name(
1125             r#"
1126 enum Foo { Bar, Baz, Quux }
1127
1128 fn foo() {
1129     let f = Foo::Quux;
1130     if let c$0 = f { }
1131 }
1132 "#,
1133             expect![[r#"ty: Foo, name: ?"#]],
1134         )
1135     }
1136
1137     #[test]
1138     fn expected_type_fn_ret_without_leading_char() {
1139         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1140         check_expected_type_and_name(
1141             r#"
1142 fn foo() -> u32 {
1143     $0
1144 }
1145 "#,
1146             expect![[r#"ty: u32, name: ?"#]],
1147         )
1148     }
1149
1150     #[test]
1151     fn expected_type_fn_ret_with_leading_char() {
1152         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1153         check_expected_type_and_name(
1154             r#"
1155 fn foo() -> u32 {
1156     c$0
1157 }
1158 "#,
1159             expect![[r#"ty: u32, name: ?"#]],
1160         )
1161     }
1162
1163     #[test]
1164     fn expected_type_fn_ret_fn_ref_fully_typed() {
1165         check_expected_type_and_name(
1166             r#"
1167 fn foo() -> u32 {
1168     foo$0
1169 }
1170 "#,
1171             expect![[r#"ty: u32, name: ?"#]],
1172         )
1173     }
1174
1175     #[test]
1176     fn expected_type_closure_param_return() {
1177         // FIXME: make this work with `|| $0`
1178         check_expected_type_and_name(
1179             r#"
1180 //- minicore: fn
1181 fn foo() {
1182     bar(|| a$0);
1183 }
1184
1185 fn bar(f: impl FnOnce() -> u32) {}
1186 "#,
1187             expect![[r#"ty: u32, name: ?"#]],
1188         );
1189     }
1190
1191     #[test]
1192     fn expected_type_generic_function() {
1193         check_expected_type_and_name(
1194             r#"
1195 fn foo() {
1196     bar::<u32>($0);
1197 }
1198
1199 fn bar<T>(t: T) {}
1200 "#,
1201             expect![[r#"ty: u32, name: t"#]],
1202         );
1203     }
1204
1205     #[test]
1206     fn expected_type_generic_method() {
1207         check_expected_type_and_name(
1208             r#"
1209 fn foo() {
1210     S(1u32).bar($0);
1211 }
1212
1213 struct S<T>(T);
1214 impl<T> S<T> {
1215     fn bar(self, t: T) {}
1216 }
1217 "#,
1218             expect![[r#"ty: u32, name: t"#]],
1219         );
1220     }
1221
1222     #[test]
1223     fn expected_type_functional_update() {
1224         cov_mark::check!(expected_type_struct_func_update);
1225         check_expected_type_and_name(
1226             r#"
1227 struct Foo { field: u32 }
1228 fn foo() {
1229     Foo {
1230         ..$0
1231     }
1232 }
1233 "#,
1234             expect![[r#"ty: Foo, name: ?"#]],
1235         );
1236     }
1237
1238     #[test]
1239     fn expected_type_param_pat() {
1240         check_expected_type_and_name(
1241             r#"
1242 struct Foo { field: u32 }
1243 fn foo(a$0: Foo) {}
1244 "#,
1245             expect![[r#"ty: Foo, name: ?"#]],
1246         );
1247         check_expected_type_and_name(
1248             r#"
1249 struct Foo { field: u32 }
1250 fn foo($0: Foo) {}
1251 "#,
1252             // FIXME make this work, currently fails due to pattern recovery eating the `:`
1253             expect![[r#"ty: ?, name: ?"#]],
1254         );
1255     }
1256 }