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