crates/ide_completion/src/context.rs

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