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