crates/ide_completion/src/context.rs

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