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_with_leading_char);
 392                         cov_mark::hit!(expected_type_fn_param_without_leading_char);
 393                         ActiveParameter::at_token(
 394                             &self.sema,
 395                             self.token.clone(),
 396                         ).map(|ap| {
 397                             let name = ap.ident().map(NameOrNameRef::Name);
 398                             (Some(ap.ty), name)
 399                         })
 400                         .unwrap_or((None, None))
 401                     },
 402                     ast::RecordExprFieldList(_it) => {
 403                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
 404                         // wouldn't try {} be nice...
 405                         (|| {
 406                             let expr_field = self.token.prev_sibling_or_token()?
 407                                       .into_node()
 408                                       .and_then(ast::RecordExprField::cast)?;
 409                             let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 410                             Some((
 411                                 Some(ty),
 412                                 expr_field.field_name().map(NameOrNameRef::NameRef),
 413                             ))
 414                         })().unwrap_or((None, None))
 415                     },
 416                     ast::RecordExprField(it) => {
 417                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 418                         (
 419                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)),
 420                             it.field_name().map(NameOrNameRef::NameRef),
 421                         )
 422                     },
 423                     ast::MatchExpr(it) => {
 424                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 425                         let ty = it.expr()
 426                             .and_then(|e| self.sema.type_of_expr(&e));
 427                         (ty, None)
 428                     },
 429                     ast::IfExpr(it) => {
 430                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 431                         let ty = it.condition()
 432                             .and_then(|cond| cond.expr())
 433                             .and_then(|e| self.sema.type_of_expr(&e));
 434                         (ty, None)
 435                     },
 436                     ast::IdentPat(it) => {
 437                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 438                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 439                         let ty = self.sema.type_of_pat(&ast::Pat::from(it));
 440                         (ty, None)
 441                     },
 442                     ast::Fn(it) => {
 443                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 444                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 445                         let def = self.sema.to_def(&it);
 446                         (def.map(|def| def.ret_type(self.db)), None)
 447                     },
 448                     ast::ClosureExpr(it) => {
 449                         let ty = self.sema.type_of_expr(&it.into());
 450                         ty.and_then(|ty| ty.as_callable(self.db))
 451                             .map(|c| (Some(c.return_type()), None))
 452                             .unwrap_or((None, None))
 453                     },
 454                     ast::Stmt(_it) => (None, None),
 455                     _ => {
 456                         match node.parent() {
 457                             Some(n) => {
 458                                 node = n;
 459                                 continue;
 460                             },
 461                             None => (None, None),
 462                         }
 463                     },
 464                 }
 465             };
 466         }
 467     }
 468
 469     fn fill(
 470         &mut self,
 471         original_file: &SyntaxNode,
 472         file_with_fake_ident: SyntaxNode,
 473         offset: TextSize,
 474     ) {
 475         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 476         let syntax_element = NodeOrToken::Token(fake_ident_token);
 477         self.previous_token = previous_token(syntax_element.clone());
 478         self.attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
 479         self.no_completion_required = {
 480             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 481             let fn_is_prev = self.previous_token_is(T![fn]);
 482             let for_is_prev2 = for_is_prev2(syntax_element.clone());
 483             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
 484         };
 485
 486         self.incomplete_let =
 487             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 488                 it.syntax().text_range().end() == syntax_element.text_range().end()
 489             });
 490
 491         let (expected_type, expected_name) = self.expected_type_and_name();
 492         self.expected_type = expected_type;
 493         self.expected_name = expected_name;
 494
 495         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 496             Some(it) => it,
 497             None => return,
 498         };
 499         self.completion_location =
 500             determine_location(&self.sema, original_file, offset, &name_like);
 501         self.prev_sibling = determine_prev_sibling(&name_like);
 502         match name_like {
 503             ast::NameLike::Lifetime(lifetime) => {
 504                 self.classify_lifetime(original_file, lifetime, offset);
 505             }
 506             ast::NameLike::NameRef(name_ref) => {
 507                 self.classify_name_ref(original_file, name_ref);
 508             }
 509             ast::NameLike::Name(name) => {
 510                 self.classify_name(name);
 511             }
 512         }
 513     }
 514
 515     fn classify_lifetime(
 516         &mut self,
 517         original_file: &SyntaxNode,
 518         lifetime: ast::Lifetime,
 519         offset: TextSize,
 520     ) {
 521         self.lifetime_syntax =
 522             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 523         if let Some(parent) = lifetime.syntax().parent() {
 524             if parent.kind() == ERROR {
 525                 return;
 526             }
 527
 528             match_ast! {
 529                 match parent {
 530                     ast::LifetimeParam(_it) => {
 531                         self.lifetime_allowed = true;
 532                         self.lifetime_param_syntax =
 533                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 534                     },
 535                     ast::BreakExpr(_it) => self.is_label_ref = true,
 536                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 537                     ast::Label(_it) => (),
 538                     _ => self.lifetime_allowed = true,
 539                 }
 540             }
 541         }
 542     }
 543
 544     fn classify_name(&mut self, name: ast::Name) {
 545         if let Some(bind_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
 546             self.is_pat_or_const = Some(PatternRefutability::Refutable);
 547             // if any of these is here our bind pat can't be a const pat anymore
 548             let complex_ident_pat = bind_pat.at_token().is_some()
 549                 || bind_pat.ref_token().is_some()
 550                 || bind_pat.mut_token().is_some();
 551             if complex_ident_pat {
 552                 self.is_pat_or_const = None;
 553             } else {
 554                 let irrefutable_pat = bind_pat.syntax().ancestors().find_map(|node| {
 555                     match_ast! {
 556                         match node {
 557                             ast::LetStmt(it) => Some(it.pat()),
 558                             ast::Param(it) => Some(it.pat()),
 559                             _ => None,
 560                         }
 561                     }
 562                 });
 563                 if let Some(Some(pat)) = irrefutable_pat {
 564                     // This check is here since we could be inside a pattern in the initializer expression of the let statement.
 565                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 566                         self.is_pat_or_const = Some(PatternRefutability::Irrefutable);
 567                     }
 568                 }
 569
 570                 let is_name_in_field_pat = bind_pat
 571                     .syntax()
 572                     .parent()
 573                     .and_then(ast::RecordPatField::cast)
 574                     .map_or(false, |pat_field| pat_field.name_ref().is_none());
 575                 if is_name_in_field_pat {
 576                     self.is_pat_or_const = None;
 577                 }
 578             }
 579
 580             self.fill_impl_def();
 581         }
 582
 583         self.is_param |= is_node::<ast::Param>(name.syntax());
 584     }
 585
 586     fn classify_name_ref(&mut self, original_file: &SyntaxNode, name_ref: ast::NameRef) {
 587         self.fill_impl_def();
 588
 589         self.name_ref_syntax =
 590             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 591
 592         self.function_def = self
 593             .sema
 594             .token_ancestors_with_macros(self.token.clone())
 595             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 596             .find_map(ast::Fn::cast);
 597
 598         let parent = match name_ref.syntax().parent() {
 599             Some(it) => it,
 600             None => return,
 601         };
 602
 603         if let Some(segment) = ast::PathSegment::cast(parent) {
 604             let path_ctx = self.path_context.get_or_insert(PathCompletionContext {
 605                 call_kind: None,
 606                 is_trivial_path: false,
 607                 qualifier: None,
 608                 has_type_args: false,
 609                 can_be_stmt: false,
 610                 in_loop_body: false,
 611                 use_tree_parent: false,
 612                 kind: None,
 613             });
 614             path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
 615             let path = segment.parent_path();
 616
 617             if let Some(p) = path.syntax().parent() {
 618                 path_ctx.call_kind = match_ast! {
 619                     match p {
 620                         ast::PathExpr(it) => it.syntax().parent().and_then(ast::CallExpr::cast).map(|_| CallKind::Expr),
 621                         ast::MacroCall(it) => it.excl_token().and(Some(CallKind::Mac)),
 622                         ast::TupleStructPat(_it) => Some(CallKind::Pat),
 623                         _ => None
 624                     }
 625                 };
 626             }
 627
 628             if let Some(parent) = path.syntax().parent() {
 629                 path_ctx.kind = match_ast! {
 630                     match parent {
 631                         ast::PathType(_it) => Some(PathKind::Type),
 632                         ast::PathExpr(_it) => Some(PathKind::Expr),
 633                         _ => None,
 634                     }
 635                 };
 636             }
 637             path_ctx.has_type_args = segment.generic_arg_list().is_some();
 638
 639             if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
 640                 path_ctx.use_tree_parent = use_tree_parent;
 641                 path_ctx.qualifier = path
 642                     .segment()
 643                     .and_then(|it| {
 644                         find_node_with_range::<ast::PathSegment>(
 645                             original_file,
 646                             it.syntax().text_range(),
 647                         )
 648                     })
 649                     .map(|it| it.parent_path());
 650                 return;
 651             }
 652
 653             if let Some(segment) = path.segment() {
 654                 if segment.coloncolon_token().is_some() {
 655                     return;
 656                 }
 657             }
 658
 659             path_ctx.is_trivial_path = true;
 660
 661             // Find either enclosing expr statement (thing with `;`) or a
 662             // block. If block, check that we are the last expr.
 663             path_ctx.can_be_stmt = name_ref
 664                 .syntax()
 665                 .ancestors()
 666                 .find_map(|node| {
 667                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 668                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 669                     }
 670                     if let Some(block) = ast::BlockExpr::cast(node) {
 671                         return Some(
 672                             block.tail_expr().map(|e| e.syntax().text_range())
 673                                 == Some(name_ref.syntax().text_range()),
 674                         );
 675                     }
 676                     None
 677                 })
 678                 .unwrap_or(false);
 679         }
 680     }
 681 }
 682
 683 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 684     syntax.covering_element(range).ancestors().find_map(N::cast)
 685 }
 686
 687 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 688     match node.ancestors().find_map(N::cast) {
 689         None => false,
 690         Some(n) => n.syntax().text_range() == node.text_range(),
 691     }
 692 }
 693
 694 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
 695     if let Some(qual) = path.qualifier() {
 696         return Some((qual, false));
 697     }
 698     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 699     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 700     use_tree.path().zip(Some(true))
 701 }
 702
 703 #[cfg(test)]
 704 mod tests {
 705     use expect_test::{expect, Expect};
 706     use hir::HirDisplay;
 707
 708     use crate::tests::{position, TEST_CONFIG};
 709
 710     use super::CompletionContext;
 711
 712     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 713         let (db, pos) = position(ra_fixture);
 714         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 715
 716         let ty = completion_context
 717             .expected_type
 718             .map(|t| t.display_test(&db).to_string())
 719             .unwrap_or("?".to_owned());
 720
 721         let name = completion_context
 722             .expected_name
 723             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 724
 725         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 726     }
 727
 728     #[test]
 729     fn expected_type_let_without_leading_char() {
 730         cov_mark::check!(expected_type_let_without_leading_char);
 731         check_expected_type_and_name(
 732             r#"
 733 fn foo() {
 734     let x: u32 = $0;
 735 }
 736 "#,
 737             expect![[r#"ty: u32, name: x"#]],
 738         );
 739     }
 740
 741     #[test]
 742     fn expected_type_let_with_leading_char() {
 743         cov_mark::check!(expected_type_let_with_leading_char);
 744         check_expected_type_and_name(
 745             r#"
 746 fn foo() {
 747     let x: u32 = c$0;
 748 }
 749 "#,
 750             expect![[r#"ty: u32, name: x"#]],
 751         );
 752     }
 753
 754     #[test]
 755     fn expected_type_let_pat() {
 756         check_expected_type_and_name(
 757             r#"
 758 fn foo() {
 759     let x$0 = 0u32;
 760 }
 761 "#,
 762             expect![[r#"ty: u32, name: ?"#]],
 763         );
 764         check_expected_type_and_name(
 765             r#"
 766 fn foo() {
 767     let $0 = 0u32;
 768 }
 769 "#,
 770             expect![[r#"ty: u32, name: ?"#]],
 771         );
 772     }
 773
 774     #[test]
 775     fn expected_type_fn_param_without_leading_char() {
 776         cov_mark::check!(expected_type_fn_param_without_leading_char);
 777         check_expected_type_and_name(
 778             r#"
 779 fn foo() {
 780     bar($0);
 781 }
 782
 783 fn bar(x: u32) {}
 784 "#,
 785             expect![[r#"ty: u32, name: x"#]],
 786         );
 787     }
 788
 789     #[test]
 790     fn expected_type_fn_param_with_leading_char() {
 791         cov_mark::check!(expected_type_fn_param_with_leading_char);
 792         check_expected_type_and_name(
 793             r#"
 794 fn foo() {
 795     bar(c$0);
 796 }
 797
 798 fn bar(x: u32) {}
 799 "#,
 800             expect![[r#"ty: u32, name: x"#]],
 801         );
 802     }
 803
 804     #[test]
 805     fn expected_type_struct_field_without_leading_char() {
 806         cov_mark::check!(expected_type_struct_field_without_leading_char);
 807         check_expected_type_and_name(
 808             r#"
 809 struct Foo { a: u32 }
 810 fn foo() {
 811     Foo { a: $0 };
 812 }
 813 "#,
 814             expect![[r#"ty: u32, name: a"#]],
 815         )
 816     }
 817
 818     #[test]
 819     fn expected_type_generic_struct_field() {
 820         check_expected_type_and_name(
 821             r#"
 822 struct Foo<T> { a: T }
 823 fn foo() -> Foo<u32> {
 824     Foo { a: $0 }
 825 }
 826 "#,
 827             expect![[r#"ty: u32, name: a"#]],
 828         )
 829     }
 830
 831     #[test]
 832     fn expected_type_struct_field_with_leading_char() {
 833         cov_mark::check!(expected_type_struct_field_with_leading_char);
 834         check_expected_type_and_name(
 835             r#"
 836 struct Foo { a: u32 }
 837 fn foo() {
 838     Foo { a: c$0 };
 839 }
 840 "#,
 841             expect![[r#"ty: u32, name: a"#]],
 842         );
 843     }
 844
 845     #[test]
 846     fn expected_type_match_arm_without_leading_char() {
 847         cov_mark::check!(expected_type_match_arm_without_leading_char);
 848         check_expected_type_and_name(
 849             r#"
 850 enum E { X }
 851 fn foo() {
 852    match E::X { $0 }
 853 }
 854 "#,
 855             expect![[r#"ty: E, name: ?"#]],
 856         );
 857     }
 858
 859     #[test]
 860     fn expected_type_match_arm_with_leading_char() {
 861         cov_mark::check!(expected_type_match_arm_with_leading_char);
 862         check_expected_type_and_name(
 863             r#"
 864 enum E { X }
 865 fn foo() {
 866    match E::X { c$0 }
 867 }
 868 "#,
 869             expect![[r#"ty: E, name: ?"#]],
 870         );
 871     }
 872
 873     #[test]
 874     fn expected_type_if_let_without_leading_char() {
 875         cov_mark::check!(expected_type_if_let_without_leading_char);
 876         check_expected_type_and_name(
 877             r#"
 878 enum Foo { Bar, Baz, Quux }
 879
 880 fn foo() {
 881     let f = Foo::Quux;
 882     if let $0 = f { }
 883 }
 884 "#,
 885             expect![[r#"ty: Foo, name: ?"#]],
 886         )
 887     }
 888
 889     #[test]
 890     fn expected_type_if_let_with_leading_char() {
 891         cov_mark::check!(expected_type_if_let_with_leading_char);
 892         check_expected_type_and_name(
 893             r#"
 894 enum Foo { Bar, Baz, Quux }
 895
 896 fn foo() {
 897     let f = Foo::Quux;
 898     if let c$0 = f { }
 899 }
 900 "#,
 901             expect![[r#"ty: Foo, name: ?"#]],
 902         )
 903     }
 904
 905     #[test]
 906     fn expected_type_fn_ret_without_leading_char() {
 907         cov_mark::check!(expected_type_fn_ret_without_leading_char);
 908         check_expected_type_and_name(
 909             r#"
 910 fn foo() -> u32 {
 911     $0
 912 }
 913 "#,
 914             expect![[r#"ty: u32, name: ?"#]],
 915         )
 916     }
 917
 918     #[test]
 919     fn expected_type_fn_ret_with_leading_char() {
 920         cov_mark::check!(expected_type_fn_ret_with_leading_char);
 921         check_expected_type_and_name(
 922             r#"
 923 fn foo() -> u32 {
 924     c$0
 925 }
 926 "#,
 927             expect![[r#"ty: u32, name: ?"#]],
 928         )
 929     }
 930
 931     #[test]
 932     fn expected_type_fn_ret_fn_ref_fully_typed() {
 933         check_expected_type_and_name(
 934             r#"
 935 fn foo() -> u32 {
 936     foo$0
 937 }
 938 "#,
 939             expect![[r#"ty: u32, name: ?"#]],
 940         )
 941     }
 942
 943     #[test]
 944     fn expected_type_closure_param_return() {
 945         // FIXME: make this work with `|| $0`
 946         check_expected_type_and_name(
 947             r#"
 948 //- minicore: fn
 949 fn foo() {
 950     bar(|| a$0);
 951 }
 952
 953 fn bar(f: impl FnOnce() -> u32) {}
 954 "#,
 955             expect![[r#"ty: u32, name: ?"#]],
 956         );
 957     }
 958
 959     #[test]
 960     fn expected_type_generic_function() {
 961         check_expected_type_and_name(
 962             r#"
 963 fn foo() {
 964     bar::<u32>($0);
 965 }
 966
 967 fn bar<T>(t: T) {}
 968 "#,
 969             expect![[r#"ty: u32, name: t"#]],
 970         );
 971     }
 972
 973     #[test]
 974     fn expected_type_generic_method() {
 975         check_expected_type_and_name(
 976             r#"
 977 fn foo() {
 978     S(1u32).bar($0);
 979 }
 980
 981 struct S<T>(T);
 982 impl<T> S<T> {
 983     fn bar(self, t: T) {}
 984 }
 985 "#,
 986             expect![[r#"ty: u32, name: t"#]],
 987         );
 988     }
 989 }