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