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         for_is_prev2, has_bind_pat_parent, has_block_expr_parent, has_field_list_parent,
  21         has_impl_parent, has_item_list_or_source_file_parent, has_prev_sibling, has_ref_parent,
  22         has_trait_parent, inside_impl_trait_block, is_in_loop_body, is_match_arm, previous_token,
  23     },
  24     CompletionConfig,
  25 };
  26
  27 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  28 pub(crate) enum PatternRefutability {
  29     Refutable,
  30     Irrefutable,
  31 }
  32
  33 /// Direct parent container of the cursor position
  34 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  35 pub(crate) enum ImmediateLocation {
  36     Impl,
  37     Trait,
  38     RecordFieldList,
  39     RefPatOrExpr,
  40     IdentPat,
  41     BlockExpr,
  42     ItemList,
  43 }
  44
  45 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  46 pub(crate) enum PrevSibling {
  47     Trait,
  48     Impl,
  49 }
  50
  51 /// `CompletionContext` is created early during completion to figure out, where
  52 /// exactly is the cursor, syntax-wise.
  53 #[derive(Debug)]
  54 pub(crate) struct CompletionContext<'a> {
  55     pub(super) sema: Semantics<'a, RootDatabase>,
  56     pub(super) scope: SemanticsScope<'a>,
  57     pub(super) db: &'a RootDatabase,
  58     pub(super) config: &'a CompletionConfig,
  59     pub(super) position: FilePosition,
  60     /// The token before the cursor, in the original file.
  61     pub(super) original_token: SyntaxToken,
  62     /// The token before the cursor, in the macro-expanded file.
  63     pub(super) token: SyntaxToken,
  64     pub(super) krate: Option<hir::Crate>,
  65     pub(super) expected_name: Option<NameOrNameRef>,
  66     pub(super) expected_type: Option<Type>,
  67     pub(super) name_ref_syntax: Option<ast::NameRef>,
  68
  69     pub(super) use_item_syntax: Option<ast::Use>,
  70
  71     /// The parent function of the cursor position if it exists.
  72     pub(super) function_def: Option<ast::Fn>,
  73     /// The parent impl of the cursor position if it exists.
  74     pub(super) impl_def: Option<ast::Impl>,
  75
  76     /// RecordExpr the token is a field of
  77     pub(super) record_lit_syntax: Option<ast::RecordExpr>,
  78     /// RecordPat the token is a field of
  79     pub(super) record_pat_syntax: Option<ast::RecordPat>,
  80
  81     // potentially set if we are completing a lifetime
  82     pub(super) lifetime_syntax: Option<ast::Lifetime>,
  83     pub(super) lifetime_param_syntax: Option<ast::LifetimeParam>,
  84     pub(super) lifetime_allowed: bool,
  85     pub(super) is_label_ref: bool,
  86
  87     // potentially set if we are completing a name
  88     pub(super) is_pat_or_const: Option<PatternRefutability>,
  89     pub(super) is_param: bool,
  90
  91     pub(super) completion_location: Option<ImmediateLocation>,
  92
  93     /// FIXME: `ActiveParameter` is string-based, which is very very wrong
  94     pub(super) active_parameter: Option<ActiveParameter>,
  95     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  96     pub(super) is_trivial_path: bool,
  97     /// If not a trivial path, the prefix (qualifier).
  98     pub(super) path_qual: Option<ast::Path>,
  99     pub(super) after_if: bool,
 100     /// `true` if we are a statement or a last expr in the block.
 101     pub(super) can_be_stmt: bool,
 102     /// `true` if we expect an expression at the cursor position.
 103     pub(super) is_expr: bool,
 104     /// Something is typed at the "top" level, in module or impl/trait.
 105     pub(super) is_new_item: bool,
 106     /// The receiver if this is a field or method access, i.e. writing something.$0
 107     pub(super) dot_receiver: Option<ast::Expr>,
 108     pub(super) dot_receiver_is_ambiguous_float_literal: bool,
 109     /// If this is a call (method or function) in particular, i.e. the () are already there.
 110     pub(super) is_call: bool,
 111     /// Like `is_call`, but for tuple patterns.
 112     pub(super) is_pattern_call: bool,
 113     /// If this is a macro call, i.e. the () are already there.
 114     pub(super) is_macro_call: bool,
 115     pub(super) is_path_type: bool,
 116     pub(super) has_type_args: bool,
 117     pub(super) attribute_under_caret: Option<ast::Attr>,
 118     pub(super) mod_declaration_under_caret: Option<ast::Module>,
 119     pub(super) locals: Vec<(String, Local)>,
 120
 121     // keyword patterns
 122     pub(super) previous_token: Option<SyntaxToken>,
 123     pub(super) prev_sibling: Option<PrevSibling>,
 124     pub(super) in_loop_body: bool,
 125     pub(super) is_match_arm: bool,
 126     pub(super) incomplete_let: bool,
 127
 128     no_completion_required: bool,
 129 }
 130 impl<'a> CompletionContext<'a> {
 131     pub(super) fn new(
 132         db: &'a RootDatabase,
 133         position: FilePosition,
 134         config: &'a CompletionConfig,
 135     ) -> Option<CompletionContext<'a>> {
 136         let sema = Semantics::new(db);
 137
 138         let original_file = sema.parse(position.file_id);
 139
 140         // Insert a fake ident to get a valid parse tree. We will use this file
 141         // to determine context, though the original_file will be used for
 142         // actual completion.
 143         let file_with_fake_ident = {
 144             let parse = db.parse(position.file_id);
 145             let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
 146             parse.reparse(&edit).tree()
 147         };
 148         let fake_ident_token =
 149             file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 150
 151         let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
 152         let original_token =
 153             original_file.syntax().token_at_offset(position.offset).left_biased()?;
 154         let token = sema.descend_into_macros(original_token.clone());
 155         let scope = sema.scope_at_offset(&token, position.offset);
 156         let mut locals = vec![];
 157         scope.process_all_names(&mut |name, scope| {
 158             if let ScopeDef::Local(local) = scope {
 159                 locals.push((name.to_string(), local));
 160             }
 161         });
 162         let mut ctx = CompletionContext {
 163             sema,
 164             scope,
 165             db,
 166             config,
 167             position,
 168             original_token,
 169             token,
 170             krate,
 171             lifetime_allowed: false,
 172             expected_name: None,
 173             expected_type: None,
 174             name_ref_syntax: None,
 175             lifetime_syntax: None,
 176             lifetime_param_syntax: None,
 177             function_def: None,
 178             use_item_syntax: None,
 179             record_lit_syntax: None,
 180             record_pat_syntax: None,
 181             impl_def: None,
 182             active_parameter: ActiveParameter::at(db, position),
 183             is_label_ref: false,
 184             is_param: false,
 185             is_pat_or_const: None,
 186             is_trivial_path: false,
 187             path_qual: None,
 188             after_if: false,
 189             can_be_stmt: false,
 190             is_expr: false,
 191             is_new_item: false,
 192             dot_receiver: None,
 193             dot_receiver_is_ambiguous_float_literal: false,
 194             is_call: false,
 195             is_pattern_call: false,
 196             is_macro_call: false,
 197             is_path_type: false,
 198             has_type_args: false,
 199             attribute_under_caret: None,
 200             mod_declaration_under_caret: None,
 201             previous_token: None,
 202             in_loop_body: false,
 203             completion_location: None,
 204             prev_sibling: None,
 205             is_match_arm: false,
 206             no_completion_required: false,
 207             incomplete_let: false,
 208             locals,
 209         };
 210
 211         let mut original_file = original_file.syntax().clone();
 212         let mut speculative_file = file_with_fake_ident.syntax().clone();
 213         let mut offset = position.offset;
 214         let mut fake_ident_token = fake_ident_token;
 215
 216         // Are we inside a macro call?
 217         while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 218             find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 219             find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 220         ) {
 221             if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
 222                 != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
 223             {
 224                 break;
 225             }
 226             let speculative_args = match macro_call_with_fake_ident.token_tree() {
 227                 Some(tt) => tt,
 228                 None => break,
 229             };
 230             if let (Some(actual_expansion), Some(speculative_expansion)) = (
 231                 ctx.sema.expand(&actual_macro_call),
 232                 ctx.sema.speculative_expand(
 233                     &actual_macro_call,
 234                     &speculative_args,
 235                     fake_ident_token,
 236                 ),
 237             ) {
 238                 let new_offset = speculative_expansion.1.text_range().start();
 239                 if new_offset > actual_expansion.text_range().end() {
 240                     break;
 241                 }
 242                 original_file = actual_expansion;
 243                 speculative_file = speculative_expansion.0;
 244                 fake_ident_token = speculative_expansion.1;
 245                 offset = new_offset;
 246             } else {
 247                 break;
 248             }
 249         }
 250         ctx.fill_keyword_patterns(&speculative_file, offset);
 251         ctx.fill(&original_file, speculative_file, offset);
 252         Some(ctx)
 253     }
 254
 255     /// Checks whether completions in that particular case don't make much sense.
 256     /// Examples:
 257     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 258     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 259     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 260     pub(crate) fn no_completion_required(&self) -> bool {
 261         self.no_completion_required
 262     }
 263
 264     /// The range of the identifier that is being completed.
 265     pub(crate) fn source_range(&self) -> TextRange {
 266         // check kind of macro-expanded token, but use range of original token
 267         let kind = self.token.kind();
 268         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 269             cov_mark::hit!(completes_if_prefix_is_keyword);
 270             self.original_token.text_range()
 271         } else if kind == CHAR {
 272             // assume we are completing a lifetime but the user has only typed the '
 273             cov_mark::hit!(completes_if_lifetime_without_idents);
 274             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 275         } else {
 276             TextRange::empty(self.position.offset)
 277         }
 278     }
 279
 280     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 281         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 282     }
 283
 284     pub(crate) fn has_impl_or_trait_parent(&self) -> bool {
 285         matches!(
 286             self.completion_location,
 287             Some(ImmediateLocation::Trait) | Some(ImmediateLocation::Impl)
 288         )
 289     }
 290
 291     pub(crate) fn has_block_expr_parent(&self) -> bool {
 292         matches!(self.completion_location, Some(ImmediateLocation::BlockExpr))
 293     }
 294
 295     pub(crate) fn has_item_list_parent(&self) -> bool {
 296         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 297     }
 298
 299     pub(crate) fn has_ident_or_ref_pat_parent(&self) -> bool {
 300         matches!(
 301             self.completion_location,
 302             Some(ImmediateLocation::IdentPat) | Some(ImmediateLocation::RefPatOrExpr)
 303         )
 304     }
 305
 306     pub(crate) fn has_impl_parent(&self) -> bool {
 307         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 308     }
 309
 310     pub(crate) fn has_field_list_parent(&self) -> bool {
 311         matches!(self.completion_location, Some(ImmediateLocation::RecordFieldList))
 312     }
 313
 314     pub(crate) fn has_impl_or_trait_prev_sibling(&self) -> bool {
 315         self.prev_sibling.is_some()
 316     }
 317
 318     pub(crate) fn is_path_disallowed(&self) -> bool {
 319         self.record_lit_syntax.is_some()
 320             || self.record_pat_syntax.is_some()
 321             || self.attribute_under_caret.is_some()
 322             || self.mod_declaration_under_caret.is_some()
 323             || self.has_impl_or_trait_parent()
 324     }
 325
 326     fn fill_keyword_patterns(&mut self, file_with_fake_ident: &SyntaxNode, offset: TextSize) {
 327         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 328         let syntax_element = NodeOrToken::Token(fake_ident_token);
 329         self.previous_token = previous_token(syntax_element.clone());
 330         self.in_loop_body = is_in_loop_body(syntax_element.clone());
 331         self.is_match_arm = is_match_arm(syntax_element.clone());
 332         if has_prev_sibling(syntax_element.clone(), IMPL) {
 333             self.prev_sibling = Some(PrevSibling::Impl)
 334         } else if has_prev_sibling(syntax_element.clone(), TRAIT) {
 335             self.prev_sibling = Some(PrevSibling::Trait)
 336         }
 337
 338         if has_block_expr_parent(syntax_element.clone()) {
 339             self.completion_location = Some(ImmediateLocation::BlockExpr);
 340         } else if has_bind_pat_parent(syntax_element.clone()) {
 341             self.completion_location = Some(ImmediateLocation::IdentPat);
 342         } else if has_ref_parent(syntax_element.clone()) {
 343             self.completion_location = Some(ImmediateLocation::RefPatOrExpr);
 344         } else if has_impl_parent(syntax_element.clone()) {
 345             self.completion_location = Some(ImmediateLocation::Impl);
 346         } else if has_field_list_parent(syntax_element.clone()) {
 347             self.completion_location = Some(ImmediateLocation::RecordFieldList);
 348         } else if has_trait_parent(syntax_element.clone()) {
 349             self.completion_location = Some(ImmediateLocation::Trait);
 350         } else if has_item_list_or_source_file_parent(syntax_element.clone()) {
 351             self.completion_location = Some(ImmediateLocation::ItemList);
 352         }
 353
 354         self.mod_declaration_under_caret =
 355             find_node_at_offset::<ast::Module>(&file_with_fake_ident, offset)
 356                 .filter(|module| module.item_list().is_none());
 357         self.incomplete_let =
 358             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 359                 it.syntax().text_range().end() == syntax_element.text_range().end()
 360             });
 361
 362         let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 363         let fn_is_prev = self.previous_token_is(T![fn]);
 364         let for_is_prev2 = for_is_prev2(syntax_element.clone());
 365         self.no_completion_required = (fn_is_prev && !inside_impl_trait_block) || for_is_prev2;
 366     }
 367
 368     fn fill_impl_def(&mut self) {
 369         self.impl_def = self
 370             .sema
 371             .token_ancestors_with_macros(self.token.clone())
 372             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 373             .find_map(ast::Impl::cast);
 374     }
 375
 376     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 377         let mut node = match self.token.parent() {
 378             Some(it) => it,
 379             None => return (None, None),
 380         };
 381         loop {
 382             break match_ast! {
 383                 match node {
 384                     ast::LetStmt(it) => {
 385                         cov_mark::hit!(expected_type_let_with_leading_char);
 386                         cov_mark::hit!(expected_type_let_without_leading_char);
 387                         let ty = it.pat()
 388                             .and_then(|pat| self.sema.type_of_pat(&pat))
 389                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)));
 390                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 391                             ident.name().map(NameOrNameRef::Name)
 392                         } else {
 393                             None
 394                         };
 395
 396                         (ty, name)
 397                     },
 398                     ast::ArgList(_it) => {
 399                         cov_mark::hit!(expected_type_fn_param_with_leading_char);
 400                         cov_mark::hit!(expected_type_fn_param_without_leading_char);
 401                         ActiveParameter::at_token(
 402                             &self.sema,
 403                             self.token.clone(),
 404                         ).map(|ap| {
 405                             let name = ap.ident().map(NameOrNameRef::Name);
 406                             (Some(ap.ty), name)
 407                         })
 408                         .unwrap_or((None, None))
 409                     },
 410                     ast::RecordExprFieldList(_it) => {
 411                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
 412                         // wouldn't try {} be nice...
 413                         (|| {
 414                             let expr_field = self.token.prev_sibling_or_token()?
 415                                       .into_node()
 416                                       .and_then(|node| ast::RecordExprField::cast(node))?;
 417                             let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 418                             Some((
 419                                 Some(ty),
 420                                 expr_field.field_name().map(NameOrNameRef::NameRef),
 421                             ))
 422                         })().unwrap_or((None, None))
 423                     },
 424                     ast::RecordExprField(it) => {
 425                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 426                         (
 427                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)),
 428                             it.field_name().map(NameOrNameRef::NameRef),
 429                         )
 430                     },
 431                     ast::MatchExpr(it) => {
 432                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 433                         let ty = it.expr()
 434                             .and_then(|e| self.sema.type_of_expr(&e));
 435                         (ty, None)
 436                     },
 437                     ast::IfExpr(it) => {
 438                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 439                         let ty = it.condition()
 440                             .and_then(|cond| cond.expr())
 441                             .and_then(|e| self.sema.type_of_expr(&e));
 442                         (ty, None)
 443                     },
 444                     ast::IdentPat(it) => {
 445                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 446                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 447                         let ty = self.sema.type_of_pat(&ast::Pat::from(it));
 448                         (ty, None)
 449                     },
 450                     ast::Fn(it) => {
 451                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 452                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 453                         let def = self.sema.to_def(&it);
 454                         (def.map(|def| def.ret_type(self.db)), None)
 455                     },
 456                     ast::ClosureExpr(it) => {
 457                         let ty = self.sema.type_of_expr(&it.into());
 458                         ty.and_then(|ty| ty.as_callable(self.db))
 459                             .map(|c| (Some(c.return_type()), None))
 460                             .unwrap_or((None, None))
 461                     },
 462                     ast::Stmt(_it) => (None, None),
 463                     _ => {
 464                         match node.parent() {
 465                             Some(n) => {
 466                                 node = n;
 467                                 continue;
 468                             },
 469                             None => (None, None),
 470                         }
 471                     },
 472                 }
 473             };
 474         }
 475     }
 476
 477     fn fill(
 478         &mut self,
 479         original_file: &SyntaxNode,
 480         file_with_fake_ident: SyntaxNode,
 481         offset: TextSize,
 482     ) {
 483         let (expected_type, expected_name) = self.expected_type_and_name();
 484         self.expected_type = expected_type;
 485         self.expected_name = expected_name;
 486         self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);
 487         let name_like = match find_node_at_offset(&&file_with_fake_ident, offset) {
 488             Some(it) => it,
 489             None => return,
 490         };
 491         match name_like {
 492             ast::NameLike::Lifetime(lifetime) => {
 493                 self.classify_lifetime(original_file, lifetime, offset);
 494             }
 495             ast::NameLike::NameRef(name_ref) => {
 496                 self.classify_name_ref(original_file, name_ref, offset);
 497             }
 498             ast::NameLike::Name(name) => {
 499                 self.classify_name(original_file, name, offset);
 500             }
 501         }
 502     }
 503
 504     fn classify_lifetime(
 505         &mut self,
 506         original_file: &SyntaxNode,
 507         lifetime: ast::Lifetime,
 508         offset: TextSize,
 509     ) {
 510         self.lifetime_syntax =
 511             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 512         if let Some(parent) = lifetime.syntax().parent() {
 513             if parent.kind() == ERROR {
 514                 return;
 515             }
 516
 517             match_ast! {
 518                 match parent {
 519                     ast::LifetimeParam(_it) => {
 520                         self.lifetime_allowed = true;
 521                         self.lifetime_param_syntax =
 522                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 523                     },
 524                     ast::BreakExpr(_it) => self.is_label_ref = true,
 525                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 526                     ast::Label(_it) => (),
 527                     _ => self.lifetime_allowed = true,
 528                 }
 529             }
 530         }
 531     }
 532
 533     fn classify_name(&mut self, original_file: &SyntaxNode, name: ast::Name, offset: TextSize) {
 534         if let Some(bind_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
 535             self.is_pat_or_const = Some(PatternRefutability::Refutable);
 536             // if any of these is here our bind pat can't be a const pat anymore
 537             let complex_ident_pat = bind_pat.at_token().is_some()
 538                 || bind_pat.ref_token().is_some()
 539                 || bind_pat.mut_token().is_some();
 540             if complex_ident_pat {
 541                 self.is_pat_or_const = None;
 542             } else {
 543                 let irrefutable_pat = bind_pat.syntax().ancestors().find_map(|node| {
 544                     match_ast! {
 545                         match node {
 546                             ast::LetStmt(it) => Some(it.pat()),
 547                             ast::Param(it) => Some(it.pat()),
 548                             _ => None,
 549                         }
 550                     }
 551                 });
 552                 if let Some(Some(pat)) = irrefutable_pat {
 553                     // This check is here since we could be inside a pattern in the initializer expression of the let statement.
 554                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 555                         self.is_pat_or_const = Some(PatternRefutability::Irrefutable);
 556                     }
 557                 }
 558
 559                 let is_name_in_field_pat = bind_pat
 560                     .syntax()
 561                     .parent()
 562                     .and_then(ast::RecordPatField::cast)
 563                     .map_or(false, |pat_field| pat_field.name_ref().is_none());
 564                 if is_name_in_field_pat {
 565                     self.is_pat_or_const = None;
 566                 }
 567             }
 568
 569             self.fill_impl_def();
 570         }
 571         self.is_param |= is_node::<ast::Param>(name.syntax());
 572         if ast::RecordPatField::for_field_name(&name).is_some() {
 573             self.record_pat_syntax =
 574                 self.sema.find_node_at_offset_with_macros(&original_file, offset);
 575         }
 576     }
 577
 578     fn classify_name_ref(
 579         &mut self,
 580         original_file: &SyntaxNode,
 581         name_ref: ast::NameRef,
 582         offset: TextSize,
 583     ) {
 584         self.fill_impl_def();
 585         if ast::RecordExprField::for_field_name(&name_ref).is_some() {
 586             self.record_lit_syntax =
 587                 self.sema.find_node_at_offset_with_macros(original_file, offset);
 588         }
 589         if ast::RecordPatField::for_field_name_ref(&name_ref).is_some() {
 590             self.record_pat_syntax =
 591                 self.sema.find_node_at_offset_with_macros(&original_file, offset);
 592         }
 593
 594         self.name_ref_syntax =
 595             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 596
 597         let name_range = name_ref.syntax().text_range();
 598         let top_node = name_ref
 599             .syntax()
 600             .ancestors()
 601             .take_while(|it| it.text_range() == name_range)
 602             .last()
 603             .unwrap();
 604
 605         if matches!(top_node.parent().map(|it| it.kind()), Some(SOURCE_FILE) | Some(ITEM_LIST)) {
 606             self.is_new_item = true;
 607             return;
 608         }
 609
 610         self.use_item_syntax =
 611             self.sema.token_ancestors_with_macros(self.token.clone()).find_map(ast::Use::cast);
 612
 613         self.function_def = self
 614             .sema
 615             .token_ancestors_with_macros(self.token.clone())
 616             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 617             .find_map(ast::Fn::cast);
 618
 619         let parent = match name_ref.syntax().parent() {
 620             Some(it) => it,
 621             None => return,
 622         };
 623
 624         if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
 625             let path = segment.parent_path();
 626             self.is_call = path
 627                 .syntax()
 628                 .parent()
 629                 .and_then(ast::PathExpr::cast)
 630                 .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
 631                 .is_some();
 632             self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();
 633             self.is_pattern_call =
 634                 path.syntax().parent().and_then(ast::TupleStructPat::cast).is_some();
 635
 636             self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
 637             self.has_type_args = segment.generic_arg_list().is_some();
 638
 639             if let Some(path) = path_or_use_tree_qualifier(&path) {
 640                 self.path_qual = path
 641                     .segment()
 642                     .and_then(|it| {
 643                         find_node_with_range::<ast::PathSegment>(
 644                             original_file,
 645                             it.syntax().text_range(),
 646                         )
 647                     })
 648                     .map(|it| it.parent_path());
 649                 return;
 650             }
 651
 652             if let Some(segment) = path.segment() {
 653                 if segment.coloncolon_token().is_some() {
 654                     return;
 655                 }
 656             }
 657
 658             self.is_trivial_path = true;
 659
 660             // Find either enclosing expr statement (thing with `;`) or a
 661             // block. If block, check that we are the last expr.
 662             self.can_be_stmt = name_ref
 663                 .syntax()
 664                 .ancestors()
 665                 .find_map(|node| {
 666                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 667                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 668                     }
 669                     if let Some(block) = ast::BlockExpr::cast(node) {
 670                         return Some(
 671                             block.tail_expr().map(|e| e.syntax().text_range())
 672                                 == Some(name_ref.syntax().text_range()),
 673                         );
 674                     }
 675                     None
 676                 })
 677                 .unwrap_or(false);
 678             self.is_expr = path.syntax().parent().and_then(ast::PathExpr::cast).is_some();
 679
 680             if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
 681                 if let Some(if_expr) =
 682                     self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
 683                 {
 684                     if if_expr.syntax().text_range().end() < name_ref.syntax().text_range().start()
 685                     {
 686                         self.after_if = true;
 687                     }
 688                 }
 689             }
 690         }
 691
 692         if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
 693             // The receiver comes before the point of insertion of the fake
 694             // ident, so it should have the same range in the non-modified file
 695             self.dot_receiver = field_expr
 696                 .expr()
 697                 .map(|e| e.syntax().text_range())
 698                 .and_then(|r| find_node_with_range(original_file, r));
 699             self.dot_receiver_is_ambiguous_float_literal =
 700                 if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
 701                     match l.kind() {
 702                         ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
 703                         _ => false,
 704                     }
 705                 } else {
 706                     false
 707                 };
 708         }
 709
 710         if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
 711             // As above
 712             self.dot_receiver = method_call_expr
 713                 .receiver()
 714                 .map(|e| e.syntax().text_range())
 715                 .and_then(|r| find_node_with_range(original_file, r));
 716             self.is_call = true;
 717         }
 718     }
 719 }
 720
 721 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 722     syntax.covering_element(range).ancestors().find_map(N::cast)
 723 }
 724
 725 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 726     match node.ancestors().find_map(N::cast) {
 727         None => false,
 728         Some(n) => n.syntax().text_range() == node.text_range(),
 729     }
 730 }
 731
 732 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<ast::Path> {
 733     if let Some(qual) = path.qualifier() {
 734         return Some(qual);
 735     }
 736     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 737     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 738     use_tree.path()
 739 }
 740
 741 #[cfg(test)]
 742 mod tests {
 743     use expect_test::{expect, Expect};
 744     use hir::HirDisplay;
 745
 746     use crate::test_utils::{position, TEST_CONFIG};
 747
 748     use super::CompletionContext;
 749
 750     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 751         let (db, pos) = position(ra_fixture);
 752         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 753
 754         let ty = completion_context
 755             .expected_type
 756             .map(|t| t.display_test(&db).to_string())
 757             .unwrap_or("?".to_owned());
 758
 759         let name = completion_context
 760             .expected_name
 761             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 762
 763         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 764     }
 765
 766     #[test]
 767     fn expected_type_let_without_leading_char() {
 768         cov_mark::check!(expected_type_let_without_leading_char);
 769         check_expected_type_and_name(
 770             r#"
 771 fn foo() {
 772     let x: u32 = $0;
 773 }
 774 "#,
 775             expect![[r#"ty: u32, name: x"#]],
 776         );
 777     }
 778
 779     #[test]
 780     fn expected_type_let_with_leading_char() {
 781         cov_mark::check!(expected_type_let_with_leading_char);
 782         check_expected_type_and_name(
 783             r#"
 784 fn foo() {
 785     let x: u32 = c$0;
 786 }
 787 "#,
 788             expect![[r#"ty: u32, name: x"#]],
 789         );
 790     }
 791
 792     #[test]
 793     fn expected_type_let_pat() {
 794         check_expected_type_and_name(
 795             r#"
 796 fn foo() {
 797     let x$0 = 0u32;
 798 }
 799 "#,
 800             expect![[r#"ty: u32, name: ?"#]],
 801         );
 802         check_expected_type_and_name(
 803             r#"
 804 fn foo() {
 805     let $0 = 0u32;
 806 }
 807 "#,
 808             expect![[r#"ty: u32, name: ?"#]],
 809         );
 810     }
 811
 812     #[test]
 813     fn expected_type_fn_param_without_leading_char() {
 814         cov_mark::check!(expected_type_fn_param_without_leading_char);
 815         check_expected_type_and_name(
 816             r#"
 817 fn foo() {
 818     bar($0);
 819 }
 820
 821 fn bar(x: u32) {}
 822 "#,
 823             expect![[r#"ty: u32, name: x"#]],
 824         );
 825     }
 826
 827     #[test]
 828     fn expected_type_fn_param_with_leading_char() {
 829         cov_mark::check!(expected_type_fn_param_with_leading_char);
 830         check_expected_type_and_name(
 831             r#"
 832 fn foo() {
 833     bar(c$0);
 834 }
 835
 836 fn bar(x: u32) {}
 837 "#,
 838             expect![[r#"ty: u32, name: x"#]],
 839         );
 840     }
 841
 842     #[test]
 843     fn expected_type_struct_field_without_leading_char() {
 844         cov_mark::check!(expected_type_struct_field_without_leading_char);
 845         check_expected_type_and_name(
 846             r#"
 847 struct Foo { a: u32 }
 848 fn foo() {
 849     Foo { a: $0 };
 850 }
 851 "#,
 852             expect![[r#"ty: u32, name: a"#]],
 853         )
 854     }
 855
 856     #[test]
 857     fn expected_type_generic_struct_field() {
 858         check_expected_type_and_name(
 859             r#"
 860 struct Foo<T> { a: T }
 861 fn foo() -> Foo<u32> {
 862     Foo { a: $0 }
 863 }
 864 "#,
 865             expect![[r#"ty: u32, name: a"#]],
 866         )
 867     }
 868
 869     #[test]
 870     fn expected_type_struct_field_with_leading_char() {
 871         cov_mark::check!(expected_type_struct_field_with_leading_char);
 872         check_expected_type_and_name(
 873             r#"
 874 struct Foo { a: u32 }
 875 fn foo() {
 876     Foo { a: c$0 };
 877 }
 878 "#,
 879             expect![[r#"ty: u32, name: a"#]],
 880         );
 881     }
 882
 883     #[test]
 884     fn expected_type_match_arm_without_leading_char() {
 885         cov_mark::check!(expected_type_match_arm_without_leading_char);
 886         check_expected_type_and_name(
 887             r#"
 888 enum E { X }
 889 fn foo() {
 890    match E::X { $0 }
 891 }
 892 "#,
 893             expect![[r#"ty: E, name: ?"#]],
 894         );
 895     }
 896
 897     #[test]
 898     fn expected_type_match_arm_with_leading_char() {
 899         cov_mark::check!(expected_type_match_arm_with_leading_char);
 900         check_expected_type_and_name(
 901             r#"
 902 enum E { X }
 903 fn foo() {
 904    match E::X { c$0 }
 905 }
 906 "#,
 907             expect![[r#"ty: E, name: ?"#]],
 908         );
 909     }
 910
 911     #[test]
 912     fn expected_type_if_let_without_leading_char() {
 913         cov_mark::check!(expected_type_if_let_without_leading_char);
 914         check_expected_type_and_name(
 915             r#"
 916 enum Foo { Bar, Baz, Quux }
 917
 918 fn foo() {
 919     let f = Foo::Quux;
 920     if let $0 = f { }
 921 }
 922 "#,
 923             expect![[r#"ty: Foo, name: ?"#]],
 924         )
 925     }
 926
 927     #[test]
 928     fn expected_type_if_let_with_leading_char() {
 929         cov_mark::check!(expected_type_if_let_with_leading_char);
 930         check_expected_type_and_name(
 931             r#"
 932 enum Foo { Bar, Baz, Quux }
 933
 934 fn foo() {
 935     let f = Foo::Quux;
 936     if let c$0 = f { }
 937 }
 938 "#,
 939             expect![[r#"ty: Foo, name: ?"#]],
 940         )
 941     }
 942
 943     #[test]
 944     fn expected_type_fn_ret_without_leading_char() {
 945         cov_mark::check!(expected_type_fn_ret_without_leading_char);
 946         check_expected_type_and_name(
 947             r#"
 948 fn foo() -> u32 {
 949     $0
 950 }
 951 "#,
 952             expect![[r#"ty: u32, name: ?"#]],
 953         )
 954     }
 955
 956     #[test]
 957     fn expected_type_fn_ret_with_leading_char() {
 958         cov_mark::check!(expected_type_fn_ret_with_leading_char);
 959         check_expected_type_and_name(
 960             r#"
 961 fn foo() -> u32 {
 962     c$0
 963 }
 964 "#,
 965             expect![[r#"ty: u32, name: ?"#]],
 966         )
 967     }
 968
 969     #[test]
 970     fn expected_type_fn_ret_fn_ref_fully_typed() {
 971         check_expected_type_and_name(
 972             r#"
 973 fn foo() -> u32 {
 974     foo$0
 975 }
 976 "#,
 977             expect![[r#"ty: u32, name: ?"#]],
 978         )
 979     }
 980
 981     #[test]
 982     fn expected_type_closure_param_return() {
 983         // FIXME: make this work with `|| $0`
 984         check_expected_type_and_name(
 985             r#"
 986 fn foo() {
 987     bar(|| a$0);
 988 }
 989
 990 fn bar(f: impl FnOnce() -> u32) {}
 991 #[lang = "fn_once"]
 992 trait FnOnce { type Output; }
 993 "#,
 994             expect![[r#"ty: u32, name: ?"#]],
 995         );
 996     }
 997
 998     #[test]
 999     fn expected_type_generic_function() {
1000         check_expected_type_and_name(
1001             r#"
1002 fn foo() {
1003     bar::<u32>($0);
1004 }
1005
1006 fn bar<T>(t: T) {}
1007 "#,
1008             expect![[r#"ty: u32, name: t"#]],
1009         );
1010     }
1011
1012     #[test]
1013     fn expected_type_generic_method() {
1014         check_expected_type_and_name(
1015             r#"
1016 fn foo() {
1017     S(1u32).bar($0);
1018 }
1019
1020 struct S<T>(T);
1021 impl<T> S<T> {
1022     fn bar(self, t: T) {}
1023 }
1024 "#,
1025             expect![[r#"ty: u32, name: t"#]],
1026         );
1027     }
1028 }