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