crates/ide_completion/src/context.rs

   1 //! See `CompletionContext` structure.
   2
   3 use base_db::SourceDatabaseExt;
   4 use hir::{Local, Name, ScopeDef, Semantics, SemanticsScope, Type, TypeInfo};
   5 use ide_db::{
   6     base_db::{FilePosition, SourceDatabase},
   7     call_info::ActiveParameter,
   8     RootDatabase,
   9 };
  10 use syntax::{
  11     algo::find_node_at_offset,
  12     ast::{self, NameOrNameRef, NameOwner},
  13     match_ast, AstNode, NodeOrToken,
  14     SyntaxKind::{self, *},
  15     SyntaxNode, SyntaxToken, TextRange, TextSize, T,
  16 };
  17 use text_edit::Indel;
  18
  19 use crate::{
  20     patterns::{
  21         determine_location, determine_prev_sibling, for_is_prev2, inside_impl_trait_block,
  22         is_in_loop_body, previous_token, ImmediateLocation, ImmediatePrevSibling,
  23     },
  24     CompletionConfig,
  25 };
  26
  27 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  28 pub(crate) enum PatternRefutability {
  29     Refutable,
  30     Irrefutable,
  31 }
  32
  33 #[derive(Debug)]
  34 pub(super) enum PathKind {
  35     Expr,
  36     Type,
  37 }
  38
  39 #[derive(Debug)]
  40 pub(crate) struct PathCompletionContext {
  41     /// If this is a call with () already there
  42     call_kind: Option<CallKind>,
  43     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  44     pub(super) is_trivial_path: bool,
  45     /// If not a trivial path, the prefix (qualifier).
  46     pub(super) qualifier: Option<ast::Path>,
  47     /// Whether the qualifier comes from a use tree parent or not
  48     pub(super) use_tree_parent: bool,
  49     pub(super) kind: Option<PathKind>,
  50     /// Whether the path segment has type args or not.
  51     pub(super) has_type_args: bool,
  52     /// `true` if we are a statement or a last expr in the block.
  53     pub(super) can_be_stmt: bool,
  54     pub(super) in_loop_body: bool,
  55 }
  56
  57 #[derive(Debug)]
  58 pub(super) struct PatternContext {
  59     pub(super) refutability: PatternRefutability,
  60     pub(super) is_param: Option<ParamKind>,
  61 }
  62
  63 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  64 pub(crate) enum CallKind {
  65     Pat,
  66     Mac,
  67     Expr,
  68 }
  69
  70 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  71 pub(crate) enum ParamKind {
  72     Function,
  73     Closure,
  74 }
  75 /// `CompletionContext` is created early during completion to figure out, where
  76 /// exactly is the cursor, syntax-wise.
  77 #[derive(Debug)]
  78 pub(crate) struct CompletionContext<'a> {
  79     pub(super) sema: Semantics<'a, RootDatabase>,
  80     pub(super) scope: SemanticsScope<'a>,
  81     pub(super) db: &'a RootDatabase,
  82     pub(super) config: &'a CompletionConfig,
  83     pub(super) position: FilePosition,
  84     /// The token before the cursor, in the original file.
  85     pub(super) original_token: SyntaxToken,
  86     /// The token before the cursor, in the macro-expanded file.
  87     pub(super) token: SyntaxToken,
  88     pub(super) krate: Option<hir::Crate>,
  89     pub(super) expected_name: Option<NameOrNameRef>,
  90     pub(super) expected_type: Option<Type>,
  91
  92     /// The parent function of the cursor position if it exists.
  93     pub(super) function_def: Option<ast::Fn>,
  94     /// The parent impl of the cursor position if it exists.
  95     pub(super) impl_def: Option<ast::Impl>,
  96     pub(super) name_syntax: Option<ast::NameLike>,
  97
  98     // potentially set if we are completing a lifetime
  99     pub(super) lifetime_param_syntax: Option<ast::LifetimeParam>,
 100     pub(super) lifetime_allowed: bool,
 101     pub(super) is_label_ref: bool,
 102
 103     pub(super) completion_location: Option<ImmediateLocation>,
 104     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
 105     pub(super) attribute_under_caret: Option<ast::Attr>,
 106     pub(super) previous_token: Option<SyntaxToken>,
 107
 108     pub(super) pattern_ctx: Option<PatternContext>,
 109     pub(super) path_context: Option<PathCompletionContext>,
 110     pub(super) active_parameter: Option<ActiveParameter>,
 111     pub(super) locals: Vec<(String, Local)>,
 112
 113     pub(super) incomplete_let: bool,
 114
 115     no_completion_required: bool,
 116 }
 117
 118 impl<'a> CompletionContext<'a> {
 119     pub(super) fn new(
 120         db: &'a RootDatabase,
 121         position: FilePosition,
 122         config: &'a CompletionConfig,
 123     ) -> Option<CompletionContext<'a>> {
 124         let sema = Semantics::new(db);
 125
 126         let original_file = sema.parse(position.file_id);
 127
 128         // Insert a fake ident to get a valid parse tree. We will use this file
 129         // to determine context, though the original_file will be used for
 130         // actual completion.
 131         let file_with_fake_ident = {
 132             let parse = db.parse(position.file_id);
 133             let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
 134             parse.reparse(&edit).tree()
 135         };
 136         let fake_ident_token =
 137             file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 138
 139         let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
 140         let original_token =
 141             original_file.syntax().token_at_offset(position.offset).left_biased()?;
 142         let token = sema.descend_into_macros(original_token.clone());
 143         let scope = sema.scope_at_offset(&token, position.offset);
 144         let mut locals = vec![];
 145         scope.process_all_names(&mut |name, scope| {
 146             if let ScopeDef::Local(local) = scope {
 147                 locals.push((name.to_string(), local));
 148             }
 149         });
 150         let mut ctx = CompletionContext {
 151             sema,
 152             scope,
 153             db,
 154             config,
 155             position,
 156             original_token,
 157             token,
 158             krate,
 159             expected_name: None,
 160             expected_type: None,
 161             function_def: None,
 162             impl_def: None,
 163             name_syntax: None,
 164             lifetime_param_syntax: None,
 165             lifetime_allowed: false,
 166             is_label_ref: false,
 167             pattern_ctx: None,
 168             completion_location: None,
 169             prev_sibling: None,
 170             attribute_under_caret: None,
 171             previous_token: None,
 172             path_context: None,
 173             active_parameter: ActiveParameter::at(db, position),
 174             locals,
 175             incomplete_let: false,
 176             no_completion_required: false,
 177         };
 178         ctx.expand_and_fill(
 179             original_file.syntax().clone(),
 180             file_with_fake_ident.syntax().clone(),
 181             position.offset,
 182             fake_ident_token,
 183         );
 184         Some(ctx)
 185     }
 186
 187     fn expand_and_fill(
 188         &mut self,
 189         mut original_file: SyntaxNode,
 190         mut speculative_file: SyntaxNode,
 191         mut offset: TextSize,
 192         mut fake_ident_token: SyntaxToken,
 193     ) {
 194         loop {
 195             // Expand attributes
 196             if let (Some(actual_item), Some(item_with_fake_ident)) = (
 197                 find_node_at_offset::<ast::Item>(&original_file, offset),
 198                 find_node_at_offset::<ast::Item>(&speculative_file, offset),
 199             ) {
 200                 match (
 201                     self.sema.expand_attr_macro(&actual_item),
 202                     self.sema.speculative_expand_attr_macro(
 203                         &actual_item,
 204                         &item_with_fake_ident,
 205                         fake_ident_token.clone(),
 206                     ),
 207                 ) {
 208                     (Some(actual_expansion), Some(speculative_expansion)) => {
 209                         let new_offset = speculative_expansion.1.text_range().start();
 210                         if new_offset > actual_expansion.text_range().end() {
 211                             break;
 212                         }
 213                         original_file = actual_expansion;
 214                         speculative_file = speculative_expansion.0;
 215                         fake_ident_token = speculative_expansion.1;
 216                         offset = new_offset;
 217                         continue;
 218                     }
 219                     (None, None) => (),
 220                     _ => break,
 221                 }
 222             }
 223
 224             // Expand fn-like macro calls
 225             if let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 226                 find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 227                 find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 228             ) {
 229                 let mac_call_path0 = actual_macro_call.path().as_ref().map(|s| s.syntax().text());
 230                 let mac_call_path1 =
 231                     macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text());
 232                 if mac_call_path0 != mac_call_path1 {
 233                     break;
 234                 }
 235                 let speculative_args = match macro_call_with_fake_ident.token_tree() {
 236                     Some(tt) => tt,
 237                     None => break,
 238                 };
 239
 240                 if let (Some(actual_expansion), Some(speculative_expansion)) = (
 241                     self.sema.expand(&actual_macro_call),
 242                     self.sema.speculative_expand(
 243                         &actual_macro_call,
 244                         &speculative_args,
 245                         fake_ident_token,
 246                     ),
 247                 ) {
 248                     let new_offset = speculative_expansion.1.text_range().start();
 249                     if new_offset > actual_expansion.text_range().end() {
 250                         break;
 251                     }
 252                     original_file = actual_expansion;
 253                     speculative_file = speculative_expansion.0;
 254                     fake_ident_token = speculative_expansion.1;
 255                     offset = new_offset;
 256                 } else {
 257                     break;
 258                 }
 259             } else {
 260                 break;
 261             }
 262         }
 263
 264         self.fill(&original_file, speculative_file, offset);
 265     }
 266
 267     /// Checks whether completions in that particular case don't make much sense.
 268     /// Examples:
 269     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 270     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 271     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 272     pub(crate) fn no_completion_required(&self) -> bool {
 273         self.no_completion_required
 274     }
 275
 276     /// The range of the identifier that is being completed.
 277     pub(crate) fn source_range(&self) -> TextRange {
 278         // check kind of macro-expanded token, but use range of original token
 279         let kind = self.token.kind();
 280         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 281             cov_mark::hit!(completes_if_prefix_is_keyword);
 282             self.original_token.text_range()
 283         } else if kind == CHAR {
 284             // assume we are completing a lifetime but the user has only typed the '
 285             cov_mark::hit!(completes_if_lifetime_without_idents);
 286             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 287         } else {
 288             TextRange::empty(self.position.offset)
 289         }
 290     }
 291
 292     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 293         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 294     }
 295
 296     pub(crate) fn expects_assoc_item(&self) -> bool {
 297         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 298     }
 299
 300     pub(crate) fn has_dot_receiver(&self) -> bool {
 301         matches!(
 302             &self.completion_location,
 303             Some(ImmediateLocation::FieldAccess { receiver, .. } | ImmediateLocation::MethodCall { receiver,.. })
 304                 if receiver.is_some()
 305         )
 306     }
 307
 308     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 309         match &self.completion_location {
 310             Some(
 311                 ImmediateLocation::MethodCall { receiver, .. }
 312                 | ImmediateLocation::FieldAccess { receiver, .. },
 313             ) => receiver.as_ref(),
 314             _ => None,
 315         }
 316     }
 317
 318     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 319         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 320     }
 321
 322     pub(crate) fn expects_item(&self) -> bool {
 323         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 324     }
 325
 326     pub(crate) fn expects_generic_arg(&self) -> bool {
 327         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 328     }
 329
 330     pub(crate) fn has_block_expr_parent(&self) -> bool {
 331         matches!(self.completion_location, Some(ImmediateLocation::BlockExpr))
 332     }
 333
 334     pub(crate) fn expects_ident_pat_or_ref_expr(&self) -> bool {
 335         matches!(
 336             self.completion_location,
 337             Some(ImmediateLocation::IdentPat | ImmediateLocation::RefExpr)
 338         )
 339     }
 340
 341     pub(crate) fn expect_field(&self) -> bool {
 342         matches!(
 343             self.completion_location,
 344             Some(ImmediateLocation::RecordField | ImmediateLocation::TupleField)
 345         )
 346     }
 347
 348     pub(crate) fn in_use_tree(&self) -> bool {
 349         matches!(
 350             self.completion_location,
 351             Some(ImmediateLocation::Use | ImmediateLocation::UseTree)
 352         )
 353     }
 354
 355     pub(crate) fn has_impl_or_trait_prev_sibling(&self) -> bool {
 356         matches!(
 357             self.prev_sibling,
 358             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 359         )
 360     }
 361
 362     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 363         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 364     }
 365
 366     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 367         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 368     }
 369
 370     pub(crate) fn after_if(&self) -> bool {
 371         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 372     }
 373
 374     pub(crate) fn is_path_disallowed(&self) -> bool {
 375         self.attribute_under_caret.is_some()
 376             || self.previous_token_is(T![unsafe])
 377             || matches!(
 378                 self.prev_sibling,
 379                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 380             )
 381             || matches!(
 382                 self.completion_location,
 383                 Some(
 384                     ImmediateLocation::Attribute(_)
 385                         | ImmediateLocation::ModDeclaration(_)
 386                         | ImmediateLocation::RecordPat(_)
 387                         | ImmediateLocation::RecordExpr(_)
 388                 )
 389             )
 390     }
 391
 392     pub(crate) fn expects_expression(&self) -> bool {
 393         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Expr), .. }))
 394     }
 395
 396     pub(crate) fn expects_type(&self) -> bool {
 397         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Type), .. }))
 398     }
 399
 400     pub(crate) fn path_call_kind(&self) -> Option<CallKind> {
 401         self.path_context.as_ref().and_then(|it| it.call_kind)
 402     }
 403
 404     pub(crate) fn is_trivial_path(&self) -> bool {
 405         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: true, .. }))
 406     }
 407
 408     pub(crate) fn is_non_trivial_path(&self) -> bool {
 409         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: false, .. }))
 410     }
 411
 412     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 413         self.path_context.as_ref().and_then(|it| it.qualifier.as_ref())
 414     }
 415
 416     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 417     pub(crate) fn is_visible<I>(&self, item: &I) -> bool
 418     where
 419         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 420     {
 421         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 422     }
 423
 424     pub(crate) fn is_scope_def_hidden(&self, scope_def: &ScopeDef) -> bool {
 425         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 426             return self.is_doc_hidden(&attrs, krate);
 427         }
 428
 429         false
 430     }
 431
 432     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
 433         let attrs = item.attrs(self.db);
 434         let krate = item.krate(self.db);
 435         match (attrs, krate) {
 436             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
 437             _ => false,
 438         }
 439     }
 440
 441     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 442     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 443         self.scope.process_all_names(&mut |name, def| {
 444             if self.is_scope_def_hidden(&def) {
 445                 return;
 446             }
 447
 448             f(name, def);
 449         })
 450     }
 451
 452     fn is_visible_impl(
 453         &self,
 454         vis: &hir::Visibility,
 455         attrs: &hir::Attrs,
 456         defining_crate: hir::Crate,
 457     ) -> bool {
 458         let module = match self.scope.module() {
 459             Some(it) => it,
 460             None => return false,
 461         };
 462         if !vis.is_visible_from(self.db, module.into()) {
 463             // If the definition location is editable, also show private items
 464             let root_file = defining_crate.root_file(self.db);
 465             let source_root_id = self.db.file_source_root(root_file);
 466             let is_editable = !self.db.source_root(source_root_id).is_library;
 467             return is_editable;
 468         }
 469
 470         !self.is_doc_hidden(attrs, defining_crate)
 471     }
 472
 473     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 474         let module = match self.scope.module() {
 475             Some(it) => it,
 476             None => return true,
 477         };
 478         if module.krate() != defining_crate && attrs.has_doc_hidden() {
 479             // `doc(hidden)` items are only completed within the defining crate.
 480             return true;
 481         }
 482
 483         false
 484     }
 485
 486     fn fill_impl_def(&mut self) {
 487         self.impl_def = self
 488             .sema
 489             .token_ancestors_with_macros(self.token.clone())
 490             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 491             .find_map(ast::Impl::cast);
 492     }
 493
 494     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 495         let mut node = match self.token.parent() {
 496             Some(it) => it,
 497             None => return (None, None),
 498         };
 499         loop {
 500             break match_ast! {
 501                 match node {
 502                     ast::LetStmt(it) => {
 503                         cov_mark::hit!(expected_type_let_with_leading_char);
 504                         cov_mark::hit!(expected_type_let_without_leading_char);
 505                         let ty = it.pat()
 506                             .and_then(|pat| self.sema.type_of_pat(&pat))
 507                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)))
 508                             .map(TypeInfo::original);
 509                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 510                             ident.name().map(NameOrNameRef::Name)
 511                         } else {
 512                             None
 513                         };
 514
 515                         (ty, name)
 516                     },
 517                     ast::ArgList(_it) => {
 518                         cov_mark::hit!(expected_type_fn_param);
 519                         ActiveParameter::at_token(
 520                             &self.sema,
 521                             self.token.clone(),
 522                         ).map(|ap| {
 523                             let name = ap.ident().map(NameOrNameRef::Name);
 524                             let ty = if has_ref(&self.token) {
 525                                 cov_mark::hit!(expected_type_fn_param_ref);
 526                                 ap.ty.remove_ref()
 527                             } else {
 528                                 Some(ap.ty)
 529                             };
 530                             (ty, name)
 531                         })
 532                         .unwrap_or((None, None))
 533                     },
 534                     ast::RecordExprFieldList(it) => {
 535                         // wouldn't try {} be nice...
 536                         (|| {
 537                             if self.token.kind() == T![..]
 538                                 || self.token.prev_token().map(|t| t.kind()) == Some(T![..])
 539                             {
 540                                 cov_mark::hit!(expected_type_struct_func_update);
 541                                 let record_expr = it.syntax().parent().and_then(ast::RecordExpr::cast)?;
 542                                 let ty = self.sema.type_of_expr(&record_expr.into())?;
 543                                 Some((
 544                                     Some(ty.original),
 545                                     None
 546                                 ))
 547                             } else {
 548                                 cov_mark::hit!(expected_type_struct_field_without_leading_char);
 549                                 let expr_field = self.token.prev_sibling_or_token()?
 550                                     .into_node()
 551                                     .and_then(ast::RecordExprField::cast)?;
 552                                 let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 553                                 Some((
 554                                     Some(ty),
 555                                     expr_field.field_name().map(NameOrNameRef::NameRef),
 556                                 ))
 557                             }
 558                         })().unwrap_or((None, None))
 559                     },
 560                     ast::RecordExprField(it) => {
 561                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 562                         (
 563                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)).map(TypeInfo::original),
 564                             it.field_name().map(NameOrNameRef::NameRef),
 565                         )
 566                     },
 567                     ast::MatchExpr(it) => {
 568                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 569                         let ty = it.expr().and_then(|e| self.sema.type_of_expr(&e)).map(TypeInfo::original);
 570                         (ty, None)
 571                     },
 572                     ast::IfExpr(it) => {
 573                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 574                         let ty = it.condition()
 575                             .and_then(|cond| cond.expr())
 576                             .and_then(|e| self.sema.type_of_expr(&e))
 577                             .map(TypeInfo::original);
 578                         (ty, None)
 579                     },
 580                     ast::IdentPat(it) => {
 581                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 582                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 583                         let ty = self.sema.type_of_pat(&ast::Pat::from(it)).map(TypeInfo::original);
 584                         (ty, None)
 585                     },
 586                     ast::Fn(it) => {
 587                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 588                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 589                         let def = self.sema.to_def(&it);
 590                         (def.map(|def| def.ret_type(self.db)), None)
 591                     },
 592                     ast::ClosureExpr(it) => {
 593                         let ty = self.sema.type_of_expr(&it.into());
 594                         ty.and_then(|ty| ty.original.as_callable(self.db))
 595                             .map(|c| (Some(c.return_type()), None))
 596                             .unwrap_or((None, None))
 597                     },
 598                     ast::Stmt(_it) => (None, None),
 599                     ast::Item(__) => (None, None),
 600                     _ => {
 601                         match node.parent() {
 602                             Some(n) => {
 603                                 node = n;
 604                                 continue;
 605                             },
 606                             None => (None, None),
 607                         }
 608                     },
 609                 }
 610             };
 611         }
 612     }
 613
 614     fn fill(
 615         &mut self,
 616         original_file: &SyntaxNode,
 617         file_with_fake_ident: SyntaxNode,
 618         offset: TextSize,
 619     ) {
 620         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 621         let syntax_element = NodeOrToken::Token(fake_ident_token);
 622         self.previous_token = previous_token(syntax_element.clone());
 623         self.attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
 624         self.no_completion_required = {
 625             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 626             let fn_is_prev = self.previous_token_is(T![fn]);
 627             let for_is_prev2 = for_is_prev2(syntax_element.clone());
 628             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
 629         };
 630
 631         self.incomplete_let =
 632             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 633                 it.syntax().text_range().end() == syntax_element.text_range().end()
 634             });
 635
 636         let (expected_type, expected_name) = self.expected_type_and_name();
 637         self.expected_type = expected_type;
 638         self.expected_name = expected_name;
 639
 640         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 641             Some(it) => it,
 642             None => return,
 643         };
 644         self.completion_location =
 645             determine_location(&self.sema, original_file, offset, &name_like);
 646         self.prev_sibling = determine_prev_sibling(&name_like);
 647         self.name_syntax =
 648             find_node_at_offset(original_file, name_like.syntax().text_range().start());
 649         match name_like {
 650             ast::NameLike::Lifetime(lifetime) => {
 651                 self.classify_lifetime(original_file, lifetime, offset);
 652             }
 653             ast::NameLike::NameRef(name_ref) => {
 654                 self.classify_name_ref(original_file, name_ref);
 655             }
 656             ast::NameLike::Name(name) => {
 657                 self.classify_name(name);
 658             }
 659         }
 660     }
 661
 662     fn classify_lifetime(
 663         &mut self,
 664         original_file: &SyntaxNode,
 665         lifetime: ast::Lifetime,
 666         offset: TextSize,
 667     ) {
 668         if let Some(parent) = lifetime.syntax().parent() {
 669             if parent.kind() == ERROR {
 670                 return;
 671             }
 672
 673             match_ast! {
 674                 match parent {
 675                     ast::LifetimeParam(_it) => {
 676                         self.lifetime_allowed = true;
 677                         self.lifetime_param_syntax =
 678                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 679                     },
 680                     ast::BreakExpr(_it) => self.is_label_ref = true,
 681                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 682                     ast::Label(_it) => (),
 683                     _ => self.lifetime_allowed = true,
 684                 }
 685             }
 686         }
 687     }
 688
 689     fn classify_name(&mut self, name: ast::Name) {
 690         self.fill_impl_def();
 691
 692         if let Some(bind_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
 693             let is_name_in_field_pat = bind_pat
 694                 .syntax()
 695                 .parent()
 696                 .and_then(ast::RecordPatField::cast)
 697                 .map_or(false, |pat_field| pat_field.name_ref().is_none());
 698             if is_name_in_field_pat {
 699                 return;
 700             }
 701             if bind_pat.is_simple_ident() {
 702                 let mut is_param = None;
 703                 let refutability = bind_pat
 704                     .syntax()
 705                     .ancestors()
 706                     .skip_while(|it| ast::Pat::can_cast(it.kind()))
 707                     .next()
 708                     .map_or(PatternRefutability::Irrefutable, |node| {
 709                         match_ast! {
 710                             match node {
 711                                 ast::LetStmt(__) => PatternRefutability::Irrefutable,
 712                                 ast::Param(param) => {
 713                                     let is_closure_param = param
 714                                         .syntax()
 715                                         .ancestors()
 716                                         .nth(2)
 717                                         .and_then(ast::ClosureExpr::cast)
 718                                         .is_some();
 719                                     is_param = Some(if is_closure_param {
 720                                         ParamKind::Closure
 721                                     } else {
 722                                         ParamKind::Function
 723                                     });
 724                                     PatternRefutability::Irrefutable
 725                                 },
 726                                 ast::MatchArm(__) => PatternRefutability::Refutable,
 727                                 ast::Condition(__) => PatternRefutability::Refutable,
 728                                 ast::ForExpr(__) => PatternRefutability::Irrefutable,
 729                                 _ => PatternRefutability::Irrefutable,
 730                             }
 731                         }
 732                     });
 733                 self.pattern_ctx = Some(PatternContext { refutability, is_param });
 734             }
 735         }
 736     }
 737
 738     fn classify_name_ref(&mut self, original_file: &SyntaxNode, name_ref: ast::NameRef) {
 739         self.fill_impl_def();
 740
 741         self.function_def = self
 742             .sema
 743             .token_ancestors_with_macros(self.token.clone())
 744             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 745             .find_map(ast::Fn::cast);
 746
 747         let parent = match name_ref.syntax().parent() {
 748             Some(it) => it,
 749             None => return,
 750         };
 751
 752         if let Some(segment) = ast::PathSegment::cast(parent) {
 753             let path_ctx = self.path_context.get_or_insert(PathCompletionContext {
 754                 call_kind: None,
 755                 is_trivial_path: false,
 756                 qualifier: None,
 757                 has_type_args: false,
 758                 can_be_stmt: false,
 759                 in_loop_body: false,
 760                 use_tree_parent: false,
 761                 kind: None,
 762             });
 763             path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
 764             let path = segment.parent_path();
 765
 766             if let Some(p) = path.syntax().parent() {
 767                 path_ctx.call_kind = match_ast! {
 768                     match p {
 769                         ast::PathExpr(it) => it.syntax().parent().and_then(ast::CallExpr::cast).map(|_| CallKind::Expr),
 770                         ast::MacroCall(it) => it.excl_token().and(Some(CallKind::Mac)),
 771                         ast::TupleStructPat(_it) => Some(CallKind::Pat),
 772                         _ => None
 773                     }
 774                 };
 775             }
 776
 777             if let Some(parent) = path.syntax().parent() {
 778                 path_ctx.kind = match_ast! {
 779                     match parent {
 780                         ast::PathType(_it) => Some(PathKind::Type),
 781                         ast::PathExpr(_it) => Some(PathKind::Expr),
 782                         _ => None,
 783                     }
 784                 };
 785             }
 786             path_ctx.has_type_args = segment.generic_arg_list().is_some();
 787
 788             if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
 789                 path_ctx.use_tree_parent = use_tree_parent;
 790                 path_ctx.qualifier = path
 791                     .segment()
 792                     .and_then(|it| {
 793                         find_node_with_range::<ast::PathSegment>(
 794                             original_file,
 795                             it.syntax().text_range(),
 796                         )
 797                     })
 798                     .map(|it| it.parent_path());
 799                 return;
 800             }
 801
 802             if let Some(segment) = path.segment() {
 803                 if segment.coloncolon_token().is_some() {
 804                     return;
 805                 }
 806             }
 807
 808             path_ctx.is_trivial_path = true;
 809
 810             // Find either enclosing expr statement (thing with `;`) or a
 811             // block. If block, check that we are the last expr.
 812             path_ctx.can_be_stmt = name_ref
 813                 .syntax()
 814                 .ancestors()
 815                 .find_map(|node| {
 816                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 817                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 818                     }
 819                     if let Some(block) = ast::BlockExpr::cast(node) {
 820                         return Some(
 821                             block.tail_expr().map(|e| e.syntax().text_range())
 822                                 == Some(name_ref.syntax().text_range()),
 823                         );
 824                     }
 825                     None
 826                 })
 827                 .unwrap_or(false);
 828         }
 829     }
 830 }
 831
 832 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 833     syntax.covering_element(range).ancestors().find_map(N::cast)
 834 }
 835
 836 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
 837     if let Some(qual) = path.qualifier() {
 838         return Some((qual, false));
 839     }
 840     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 841     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 842     use_tree.path().zip(Some(true))
 843 }
 844
 845 fn has_ref(token: &SyntaxToken) -> bool {
 846     let mut token = token.clone();
 847     for skip in [WHITESPACE, IDENT, T![mut]] {
 848         if token.kind() == skip {
 849             token = match token.prev_token() {
 850                 Some(it) => it,
 851                 None => return false,
 852             }
 853         }
 854     }
 855     token.kind() == T![&]
 856 }
 857
 858 #[cfg(test)]
 859 mod tests {
 860     use expect_test::{expect, Expect};
 861     use hir::HirDisplay;
 862
 863     use crate::tests::{position, TEST_CONFIG};
 864
 865     use super::CompletionContext;
 866
 867     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 868         let (db, pos) = position(ra_fixture);
 869         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 870
 871         let ty = completion_context
 872             .expected_type
 873             .map(|t| t.display_test(&db).to_string())
 874             .unwrap_or("?".to_owned());
 875
 876         let name = completion_context
 877             .expected_name
 878             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 879
 880         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 881     }
 882
 883     #[test]
 884     fn expected_type_let_without_leading_char() {
 885         cov_mark::check!(expected_type_let_without_leading_char);
 886         check_expected_type_and_name(
 887             r#"
 888 fn foo() {
 889     let x: u32 = $0;
 890 }
 891 "#,
 892             expect![[r#"ty: u32, name: x"#]],
 893         );
 894     }
 895
 896     #[test]
 897     fn expected_type_let_with_leading_char() {
 898         cov_mark::check!(expected_type_let_with_leading_char);
 899         check_expected_type_and_name(
 900             r#"
 901 fn foo() {
 902     let x: u32 = c$0;
 903 }
 904 "#,
 905             expect![[r#"ty: u32, name: x"#]],
 906         );
 907     }
 908
 909     #[test]
 910     fn expected_type_let_pat() {
 911         check_expected_type_and_name(
 912             r#"
 913 fn foo() {
 914     let x$0 = 0u32;
 915 }
 916 "#,
 917             expect![[r#"ty: u32, name: ?"#]],
 918         );
 919         check_expected_type_and_name(
 920             r#"
 921 fn foo() {
 922     let $0 = 0u32;
 923 }
 924 "#,
 925             expect![[r#"ty: u32, name: ?"#]],
 926         );
 927     }
 928
 929     #[test]
 930     fn expected_type_fn_param() {
 931         cov_mark::check!(expected_type_fn_param);
 932         check_expected_type_and_name(
 933             r#"
 934 fn foo() { bar($0); }
 935 fn bar(x: u32) {}
 936 "#,
 937             expect![[r#"ty: u32, name: x"#]],
 938         );
 939         check_expected_type_and_name(
 940             r#"
 941 fn foo() { bar(c$0); }
 942 fn bar(x: u32) {}
 943 "#,
 944             expect![[r#"ty: u32, name: x"#]],
 945         );
 946     }
 947
 948     #[test]
 949     fn expected_type_fn_param_ref() {
 950         cov_mark::check!(expected_type_fn_param_ref);
 951         check_expected_type_and_name(
 952             r#"
 953 fn foo() { bar(&$0); }
 954 fn bar(x: &u32) {}
 955 "#,
 956             expect![[r#"ty: u32, name: x"#]],
 957         );
 958         check_expected_type_and_name(
 959             r#"
 960 fn foo() { bar(&mut $0); }
 961 fn bar(x: &mut u32) {}
 962 "#,
 963             expect![[r#"ty: u32, name: x"#]],
 964         );
 965         check_expected_type_and_name(
 966             r#"
 967 fn foo() { bar(&c$0); }
 968 fn bar(x: &u32) {}
 969         "#,
 970             expect![[r#"ty: u32, name: x"#]],
 971         );
 972     }
 973
 974     #[test]
 975     fn expected_type_struct_field_without_leading_char() {
 976         cov_mark::check!(expected_type_struct_field_without_leading_char);
 977         check_expected_type_and_name(
 978             r#"
 979 struct Foo { a: u32 }
 980 fn foo() {
 981     Foo { a: $0 };
 982 }
 983 "#,
 984             expect![[r#"ty: u32, name: a"#]],
 985         )
 986     }
 987
 988     #[test]
 989     fn expected_type_generic_struct_field() {
 990         check_expected_type_and_name(
 991             r#"
 992 struct Foo<T> { a: T }
 993 fn foo() -> Foo<u32> {
 994     Foo { a: $0 }
 995 }
 996 "#,
 997             expect![[r#"ty: u32, name: a"#]],
 998         )
 999     }
1000
1001     #[test]
1002     fn expected_type_struct_field_with_leading_char() {
1003         cov_mark::check!(expected_type_struct_field_with_leading_char);
1004         check_expected_type_and_name(
1005             r#"
1006 struct Foo { a: u32 }
1007 fn foo() {
1008     Foo { a: c$0 };
1009 }
1010 "#,
1011             expect![[r#"ty: u32, name: a"#]],
1012         );
1013     }
1014
1015     #[test]
1016     fn expected_type_match_arm_without_leading_char() {
1017         cov_mark::check!(expected_type_match_arm_without_leading_char);
1018         check_expected_type_and_name(
1019             r#"
1020 enum E { X }
1021 fn foo() {
1022    match E::X { $0 }
1023 }
1024 "#,
1025             expect![[r#"ty: E, name: ?"#]],
1026         );
1027     }
1028
1029     #[test]
1030     fn expected_type_match_arm_with_leading_char() {
1031         cov_mark::check!(expected_type_match_arm_with_leading_char);
1032         check_expected_type_and_name(
1033             r#"
1034 enum E { X }
1035 fn foo() {
1036    match E::X { c$0 }
1037 }
1038 "#,
1039             expect![[r#"ty: E, name: ?"#]],
1040         );
1041     }
1042
1043     #[test]
1044     fn expected_type_if_let_without_leading_char() {
1045         cov_mark::check!(expected_type_if_let_without_leading_char);
1046         check_expected_type_and_name(
1047             r#"
1048 enum Foo { Bar, Baz, Quux }
1049
1050 fn foo() {
1051     let f = Foo::Quux;
1052     if let $0 = f { }
1053 }
1054 "#,
1055             expect![[r#"ty: Foo, name: ?"#]],
1056         )
1057     }
1058
1059     #[test]
1060     fn expected_type_if_let_with_leading_char() {
1061         cov_mark::check!(expected_type_if_let_with_leading_char);
1062         check_expected_type_and_name(
1063             r#"
1064 enum Foo { Bar, Baz, Quux }
1065
1066 fn foo() {
1067     let f = Foo::Quux;
1068     if let c$0 = f { }
1069 }
1070 "#,
1071             expect![[r#"ty: Foo, name: ?"#]],
1072         )
1073     }
1074
1075     #[test]
1076     fn expected_type_fn_ret_without_leading_char() {
1077         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1078         check_expected_type_and_name(
1079             r#"
1080 fn foo() -> u32 {
1081     $0
1082 }
1083 "#,
1084             expect![[r#"ty: u32, name: ?"#]],
1085         )
1086     }
1087
1088     #[test]
1089     fn expected_type_fn_ret_with_leading_char() {
1090         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1091         check_expected_type_and_name(
1092             r#"
1093 fn foo() -> u32 {
1094     c$0
1095 }
1096 "#,
1097             expect![[r#"ty: u32, name: ?"#]],
1098         )
1099     }
1100
1101     #[test]
1102     fn expected_type_fn_ret_fn_ref_fully_typed() {
1103         check_expected_type_and_name(
1104             r#"
1105 fn foo() -> u32 {
1106     foo$0
1107 }
1108 "#,
1109             expect![[r#"ty: u32, name: ?"#]],
1110         )
1111     }
1112
1113     #[test]
1114     fn expected_type_closure_param_return() {
1115         // FIXME: make this work with `|| $0`
1116         check_expected_type_and_name(
1117             r#"
1118 //- minicore: fn
1119 fn foo() {
1120     bar(|| a$0);
1121 }
1122
1123 fn bar(f: impl FnOnce() -> u32) {}
1124 "#,
1125             expect![[r#"ty: u32, name: ?"#]],
1126         );
1127     }
1128
1129     #[test]
1130     fn expected_type_generic_function() {
1131         check_expected_type_and_name(
1132             r#"
1133 fn foo() {
1134     bar::<u32>($0);
1135 }
1136
1137 fn bar<T>(t: T) {}
1138 "#,
1139             expect![[r#"ty: u32, name: t"#]],
1140         );
1141     }
1142
1143     #[test]
1144     fn expected_type_generic_method() {
1145         check_expected_type_and_name(
1146             r#"
1147 fn foo() {
1148     S(1u32).bar($0);
1149 }
1150
1151 struct S<T>(T);
1152 impl<T> S<T> {
1153     fn bar(self, t: T) {}
1154 }
1155 "#,
1156             expect![[r#"ty: u32, name: t"#]],
1157         );
1158     }
1159
1160     #[test]
1161     fn expected_type_functional_update() {
1162         cov_mark::check!(expected_type_struct_func_update);
1163         check_expected_type_and_name(
1164             r#"
1165 struct Foo { field: u32 }
1166 fn foo() {
1167     Foo {
1168         ..$0
1169     }
1170 }
1171 "#,
1172             expect![[r#"ty: Foo, name: ?"#]],
1173         );
1174     }
1175 }