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