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, HasName, NameOrNameRef},
  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     pub(super) has_type_ascription: bool,
  62 }
  63
  64 #[derive(Debug)]
  65 pub(super) enum LifetimeContext {
  66     LifetimeParam(Option<ast::LifetimeParam>),
  67     Lifetime,
  68     LabelRef,
  69     LabelDef,
  70 }
  71
  72 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  73 pub(crate) enum CallKind {
  74     Pat,
  75     Mac,
  76     Expr,
  77 }
  78
  79 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  80 pub(crate) enum ParamKind {
  81     Function,
  82     Closure,
  83 }
  84 /// `CompletionContext` is created early during completion to figure out, where
  85 /// exactly is the cursor, syntax-wise.
  86 #[derive(Debug)]
  87 pub(crate) struct CompletionContext<'a> {
  88     pub(super) sema: Semantics<'a, RootDatabase>,
  89     pub(super) scope: SemanticsScope<'a>,
  90     pub(super) db: &'a RootDatabase,
  91     pub(super) config: &'a CompletionConfig,
  92     pub(super) position: FilePosition,
  93     /// The token before the cursor, in the original file.
  94     pub(super) original_token: SyntaxToken,
  95     /// The token before the cursor, in the macro-expanded file.
  96     pub(super) token: SyntaxToken,
  97     /// The crate of the current file.
  98     pub(super) krate: Option<hir::Crate>,
  99     pub(super) expected_name: Option<NameOrNameRef>,
 100     pub(super) expected_type: Option<Type>,
 101
 102     /// The parent function of the cursor position if it exists.
 103     pub(super) function_def: Option<ast::Fn>,
 104     /// The parent impl of the cursor position if it exists.
 105     pub(super) impl_def: Option<ast::Impl>,
 106     /// The NameLike under the cursor in the original file if it exists.
 107     pub(super) name_syntax: Option<ast::NameLike>,
 108     pub(super) incomplete_let: bool,
 109
 110     pub(super) completion_location: Option<ImmediateLocation>,
 111     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
 112     pub(super) attribute_under_caret: Option<ast::Attr>,
 113     pub(super) previous_token: Option<SyntaxToken>,
 114
 115     pub(super) lifetime_ctx: Option<LifetimeContext>,
 116     pub(super) pattern_ctx: Option<PatternContext>,
 117     pub(super) path_context: Option<PathCompletionContext>,
 118     pub(super) locals: Vec<(Name, Local)>,
 119
 120     no_completion_required: bool,
 121 }
 122
 123 impl<'a> CompletionContext<'a> {
 124     /// Checks whether completions in that particular case don't make much sense.
 125     /// Examples:
 126     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 127     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 128     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 129     pub(crate) fn no_completion_required(&self) -> bool {
 130         self.no_completion_required
 131     }
 132
 133     /// The range of the identifier that is being completed.
 134     pub(crate) fn source_range(&self) -> TextRange {
 135         // check kind of macro-expanded token, but use range of original token
 136         let kind = self.token.kind();
 137         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 138             self.original_token.text_range()
 139         } else if kind == CHAR {
 140             // assume we are completing a lifetime but the user has only typed the '
 141             cov_mark::hit!(completes_if_lifetime_without_idents);
 142             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 143         } else {
 144             TextRange::empty(self.position.offset)
 145         }
 146     }
 147
 148     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 149         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 150     }
 151
 152     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 153         match &self.completion_location {
 154             Some(
 155                 ImmediateLocation::MethodCall { receiver, .. }
 156                 | ImmediateLocation::FieldAccess { receiver, .. },
 157             ) => receiver.as_ref(),
 158             _ => None,
 159         }
 160     }
 161
 162     pub(crate) fn has_dot_receiver(&self) -> bool {
 163         matches!(
 164             &self.completion_location,
 165             Some(ImmediateLocation::FieldAccess { receiver, .. } | ImmediateLocation::MethodCall { receiver,.. })
 166                 if receiver.is_some()
 167         )
 168     }
 169
 170     pub(crate) fn expects_assoc_item(&self) -> bool {
 171         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 172     }
 173
 174     pub(crate) fn expects_variant(&self) -> bool {
 175         matches!(self.completion_location, Some(ImmediateLocation::Variant))
 176     }
 177
 178     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 179         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 180     }
 181
 182     pub(crate) fn expects_item(&self) -> bool {
 183         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 184     }
 185
 186     pub(crate) fn expects_generic_arg(&self) -> bool {
 187         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 188     }
 189
 190     pub(crate) fn has_block_expr_parent(&self) -> bool {
 191         matches!(self.completion_location, Some(ImmediateLocation::StmtList))
 192     }
 193
 194     pub(crate) fn expects_ident_pat_or_ref_expr(&self) -> bool {
 195         matches!(
 196             self.completion_location,
 197             Some(ImmediateLocation::IdentPat | ImmediateLocation::RefExpr)
 198         )
 199     }
 200
 201     pub(crate) fn expect_field(&self) -> bool {
 202         matches!(
 203             self.completion_location,
 204             Some(ImmediateLocation::RecordField | ImmediateLocation::TupleField)
 205         )
 206     }
 207
 208     pub(crate) fn in_use_tree(&self) -> bool {
 209         matches!(
 210             self.completion_location,
 211             Some(ImmediateLocation::Use | ImmediateLocation::UseTree)
 212         )
 213     }
 214
 215     pub(crate) fn has_impl_or_trait_prev_sibling(&self) -> bool {
 216         matches!(
 217             self.prev_sibling,
 218             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 219         )
 220     }
 221
 222     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 223         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 224     }
 225
 226     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 227         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 228     }
 229
 230     pub(crate) fn after_if(&self) -> bool {
 231         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 232     }
 233
 234     pub(crate) fn is_path_disallowed(&self) -> bool {
 235         self.attribute_under_caret.is_some()
 236             || self.previous_token_is(T![unsafe])
 237             || matches!(
 238                 self.prev_sibling,
 239                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 240             )
 241             || matches!(
 242                 self.completion_location,
 243                 Some(
 244                     ImmediateLocation::Attribute(_)
 245                         | ImmediateLocation::ModDeclaration(_)
 246                         | ImmediateLocation::RecordPat(_)
 247                         | ImmediateLocation::RecordExpr(_)
 248                         | ImmediateLocation::Rename
 249                 )
 250             )
 251     }
 252
 253     pub(crate) fn expects_expression(&self) -> bool {
 254         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Expr), .. }))
 255     }
 256
 257     pub(crate) fn expects_type(&self) -> bool {
 258         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Type), .. }))
 259     }
 260
 261     pub(crate) fn path_call_kind(&self) -> Option<CallKind> {
 262         self.path_context.as_ref().and_then(|it| it.call_kind)
 263     }
 264
 265     pub(crate) fn is_trivial_path(&self) -> bool {
 266         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: true, .. }))
 267     }
 268
 269     pub(crate) fn is_non_trivial_path(&self) -> bool {
 270         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: false, .. }))
 271     }
 272
 273     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 274         self.path_context.as_ref().and_then(|it| it.qualifier.as_ref())
 275     }
 276
 277     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 278     pub(crate) fn is_visible<I>(&self, item: &I) -> bool
 279     where
 280         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 281     {
 282         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 283     }
 284
 285     pub(crate) fn is_scope_def_hidden(&self, scope_def: &ScopeDef) -> bool {
 286         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 287             return self.is_doc_hidden(&attrs, krate);
 288         }
 289
 290         false
 291     }
 292
 293     /// Check if an item is `#[doc(hidden)]`.
 294     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
 295         let attrs = item.attrs(self.db);
 296         let krate = item.krate(self.db);
 297         match (attrs, krate) {
 298             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
 299             _ => false,
 300         }
 301     }
 302
 303     pub(crate) fn is_immediately_after_macro_bang(&self) -> bool {
 304         self.token.kind() == BANG && self.token.parent().map_or(false, |it| it.kind() == MACRO_CALL)
 305     }
 306
 307     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 308     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 309         self.scope.process_all_names(&mut |name, def| {
 310             if self.is_scope_def_hidden(&def) {
 311                 return;
 312             }
 313
 314             f(name, def);
 315         })
 316     }
 317
 318     fn is_visible_impl(
 319         &self,
 320         vis: &hir::Visibility,
 321         attrs: &hir::Attrs,
 322         defining_crate: hir::Crate,
 323     ) -> bool {
 324         let module = match self.scope.module() {
 325             Some(it) => it,
 326             None => return false,
 327         };
 328         if !vis.is_visible_from(self.db, module.into()) {
 329             // If the definition location is editable, also show private items
 330             let root_file = defining_crate.root_file(self.db);
 331             let source_root_id = self.db.file_source_root(root_file);
 332             let is_editable = !self.db.source_root(source_root_id).is_library;
 333             return is_editable;
 334         }
 335
 336         !self.is_doc_hidden(attrs, defining_crate)
 337     }
 338
 339     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 340         let krate = match self.krate {
 341             Some(it) => it,
 342             None => return true,
 343         };
 344         if krate != defining_crate && attrs.has_doc_hidden() {
 345             // `doc(hidden)` items are only completed within the defining crate.
 346             return true;
 347         }
 348
 349         false
 350     }
 351 }
 352
 353 // CompletionContext construction
 354 impl<'a> CompletionContext<'a> {
 355     pub(super) fn new(
 356         db: &'a RootDatabase,
 357         position @ FilePosition { file_id, offset }: FilePosition,
 358         config: &'a CompletionConfig,
 359     ) -> Option<CompletionContext<'a>> {
 360         let _p = profile::span("CompletionContext::new");
 361         let sema = Semantics::new(db);
 362
 363         let original_file = sema.parse(file_id);
 364
 365         // Insert a fake ident to get a valid parse tree. We will use this file
 366         // to determine context, though the original_file will be used for
 367         // actual completion.
 368         let file_with_fake_ident = {
 369             let parse = db.parse(file_id);
 370             let edit = Indel::insert(offset, "intellijRulezz".to_string());
 371             parse.reparse(&edit).tree()
 372         };
 373         let fake_ident_token =
 374             file_with_fake_ident.syntax().token_at_offset(offset).right_biased().unwrap();
 375
 376         let original_token = original_file.syntax().token_at_offset(offset).left_biased()?;
 377         let token = sema.descend_into_macros_single(original_token.clone());
 378         let scope = sema.scope_at_offset(&token, offset);
 379         let krate = scope.krate();
 380         let mut locals = vec![];
 381         scope.process_all_names(&mut |name, scope| {
 382             if let ScopeDef::Local(local) = scope {
 383                 locals.push((name, local));
 384             }
 385         });
 386         let mut ctx = CompletionContext {
 387             sema,
 388             scope,
 389             db,
 390             config,
 391             position,
 392             original_token,
 393             token,
 394             krate,
 395             expected_name: None,
 396             expected_type: None,
 397             function_def: None,
 398             impl_def: None,
 399             name_syntax: None,
 400             lifetime_ctx: None,
 401             pattern_ctx: None,
 402             completion_location: None,
 403             prev_sibling: None,
 404             attribute_under_caret: None,
 405             previous_token: None,
 406             path_context: None,
 407             locals,
 408             incomplete_let: false,
 409             no_completion_required: false,
 410         };
 411         ctx.expand_and_fill(
 412             original_file.syntax().clone(),
 413             file_with_fake_ident.syntax().clone(),
 414             offset,
 415             fake_ident_token,
 416         );
 417         Some(ctx)
 418     }
 419
 420     /// Do the attribute expansion at the current cursor position for both original file and fake file
 421     /// as long as possible. As soon as one of the two expansions fail we stop to stay in sync.
 422     fn expand_and_fill(
 423         &mut self,
 424         mut original_file: SyntaxNode,
 425         mut speculative_file: SyntaxNode,
 426         mut offset: TextSize,
 427         mut fake_ident_token: SyntaxToken,
 428     ) {
 429         loop {
 430             // Expand attributes
 431             if let (Some(actual_item), Some(item_with_fake_ident)) = (
 432                 find_node_at_offset::<ast::Item>(&original_file, offset),
 433                 find_node_at_offset::<ast::Item>(&speculative_file, offset),
 434             ) {
 435                 match (
 436                     self.sema.expand_attr_macro(&actual_item),
 437                     self.sema.speculative_expand_attr_macro(
 438                         &actual_item,
 439                         &item_with_fake_ident,
 440                         fake_ident_token.clone(),
 441                     ),
 442                 ) {
 443                     (Some(actual_expansion), Some(speculative_expansion)) => {
 444                         let new_offset = speculative_expansion.1.text_range().start();
 445                         if new_offset > actual_expansion.text_range().end() {
 446                             break;
 447                         }
 448                         original_file = actual_expansion;
 449                         speculative_file = speculative_expansion.0;
 450                         fake_ident_token = speculative_expansion.1;
 451                         offset = new_offset;
 452                         continue;
 453                     }
 454                     (None, None) => (),
 455                     _ => break,
 456                 }
 457             }
 458
 459             // Expand fn-like macro calls
 460             if let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 461                 find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 462                 find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 463             ) {
 464                 let mac_call_path0 = actual_macro_call.path().as_ref().map(|s| s.syntax().text());
 465                 let mac_call_path1 =
 466                     macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text());
 467                 if mac_call_path0 != mac_call_path1 {
 468                     break;
 469                 }
 470                 let speculative_args = match macro_call_with_fake_ident.token_tree() {
 471                     Some(tt) => tt,
 472                     None => break,
 473                 };
 474
 475                 if let (Some(actual_expansion), Some(speculative_expansion)) = (
 476                     self.sema.expand(&actual_macro_call),
 477                     self.sema.speculative_expand(
 478                         &actual_macro_call,
 479                         &speculative_args,
 480                         fake_ident_token,
 481                     ),
 482                 ) {
 483                     let new_offset = speculative_expansion.1.text_range().start();
 484                     if new_offset > actual_expansion.text_range().end() {
 485                         break;
 486                     }
 487                     original_file = actual_expansion;
 488                     speculative_file = speculative_expansion.0;
 489                     fake_ident_token = speculative_expansion.1;
 490                     offset = new_offset;
 491                 } else {
 492                     break;
 493                 }
 494             } else {
 495                 break;
 496             }
 497         }
 498
 499         self.fill(&original_file, speculative_file, offset);
 500     }
 501
 502     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 503         let mut node = match self.token.parent() {
 504             Some(it) => it,
 505             None => return (None, None),
 506         };
 507         loop {
 508             break match_ast! {
 509                 match node {
 510                     ast::LetStmt(it) => {
 511                         cov_mark::hit!(expected_type_let_with_leading_char);
 512                         cov_mark::hit!(expected_type_let_without_leading_char);
 513                         let ty = it.pat()
 514                             .and_then(|pat| self.sema.type_of_pat(&pat))
 515                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)))
 516                             .map(TypeInfo::original);
 517                         let name = match it.pat() {
 518                             Some(ast::Pat::IdentPat(ident)) => ident.name().map(NameOrNameRef::Name),
 519                             Some(_) | None => None,
 520                         };
 521
 522                         (ty, name)
 523                     },
 524                     ast::ArgList(_it) => {
 525                         cov_mark::hit!(expected_type_fn_param);
 526                         ActiveParameter::at_token(
 527                             &self.sema,
 528                             self.token.clone(),
 529                         ).map(|ap| {
 530                             let name = ap.ident().map(NameOrNameRef::Name);
 531                             let ty = if has_ref(&self.token) {
 532                                 cov_mark::hit!(expected_type_fn_param_ref);
 533                                 ap.ty.remove_ref()
 534                             } else {
 535                                 Some(ap.ty)
 536                             };
 537                             (ty, name)
 538                         })
 539                         .unwrap_or((None, None))
 540                     },
 541                     ast::RecordExprFieldList(it) => {
 542                         // wouldn't try {} be nice...
 543                         (|| {
 544                             if self.token.kind() == T![..]
 545                                 || self.token.prev_token().map(|t| t.kind()) == Some(T![..])
 546                             {
 547                                 cov_mark::hit!(expected_type_struct_func_update);
 548                                 let record_expr = it.syntax().parent().and_then(ast::RecordExpr::cast)?;
 549                                 let ty = self.sema.type_of_expr(&record_expr.into())?;
 550                                 Some((
 551                                     Some(ty.original),
 552                                     None
 553                                 ))
 554                             } else {
 555                                 cov_mark::hit!(expected_type_struct_field_without_leading_char);
 556                                 let expr_field = self.token.prev_sibling_or_token()?
 557                                     .into_node()
 558                                     .and_then(ast::RecordExprField::cast)?;
 559                                 let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 560                                 Some((
 561                                     Some(ty),
 562                                     expr_field.field_name().map(NameOrNameRef::NameRef),
 563                                 ))
 564                             }
 565                         })().unwrap_or((None, None))
 566                     },
 567                     ast::RecordExprField(it) => {
 568                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 569                         (
 570                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)).map(TypeInfo::original),
 571                             it.field_name().map(NameOrNameRef::NameRef),
 572                         )
 573                     },
 574                     ast::MatchExpr(it) => {
 575                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 576                         let ty = it.expr().and_then(|e| self.sema.type_of_expr(&e)).map(TypeInfo::original);
 577                         (ty, None)
 578                     },
 579                     ast::IfExpr(it) => {
 580                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 581                         let ty = it.condition()
 582                             .and_then(|cond| cond.expr())
 583                             .and_then(|e| self.sema.type_of_expr(&e))
 584                             .map(TypeInfo::original);
 585                         (ty, None)
 586                     },
 587                     ast::IdentPat(it) => {
 588                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 589                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 590                         let ty = self.sema.type_of_pat(&ast::Pat::from(it)).map(TypeInfo::original);
 591                         (ty, None)
 592                     },
 593                     ast::Fn(it) => {
 594                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 595                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 596                         let def = self.sema.to_def(&it);
 597                         (def.map(|def| def.ret_type(self.db)), None)
 598                     },
 599                     ast::ClosureExpr(it) => {
 600                         let ty = self.sema.type_of_expr(&it.into());
 601                         ty.and_then(|ty| ty.original.as_callable(self.db))
 602                             .map(|c| (Some(c.return_type()), None))
 603                             .unwrap_or((None, None))
 604                     },
 605                     ast::ParamList(__) => (None, None),
 606                     ast::Stmt(__) => (None, None),
 607                     ast::Item(__) => (None, None),
 608                     _ => {
 609                         match node.parent() {
 610                             Some(n) => {
 611                                 node = n;
 612                                 continue;
 613                             },
 614                             None => (None, None),
 615                         }
 616                     },
 617                 }
 618             };
 619         }
 620     }
 621
 622     fn fill(
 623         &mut self,
 624         original_file: &SyntaxNode,
 625         file_with_fake_ident: SyntaxNode,
 626         offset: TextSize,
 627     ) {
 628         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 629         let syntax_element = NodeOrToken::Token(fake_ident_token);
 630         self.previous_token = previous_token(syntax_element.clone());
 631         self.attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
 632         self.no_completion_required = {
 633             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 634             let fn_is_prev = self.previous_token_is(T![fn]);
 635             let for_is_prev2 = for_is_prev2(syntax_element.clone());
 636             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
 637         };
 638
 639         self.incomplete_let =
 640             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 641                 it.syntax().text_range().end() == syntax_element.text_range().end()
 642             });
 643
 644         let (expected_type, expected_name) = self.expected_type_and_name();
 645         self.expected_type = expected_type;
 646         self.expected_name = expected_name;
 647
 648         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 649             Some(it) => it,
 650             None => return,
 651         };
 652         self.completion_location =
 653             determine_location(&self.sema, original_file, offset, &name_like);
 654         self.prev_sibling = determine_prev_sibling(&name_like);
 655         self.name_syntax =
 656             find_node_at_offset(original_file, name_like.syntax().text_range().start());
 657         self.impl_def = self
 658             .sema
 659             .token_ancestors_with_macros(self.token.clone())
 660             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 661             .find_map(ast::Impl::cast);
 662         self.function_def = self
 663             .sema
 664             .token_ancestors_with_macros(self.token.clone())
 665             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 666             .find_map(ast::Fn::cast);
 667         match name_like {
 668             ast::NameLike::Lifetime(lifetime) => {
 669                 self.lifetime_ctx =
 670                     Self::classify_lifetime(&self.sema, original_file, lifetime, offset);
 671             }
 672             ast::NameLike::NameRef(name_ref) => {
 673                 self.path_context = Self::classify_name_ref(&self.sema, original_file, name_ref);
 674             }
 675             ast::NameLike::Name(name) => {
 676                 self.pattern_ctx = Self::classify_name(&self.sema, name);
 677             }
 678         }
 679     }
 680
 681     fn classify_lifetime(
 682         sema: &Semantics<RootDatabase>,
 683         original_file: &SyntaxNode,
 684         lifetime: ast::Lifetime,
 685         offset: TextSize,
 686     ) -> Option<LifetimeContext> {
 687         let parent = lifetime.syntax().parent()?;
 688         if parent.kind() == ERROR {
 689             return None;
 690         }
 691
 692         Some(match_ast! {
 693             match parent {
 694                 ast::LifetimeParam(_it) => LifetimeContext::LifetimeParam(sema.find_node_at_offset_with_macros(original_file, offset)),
 695                 ast::BreakExpr(_it) => LifetimeContext::LabelRef,
 696                 ast::ContinueExpr(_it) => LifetimeContext::LabelRef,
 697                 ast::Label(_it) => LifetimeContext::LabelDef,
 698                 _ => LifetimeContext::Lifetime,
 699             }
 700         })
 701     }
 702
 703     fn classify_name(_sema: &Semantics<RootDatabase>, name: ast::Name) -> Option<PatternContext> {
 704         let bind_pat = name.syntax().parent().and_then(ast::IdentPat::cast)?;
 705         let is_name_in_field_pat = bind_pat
 706             .syntax()
 707             .parent()
 708             .and_then(ast::RecordPatField::cast)
 709             .map_or(false, |pat_field| pat_field.name_ref().is_none());
 710         if is_name_in_field_pat {
 711             return None;
 712         }
 713         if !bind_pat.is_simple_ident() {
 714             return None;
 715         }
 716         let mut is_param = None;
 717         let (refutability, has_type_ascription) = bind_pat
 718             .syntax()
 719             .ancestors()
 720             .skip_while(|it| ast::Pat::can_cast(it.kind()))
 721             .next()
 722             .map_or((PatternRefutability::Irrefutable, false), |node| {
 723                 let refutability = match_ast! {
 724                     match node {
 725                         ast::LetStmt(let_) => return (PatternRefutability::Irrefutable, let_.ty().is_some()),
 726                         ast::Param(param) => {
 727                             let is_closure_param = param
 728                                 .syntax()
 729                                 .ancestors()
 730                                 .nth(2)
 731                                 .and_then(ast::ClosureExpr::cast)
 732                                 .is_some();
 733                             is_param = Some(if is_closure_param {
 734                                 ParamKind::Closure
 735                             } else {
 736                                 ParamKind::Function
 737                             });
 738                             return (PatternRefutability::Irrefutable, param.ty().is_some())
 739                         },
 740                         ast::MatchArm(__) => PatternRefutability::Refutable,
 741                         ast::Condition(__) => PatternRefutability::Refutable,
 742                         ast::ForExpr(__) => PatternRefutability::Irrefutable,
 743                         _ => PatternRefutability::Irrefutable,
 744                     }
 745                 };
 746                 (refutability, false)
 747             });
 748         Some(PatternContext { refutability, is_param, has_type_ascription })
 749     }
 750
 751     fn classify_name_ref(
 752         _sema: &Semantics<RootDatabase>,
 753         original_file: &SyntaxNode,
 754         name_ref: ast::NameRef,
 755     ) -> Option<PathCompletionContext> {
 756         let parent = name_ref.syntax().parent()?;
 757         let segment = ast::PathSegment::cast(parent)?;
 758
 759         let mut path_ctx = PathCompletionContext {
 760             call_kind: None,
 761             is_trivial_path: false,
 762             qualifier: None,
 763             has_type_args: false,
 764             can_be_stmt: false,
 765             in_loop_body: false,
 766             use_tree_parent: false,
 767             kind: None,
 768         };
 769         path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
 770         let path = segment.parent_path();
 771
 772         if let Some(p) = path.syntax().parent() {
 773             path_ctx.call_kind = match_ast! {
 774                 match p {
 775                     ast::PathExpr(it) => it.syntax().parent().and_then(ast::CallExpr::cast).map(|_| CallKind::Expr),
 776                     ast::MacroCall(it) => it.excl_token().and(Some(CallKind::Mac)),
 777                     ast::TupleStructPat(_it) => Some(CallKind::Pat),
 778                     _ => None
 779                 }
 780             };
 781         }
 782
 783         if let Some(parent) = path.syntax().parent() {
 784             path_ctx.kind = match_ast! {
 785                 match parent {
 786                     ast::PathType(_it) => Some(PathKind::Type),
 787                     ast::PathExpr(_it) => Some(PathKind::Expr),
 788                     _ => None,
 789                 }
 790             };
 791         }
 792         path_ctx.has_type_args = segment.generic_arg_list().is_some();
 793
 794         if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
 795             path_ctx.use_tree_parent = use_tree_parent;
 796             path_ctx.qualifier = path
 797                 .segment()
 798                 .and_then(|it| {
 799                     find_node_with_range::<ast::PathSegment>(
 800                         original_file,
 801                         it.syntax().text_range(),
 802                     )
 803                 })
 804                 .map(|it| it.parent_path());
 805             return Some(path_ctx);
 806         }
 807
 808         if let Some(segment) = path.segment() {
 809             if segment.coloncolon_token().is_some() {
 810                 return Some(path_ctx);
 811             }
 812         }
 813
 814         path_ctx.is_trivial_path = true;
 815
 816         // Find either enclosing expr statement (thing with `;`) or a
 817         // block. If block, check that we are the last expr.
 818         path_ctx.can_be_stmt = name_ref
 819             .syntax()
 820             .ancestors()
 821             .find_map(|node| {
 822                 if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 823                     return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 824                 }
 825                 if let Some(stmt_list) = ast::StmtList::cast(node) {
 826                     return Some(
 827                         stmt_list.tail_expr().map(|e| e.syntax().text_range())
 828                             == Some(name_ref.syntax().text_range()),
 829                     );
 830                 }
 831                 None
 832             })
 833             .unwrap_or(false);
 834         Some(path_ctx)
 835     }
 836 }
 837
 838 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 839     syntax.covering_element(range).ancestors().find_map(N::cast)
 840 }
 841
 842 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
 843     if let Some(qual) = path.qualifier() {
 844         return Some((qual, false));
 845     }
 846     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 847     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 848     use_tree.path().zip(Some(true))
 849 }
 850
 851 fn has_ref(token: &SyntaxToken) -> bool {
 852     let mut token = token.clone();
 853     for skip in [WHITESPACE, IDENT, T![mut]] {
 854         if token.kind() == skip {
 855             token = match token.prev_token() {
 856                 Some(it) => it,
 857                 None => return false,
 858             }
 859         }
 860     }
 861     token.kind() == T![&]
 862 }
 863
 864 #[cfg(test)]
 865 mod tests {
 866     use expect_test::{expect, Expect};
 867     use hir::HirDisplay;
 868
 869     use crate::tests::{position, TEST_CONFIG};
 870
 871     use super::CompletionContext;
 872
 873     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 874         let (db, pos) = position(ra_fixture);
 875         let config = TEST_CONFIG;
 876         let completion_context = CompletionContext::new(&db, pos, &config).unwrap();
 877
 878         let ty = completion_context
 879             .expected_type
 880             .map(|t| t.display_test(&db).to_string())
 881             .unwrap_or("?".to_owned());
 882
 883         let name = completion_context
 884             .expected_name
 885             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 886
 887         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 888     }
 889
 890     #[test]
 891     fn expected_type_let_without_leading_char() {
 892         cov_mark::check!(expected_type_let_without_leading_char);
 893         check_expected_type_and_name(
 894             r#"
 895 fn foo() {
 896     let x: u32 = $0;
 897 }
 898 "#,
 899             expect![[r#"ty: u32, name: x"#]],
 900         );
 901     }
 902
 903     #[test]
 904     fn expected_type_let_with_leading_char() {
 905         cov_mark::check!(expected_type_let_with_leading_char);
 906         check_expected_type_and_name(
 907             r#"
 908 fn foo() {
 909     let x: u32 = c$0;
 910 }
 911 "#,
 912             expect![[r#"ty: u32, name: x"#]],
 913         );
 914     }
 915
 916     #[test]
 917     fn expected_type_let_pat() {
 918         check_expected_type_and_name(
 919             r#"
 920 fn foo() {
 921     let x$0 = 0u32;
 922 }
 923 "#,
 924             expect![[r#"ty: u32, name: ?"#]],
 925         );
 926         check_expected_type_and_name(
 927             r#"
 928 fn foo() {
 929     let $0 = 0u32;
 930 }
 931 "#,
 932             expect![[r#"ty: u32, name: ?"#]],
 933         );
 934     }
 935
 936     #[test]
 937     fn expected_type_fn_param() {
 938         cov_mark::check!(expected_type_fn_param);
 939         check_expected_type_and_name(
 940             r#"
 941 fn foo() { bar($0); }
 942 fn bar(x: u32) {}
 943 "#,
 944             expect![[r#"ty: u32, name: x"#]],
 945         );
 946         check_expected_type_and_name(
 947             r#"
 948 fn foo() { bar(c$0); }
 949 fn bar(x: u32) {}
 950 "#,
 951             expect![[r#"ty: u32, name: x"#]],
 952         );
 953     }
 954
 955     #[test]
 956     fn expected_type_fn_param_ref() {
 957         cov_mark::check!(expected_type_fn_param_ref);
 958         check_expected_type_and_name(
 959             r#"
 960 fn foo() { bar(&$0); }
 961 fn bar(x: &u32) {}
 962 "#,
 963             expect![[r#"ty: u32, name: x"#]],
 964         );
 965         check_expected_type_and_name(
 966             r#"
 967 fn foo() { bar(&mut $0); }
 968 fn bar(x: &mut u32) {}
 969 "#,
 970             expect![[r#"ty: u32, name: x"#]],
 971         );
 972         check_expected_type_and_name(
 973             r#"
 974 fn foo() { bar(&c$0); }
 975 fn bar(x: &u32) {}
 976         "#,
 977             expect![[r#"ty: u32, name: x"#]],
 978         );
 979     }
 980
 981     #[test]
 982     fn expected_type_struct_field_without_leading_char() {
 983         cov_mark::check!(expected_type_struct_field_without_leading_char);
 984         check_expected_type_and_name(
 985             r#"
 986 struct Foo { a: u32 }
 987 fn foo() {
 988     Foo { a: $0 };
 989 }
 990 "#,
 991             expect![[r#"ty: u32, name: a"#]],
 992         )
 993     }
 994
 995     #[test]
 996     fn expected_type_generic_struct_field() {
 997         check_expected_type_and_name(
 998             r#"
 999 struct Foo<T> { a: T }
1000 fn foo() -> Foo<u32> {
1001     Foo { a: $0 }
1002 }
1003 "#,
1004             expect![[r#"ty: u32, name: a"#]],
1005         )
1006     }
1007
1008     #[test]
1009     fn expected_type_struct_field_with_leading_char() {
1010         cov_mark::check!(expected_type_struct_field_with_leading_char);
1011         check_expected_type_and_name(
1012             r#"
1013 struct Foo { a: u32 }
1014 fn foo() {
1015     Foo { a: c$0 };
1016 }
1017 "#,
1018             expect![[r#"ty: u32, name: a"#]],
1019         );
1020     }
1021
1022     #[test]
1023     fn expected_type_match_arm_without_leading_char() {
1024         cov_mark::check!(expected_type_match_arm_without_leading_char);
1025         check_expected_type_and_name(
1026             r#"
1027 enum E { X }
1028 fn foo() {
1029    match E::X { $0 }
1030 }
1031 "#,
1032             expect![[r#"ty: E, name: ?"#]],
1033         );
1034     }
1035
1036     #[test]
1037     fn expected_type_match_arm_with_leading_char() {
1038         cov_mark::check!(expected_type_match_arm_with_leading_char);
1039         check_expected_type_and_name(
1040             r#"
1041 enum E { X }
1042 fn foo() {
1043    match E::X { c$0 }
1044 }
1045 "#,
1046             expect![[r#"ty: E, name: ?"#]],
1047         );
1048     }
1049
1050     #[test]
1051     fn expected_type_if_let_without_leading_char() {
1052         cov_mark::check!(expected_type_if_let_without_leading_char);
1053         check_expected_type_and_name(
1054             r#"
1055 enum Foo { Bar, Baz, Quux }
1056
1057 fn foo() {
1058     let f = Foo::Quux;
1059     if let $0 = f { }
1060 }
1061 "#,
1062             expect![[r#"ty: Foo, name: ?"#]],
1063         )
1064     }
1065
1066     #[test]
1067     fn expected_type_if_let_with_leading_char() {
1068         cov_mark::check!(expected_type_if_let_with_leading_char);
1069         check_expected_type_and_name(
1070             r#"
1071 enum Foo { Bar, Baz, Quux }
1072
1073 fn foo() {
1074     let f = Foo::Quux;
1075     if let c$0 = f { }
1076 }
1077 "#,
1078             expect![[r#"ty: Foo, name: ?"#]],
1079         )
1080     }
1081
1082     #[test]
1083     fn expected_type_fn_ret_without_leading_char() {
1084         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1085         check_expected_type_and_name(
1086             r#"
1087 fn foo() -> u32 {
1088     $0
1089 }
1090 "#,
1091             expect![[r#"ty: u32, name: ?"#]],
1092         )
1093     }
1094
1095     #[test]
1096     fn expected_type_fn_ret_with_leading_char() {
1097         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1098         check_expected_type_and_name(
1099             r#"
1100 fn foo() -> u32 {
1101     c$0
1102 }
1103 "#,
1104             expect![[r#"ty: u32, name: ?"#]],
1105         )
1106     }
1107
1108     #[test]
1109     fn expected_type_fn_ret_fn_ref_fully_typed() {
1110         check_expected_type_and_name(
1111             r#"
1112 fn foo() -> u32 {
1113     foo$0
1114 }
1115 "#,
1116             expect![[r#"ty: u32, name: ?"#]],
1117         )
1118     }
1119
1120     #[test]
1121     fn expected_type_closure_param_return() {
1122         // FIXME: make this work with `|| $0`
1123         check_expected_type_and_name(
1124             r#"
1125 //- minicore: fn
1126 fn foo() {
1127     bar(|| a$0);
1128 }
1129
1130 fn bar(f: impl FnOnce() -> u32) {}
1131 "#,
1132             expect![[r#"ty: u32, name: ?"#]],
1133         );
1134     }
1135
1136     #[test]
1137     fn expected_type_generic_function() {
1138         check_expected_type_and_name(
1139             r#"
1140 fn foo() {
1141     bar::<u32>($0);
1142 }
1143
1144 fn bar<T>(t: T) {}
1145 "#,
1146             expect![[r#"ty: u32, name: t"#]],
1147         );
1148     }
1149
1150     #[test]
1151     fn expected_type_generic_method() {
1152         check_expected_type_and_name(
1153             r#"
1154 fn foo() {
1155     S(1u32).bar($0);
1156 }
1157
1158 struct S<T>(T);
1159 impl<T> S<T> {
1160     fn bar(self, t: T) {}
1161 }
1162 "#,
1163             expect![[r#"ty: u32, name: t"#]],
1164         );
1165     }
1166
1167     #[test]
1168     fn expected_type_functional_update() {
1169         cov_mark::check!(expected_type_struct_func_update);
1170         check_expected_type_and_name(
1171             r#"
1172 struct Foo { field: u32 }
1173 fn foo() {
1174     Foo {
1175         ..$0
1176     }
1177 }
1178 "#,
1179             expect![[r#"ty: Foo, name: ?"#]],
1180         );
1181     }
1182
1183     #[test]
1184     fn expected_type_param_pat() {
1185         check_expected_type_and_name(
1186             r#"
1187 struct Foo { field: u32 }
1188 fn foo(a$0: Foo) {}
1189 "#,
1190             expect![[r#"ty: Foo, name: ?"#]],
1191         );
1192         check_expected_type_and_name(
1193             r#"
1194 struct Foo { field: u32 }
1195 fn foo($0: Foo) {}
1196 "#,
1197             // FIXME make this work, currently fails due to pattern recovery eating the `:`
1198             expect![[r#"ty: ?, name: ?"#]],
1199         );
1200     }
1201 }