crates/ide/src/syntax_highlighting/highlight.rs

   1 //! Computes color for a single element.
   2
   3 use hir::{AsAssocItem, Semantics};
   4 use ide_db::{
   5     defs::{Definition, NameClass, NameRefClass},
   6     RootDatabase, SymbolKind,
   7 };
   8 use rustc_hash::FxHashMap;
   9 use syntax::{
  10     ast, AstNode, AstToken, NodeOrToken, SyntaxElement,
  11     SyntaxKind::{self, *},
  12     SyntaxNode, SyntaxToken, T,
  13 };
  14
  15 use crate::{
  16     syntax_highlighting::tags::{HlOperator, HlPunct},
  17     Highlight, HlMod, HlTag,
  18 };
  19
  20 pub(super) fn element(
  21     sema: &Semantics<RootDatabase>,
  22     krate: Option<hir::Crate>,
  23     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
  24     syntactic_name_ref_highlighting: bool,
  25     element: SyntaxElement,
  26 ) -> Option<(Highlight, Option<u64>)> {
  27     let db = sema.db;
  28     let mut binding_hash = None;
  29     let highlight: Highlight = match element.kind() {
  30         FN => {
  31             bindings_shadow_count.clear();
  32             return None;
  33         }
  34
  35         // Highlight definitions depending on the "type" of the definition.
  36         NAME => {
  37             let name = element.into_node().and_then(ast::Name::cast).unwrap();
  38             let name_kind = NameClass::classify(sema, &name);
  39
  40             if let Some(NameClass::Definition(Definition::Local(local))) = &name_kind {
  41                 if let Some(name) = local.name(db) {
  42                     let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
  43                     *shadow_count += 1;
  44                     binding_hash = Some(calc_binding_hash(&name, *shadow_count))
  45                 }
  46             };
  47
  48             match name_kind {
  49                 Some(NameClass::ExternCrate(_)) => SymbolKind::Module.into(),
  50                 Some(NameClass::Definition(def)) => {
  51                     highlight_def(db, krate, def) | HlMod::Definition
  52                 }
  53                 Some(NameClass::ConstReference(def)) => highlight_def(db, krate, def),
  54                 Some(NameClass::PatFieldShorthand { field_ref, .. }) => {
  55                     let mut h = HlTag::Symbol(SymbolKind::Field).into();
  56                     if let Definition::Field(field) = field_ref {
  57                         if let hir::VariantDef::Union(_) = field.parent_def(db) {
  58                             h |= HlMod::Unsafe;
  59                         }
  60                     }
  61                     h
  62                 }
  63                 None => highlight_name_by_syntax(name) | HlMod::Definition,
  64             }
  65         }
  66         // Highlight references like the definitions they resolve to
  67         NAME_REF if element.ancestors().any(|it| it.kind() == ATTR) => {
  68             // even though we track whether we are in an attribute or not we still need this special case
  69             // as otherwise we would emit unresolved references for name refs inside attributes
  70             SymbolKind::Function.into()
  71         }
  72         NAME_REF => {
  73             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
  74             highlight_func_by_name_ref(sema, krate, &name_ref).unwrap_or_else(|| {
  75                 let is_self = name_ref.self_token().is_some();
  76                 let h = match NameRefClass::classify(sema, &name_ref) {
  77                     Some(name_kind) => match name_kind {
  78                         NameRefClass::ExternCrate(_) => SymbolKind::Module.into(),
  79                         NameRefClass::Definition(def) => {
  80                             if let Definition::Local(local) = &def {
  81                                 if let Some(name) = local.name(db) {
  82                                     let shadow_count =
  83                                         bindings_shadow_count.entry(name.clone()).or_default();
  84                                     binding_hash = Some(calc_binding_hash(&name, *shadow_count))
  85                                 }
  86                             };
  87
  88                             let mut h = highlight_def(db, krate, def);
  89
  90                             if let Definition::Local(local) = &def {
  91                                 if is_consumed_lvalue(name_ref.syntax().clone().into(), local, db) {
  92                                     h |= HlMod::Consuming;
  93                                 }
  94                             }
  95
  96                             if let Some(parent) = name_ref.syntax().parent() {
  97                                 if matches!(parent.kind(), FIELD_EXPR | RECORD_PAT_FIELD) {
  98                                     if let Definition::Field(field) = def {
  99                                         if let hir::VariantDef::Union(_) = field.parent_def(db) {
 100                                             h |= HlMod::Unsafe;
 101                                         }
 102                                     }
 103                                 }
 104                             }
 105
 106                             h
 107                         }
 108                         NameRefClass::FieldShorthand { .. } => SymbolKind::Field.into(),
 109                     },
 110                     None if syntactic_name_ref_highlighting => {
 111                         highlight_name_ref_by_syntax(name_ref, sema, krate)
 112                     }
 113                     None => HlTag::UnresolvedReference.into(),
 114                 };
 115                 if h.tag == HlTag::Symbol(SymbolKind::Module) && is_self {
 116                     SymbolKind::SelfParam.into()
 117                 } else {
 118                     h
 119                 }
 120             })
 121         }
 122
 123         // Simple token-based highlighting
 124         COMMENT => {
 125             let comment = element.into_token().and_then(ast::Comment::cast)?;
 126             let h = HlTag::Comment;
 127             match comment.kind().doc {
 128                 Some(_) => h | HlMod::Documentation,
 129                 None => h.into(),
 130             }
 131         }
 132         STRING | BYTE_STRING => HlTag::StringLiteral.into(),
 133         ATTR => HlTag::Attribute.into(),
 134         INT_NUMBER if element.ancestors().nth(1).map_or(false, |it| it.kind() == FIELD_EXPR) => {
 135             SymbolKind::Field.into()
 136         }
 137         INT_NUMBER | FLOAT_NUMBER => HlTag::NumericLiteral.into(),
 138         BYTE => HlTag::ByteLiteral.into(),
 139         CHAR => HlTag::CharLiteral.into(),
 140         QUESTION => HlTag::Operator(HlOperator::Other) | HlMod::ControlFlow,
 141         LIFETIME => {
 142             let lifetime = element.into_node().and_then(ast::Lifetime::cast).unwrap();
 143
 144             match NameClass::classify_lifetime(sema, &lifetime) {
 145                 Some(NameClass::Definition(def)) => {
 146                     highlight_def(db, krate, def) | HlMod::Definition
 147                 }
 148                 None => match NameRefClass::classify_lifetime(sema, &lifetime) {
 149                     Some(NameRefClass::Definition(def)) => highlight_def(db, krate, def),
 150                     _ => SymbolKind::LifetimeParam.into(),
 151                 },
 152                 _ => Highlight::from(SymbolKind::LifetimeParam) | HlMod::Definition,
 153             }
 154         }
 155         p if p.is_punct() => match p {
 156             T![&] if parent_matches::<ast::BinExpr>(&element) => HlOperator::Bitwise.into(),
 157             T![&] => {
 158                 let h = HlTag::Operator(HlOperator::Other).into();
 159                 let is_unsafe = element
 160                     .parent()
 161                     .and_then(ast::RefExpr::cast)
 162                     .map_or(false, |ref_expr| sema.is_unsafe_ref_expr(&ref_expr));
 163                 if is_unsafe {
 164                     h | HlMod::Unsafe
 165                 } else {
 166                     h
 167                 }
 168             }
 169             T![::] | T![->] | T![=>] | T![..] | T![=] | T![@] | T![.] => HlOperator::Other.into(),
 170             T![!] if parent_matches::<ast::MacroCall>(&element) => SymbolKind::Macro.into(),
 171             T![!] if parent_matches::<ast::NeverType>(&element) => HlTag::BuiltinType.into(),
 172             T![!] if parent_matches::<ast::PrefixExpr>(&element) => HlOperator::Logical.into(),
 173             T![*] if parent_matches::<ast::PtrType>(&element) => HlTag::Keyword.into(),
 174             T![*] if parent_matches::<ast::PrefixExpr>(&element) => {
 175                 let prefix_expr = element.parent().and_then(ast::PrefixExpr::cast)?;
 176
 177                 let expr = prefix_expr.expr()?;
 178                 let ty = sema.type_of_expr(&expr)?;
 179                 if ty.is_raw_ptr() {
 180                     HlTag::Operator(HlOperator::Other) | HlMod::Unsafe
 181                 } else if let Some(ast::PrefixOp::Deref) = prefix_expr.op_kind() {
 182                     HlOperator::Other.into()
 183                 } else {
 184                     HlPunct::Other.into()
 185                 }
 186             }
 187             T![-] if parent_matches::<ast::PrefixExpr>(&element) => {
 188                 let prefix_expr = element.parent().and_then(ast::PrefixExpr::cast)?;
 189
 190                 let expr = prefix_expr.expr()?;
 191                 match expr {
 192                     ast::Expr::Literal(_) => HlTag::NumericLiteral,
 193                     _ => HlTag::Operator(HlOperator::Other),
 194                 }
 195                 .into()
 196             }
 197             _ if parent_matches::<ast::PrefixExpr>(&element) => HlOperator::Other.into(),
 198             T![+] | T![-] | T![*] | T![/] | T![+=] | T![-=] | T![*=] | T![/=]
 199                 if parent_matches::<ast::BinExpr>(&element) =>
 200             {
 201                 HlOperator::Arithmetic.into()
 202             }
 203             T![|] | T![&] | T![!] | T![^] | T![|=] | T![&=] | T![^=]
 204                 if parent_matches::<ast::BinExpr>(&element) =>
 205             {
 206                 HlOperator::Bitwise.into()
 207             }
 208             T![&&] | T![||] if parent_matches::<ast::BinExpr>(&element) => {
 209                 HlOperator::Logical.into()
 210             }
 211             T![>] | T![<] | T![==] | T![>=] | T![<=] | T![!=]
 212                 if parent_matches::<ast::BinExpr>(&element) =>
 213             {
 214                 HlOperator::Comparison.into()
 215             }
 216             _ if parent_matches::<ast::BinExpr>(&element) => HlOperator::Other.into(),
 217             _ if parent_matches::<ast::RangeExpr>(&element) => HlOperator::Other.into(),
 218             _ if parent_matches::<ast::RangePat>(&element) => HlOperator::Other.into(),
 219             _ if parent_matches::<ast::RestPat>(&element) => HlOperator::Other.into(),
 220             _ if parent_matches::<ast::Attr>(&element) => HlTag::Attribute.into(),
 221             kind => match kind {
 222                 T!['['] | T![']'] => HlPunct::Bracket,
 223                 T!['{'] | T!['}'] => HlPunct::Brace,
 224                 T!['('] | T![')'] => HlPunct::Parenthesis,
 225                 T![<] | T![>] => HlPunct::Angle,
 226                 T![,] => HlPunct::Comma,
 227                 T![:] => HlPunct::Colon,
 228                 T![;] => HlPunct::Semi,
 229                 T![.] => HlPunct::Dot,
 230                 _ => HlPunct::Other,
 231             }
 232             .into(),
 233         },
 234
 235         k if k.is_keyword() => {
 236             let h = Highlight::new(HlTag::Keyword);
 237             match k {
 238                 T![await] => h | HlMod::Async | HlMod::ControlFlow,
 239                 T![break]
 240                 | T![continue]
 241                 | T![else]
 242                 | T![if]
 243                 | T![in]
 244                 | T![loop]
 245                 | T![match]
 246                 | T![return]
 247                 | T![while]
 248                 | T![yield] => h | HlMod::ControlFlow,
 249                 T![for] if !is_child_of_impl(&element) => h | HlMod::ControlFlow,
 250                 T![unsafe] => h | HlMod::Unsafe,
 251                 T![true] | T![false] => HlTag::BoolLiteral.into(),
 252                 // self is handled as either a Name or NameRef already
 253                 T![self] => return None,
 254                 T![ref] => element
 255                     .parent()
 256                     .and_then(ast::IdentPat::cast)
 257                     .and_then(|ident_pat| {
 258                         if sema.is_unsafe_ident_pat(&ident_pat) {
 259                             Some(HlMod::Unsafe)
 260                         } else {
 261                             None
 262                         }
 263                     })
 264                     .map(|modifier| h | modifier)
 265                     .unwrap_or(h),
 266                 T![async] => h | HlMod::Async,
 267                 _ => h,
 268             }
 269         }
 270
 271         _ => return None,
 272     };
 273
 274     return Some((highlight, binding_hash));
 275
 276     fn calc_binding_hash(name: &hir::Name, shadow_count: u32) -> u64 {
 277         fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
 278             use std::{collections::hash_map::DefaultHasher, hash::Hasher};
 279
 280             let mut hasher = DefaultHasher::new();
 281             x.hash(&mut hasher);
 282             hasher.finish()
 283         }
 284
 285         hash((name, shadow_count))
 286     }
 287 }
 288 fn highlight_def(db: &RootDatabase, krate: Option<hir::Crate>, def: Definition) -> Highlight {
 289     let mut h = match def {
 290         Definition::Macro(_) => Highlight::new(HlTag::Symbol(SymbolKind::Macro)),
 291         Definition::Field(_) => Highlight::new(HlTag::Symbol(SymbolKind::Field)),
 292         Definition::ModuleDef(def) => match def {
 293             hir::ModuleDef::Module(_) => Highlight::new(HlTag::Symbol(SymbolKind::Module)),
 294             hir::ModuleDef::Function(func) => {
 295                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Function));
 296                 if let Some(item) = func.as_assoc_item(db) {
 297                     h |= HlMod::Associated;
 298                     match func.self_param(db) {
 299                         Some(sp) => {
 300                             if let hir::Access::Exclusive = sp.access(db) {
 301                                 h |= HlMod::Mutable;
 302                             }
 303                         }
 304                         None => h |= HlMod::Static,
 305                     }
 306
 307                     match item.container(db) {
 308                         hir::AssocItemContainer::Impl(i) => {
 309                             if i.trait_(db).is_some() {
 310                                 h |= HlMod::Trait;
 311                             }
 312                         }
 313                         hir::AssocItemContainer::Trait(_t) => {
 314                             h |= HlMod::Trait;
 315                         }
 316                     }
 317                 }
 318
 319                 if func.is_unsafe(db) {
 320                     h |= HlMod::Unsafe;
 321                 }
 322                 if func.is_async(db) {
 323                     h |= HlMod::Async;
 324                 }
 325
 326                 h
 327             }
 328             hir::ModuleDef::Adt(adt) => {
 329                 let h = match adt {
 330                     hir::Adt::Struct(_) => HlTag::Symbol(SymbolKind::Struct),
 331                     hir::Adt::Enum(_) => HlTag::Symbol(SymbolKind::Enum),
 332                     hir::Adt::Union(_) => HlTag::Symbol(SymbolKind::Union),
 333                 };
 334
 335                 Highlight::new(h)
 336             }
 337             hir::ModuleDef::Variant(_) => Highlight::new(HlTag::Symbol(SymbolKind::Variant)),
 338             hir::ModuleDef::Const(konst) => {
 339                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Const));
 340
 341                 if let Some(item) = konst.as_assoc_item(db) {
 342                     h |= HlMod::Associated;
 343                     match item.container(db) {
 344                         hir::AssocItemContainer::Impl(i) => {
 345                             if i.trait_(db).is_some() {
 346                                 h |= HlMod::Trait;
 347                             }
 348                         }
 349                         hir::AssocItemContainer::Trait(_t) => {
 350                             h |= HlMod::Trait;
 351                         }
 352                     }
 353                 }
 354
 355                 h
 356             }
 357             hir::ModuleDef::Trait(trait_) => {
 358                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Trait));
 359
 360                 if trait_.is_unsafe(db) {
 361                     h |= HlMod::Unsafe;
 362                 }
 363
 364                 h
 365             }
 366             hir::ModuleDef::TypeAlias(type_) => {
 367                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::TypeAlias));
 368
 369                 if let Some(item) = type_.as_assoc_item(db) {
 370                     h |= HlMod::Associated;
 371                     match item.container(db) {
 372                         hir::AssocItemContainer::Impl(i) => {
 373                             if i.trait_(db).is_some() {
 374                                 h |= HlMod::Trait;
 375                             }
 376                         }
 377                         hir::AssocItemContainer::Trait(_t) => {
 378                             h |= HlMod::Trait;
 379                         }
 380                     }
 381                 }
 382
 383                 h
 384             }
 385             hir::ModuleDef::BuiltinType(_) => Highlight::new(HlTag::BuiltinType),
 386             hir::ModuleDef::Static(s) => {
 387                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Static));
 388
 389                 if s.is_mut(db) {
 390                     h |= HlMod::Mutable;
 391                     h |= HlMod::Unsafe;
 392                 }
 393
 394                 h
 395             }
 396         },
 397         Definition::SelfType(_) => Highlight::new(HlTag::Symbol(SymbolKind::Impl)),
 398         Definition::GenericParam(it) => match it {
 399             hir::GenericParam::TypeParam(_) => Highlight::new(HlTag::Symbol(SymbolKind::TypeParam)),
 400             hir::GenericParam::ConstParam(_) => {
 401                 Highlight::new(HlTag::Symbol(SymbolKind::ConstParam))
 402             }
 403             hir::GenericParam::LifetimeParam(_) => {
 404                 Highlight::new(HlTag::Symbol(SymbolKind::LifetimeParam))
 405             }
 406         },
 407         Definition::Local(local) => {
 408             let tag = if local.is_self(db) {
 409                 HlTag::Symbol(SymbolKind::SelfParam)
 410             } else if local.is_param(db) {
 411                 HlTag::Symbol(SymbolKind::ValueParam)
 412             } else {
 413                 HlTag::Symbol(SymbolKind::Local)
 414             };
 415             let mut h = Highlight::new(tag);
 416             let ty = local.ty(db);
 417             if local.is_mut(db) || ty.is_mutable_reference() {
 418                 h |= HlMod::Mutable;
 419             }
 420             if ty.as_callable(db).is_some() || ty.impls_fnonce(db) {
 421                 h |= HlMod::Callable;
 422             }
 423             h
 424         }
 425         Definition::Label(_) => Highlight::new(HlTag::Symbol(SymbolKind::Label)),
 426     };
 427
 428     let is_from_other_crate = def.module(db).map(hir::Module::krate) != krate;
 429     let is_builtin_type = matches!(def, Definition::ModuleDef(hir::ModuleDef::BuiltinType(_)));
 430
 431     if is_from_other_crate && !is_builtin_type {
 432         h |= HlMod::Library;
 433     }
 434
 435     h
 436 }
 437
 438 fn highlight_func_by_name_ref(
 439     sema: &Semantics<RootDatabase>,
 440     krate: Option<hir::Crate>,
 441     name_ref: &ast::NameRef,
 442 ) -> Option<Highlight> {
 443     let mc = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
 444     highlight_method_call(sema, krate, &mc)
 445 }
 446
 447 fn highlight_method_call(
 448     sema: &Semantics<RootDatabase>,
 449     krate: Option<hir::Crate>,
 450     method_call: &ast::MethodCallExpr,
 451 ) -> Option<Highlight> {
 452     let func = sema.resolve_method_call(method_call)?;
 453
 454     let mut h = SymbolKind::Function.into();
 455     h |= HlMod::Associated;
 456
 457     if func.is_unsafe(sema.db) || sema.is_unsafe_method_call(method_call) {
 458         h |= HlMod::Unsafe;
 459     }
 460     if func.is_async(sema.db) {
 461         h |= HlMod::Async;
 462     }
 463     if func.as_assoc_item(sema.db).and_then(|it| it.containing_trait(sema.db)).is_some() {
 464         h |= HlMod::Trait;
 465     }
 466     if Some(func.module(sema.db).krate()) != krate {
 467         h |= HlMod::Library;
 468     }
 469
 470     if let Some(self_param) = func.self_param(sema.db) {
 471         match self_param.access(sema.db) {
 472             hir::Access::Shared => (),
 473             hir::Access::Exclusive => h |= HlMod::Mutable,
 474             hir::Access::Owned => {
 475                 if let Some(receiver_ty) =
 476                     method_call.receiver().and_then(|it| sema.type_of_expr(&it))
 477                 {
 478                     if !receiver_ty.is_copy(sema.db) {
 479                         h |= HlMod::Consuming
 480                     }
 481                 }
 482             }
 483         }
 484     }
 485     Some(h)
 486 }
 487
 488 fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
 489     let default = HlTag::UnresolvedReference;
 490
 491     let parent = match name.syntax().parent() {
 492         Some(it) => it,
 493         _ => return default.into(),
 494     };
 495
 496     let tag = match parent.kind() {
 497         STRUCT => SymbolKind::Struct,
 498         ENUM => SymbolKind::Enum,
 499         VARIANT => SymbolKind::Variant,
 500         UNION => SymbolKind::Union,
 501         TRAIT => SymbolKind::Trait,
 502         TYPE_ALIAS => SymbolKind::TypeAlias,
 503         TYPE_PARAM => SymbolKind::TypeParam,
 504         RECORD_FIELD => SymbolKind::Field,
 505         MODULE => SymbolKind::Module,
 506         FN => SymbolKind::Function,
 507         CONST => SymbolKind::Const,
 508         STATIC => SymbolKind::Static,
 509         IDENT_PAT => SymbolKind::Local,
 510         _ => return default.into(),
 511     };
 512
 513     tag.into()
 514 }
 515
 516 fn highlight_name_ref_by_syntax(
 517     name: ast::NameRef,
 518     sema: &Semantics<RootDatabase>,
 519     krate: Option<hir::Crate>,
 520 ) -> Highlight {
 521     let default = HlTag::UnresolvedReference;
 522
 523     let parent = match name.syntax().parent() {
 524         Some(it) => it,
 525         _ => return default.into(),
 526     };
 527
 528     match parent.kind() {
 529         METHOD_CALL_EXPR => ast::MethodCallExpr::cast(parent)
 530             .and_then(|it| highlight_method_call(sema, krate, &it))
 531             .unwrap_or_else(|| SymbolKind::Function.into()),
 532         FIELD_EXPR => {
 533             let h = HlTag::Symbol(SymbolKind::Field);
 534             let is_union = ast::FieldExpr::cast(parent)
 535                 .and_then(|field_expr| sema.resolve_field(&field_expr))
 536                 .map_or(false, |field| {
 537                     matches!(field.parent_def(sema.db), hir::VariantDef::Union(_))
 538                 });
 539             if is_union {
 540                 h | HlMod::Unsafe
 541             } else {
 542                 h.into()
 543             }
 544         }
 545         PATH_SEGMENT => {
 546             let path = match parent.parent().and_then(ast::Path::cast) {
 547                 Some(it) => it,
 548                 _ => return default.into(),
 549             };
 550             let expr = match path.syntax().parent().and_then(ast::PathExpr::cast) {
 551                 Some(it) => it,
 552                 _ => {
 553                     // within path, decide whether it is module or adt by checking for uppercase name
 554                     return if name.text().chars().next().unwrap_or_default().is_uppercase() {
 555                         SymbolKind::Struct
 556                     } else {
 557                         SymbolKind::Module
 558                     }
 559                     .into();
 560                 }
 561             };
 562             let parent = match expr.syntax().parent() {
 563                 Some(it) => it,
 564                 None => return default.into(),
 565             };
 566
 567             match parent.kind() {
 568                 CALL_EXPR => SymbolKind::Function.into(),
 569                 _ => if name.text().chars().next().unwrap_or_default().is_uppercase() {
 570                     SymbolKind::Struct
 571                 } else {
 572                     SymbolKind::Const
 573                 }
 574                 .into(),
 575             }
 576         }
 577         _ => default.into(),
 578     }
 579 }
 580
 581 fn is_consumed_lvalue(
 582     node: NodeOrToken<SyntaxNode, SyntaxToken>,
 583     local: &hir::Local,
 584     db: &RootDatabase,
 585 ) -> bool {
 586     // When lvalues are passed as arguments and they're not Copy, then mark them as Consuming.
 587     parents_match(node, &[PATH_SEGMENT, PATH, PATH_EXPR, ARG_LIST]) && !local.ty(db).is_copy(db)
 588 }
 589
 590 /// Returns true if the parent nodes of `node` all match the `SyntaxKind`s in `kinds` exactly.
 591 fn parents_match(mut node: NodeOrToken<SyntaxNode, SyntaxToken>, mut kinds: &[SyntaxKind]) -> bool {
 592     while let (Some(parent), [kind, rest @ ..]) = (&node.parent(), kinds) {
 593         if parent.kind() != *kind {
 594             return false;
 595         }
 596
 597         // FIXME: Would be nice to get parent out of the match, but binding by-move and by-value
 598         // in the same pattern is unstable: rust-lang/rust#68354.
 599         node = node.parent().unwrap().into();
 600         kinds = rest;
 601     }
 602
 603     // Only true if we matched all expected kinds
 604     kinds.len() == 0
 605 }
 606
 607 #[inline]
 608 fn parent_matches<N: AstNode>(element: &SyntaxElement) -> bool {
 609     element.parent().map_or(false, |it| N::can_cast(it.kind()))
 610 }
 611
 612 fn is_child_of_impl(element: &SyntaxElement) -> bool {
 613     match element.parent() {
 614         Some(e) => e.kind() == IMPL,
 615         _ => false,
 616     }
 617 }