crates/ide/src/syntax_highlighting/highlight.rs

   1 //! Computes color for a single element.
   2
   3 use hir::{AsAssocItem, HasVisibility, 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         // Highlight definitions depending on the "type" of the definition.
  35         NAME => {
  36             let name = element.into_node().and_then(ast::Name::cast).unwrap();
  37             highlight_name(sema, bindings_shadow_count, &mut binding_hash, krate, name)
  38         }
  39         // Highlight references like the definitions they resolve to
  40         NAME_REF if element.ancestors().any(|it| it.kind() == ATTR) => {
  41             // FIXME: We highlight paths in attributes slightly differently to work around this module
  42             // currently not knowing about tool attributes and rustc builtin attributes as
  43             // we do not want to resolve those to functions that may be defined in scope.
  44             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
  45             highlight_name_ref_in_attr(sema, name_ref)
  46         }
  47         NAME_REF => {
  48             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
  49             highlight_name_ref(
  50                 sema,
  51                 krate,
  52                 bindings_shadow_count,
  53                 &mut binding_hash,
  54                 syntactic_name_ref_highlighting,
  55                 name_ref,
  56             )
  57         }
  58
  59         // Simple token-based highlighting
  60         COMMENT => {
  61             let comment = element.into_token().and_then(ast::Comment::cast)?;
  62             let h = HlTag::Comment;
  63             match comment.kind().doc {
  64                 Some(_) => h | HlMod::Documentation,
  65                 None => h.into(),
  66             }
  67         }
  68         STRING | BYTE_STRING => HlTag::StringLiteral.into(),
  69         ATTR => HlTag::Attribute.into(),
  70         INT_NUMBER if element.ancestors().nth(1).map_or(false, |it| it.kind() == FIELD_EXPR) => {
  71             SymbolKind::Field.into()
  72         }
  73         INT_NUMBER | FLOAT_NUMBER => HlTag::NumericLiteral.into(),
  74         BYTE => HlTag::ByteLiteral.into(),
  75         CHAR => HlTag::CharLiteral.into(),
  76         QUESTION => HlTag::Operator(HlOperator::Other) | HlMod::ControlFlow,
  77         LIFETIME => {
  78             let lifetime = element.into_node().and_then(ast::Lifetime::cast).unwrap();
  79
  80             match NameClass::classify_lifetime(sema, &lifetime) {
  81                 Some(NameClass::Definition(def)) => {
  82                     highlight_def(db, krate, def) | HlMod::Definition
  83                 }
  84                 None => match NameRefClass::classify_lifetime(sema, &lifetime) {
  85                     Some(NameRefClass::Definition(def)) => highlight_def(db, krate, def),
  86                     _ => SymbolKind::LifetimeParam.into(),
  87                 },
  88                 _ => Highlight::from(SymbolKind::LifetimeParam) | HlMod::Definition,
  89             }
  90         }
  91         IDENT if parent_matches::<ast::TokenTree>(&element) => HlTag::None.into(),
  92         p if p.is_punct() => match p {
  93             T![&] if parent_matches::<ast::BinExpr>(&element) => HlOperator::Bitwise.into(),
  94             T![&] => {
  95                 let h = HlTag::Operator(HlOperator::Other).into();
  96                 let is_unsafe = element
  97                     .parent()
  98                     .and_then(ast::RefExpr::cast)
  99                     .map_or(false, |ref_expr| sema.is_unsafe_ref_expr(&ref_expr));
 100                 if is_unsafe {
 101                     h | HlMod::Unsafe
 102                 } else {
 103                     h
 104                 }
 105             }
 106             T![::] | T![->] | T![=>] | T![..] | T![=] | T![@] | T![.] => HlOperator::Other.into(),
 107             T![!] if parent_matches::<ast::MacroCall>(&element) => SymbolKind::Macro.into(),
 108             T![!] if parent_matches::<ast::NeverType>(&element) => HlTag::BuiltinType.into(),
 109             T![!] if parent_matches::<ast::PrefixExpr>(&element) => HlOperator::Logical.into(),
 110             T![*] if parent_matches::<ast::PtrType>(&element) => HlTag::Keyword.into(),
 111             T![*] if parent_matches::<ast::PrefixExpr>(&element) => {
 112                 let prefix_expr = element.parent().and_then(ast::PrefixExpr::cast)?;
 113
 114                 let expr = prefix_expr.expr()?;
 115                 let ty = sema.type_of_expr(&expr)?;
 116                 if ty.is_raw_ptr() {
 117                     HlTag::Operator(HlOperator::Other) | HlMod::Unsafe
 118                 } else if let Some(ast::PrefixOp::Deref) = prefix_expr.op_kind() {
 119                     HlOperator::Other.into()
 120                 } else {
 121                     HlPunct::Other.into()
 122                 }
 123             }
 124             T![-] if parent_matches::<ast::PrefixExpr>(&element) => {
 125                 let prefix_expr = element.parent().and_then(ast::PrefixExpr::cast)?;
 126
 127                 let expr = prefix_expr.expr()?;
 128                 match expr {
 129                     ast::Expr::Literal(_) => HlTag::NumericLiteral,
 130                     _ => HlTag::Operator(HlOperator::Other),
 131                 }
 132                 .into()
 133             }
 134             _ if parent_matches::<ast::PrefixExpr>(&element) => HlOperator::Other.into(),
 135             T![+] | T![-] | T![*] | T![/] | T![+=] | T![-=] | T![*=] | T![/=]
 136                 if parent_matches::<ast::BinExpr>(&element) =>
 137             {
 138                 HlOperator::Arithmetic.into()
 139             }
 140             T![|] | T![&] | T![!] | T![^] | T![|=] | T![&=] | T![^=]
 141                 if parent_matches::<ast::BinExpr>(&element) =>
 142             {
 143                 HlOperator::Bitwise.into()
 144             }
 145             T![&&] | T![||] if parent_matches::<ast::BinExpr>(&element) => {
 146                 HlOperator::Logical.into()
 147             }
 148             T![>] | T![<] | T![==] | T![>=] | T![<=] | T![!=]
 149                 if parent_matches::<ast::BinExpr>(&element) =>
 150             {
 151                 HlOperator::Comparison.into()
 152             }
 153             _ if parent_matches::<ast::BinExpr>(&element) => HlOperator::Other.into(),
 154             _ if parent_matches::<ast::RangeExpr>(&element) => HlOperator::Other.into(),
 155             _ if parent_matches::<ast::RangePat>(&element) => HlOperator::Other.into(),
 156             _ if parent_matches::<ast::RestPat>(&element) => HlOperator::Other.into(),
 157             _ if parent_matches::<ast::Attr>(&element) => HlTag::Attribute.into(),
 158             kind => match kind {
 159                 T!['['] | T![']'] => HlPunct::Bracket,
 160                 T!['{'] | T!['}'] => HlPunct::Brace,
 161                 T!['('] | T![')'] => HlPunct::Parenthesis,
 162                 T![<] | T![>] => HlPunct::Angle,
 163                 T![,] => HlPunct::Comma,
 164                 T![:] => HlPunct::Colon,
 165                 T![;] => HlPunct::Semi,
 166                 T![.] => HlPunct::Dot,
 167                 _ => HlPunct::Other,
 168             }
 169             .into(),
 170         },
 171
 172         k if k.is_keyword() => {
 173             let h = Highlight::new(HlTag::Keyword);
 174             match k {
 175                 T![await] => h | HlMod::Async | HlMod::ControlFlow,
 176                 T![break]
 177                 | T![continue]
 178                 | T![else]
 179                 | T![if]
 180                 | T![in]
 181                 | T![loop]
 182                 | T![match]
 183                 | T![return]
 184                 | T![while]
 185                 | T![yield] => h | HlMod::ControlFlow,
 186                 T![for] if !is_child_of_impl(&element) => h | HlMod::ControlFlow,
 187                 T![unsafe] => h | HlMod::Unsafe,
 188                 T![true] | T![false] => HlTag::BoolLiteral.into(),
 189                 // self is handled as either a Name or NameRef already
 190                 T![self] => return None,
 191                 T![ref] => element
 192                     .parent()
 193                     .and_then(ast::IdentPat::cast)
 194                     .and_then(|ident_pat| {
 195                         if sema.is_unsafe_ident_pat(&ident_pat) {
 196                             Some(HlMod::Unsafe)
 197                         } else {
 198                             None
 199                         }
 200                     })
 201                     .map(|modifier| h | modifier)
 202                     .unwrap_or(h),
 203                 T![async] => h | HlMod::Async,
 204                 _ => h,
 205             }
 206         }
 207
 208         _ => return None,
 209     };
 210
 211     return Some((highlight, binding_hash));
 212 }
 213
 214 fn highlight_name_ref_in_attr(sema: &Semantics<RootDatabase>, name_ref: ast::NameRef) -> Highlight {
 215     match NameRefClass::classify(sema, &name_ref) {
 216         Some(name_class) => match name_class {
 217             NameRefClass::Definition(Definition::ModuleDef(hir::ModuleDef::Module(_)))
 218                 if name_ref
 219                     .syntax()
 220                     .ancestors()
 221                     .find_map(ast::Path::cast)
 222                     .map_or(false, |it| it.parent_path().is_some()) =>
 223             {
 224                 HlTag::Symbol(SymbolKind::Module)
 225             }
 226             NameRefClass::Definition(Definition::Macro(m)) if m.kind() == hir::MacroKind::Attr => {
 227                 HlTag::Symbol(SymbolKind::Macro)
 228             }
 229             _ => HlTag::BuiltinAttr,
 230         },
 231         None => HlTag::BuiltinAttr,
 232     }
 233     .into()
 234 }
 235
 236 fn highlight_name_ref(
 237     sema: &Semantics<RootDatabase>,
 238     krate: Option<hir::Crate>,
 239     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 240     binding_hash: &mut Option<u64>,
 241     syntactic_name_ref_highlighting: bool,
 242     name_ref: ast::NameRef,
 243 ) -> Highlight {
 244     let db = sema.db;
 245     highlight_method_call_by_name_ref(sema, krate, &name_ref).unwrap_or_else(|| {
 246         let name_class = match NameRefClass::classify(sema, &name_ref) {
 247             Some(name_kind) => name_kind,
 248             None => {
 249                 return if syntactic_name_ref_highlighting {
 250                     highlight_name_ref_by_syntax(name_ref, sema, krate)
 251                 } else {
 252                     HlTag::UnresolvedReference.into()
 253                 }
 254             }
 255         };
 256         let h = match name_class {
 257             NameRefClass::Definition(def) => {
 258                 if let Definition::Local(local) = &def {
 259                     if let Some(name) = local.name(db) {
 260                         let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 261                         *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 262                     }
 263                 };
 264
 265                 let mut h = highlight_def(db, krate, def);
 266
 267                 match def {
 268                     Definition::Local(local)
 269                         if is_consumed_lvalue(name_ref.syntax(), &local, db) =>
 270                     {
 271                         h |= HlMod::Consuming;
 272                     }
 273                     Definition::ModuleDef(hir::ModuleDef::Trait(trait_))
 274                         if trait_.is_unsafe(db) =>
 275                     {
 276                         if ast::Impl::for_trait_name_ref(&name_ref).is_some() {
 277                             h |= HlMod::Unsafe;
 278                         }
 279                     }
 280                     Definition::Field(field) => {
 281                         if let Some(parent) = name_ref.syntax().parent() {
 282                             if matches!(parent.kind(), FIELD_EXPR | RECORD_PAT_FIELD) {
 283                                 if let hir::VariantDef::Union(_) = field.parent_def(db) {
 284                                     h |= HlMod::Unsafe;
 285                                 }
 286                             }
 287                         }
 288                     }
 289                     _ => (),
 290                 }
 291
 292                 h
 293             }
 294             NameRefClass::FieldShorthand { .. } => SymbolKind::Field.into(),
 295         };
 296         if h.tag == HlTag::Symbol(SymbolKind::Module) && name_ref.self_token().is_some() {
 297             SymbolKind::SelfParam.into()
 298         } else {
 299             h
 300         }
 301     })
 302 }
 303
 304 fn highlight_name(
 305     sema: &Semantics<RootDatabase>,
 306     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 307     binding_hash: &mut Option<u64>,
 308     krate: Option<hir::Crate>,
 309     name: ast::Name,
 310 ) -> Highlight {
 311     let db = sema.db;
 312     let name_kind = NameClass::classify(sema, &name);
 313     if let Some(NameClass::Definition(Definition::Local(local))) = &name_kind {
 314         if let Some(name) = local.name(db) {
 315             let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 316             *shadow_count += 1;
 317             *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 318         }
 319     };
 320     match name_kind {
 321         Some(NameClass::Definition(def)) => {
 322             let mut h = highlight_def(db, krate, def) | HlMod::Definition;
 323             if let Definition::ModuleDef(hir::ModuleDef::Trait(trait_)) = &def {
 324                 if trait_.is_unsafe(db) {
 325                     h |= HlMod::Unsafe;
 326                 }
 327             }
 328             h
 329         }
 330         Some(NameClass::ConstReference(def)) => highlight_def(db, krate, def),
 331         Some(NameClass::PatFieldShorthand { field_ref, .. }) => {
 332             let mut h = HlTag::Symbol(SymbolKind::Field).into();
 333             if let hir::VariantDef::Union(_) = field_ref.parent_def(db) {
 334                 h |= HlMod::Unsafe;
 335             }
 336             h
 337         }
 338         None => highlight_name_by_syntax(name) | HlMod::Definition,
 339     }
 340 }
 341
 342 fn calc_binding_hash(name: &hir::Name, shadow_count: u32) -> u64 {
 343     fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
 344         use std::{collections::hash_map::DefaultHasher, hash::Hasher};
 345
 346         let mut hasher = DefaultHasher::new();
 347         x.hash(&mut hasher);
 348         hasher.finish()
 349     }
 350
 351     hash((name, shadow_count))
 352 }
 353
 354 fn highlight_def(db: &RootDatabase, krate: Option<hir::Crate>, def: Definition) -> Highlight {
 355     let mut h = match def {
 356         Definition::Macro(_) => Highlight::new(HlTag::Symbol(SymbolKind::Macro)),
 357         Definition::Field(_) => Highlight::new(HlTag::Symbol(SymbolKind::Field)),
 358         Definition::ModuleDef(def) => match def {
 359             hir::ModuleDef::Module(_) => Highlight::new(HlTag::Symbol(SymbolKind::Module)),
 360             hir::ModuleDef::Function(func) => {
 361                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Function));
 362                 if let Some(item) = func.as_assoc_item(db) {
 363                     h |= HlMod::Associated;
 364                     match func.self_param(db) {
 365                         Some(sp) => {
 366                             if let hir::Access::Exclusive = sp.access(db) {
 367                                 h |= HlMod::Mutable;
 368                             }
 369                         }
 370                         None => h |= HlMod::Static,
 371                     }
 372
 373                     match item.container(db) {
 374                         hir::AssocItemContainer::Impl(i) => {
 375                             if i.trait_(db).is_some() {
 376                                 h |= HlMod::Trait;
 377                             }
 378                         }
 379                         hir::AssocItemContainer::Trait(_t) => {
 380                             h |= HlMod::Trait;
 381                         }
 382                     }
 383                 }
 384
 385                 if func.is_unsafe(db) {
 386                     h |= HlMod::Unsafe;
 387                 }
 388                 if func.is_async(db) {
 389                     h |= HlMod::Async;
 390                 }
 391
 392                 h
 393             }
 394             hir::ModuleDef::Adt(adt) => {
 395                 let h = match adt {
 396                     hir::Adt::Struct(_) => HlTag::Symbol(SymbolKind::Struct),
 397                     hir::Adt::Enum(_) => HlTag::Symbol(SymbolKind::Enum),
 398                     hir::Adt::Union(_) => HlTag::Symbol(SymbolKind::Union),
 399                 };
 400
 401                 Highlight::new(h)
 402             }
 403             hir::ModuleDef::Variant(_) => Highlight::new(HlTag::Symbol(SymbolKind::Variant)),
 404             hir::ModuleDef::Const(konst) => {
 405                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Const));
 406
 407                 if let Some(item) = konst.as_assoc_item(db) {
 408                     h |= HlMod::Associated;
 409                     match item.container(db) {
 410                         hir::AssocItemContainer::Impl(i) => {
 411                             if i.trait_(db).is_some() {
 412                                 h |= HlMod::Trait;
 413                             }
 414                         }
 415                         hir::AssocItemContainer::Trait(_t) => {
 416                             h |= HlMod::Trait;
 417                         }
 418                     }
 419                 }
 420
 421                 h
 422             }
 423             hir::ModuleDef::Trait(_) => Highlight::new(HlTag::Symbol(SymbolKind::Trait)),
 424             hir::ModuleDef::TypeAlias(type_) => {
 425                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::TypeAlias));
 426
 427                 if let Some(item) = type_.as_assoc_item(db) {
 428                     h |= HlMod::Associated;
 429                     match item.container(db) {
 430                         hir::AssocItemContainer::Impl(i) => {
 431                             if i.trait_(db).is_some() {
 432                                 h |= HlMod::Trait;
 433                             }
 434                         }
 435                         hir::AssocItemContainer::Trait(_t) => {
 436                             h |= HlMod::Trait;
 437                         }
 438                     }
 439                 }
 440
 441                 h
 442             }
 443             hir::ModuleDef::BuiltinType(_) => Highlight::new(HlTag::BuiltinType),
 444             hir::ModuleDef::Static(s) => {
 445                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Static));
 446
 447                 if s.is_mut(db) {
 448                     h |= HlMod::Mutable;
 449                     h |= HlMod::Unsafe;
 450                 }
 451
 452                 h
 453             }
 454         },
 455         Definition::SelfType(_) => Highlight::new(HlTag::Symbol(SymbolKind::Impl)),
 456         Definition::GenericParam(it) => match it {
 457             hir::GenericParam::TypeParam(_) => Highlight::new(HlTag::Symbol(SymbolKind::TypeParam)),
 458             hir::GenericParam::ConstParam(_) => {
 459                 Highlight::new(HlTag::Symbol(SymbolKind::ConstParam))
 460             }
 461             hir::GenericParam::LifetimeParam(_) => {
 462                 Highlight::new(HlTag::Symbol(SymbolKind::LifetimeParam))
 463             }
 464         },
 465         Definition::Local(local) => {
 466             let tag = if local.is_self(db) {
 467                 HlTag::Symbol(SymbolKind::SelfParam)
 468             } else if local.is_param(db) {
 469                 HlTag::Symbol(SymbolKind::ValueParam)
 470             } else {
 471                 HlTag::Symbol(SymbolKind::Local)
 472             };
 473             let mut h = Highlight::new(tag);
 474             let ty = local.ty(db);
 475             if local.is_mut(db) || ty.is_mutable_reference() {
 476                 h |= HlMod::Mutable;
 477             }
 478             if ty.as_callable(db).is_some() || ty.impls_fnonce(db) {
 479                 h |= HlMod::Callable;
 480             }
 481             h
 482         }
 483         Definition::Label(_) => Highlight::new(HlTag::Symbol(SymbolKind::Label)),
 484     };
 485
 486     let is_from_other_crate = def.module(db).map(hir::Module::krate) != krate;
 487     let is_builtin_type = matches!(def, Definition::ModuleDef(hir::ModuleDef::BuiltinType(_)));
 488     let is_public = def.visibility(db) == Some(hir::Visibility::Public);
 489
 490     match (is_from_other_crate, is_builtin_type, is_public) {
 491         (true, false, _) => h |= HlMod::Library,
 492         (false, _, true) => h |= HlMod::Public,
 493         _ => {}
 494     }
 495
 496     h
 497 }
 498
 499 fn highlight_method_call_by_name_ref(
 500     sema: &Semantics<RootDatabase>,
 501     krate: Option<hir::Crate>,
 502     name_ref: &ast::NameRef,
 503 ) -> Option<Highlight> {
 504     let mc = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
 505     highlight_method_call(sema, krate, &mc)
 506 }
 507
 508 fn highlight_method_call(
 509     sema: &Semantics<RootDatabase>,
 510     krate: Option<hir::Crate>,
 511     method_call: &ast::MethodCallExpr,
 512 ) -> Option<Highlight> {
 513     let func = sema.resolve_method_call(method_call)?;
 514
 515     let mut h = SymbolKind::Function.into();
 516     h |= HlMod::Associated;
 517
 518     if func.is_unsafe(sema.db) || sema.is_unsafe_method_call(method_call) {
 519         h |= HlMod::Unsafe;
 520     }
 521     if func.is_async(sema.db) {
 522         h |= HlMod::Async;
 523     }
 524     if func.as_assoc_item(sema.db).and_then(|it| it.containing_trait(sema.db)).is_some() {
 525         h |= HlMod::Trait;
 526     }
 527
 528     let is_from_other_crate = Some(func.module(sema.db).krate()) != krate;
 529     let is_public = func.visibility(sema.db) == hir::Visibility::Public;
 530
 531     if is_from_other_crate {
 532         h |= HlMod::Library;
 533     } else if is_public {
 534         h |= HlMod::Public;
 535     }
 536
 537     if let Some(self_param) = func.self_param(sema.db) {
 538         match self_param.access(sema.db) {
 539             hir::Access::Shared => (),
 540             hir::Access::Exclusive => h |= HlMod::Mutable,
 541             hir::Access::Owned => {
 542                 if let Some(receiver_ty) =
 543                     method_call.receiver().and_then(|it| sema.type_of_expr(&it))
 544                 {
 545                     if !receiver_ty.is_copy(sema.db) {
 546                         h |= HlMod::Consuming
 547                     }
 548                 }
 549             }
 550         }
 551     }
 552     Some(h)
 553 }
 554
 555 fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
 556     let default = HlTag::UnresolvedReference;
 557
 558     let parent = match name.syntax().parent() {
 559         Some(it) => it,
 560         _ => return default.into(),
 561     };
 562
 563     let tag = match parent.kind() {
 564         STRUCT => SymbolKind::Struct,
 565         ENUM => SymbolKind::Enum,
 566         VARIANT => SymbolKind::Variant,
 567         UNION => SymbolKind::Union,
 568         TRAIT => SymbolKind::Trait,
 569         TYPE_ALIAS => SymbolKind::TypeAlias,
 570         TYPE_PARAM => SymbolKind::TypeParam,
 571         RECORD_FIELD => SymbolKind::Field,
 572         MODULE => SymbolKind::Module,
 573         FN => SymbolKind::Function,
 574         CONST => SymbolKind::Const,
 575         STATIC => SymbolKind::Static,
 576         IDENT_PAT => SymbolKind::Local,
 577         _ => return default.into(),
 578     };
 579
 580     tag.into()
 581 }
 582
 583 fn highlight_name_ref_by_syntax(
 584     name: ast::NameRef,
 585     sema: &Semantics<RootDatabase>,
 586     krate: Option<hir::Crate>,
 587 ) -> Highlight {
 588     let default = HlTag::UnresolvedReference;
 589
 590     let parent = match name.syntax().parent() {
 591         Some(it) => it,
 592         _ => return default.into(),
 593     };
 594
 595     match parent.kind() {
 596         METHOD_CALL_EXPR => ast::MethodCallExpr::cast(parent)
 597             .and_then(|it| highlight_method_call(sema, krate, &it))
 598             .unwrap_or_else(|| SymbolKind::Function.into()),
 599         FIELD_EXPR => {
 600             let h = HlTag::Symbol(SymbolKind::Field);
 601             let is_union = ast::FieldExpr::cast(parent)
 602                 .and_then(|field_expr| sema.resolve_field(&field_expr))
 603                 .map_or(false, |field| {
 604                     matches!(field.parent_def(sema.db), hir::VariantDef::Union(_))
 605                 });
 606             if is_union {
 607                 h | HlMod::Unsafe
 608             } else {
 609                 h.into()
 610             }
 611         }
 612         PATH_SEGMENT => {
 613             let path = match parent.parent().and_then(ast::Path::cast) {
 614                 Some(it) => it,
 615                 _ => return default.into(),
 616             };
 617             let expr = match path.syntax().parent().and_then(ast::PathExpr::cast) {
 618                 Some(it) => it,
 619                 _ => {
 620                     // within path, decide whether it is module or adt by checking for uppercase name
 621                     return if name.text().chars().next().unwrap_or_default().is_uppercase() {
 622                         SymbolKind::Struct
 623                     } else {
 624                         SymbolKind::Module
 625                     }
 626                     .into();
 627                 }
 628             };
 629             let parent = match expr.syntax().parent() {
 630                 Some(it) => it,
 631                 None => return default.into(),
 632             };
 633
 634             match parent.kind() {
 635                 CALL_EXPR => SymbolKind::Function.into(),
 636                 _ => if name.text().chars().next().unwrap_or_default().is_uppercase() {
 637                     SymbolKind::Struct
 638                 } else {
 639                     SymbolKind::Const
 640                 }
 641                 .into(),
 642             }
 643         }
 644         _ => default.into(),
 645     }
 646 }
 647
 648 fn is_consumed_lvalue(node: &SyntaxNode, local: &hir::Local, db: &RootDatabase) -> bool {
 649     // When lvalues are passed as arguments and they're not Copy, then mark them as Consuming.
 650     parents_match(node.clone().into(), &[PATH_SEGMENT, PATH, PATH_EXPR, ARG_LIST])
 651         && !local.ty(db).is_copy(db)
 652 }
 653
 654 /// Returns true if the parent nodes of `node` all match the `SyntaxKind`s in `kinds` exactly.
 655 fn parents_match(mut node: NodeOrToken<SyntaxNode, SyntaxToken>, mut kinds: &[SyntaxKind]) -> bool {
 656     while let (Some(parent), [kind, rest @ ..]) = (&node.parent(), kinds) {
 657         if parent.kind() != *kind {
 658             return false;
 659         }
 660
 661         // FIXME: Would be nice to get parent out of the match, but binding by-move and by-value
 662         // in the same pattern is unstable: rust-lang/rust#68354.
 663         node = node.parent().unwrap().into();
 664         kinds = rest;
 665     }
 666
 667     // Only true if we matched all expected kinds
 668     kinds.len() == 0
 669 }
 670
 671 #[inline]
 672 fn parent_matches<N: AstNode>(element: &SyntaxElement) -> bool {
 673     element.parent().map_or(false, |it| N::can_cast(it.kind()))
 674 }
 675
 676 fn is_child_of_impl(element: &SyntaxElement) -> bool {
 677     match element.parent() {
 678         Some(e) => e.kind() == IMPL,
 679         _ => false,
 680     }
 681 }