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     helpers::{try_resolve_derive_input, FamousDefs},
   7     RootDatabase, SymbolKind,
   8 };
   9 use rustc_hash::FxHashMap;
  10 use syntax::{
  11     ast, match_ast, AstNode, AstToken, NodeOrToken, SyntaxElement,
  12     SyntaxKind::{self, *},
  13     SyntaxNode, SyntaxToken, T,
  14 };
  15
  16 use crate::{
  17     syntax_highlighting::tags::{HlOperator, HlPunct},
  18     Highlight, HlMod, HlTag,
  19 };
  20
  21 pub(super) fn element(
  22     sema: &Semantics<RootDatabase>,
  23     krate: Option<hir::Crate>,
  24     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
  25     syntactic_name_ref_highlighting: bool,
  26     element: SyntaxElement,
  27 ) -> Option<(Highlight, Option<u64>)> {
  28     match element {
  29         NodeOrToken::Node(it) => {
  30             node(sema, krate, bindings_shadow_count, syntactic_name_ref_highlighting, it)
  31         }
  32         NodeOrToken::Token(it) => Some((token(sema, krate, it)?, None)),
  33     }
  34 }
  35
  36 fn token(
  37     sema: &Semantics<RootDatabase>,
  38     krate: Option<hir::Crate>,
  39     token: SyntaxToken,
  40 ) -> Option<Highlight> {
  41     let highlight: Highlight = if let Some(comment) = ast::Comment::cast(token.clone()) {
  42         let h = HlTag::Comment;
  43         match comment.kind().doc {
  44             Some(_) => h | HlMod::Documentation,
  45             None => h.into(),
  46         }
  47     } else {
  48         match token.kind() {
  49             STRING | BYTE_STRING => HlTag::StringLiteral.into(),
  50             INT_NUMBER if token.ancestors().nth(1).map_or(false, |it| it.kind() == FIELD_EXPR) => {
  51                 SymbolKind::Field.into()
  52             }
  53             INT_NUMBER | FLOAT_NUMBER => HlTag::NumericLiteral.into(),
  54             BYTE => HlTag::ByteLiteral.into(),
  55             CHAR => HlTag::CharLiteral.into(),
  56             T![?] => HlTag::Operator(HlOperator::Other) | HlMod::ControlFlow,
  57             IDENT if parent_matches::<ast::TokenTree>(&token) => {
  58                 if let Some(attr) = token.ancestors().nth(2).and_then(ast::Attr::cast) {
  59                     match try_resolve_derive_input(sema, &attr, &ast::Ident::cast(token).unwrap()) {
  60                         Some(res) => highlight_def(sema, krate, Definition::from(res)),
  61                         None => HlTag::None.into(),
  62                     }
  63                 } else {
  64                     HlTag::None.into()
  65                 }
  66             }
  67             p if p.is_punct() => match p {
  68                 T![&] if parent_matches::<ast::BinExpr>(&token) => HlOperator::Bitwise.into(),
  69                 T![&] => {
  70                     let h = HlTag::Operator(HlOperator::Other).into();
  71                     let is_unsafe = token
  72                         .parent()
  73                         .and_then(ast::RefExpr::cast)
  74                         .map_or(false, |ref_expr| sema.is_unsafe_ref_expr(&ref_expr));
  75                     if is_unsafe {
  76                         h | HlMod::Unsafe
  77                     } else {
  78                         h
  79                     }
  80                 }
  81                 T![::] | T![->] | T![=>] | T![..] | T![=] | T![@] | T![.] => {
  82                     HlOperator::Other.into()
  83                 }
  84                 T![!] if parent_matches::<ast::MacroCall>(&token) => SymbolKind::Macro.into(),
  85                 T![!] if parent_matches::<ast::NeverType>(&token) => HlTag::BuiltinType.into(),
  86                 T![!] if parent_matches::<ast::PrefixExpr>(&token) => HlOperator::Logical.into(),
  87                 T![*] if parent_matches::<ast::PtrType>(&token) => HlTag::Keyword.into(),
  88                 T![*] if parent_matches::<ast::PrefixExpr>(&token) => {
  89                     let prefix_expr = token.parent().and_then(ast::PrefixExpr::cast)?;
  90
  91                     let expr = prefix_expr.expr()?;
  92                     let ty = sema.type_of_expr(&expr)?.original;
  93                     if ty.is_raw_ptr() {
  94                         HlTag::Operator(HlOperator::Other) | HlMod::Unsafe
  95                     } else if let Some(ast::UnaryOp::Deref) = prefix_expr.op_kind() {
  96                         HlOperator::Other.into()
  97                     } else {
  98                         HlPunct::Other.into()
  99                     }
 100                 }
 101                 T![-] if parent_matches::<ast::PrefixExpr>(&token) => {
 102                     let prefix_expr = token.parent().and_then(ast::PrefixExpr::cast)?;
 103
 104                     let expr = prefix_expr.expr()?;
 105                     match expr {
 106                         ast::Expr::Literal(_) => HlTag::NumericLiteral,
 107                         _ => HlTag::Operator(HlOperator::Other),
 108                     }
 109                     .into()
 110                 }
 111                 _ if parent_matches::<ast::PrefixExpr>(&token) => HlOperator::Other.into(),
 112                 T![+] | T![-] | T![*] | T![/] if parent_matches::<ast::BinExpr>(&token) => {
 113                     HlOperator::Arithmetic.into()
 114                 }
 115                 T![+=] | T![-=] | T![*=] | T![/=] if parent_matches::<ast::BinExpr>(&token) => {
 116                     Highlight::from(HlOperator::Arithmetic) | HlMod::Mutable
 117                 }
 118                 T![|] | T![&] | T![!] | T![^] if parent_matches::<ast::BinExpr>(&token) => {
 119                     HlOperator::Bitwise.into()
 120                 }
 121                 T![|=] | T![&=] | T![^=] if parent_matches::<ast::BinExpr>(&token) => {
 122                     Highlight::from(HlOperator::Bitwise) | HlMod::Mutable
 123                 }
 124                 T![&&] | T![||] if parent_matches::<ast::BinExpr>(&token) => {
 125                     HlOperator::Logical.into()
 126                 }
 127                 T![>] | T![<] | T![==] | T![>=] | T![<=] | T![!=]
 128                     if parent_matches::<ast::BinExpr>(&token) =>
 129                 {
 130                     HlOperator::Comparison.into()
 131                 }
 132                 _ if parent_matches::<ast::BinExpr>(&token) => HlOperator::Other.into(),
 133                 _ if parent_matches::<ast::RangeExpr>(&token) => HlOperator::Other.into(),
 134                 _ if parent_matches::<ast::RangePat>(&token) => HlOperator::Other.into(),
 135                 _ if parent_matches::<ast::RestPat>(&token) => HlOperator::Other.into(),
 136                 _ if parent_matches::<ast::Attr>(&token) => HlTag::Attribute.into(),
 137                 kind => match kind {
 138                     T!['['] | T![']'] => HlPunct::Bracket,
 139                     T!['{'] | T!['}'] => HlPunct::Brace,
 140                     T!['('] | T![')'] => HlPunct::Parenthesis,
 141                     T![<] | T![>] => HlPunct::Angle,
 142                     T![,] => HlPunct::Comma,
 143                     T![:] => HlPunct::Colon,
 144                     T![;] => HlPunct::Semi,
 145                     T![.] => HlPunct::Dot,
 146                     _ => HlPunct::Other,
 147                 }
 148                 .into(),
 149             },
 150             k if k.is_keyword() => {
 151                 let h = Highlight::new(HlTag::Keyword);
 152                 match k {
 153                     T![await] => h | HlMod::Async | HlMod::ControlFlow,
 154                     T![break]
 155                     | T![continue]
 156                     | T![else]
 157                     | T![if]
 158                     | T![in]
 159                     | T![loop]
 160                     | T![match]
 161                     | T![return]
 162                     | T![while]
 163                     | T![yield] => h | HlMod::ControlFlow,
 164                     T![for] if !is_child_of_impl(&token) => h | HlMod::ControlFlow,
 165                     T![unsafe] => h | HlMod::Unsafe,
 166                     T![true] | T![false] => HlTag::BoolLiteral.into(),
 167                     // crate is handled just as a token if it's in an `extern crate`
 168                     T![crate] if parent_matches::<ast::ExternCrate>(&token) => h,
 169                     // self, crate and super are handled as either a Name or NameRef already
 170                     T![self] | T![crate] | T![super] => return None,
 171                     T![ref] => token
 172                         .parent()
 173                         .and_then(ast::IdentPat::cast)
 174                         .and_then(|ident_pat| {
 175                             (sema.is_unsafe_ident_pat(&ident_pat)).then(|| HlMod::Unsafe)
 176                         })
 177                         .map_or(h, |modifier| h | modifier),
 178                     T![async] => h | HlMod::Async,
 179                     _ => h,
 180                 }
 181             }
 182             _ => return None,
 183         }
 184     };
 185     Some(highlight)
 186 }
 187
 188 fn node(
 189     sema: &Semantics<RootDatabase>,
 190     krate: Option<hir::Crate>,
 191     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 192     syntactic_name_ref_highlighting: bool,
 193     node: SyntaxNode,
 194 ) -> Option<(Highlight, Option<u64>)> {
 195     let mut binding_hash = None;
 196     let highlight = match_ast! {
 197         match node {
 198             ast::Fn(__) => {
 199                 bindings_shadow_count.clear();
 200                 return None;
 201             },
 202             ast::Attr(__) => {
 203                 HlTag::Attribute.into()
 204             },
 205             // Highlight definitions depending on the "type" of the definition.
 206             ast::Name(name) => {
 207                 highlight_name(sema, bindings_shadow_count, &mut binding_hash, krate, name)
 208             },
 209             // Highlight references like the definitions they resolve to
 210             ast::NameRef(name_ref) => {
 211                 if node.ancestors().any(|it| it.kind() == ATTR) {
 212
 213                     // FIXME: We highlight paths in attributes slightly differently to work around this module
 214                     // currently not knowing about tool attributes and rustc builtin attributes as
 215                     // we do not want to resolve those to functions that may be defined in scope.
 216                     highlight_name_ref_in_attr(sema, name_ref)
 217                 } else {
 218                     highlight_name_ref(
 219                         sema,
 220                         krate,
 221                         bindings_shadow_count,
 222                         &mut binding_hash,
 223                         syntactic_name_ref_highlighting,
 224                         name_ref,
 225                     )
 226                 }
 227             },
 228             ast::Lifetime(lifetime) => {
 229                 match NameClass::classify_lifetime(sema, &lifetime) {
 230                     Some(NameClass::Definition(def)) => {
 231                         highlight_def(sema, krate, def) | HlMod::Definition
 232                     }
 233                     None => match NameRefClass::classify_lifetime(sema, &lifetime) {
 234                         Some(NameRefClass::Definition(def)) => highlight_def(sema, krate, def),
 235                         _ => SymbolKind::LifetimeParam.into(),
 236                     },
 237                     _ => Highlight::from(SymbolKind::LifetimeParam) | HlMod::Definition,
 238                 }
 239             },
 240             _ => return None,
 241         }
 242     };
 243     Some((highlight, binding_hash))
 244 }
 245
 246 fn highlight_name_ref_in_attr(sema: &Semantics<RootDatabase>, name_ref: ast::NameRef) -> Highlight {
 247     match NameRefClass::classify(sema, &name_ref) {
 248         Some(name_class) => match name_class {
 249             NameRefClass::Definition(Definition::ModuleDef(hir::ModuleDef::Module(_)))
 250                 if name_ref
 251                     .syntax()
 252                     .ancestors()
 253                     .find_map(ast::Path::cast)
 254                     .map_or(false, |it| it.parent_path().is_some()) =>
 255             {
 256                 HlTag::Symbol(SymbolKind::Module)
 257             }
 258             NameRefClass::Definition(Definition::Macro(m)) if m.kind() == hir::MacroKind::Attr => {
 259                 HlTag::Symbol(SymbolKind::Macro)
 260             }
 261             _ => HlTag::BuiltinAttr,
 262         },
 263         None => HlTag::BuiltinAttr,
 264     }
 265     .into()
 266 }
 267
 268 fn highlight_name_ref(
 269     sema: &Semantics<RootDatabase>,
 270     krate: Option<hir::Crate>,
 271     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 272     binding_hash: &mut Option<u64>,
 273     syntactic_name_ref_highlighting: bool,
 274     name_ref: ast::NameRef,
 275 ) -> Highlight {
 276     let db = sema.db;
 277     highlight_method_call_by_name_ref(sema, krate, &name_ref).unwrap_or_else(|| {
 278         let name_class = match NameRefClass::classify(sema, &name_ref) {
 279             Some(name_kind) => name_kind,
 280             None => {
 281                 return if syntactic_name_ref_highlighting {
 282                     highlight_name_ref_by_syntax(name_ref, sema, krate)
 283                 } else {
 284                     HlTag::UnresolvedReference.into()
 285                 }
 286             }
 287         };
 288         let mut h = match name_class {
 289             NameRefClass::Definition(def) => {
 290                 if let Definition::Local(local) = &def {
 291                     if let Some(name) = local.name(db) {
 292                         let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 293                         *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 294                     }
 295                 };
 296
 297                 let mut h = highlight_def(sema, krate, def);
 298
 299                 match def {
 300                     Definition::Local(local)
 301                         if is_consumed_lvalue(name_ref.syntax(), &local, db) =>
 302                     {
 303                         h |= HlMod::Consuming;
 304                     }
 305                     Definition::ModuleDef(hir::ModuleDef::Trait(trait_))
 306                         if trait_.is_unsafe(db) =>
 307                     {
 308                         if ast::Impl::for_trait_name_ref(&name_ref)
 309                             .map_or(false, |impl_| impl_.unsafe_token().is_some())
 310                         {
 311                             h |= HlMod::Unsafe;
 312                         }
 313                     }
 314                     Definition::Field(field) => {
 315                         if let Some(parent) = name_ref.syntax().parent() {
 316                             if matches!(parent.kind(), FIELD_EXPR | RECORD_PAT_FIELD) {
 317                                 if let hir::VariantDef::Union(_) = field.parent_def(db) {
 318                                     h |= HlMod::Unsafe;
 319                                 }
 320                             }
 321                         }
 322                     }
 323                     _ => (),
 324                 }
 325
 326                 h
 327             }
 328             NameRefClass::FieldShorthand { .. } => SymbolKind::Field.into(),
 329         };
 330         if h.tag == HlTag::Symbol(SymbolKind::Module) {
 331             if name_ref.self_token().is_some() {
 332                 return SymbolKind::SelfParam.into();
 333             }
 334             if name_ref.crate_token().is_some() || name_ref.super_token().is_some() {
 335                 h.tag = HlTag::Keyword;
 336             }
 337         }
 338         h
 339     })
 340 }
 341
 342 fn highlight_name(
 343     sema: &Semantics<RootDatabase>,
 344     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 345     binding_hash: &mut Option<u64>,
 346     krate: Option<hir::Crate>,
 347     name: ast::Name,
 348 ) -> Highlight {
 349     let db = sema.db;
 350     let name_kind = NameClass::classify(sema, &name);
 351     if let Some(NameClass::Definition(Definition::Local(local))) = &name_kind {
 352         if let Some(name) = local.name(db) {
 353             let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 354             *shadow_count += 1;
 355             *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 356         }
 357     };
 358     match name_kind {
 359         Some(NameClass::Definition(def)) => {
 360             let mut h = highlight_def(sema, krate, def) | HlMod::Definition;
 361             if let Definition::ModuleDef(hir::ModuleDef::Trait(trait_)) = &def {
 362                 if trait_.is_unsafe(db) {
 363                     h |= HlMod::Unsafe;
 364                 }
 365             }
 366             h
 367         }
 368         Some(NameClass::ConstReference(def)) => highlight_def(sema, krate, def),
 369         Some(NameClass::PatFieldShorthand { field_ref, .. }) => {
 370             let mut h = HlTag::Symbol(SymbolKind::Field).into();
 371             if let hir::VariantDef::Union(_) = field_ref.parent_def(db) {
 372                 h |= HlMod::Unsafe;
 373             }
 374             h
 375         }
 376         None => highlight_name_by_syntax(name) | HlMod::Definition,
 377     }
 378 }
 379
 380 fn calc_binding_hash(name: &hir::Name, shadow_count: u32) -> u64 {
 381     fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
 382         use std::{collections::hash_map::DefaultHasher, hash::Hasher};
 383
 384         let mut hasher = DefaultHasher::new();
 385         x.hash(&mut hasher);
 386         hasher.finish()
 387     }
 388
 389     hash((name, shadow_count))
 390 }
 391
 392 fn highlight_def(
 393     sema: &Semantics<RootDatabase>,
 394     krate: Option<hir::Crate>,
 395     def: Definition,
 396 ) -> Highlight {
 397     let db = sema.db;
 398     let mut h = match def {
 399         Definition::Macro(_) => Highlight::new(HlTag::Symbol(SymbolKind::Macro)),
 400         Definition::Field(_) => Highlight::new(HlTag::Symbol(SymbolKind::Field)),
 401         Definition::ModuleDef(def) => match def {
 402             hir::ModuleDef::Module(module) => {
 403                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Module));
 404                 if module.parent(db).is_none() {
 405                     h |= HlMod::CrateRoot
 406                 }
 407                 h
 408             }
 409             hir::ModuleDef::Function(func) => {
 410                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Function));
 411                 if let Some(item) = func.as_assoc_item(db) {
 412                     h |= HlMod::Associated;
 413                     match func.self_param(db) {
 414                         Some(sp) => match sp.access(db) {
 415                             hir::Access::Exclusive => {
 416                                 h |= HlMod::Mutable;
 417                                 h |= HlMod::Reference;
 418                             }
 419                             hir::Access::Shared => h |= HlMod::Reference,
 420                             hir::Access::Owned => h |= HlMod::Consuming,
 421                         },
 422                         None => h |= HlMod::Static,
 423                     }
 424
 425                     match item.container(db) {
 426                         hir::AssocItemContainer::Impl(i) => {
 427                             if i.trait_(db).is_some() {
 428                                 h |= HlMod::Trait;
 429                             }
 430                         }
 431                         hir::AssocItemContainer::Trait(_t) => {
 432                             h |= HlMod::Trait;
 433                         }
 434                     }
 435                 }
 436
 437                 if func.is_unsafe(db) {
 438                     h |= HlMod::Unsafe;
 439                 }
 440                 if func.is_async(db) {
 441                     h |= HlMod::Async;
 442                 }
 443
 444                 h
 445             }
 446             hir::ModuleDef::Adt(adt) => {
 447                 let h = match adt {
 448                     hir::Adt::Struct(_) => HlTag::Symbol(SymbolKind::Struct),
 449                     hir::Adt::Enum(_) => HlTag::Symbol(SymbolKind::Enum),
 450                     hir::Adt::Union(_) => HlTag::Symbol(SymbolKind::Union),
 451                 };
 452
 453                 Highlight::new(h)
 454             }
 455             hir::ModuleDef::Variant(_) => Highlight::new(HlTag::Symbol(SymbolKind::Variant)),
 456             hir::ModuleDef::Const(konst) => {
 457                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Const));
 458
 459                 if let Some(item) = konst.as_assoc_item(db) {
 460                     h |= HlMod::Associated;
 461                     match item.container(db) {
 462                         hir::AssocItemContainer::Impl(i) => {
 463                             if i.trait_(db).is_some() {
 464                                 h |= HlMod::Trait;
 465                             }
 466                         }
 467                         hir::AssocItemContainer::Trait(_t) => {
 468                             h |= HlMod::Trait;
 469                         }
 470                     }
 471                 }
 472
 473                 h
 474             }
 475             hir::ModuleDef::Trait(_) => Highlight::new(HlTag::Symbol(SymbolKind::Trait)),
 476             hir::ModuleDef::TypeAlias(type_) => {
 477                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::TypeAlias));
 478
 479                 if let Some(item) = type_.as_assoc_item(db) {
 480                     h |= HlMod::Associated;
 481                     match item.container(db) {
 482                         hir::AssocItemContainer::Impl(i) => {
 483                             if i.trait_(db).is_some() {
 484                                 h |= HlMod::Trait;
 485                             }
 486                         }
 487                         hir::AssocItemContainer::Trait(_t) => {
 488                             h |= HlMod::Trait;
 489                         }
 490                     }
 491                 }
 492
 493                 h
 494             }
 495             hir::ModuleDef::BuiltinType(_) => Highlight::new(HlTag::BuiltinType),
 496             hir::ModuleDef::Static(s) => {
 497                 let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Static));
 498
 499                 if s.is_mut(db) {
 500                     h |= HlMod::Mutable;
 501                     h |= HlMod::Unsafe;
 502                 }
 503
 504                 h
 505             }
 506         },
 507         Definition::SelfType(_) => Highlight::new(HlTag::Symbol(SymbolKind::Impl)),
 508         Definition::GenericParam(it) => match it {
 509             hir::GenericParam::TypeParam(_) => Highlight::new(HlTag::Symbol(SymbolKind::TypeParam)),
 510             hir::GenericParam::ConstParam(_) => {
 511                 Highlight::new(HlTag::Symbol(SymbolKind::ConstParam))
 512             }
 513             hir::GenericParam::LifetimeParam(_) => {
 514                 Highlight::new(HlTag::Symbol(SymbolKind::LifetimeParam))
 515             }
 516         },
 517         Definition::Local(local) => {
 518             let tag = if local.is_self(db) {
 519                 HlTag::Symbol(SymbolKind::SelfParam)
 520             } else if local.is_param(db) {
 521                 HlTag::Symbol(SymbolKind::ValueParam)
 522             } else {
 523                 HlTag::Symbol(SymbolKind::Local)
 524             };
 525             let mut h = Highlight::new(tag);
 526             let ty = local.ty(db);
 527             if local.is_mut(db) || ty.is_mutable_reference() {
 528                 h |= HlMod::Mutable;
 529             }
 530             if local.is_ref(db) || ty.is_reference() {
 531                 h |= HlMod::Reference;
 532             }
 533             if ty.as_callable(db).is_some() || ty.impls_fnonce(db) {
 534                 h |= HlMod::Callable;
 535             }
 536             h
 537         }
 538         Definition::Label(_) => Highlight::new(HlTag::Symbol(SymbolKind::Label)),
 539     };
 540
 541     let famous_defs = FamousDefs(sema, krate);
 542     let def_crate = def.module(db).map(hir::Module::krate).or_else(|| match def {
 543         Definition::ModuleDef(hir::ModuleDef::Module(module)) => Some(module.krate()),
 544         _ => None,
 545     });
 546     let is_from_other_crate = def_crate != krate;
 547     let is_from_builtin_crate =
 548         def_crate.map_or(false, |def_crate| famous_defs.builtin_crates().any(|it| def_crate == it));
 549     let is_builtin_type = matches!(def, Definition::ModuleDef(hir::ModuleDef::BuiltinType(_)));
 550     let is_public = def.visibility(db) == Some(hir::Visibility::Public);
 551
 552     match (is_from_other_crate, is_builtin_type, is_public) {
 553         (true, false, _) => h |= HlMod::Library,
 554         (false, _, true) => h |= HlMod::Public,
 555         _ => {}
 556     }
 557
 558     if is_from_builtin_crate {
 559         h |= HlMod::DefaultLibrary;
 560     }
 561
 562     h
 563 }
 564
 565 fn highlight_method_call_by_name_ref(
 566     sema: &Semantics<RootDatabase>,
 567     krate: Option<hir::Crate>,
 568     name_ref: &ast::NameRef,
 569 ) -> Option<Highlight> {
 570     let mc = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
 571     highlight_method_call(sema, krate, &mc)
 572 }
 573
 574 fn highlight_method_call(
 575     sema: &Semantics<RootDatabase>,
 576     krate: Option<hir::Crate>,
 577     method_call: &ast::MethodCallExpr,
 578 ) -> Option<Highlight> {
 579     let func = sema.resolve_method_call(method_call)?;
 580
 581     let mut h = SymbolKind::Function.into();
 582     h |= HlMod::Associated;
 583
 584     if func.is_unsafe(sema.db) || sema.is_unsafe_method_call(method_call) {
 585         h |= HlMod::Unsafe;
 586     }
 587     if func.is_async(sema.db) {
 588         h |= HlMod::Async;
 589     }
 590     if func.as_assoc_item(sema.db).and_then(|it| it.containing_trait(sema.db)).is_some() {
 591         h |= HlMod::Trait;
 592     }
 593
 594     let famous_defs = FamousDefs(sema, krate);
 595     let def_crate = func.module(sema.db).krate();
 596     let is_from_other_crate = Some(def_crate) != krate;
 597     let is_from_builtin_crate = famous_defs.builtin_crates().any(|it| def_crate == it);
 598     let is_public = func.visibility(sema.db) == hir::Visibility::Public;
 599
 600     if is_from_other_crate {
 601         h |= HlMod::Library;
 602     } else if is_public {
 603         h |= HlMod::Public;
 604     }
 605
 606     if is_from_builtin_crate {
 607         h |= HlMod::DefaultLibrary;
 608     }
 609
 610     if let Some(self_param) = func.self_param(sema.db) {
 611         match self_param.access(sema.db) {
 612             hir::Access::Shared => h |= HlMod::Reference,
 613             hir::Access::Exclusive => {
 614                 h |= HlMod::Mutable;
 615                 h |= HlMod::Reference;
 616             }
 617             hir::Access::Owned => {
 618                 if let Some(receiver_ty) =
 619                     method_call.receiver().and_then(|it| sema.type_of_expr(&it))
 620                 {
 621                     if !receiver_ty.adjusted().is_copy(sema.db) {
 622                         h |= HlMod::Consuming
 623                     }
 624                 }
 625             }
 626         }
 627     }
 628     Some(h)
 629 }
 630
 631 fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
 632     let default = HlTag::UnresolvedReference;
 633
 634     let parent = match name.syntax().parent() {
 635         Some(it) => it,
 636         _ => return default.into(),
 637     };
 638
 639     let tag = match parent.kind() {
 640         STRUCT => SymbolKind::Struct,
 641         ENUM => SymbolKind::Enum,
 642         VARIANT => SymbolKind::Variant,
 643         UNION => SymbolKind::Union,
 644         TRAIT => SymbolKind::Trait,
 645         TYPE_ALIAS => SymbolKind::TypeAlias,
 646         TYPE_PARAM => SymbolKind::TypeParam,
 647         RECORD_FIELD => SymbolKind::Field,
 648         MODULE => SymbolKind::Module,
 649         FN => SymbolKind::Function,
 650         CONST => SymbolKind::Const,
 651         STATIC => SymbolKind::Static,
 652         IDENT_PAT => SymbolKind::Local,
 653         _ => return default.into(),
 654     };
 655
 656     tag.into()
 657 }
 658
 659 fn highlight_name_ref_by_syntax(
 660     name: ast::NameRef,
 661     sema: &Semantics<RootDatabase>,
 662     krate: Option<hir::Crate>,
 663 ) -> Highlight {
 664     let default = HlTag::UnresolvedReference;
 665
 666     let parent = match name.syntax().parent() {
 667         Some(it) => it,
 668         _ => return default.into(),
 669     };
 670
 671     match parent.kind() {
 672         METHOD_CALL_EXPR => ast::MethodCallExpr::cast(parent)
 673             .and_then(|it| highlight_method_call(sema, krate, &it))
 674             .unwrap_or_else(|| SymbolKind::Function.into()),
 675         FIELD_EXPR => {
 676             let h = HlTag::Symbol(SymbolKind::Field);
 677             let is_union = ast::FieldExpr::cast(parent)
 678                 .and_then(|field_expr| sema.resolve_field(&field_expr))
 679                 .map_or(false, |field| {
 680                     matches!(field.parent_def(sema.db), hir::VariantDef::Union(_))
 681                 });
 682             if is_union {
 683                 h | HlMod::Unsafe
 684             } else {
 685                 h.into()
 686             }
 687         }
 688         PATH_SEGMENT => {
 689             let path = match parent.parent().and_then(ast::Path::cast) {
 690                 Some(it) => it,
 691                 _ => return default.into(),
 692             };
 693             let expr = match path.syntax().parent().and_then(ast::PathExpr::cast) {
 694                 Some(it) => it,
 695                 _ => {
 696                     // within path, decide whether it is module or adt by checking for uppercase name
 697                     return if name.text().chars().next().unwrap_or_default().is_uppercase() {
 698                         SymbolKind::Struct
 699                     } else {
 700                         SymbolKind::Module
 701                     }
 702                     .into();
 703                 }
 704             };
 705             let parent = match expr.syntax().parent() {
 706                 Some(it) => it,
 707                 None => return default.into(),
 708             };
 709
 710             match parent.kind() {
 711                 CALL_EXPR => SymbolKind::Function.into(),
 712                 _ => if name.text().chars().next().unwrap_or_default().is_uppercase() {
 713                     SymbolKind::Struct
 714                 } else {
 715                     SymbolKind::Const
 716                 }
 717                 .into(),
 718             }
 719         }
 720         _ => default.into(),
 721     }
 722 }
 723
 724 fn is_consumed_lvalue(node: &SyntaxNode, local: &hir::Local, db: &RootDatabase) -> bool {
 725     // When lvalues are passed as arguments and they're not Copy, then mark them as Consuming.
 726     parents_match(node.clone().into(), &[PATH_SEGMENT, PATH, PATH_EXPR, ARG_LIST])
 727         && !local.ty(db).is_copy(db)
 728 }
 729
 730 /// Returns true if the parent nodes of `node` all match the `SyntaxKind`s in `kinds` exactly.
 731 fn parents_match(mut node: NodeOrToken<SyntaxNode, SyntaxToken>, mut kinds: &[SyntaxKind]) -> bool {
 732     while let (Some(parent), [kind, rest @ ..]) = (&node.parent(), kinds) {
 733         if parent.kind() != *kind {
 734             return false;
 735         }
 736
 737         // FIXME: Would be nice to get parent out of the match, but binding by-move and by-value
 738         // in the same pattern is unstable: rust-lang/rust#68354.
 739         node = node.parent().unwrap().into();
 740         kinds = rest;
 741     }
 742
 743     // Only true if we matched all expected kinds
 744     kinds.is_empty()
 745 }
 746
 747 #[inline]
 748 fn parent_matches<N: AstNode>(token: &SyntaxToken) -> bool {
 749     token.parent().map_or(false, |it| N::can_cast(it.kind()))
 750 }
 751
 752 fn is_child_of_impl(token: &SyntaxToken) -> bool {
 753     match token.parent() {
 754         Some(e) => e.kind() == IMPL,
 755         _ => false,
 756     }
 757 }