crates/ide/src/syntax_highlighting/highlight.rs

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