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//===--- SemanticHighlighting.cpp - ------------------------- ---*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "SemanticHighlighting.h"
#include "FindTarget.h"
#include "HeuristicResolver.h"
#include "ParsedAST.h"
#include "Protocol.h"
#include "SourceCode.h"
#include "support/Logger.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclarationName.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/Type.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Tooling/Syntax/Tokens.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Base64.h"
#include "llvm/Support/Casting.h"
#include <algorithm>
namespace clang {
namespace clangd {
namespace {
/// Some names are not written in the source code and cannot be highlighted,
/// e.g. anonymous classes. This function detects those cases.
bool canHighlightName(DeclarationName Name) {
switch (Name.getNameKind()) {
case DeclarationName::Identifier: {
auto *II = Name.getAsIdentifierInfo();
return II && !II->getName().empty();
case DeclarationName::CXXConstructorName:
case DeclarationName::CXXDestructorName:
return true;
case DeclarationName::ObjCZeroArgSelector:
case DeclarationName::ObjCOneArgSelector:
case DeclarationName::ObjCMultiArgSelector:
// Multi-arg selectors need special handling, and we handle 0/1 arg
// selectors there too.
return false;
case DeclarationName::CXXConversionFunctionName:
case DeclarationName::CXXOperatorName:
case DeclarationName::CXXDeductionGuideName:
case DeclarationName::CXXLiteralOperatorName:
case DeclarationName::CXXUsingDirective:
return false;
llvm_unreachable("invalid name kind");
llvm::Optional<HighlightingKind> kindForType(const Type *TP,
const HeuristicResolver *Resolver);
kindForDecl(const NamedDecl *D, const HeuristicResolver *Resolver) {
if (auto *USD = dyn_cast<UsingShadowDecl>(D)) {
if (auto *Target = USD->getTargetDecl())
D = Target;
if (auto *TD = dyn_cast<TemplateDecl>(D)) {
if (auto *Templated = TD->getTemplatedDecl())
D = Templated;
if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
// We try to highlight typedefs as their underlying type.
if (auto K =
kindForType(TD->getUnderlyingType().getTypePtrOrNull(), Resolver))
return K;
// And fallback to a generic kind if this fails.
return HighlightingKind::Typedef;
// We highlight class decls, constructor decls and destructor decls as
// `Class` type. The destructor decls are handled in `VisitTagTypeLoc` (we
// will visit a TypeLoc where the underlying Type is a CXXRecordDecl).
if (auto *RD = llvm::dyn_cast<RecordDecl>(D)) {
// We don't want to highlight lambdas like classes.
if (RD->isLambda())
return llvm::None;
return HighlightingKind::Class;
if (isa<ClassTemplateDecl, RecordDecl, CXXConstructorDecl, ObjCInterfaceDecl,
return HighlightingKind::Class;
if (isa<ObjCProtocolDecl>(D))
return HighlightingKind::Interface;
if (isa<ObjCCategoryDecl>(D))
return HighlightingKind::Namespace;
if (auto *MD = dyn_cast<CXXMethodDecl>(D))
return MD->isStatic() ? HighlightingKind::StaticMethod
: HighlightingKind::Method;
if (auto *OMD = dyn_cast<ObjCMethodDecl>(D))
return OMD->isClassMethod() ? HighlightingKind::StaticMethod
: HighlightingKind::Method;
if (isa<FieldDecl, ObjCPropertyDecl>(D))
return HighlightingKind::Field;
if (isa<EnumDecl>(D))
return HighlightingKind::Enum;
if (isa<EnumConstantDecl>(D))
return HighlightingKind::EnumConstant;
if (isa<ParmVarDecl>(D))
return HighlightingKind::Parameter;
if (auto *VD = dyn_cast<VarDecl>(D)) {
if (isa<ImplicitParamDecl>(VD)) // e.g. ObjC Self
return llvm::None;
return VD->isStaticDataMember()
? HighlightingKind::StaticField
: VD->isLocalVarDecl() ? HighlightingKind::LocalVariable
: HighlightingKind::Variable;
if (const auto *BD = dyn_cast<BindingDecl>(D))
return BD->getDeclContext()->isFunctionOrMethod()
? HighlightingKind::LocalVariable
: HighlightingKind::Variable;
if (isa<FunctionDecl>(D))
return HighlightingKind::Function;
if (isa<NamespaceDecl>(D) || isa<NamespaceAliasDecl>(D) ||
return HighlightingKind::Namespace;
if (isa<TemplateTemplateParmDecl>(D) || isa<TemplateTypeParmDecl>(D) ||
return HighlightingKind::TemplateParameter;
if (isa<ConceptDecl>(D))
return HighlightingKind::Concept;
if (const auto *UUVD = dyn_cast<UnresolvedUsingValueDecl>(D)) {
auto Targets = Resolver->resolveUsingValueDecl(UUVD);
if (!Targets.empty()) {
return kindForDecl(Targets[0], Resolver);
return HighlightingKind::Unknown;
return llvm::None;
kindForType(const Type *TP, const HeuristicResolver *Resolver) {
if (!TP)
return llvm::None;
if (TP->isBuiltinType()) // Builtins are special, they do not have decls.
return HighlightingKind::Primitive;
if (auto *TD = dyn_cast<TemplateTypeParmType>(TP))
return kindForDecl(TD->getDecl(), Resolver);
if (isa<ObjCObjectPointerType>(TP))
return HighlightingKind::Class;
if (auto *TD = TP->getAsTagDecl())
return kindForDecl(TD, Resolver);
return llvm::None;
// Whether T is const in a loose sense - is a variable with this type readonly?
bool isConst(QualType T) {
if (T.isNull() || T->isDependentType())
return false;
T = T.getNonReferenceType();
if (T.isConstQualified())
return true;
if (const auto *AT = T->getAsArrayTypeUnsafe())
return isConst(AT->getElementType());
if (isConst(T->getPointeeType()))
return true;
return false;
// Whether D is const in a loose sense (should it be highlighted as such?)
// FIXME: This is separate from whether *a particular usage* can mutate D.
// We may want V in V.size() to be readonly even if V is mutable.
bool isConst(const Decl *D) {
if (llvm::isa<EnumConstantDecl>(D) || llvm::isa<NonTypeTemplateParmDecl>(D))
return true;
if (llvm::isa<FieldDecl>(D) || llvm::isa<VarDecl>(D) ||
llvm::isa<MSPropertyDecl>(D) || llvm::isa<BindingDecl>(D)) {
if (isConst(llvm::cast<ValueDecl>(D)->getType()))
return true;
if (const auto *OCPD = llvm::dyn_cast<ObjCPropertyDecl>(D)) {
if (OCPD->isReadOnly())
return true;
if (const auto *MPD = llvm::dyn_cast<MSPropertyDecl>(D)) {
if (!MPD->hasSetter())
return true;
if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(D)) {
if (CMD->isConst())
return true;
return false;
// "Static" means many things in C++, only some get the "static" modifier.
// Meanings that do:
// - Members associated with the class rather than the instance.
// This is what 'static' most often means across languages.
// - static local variables
// These are similarly "detached from their context" by the static keyword.
// In practice, these are rarely used inside classes, reducing confusion.
// Meanings that don't:
// - Namespace-scoped variables, which have static storage class.
// This is implicit, so the keyword "static" isn't so strongly associated.
// If we want a modifier for these, "global scope" is probably the concept.
// - Namespace-scoped variables/functions explicitly marked "static".
// There the keyword changes *linkage* , which is a totally different concept.
// If we want to model this, "file scope" would be a nice modifier.
// This is confusing, and maybe we should use another name, but because "static"
// is a standard LSP modifier, having one with that name has advantages.
bool isStatic(const Decl *D) {
if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(D))
return CMD->isStatic();
if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D))
return VD->isStaticDataMember() || VD->isStaticLocal();
if (const auto *OPD = llvm::dyn_cast<ObjCPropertyDecl>(D))
return OPD->isClassProperty();
if (const auto *OMD = llvm::dyn_cast<ObjCMethodDecl>(D))
return OMD->isClassMethod();
return false;
bool isAbstract(const Decl *D) {
if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(D))
return CMD->isPure();
if (const auto *CRD = llvm::dyn_cast<CXXRecordDecl>(D))
return CRD->hasDefinition() && CRD->isAbstract();
return false;
bool isVirtual(const Decl *D) {
if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(D))
return CMD->isVirtual();
return false;
bool isDependent(const Decl *D) {
if (isa<UnresolvedUsingValueDecl>(D))
return true;
return false;
/// Returns true if `Decl` is considered to be from a default/system library.
/// This currently checks the systemness of the file by include type, although
/// different heuristics may be used in the future (e.g. sysroot paths).
bool isDefaultLibrary(const Decl *D) {
SourceLocation Loc = D->getLocation();
if (!Loc.isValid())
return false;
return D->getASTContext().getSourceManager().isInSystemHeader(Loc);
bool isDefaultLibrary(const Type *T) {
if (!T)
return false;
const Type *Underlying = T->getPointeeOrArrayElementType();
if (Underlying->isBuiltinType())
return true;
if (auto *TD = dyn_cast<TemplateTypeParmType>(Underlying))
return isDefaultLibrary(TD->getDecl());
if (auto *TD = Underlying->getAsTagDecl())
return isDefaultLibrary(TD);
return false;
// For a macro usage `DUMP(foo)`, we want:
// - DUMP --> "macro"
// - foo --> "variable".
SourceLocation getHighlightableSpellingToken(SourceLocation L,
const SourceManager &SM) {
if (L.isFileID())
return SM.isWrittenInMainFile(L) ? L : SourceLocation{};
// Tokens expanded from the macro body contribute no highlightings.
if (!SM.isMacroArgExpansion(L))
return {};
// Tokens expanded from macro args are potentially highlightable.
return getHighlightableSpellingToken(SM.getImmediateSpellingLoc(L), SM);
unsigned evaluateHighlightPriority(const HighlightingToken &Tok) {
enum HighlightPriority { Dependent = 0, Resolved = 1 };
return (Tok.Modifiers & (1 << uint32_t(HighlightingModifier::DependentName)))
? Dependent
: Resolved;
// Sometimes we get multiple tokens at the same location:
// - findExplicitReferences() returns a heuristic result for a dependent name
// (e.g. Method) and CollectExtraHighlighting returning a fallback dependent
// highlighting (e.g. Unknown+Dependent).
// - macro arguments are expanded multiple times and have different roles
// - broken code recovery produces several AST nodes at the same location
// We should either resolve these to a single token, or drop them all.
// Our heuristics are:
// - token kinds that come with "dependent-name" modifiers are less reliable
// (these tend to be vague, like Type or Unknown)
// - if we have multiple equally reliable kinds, drop token rather than guess
// - take the union of modifiers from all tokens
// In particular, heuristically resolved dependent names get their heuristic
// kind, plus the dependent modifier.
resolveConflict(ArrayRef<HighlightingToken> Tokens) {
if (Tokens.size() == 1)
return Tokens[0];
if (Tokens.size() != 2)
return llvm::None;
unsigned Priority1 = evaluateHighlightPriority(Tokens[0]);
unsigned Priority2 = evaluateHighlightPriority(Tokens[1]);
if (Priority1 == Priority2 && Tokens[0].Kind != Tokens[1].Kind)
return llvm::None;
auto Result = Priority1 > Priority2 ? Tokens[0] : Tokens[1];
Result.Modifiers = Tokens[0].Modifiers | Tokens[1].Modifiers;
return Result;
/// Consumes source locations and maps them to text ranges for highlightings.
class HighlightingsBuilder {
HighlightingsBuilder(const ParsedAST &AST)
: TB(AST.getTokens()), SourceMgr(AST.getSourceManager()),
LangOpts(AST.getLangOpts()) {}
HighlightingToken &addToken(SourceLocation Loc, HighlightingKind Kind) {
auto Range = getRangeForSourceLocation(Loc);
if (!Range)
return InvalidHighlightingToken;
return addToken(*Range, Kind);
HighlightingToken &addToken(Range R, HighlightingKind Kind) {
HighlightingToken HT;
HT.R = std::move(R);
HT.Kind = Kind;
return Tokens.back();
void addExtraModifier(SourceLocation Loc, HighlightingModifier Modifier) {
if (auto Range = getRangeForSourceLocation(Loc))
std::vector<HighlightingToken> collect(ParsedAST &AST) && {
// Initializer lists can give duplicates of tokens, therefore all tokens
// must be deduplicated.
auto Last = std::unique(Tokens.begin(), Tokens.end());
Tokens.erase(Last, Tokens.end());
// Macros can give tokens that have the same source range but conflicting
// kinds. In this case all tokens sharing this source range should be
// removed.
std::vector<HighlightingToken> NonConflicting;
for (ArrayRef<HighlightingToken> TokRef = Tokens; !TokRef.empty();) {
ArrayRef<HighlightingToken> Conflicting =
TokRef.take_while([&](const HighlightingToken &T) {
// TokRef is guaranteed at least one element here because otherwise
// this predicate would never fire.
return T.R == TokRef.front().R;
if (auto Resolved = resolveConflict(Conflicting)) {
// Apply extra collected highlighting modifiers
auto Modifiers = ExtraModifiers.find(Resolved->R);
if (Modifiers != ExtraModifiers.end()) {
for (HighlightingModifier Mod : Modifiers->second) {
// TokRef[Conflicting.size()] is the next token with a different range (or
// the end of the Tokens).
TokRef = TokRef.drop_front(Conflicting.size());
const auto &SM = AST.getSourceManager();
StringRef MainCode = SM.getBufferOrFake(SM.getMainFileID()).getBuffer();
// Merge token stream with "inactive line" markers.
std::vector<HighlightingToken> WithInactiveLines;
auto SortedSkippedRanges = AST.getMacros().SkippedRanges;
auto It = NonConflicting.begin();
for (const Range &R : SortedSkippedRanges) {
// Create one token for each line in the skipped range, so it works
// with line-based diffing.
assert(R.start.line <= R.end.line);
for (int Line = R.start.line; Line <= R.end.line; ++Line) {
// If the end of the inactive range is at the beginning
// of a line, that line is not inactive.
if (Line == R.end.line && R.end.character == 0)
// Copy tokens before the inactive line
for (; It != NonConflicting.end() && It->R.start.line < Line; ++It)
// Add a token for the inactive line itself.
auto StartOfLine = positionToOffset(MainCode, Position{Line, 0});
if (StartOfLine) {
StringRef LineText =
MainCode.drop_front(*StartOfLine).take_until([](char C) {
return C == '\n';
HighlightingToken HT;
WithInactiveLines.back().Kind = HighlightingKind::InactiveCode;
WithInactiveLines.back().R.start.line = Line;
WithInactiveLines.back().R.end.line = Line;
WithInactiveLines.back().R.end.character =
} else {
elog("Failed to convert position to offset: {0}",
// Skip any other tokens on the inactive line. e.g.
// `#ifndef Foo` is considered as part of an inactive region when Foo is
// defined, and there is a Foo macro token.
// FIXME: we should reduce the scope of the inactive region to not
// include the directive itself.
while (It != NonConflicting.end() && It->R.start.line == Line)
// Copy tokens after the last inactive line
for (; It != NonConflicting.end(); ++It)
return WithInactiveLines;
const HeuristicResolver *getResolver() const { return Resolver; }
llvm::Optional<Range> getRangeForSourceLocation(SourceLocation Loc) {
Loc = getHighlightableSpellingToken(Loc, SourceMgr);
if (Loc.isInvalid())
return llvm::None;
const auto *Tok = TB.spelledTokenAt(Loc);
return halfOpenToRange(SourceMgr,
const syntax::TokenBuffer &TB;
const SourceManager &SourceMgr;
const LangOptions &LangOpts;
std::vector<HighlightingToken> Tokens;
std::map<Range, llvm::SmallVector<HighlightingModifier, 1>> ExtraModifiers;
const HeuristicResolver *Resolver;
// returned from addToken(InvalidLoc)
HighlightingToken InvalidHighlightingToken;
llvm::Optional<HighlightingModifier> scopeModifier(const NamedDecl *D) {
const DeclContext *DC = D->getDeclContext();
// Injected "Foo" within the class "Foo" has file scope, not class scope.
if (auto *R = dyn_cast_or_null<RecordDecl>(D))
if (R->isInjectedClassName())
DC = DC->getParent();
// Lambda captures are considered function scope, not class scope.
if (llvm::isa<FieldDecl>(D))
if (const auto *RD = llvm::dyn_cast<RecordDecl>(DC))
if (RD->isLambda())
return HighlightingModifier::FunctionScope;
// Walk up the DeclContext hierarchy until we find something interesting.
for (; !DC->isFileContext(); DC = DC->getParent()) {
if (DC->isFunctionOrMethod())
return HighlightingModifier::FunctionScope;
if (DC->isRecord())
return HighlightingModifier::ClassScope;
// Some template parameters (e.g. those for variable templates) don't have
// meaningful DeclContexts. That doesn't mean they're global!
if (DC->isTranslationUnit() && D->isTemplateParameter())
return llvm::None;
// ExternalLinkage threshold could be tweaked, e.g. module-visible as global.
if (D->getLinkageInternal() < ExternalLinkage)
return HighlightingModifier::FileScope;
return HighlightingModifier::GlobalScope;
llvm::Optional<HighlightingModifier> scopeModifier(const Type *T) {
if (!T)
return llvm::None;
if (T->isBuiltinType())
return HighlightingModifier::GlobalScope;
if (auto *TD = dyn_cast<TemplateTypeParmType>(T))
return scopeModifier(TD->getDecl());
if (auto *TD = T->getAsTagDecl())
return scopeModifier(TD);
return llvm::None;
/// Produces highlightings, which are not captured by findExplicitReferences,
/// e.g. highlights dependent names and 'auto' as the underlying type.
class CollectExtraHighlightings
: public RecursiveASTVisitor<CollectExtraHighlightings> {
CollectExtraHighlightings(HighlightingsBuilder &H) : H(H) {}
bool VisitCXXConstructExpr(CXXConstructExpr *E) {
{E->getArgs(), E->getNumArgs()});
return true;
bool VisitCallExpr(CallExpr *E) {
// Highlighting parameters passed by non-const reference does not really
// make sense for literals...
if (isa<UserDefinedLiteral>(E))
return true;
// FIXME it would make sense though.
if (isa<CXXOperatorCallExpr>(E))
return true;
{E->getArgs(), E->getNumArgs()});
return true;
highlightMutableReferenceArguments(const FunctionDecl *FD,
llvm::ArrayRef<const Expr *const> Args) {
if (!FD)
if (auto *ProtoType = FD->getType()->getAs<FunctionProtoType>()) {
// Iterate over the types of the function parameters.
// If any of them are non-const reference paramteres, add it as a
// highlighting modifier to the corresponding expression
for (size_t I = 0;
I < std::min(size_t(ProtoType->getNumParams()), Args.size()); ++I) {
auto T = ProtoType->getParamType(I);
// Is this parameter passed by non-const reference?
// FIXME The condition !T->idDependentType() could be relaxed a bit,
// e.g. std::vector<T>& is dependent but we would want to highlight it
if (T->isLValueReferenceType() &&
!T.getNonReferenceType().isConstQualified() &&
!T->isDependentType()) {
if (auto *Arg = Args[I]) {
llvm::Optional<SourceLocation> Location;
// FIXME Add "unwrapping" for ArraySubscriptExpr and UnaryOperator,
// e.g. highlight `a` in `a[i]`
// FIXME Handle dependent expression types
if (auto *DR = dyn_cast<DeclRefExpr>(Arg)) {
Location = DR->getLocation();
} else if (auto *M = dyn_cast<MemberExpr>(Arg)) {
Location = M->getMemberLoc();
if (Location)
bool VisitDecltypeTypeLoc(DecltypeTypeLoc L) {
if (auto K = kindForType(L.getTypePtr(), H.getResolver())) {
auto &Tok = H.addToken(L.getBeginLoc(), *K)
if (auto Mod = scopeModifier(L.getTypePtr()))
if (isDefaultLibrary(L.getTypePtr()))
return true;
bool VisitDeclaratorDecl(DeclaratorDecl *D) {
auto *AT = D->getType()->getContainedAutoType();
if (!AT)
return true;
auto K =
kindForType(AT->getDeducedType().getTypePtrOrNull(), H.getResolver());
if (!K)
return true;
SourceLocation StartLoc = D->getTypeSpecStartLoc();
// The AutoType may not have a corresponding token, e.g. in the case of
// init-captures. In this case, StartLoc overlaps with the location
// of the decl itself, and producing a token for the type here would result
// in both it and the token for the decl being dropped due to conflict.
if (StartLoc == D->getLocation())
return true;
auto &Tok =
H.addToken(StartLoc, *K).addModifier(HighlightingModifier::Deduced);
const Type *Deduced = AT->getDeducedType().getTypePtrOrNull();
if (auto Mod = scopeModifier(Deduced))
if (isDefaultLibrary(Deduced))
return true;
// We handle objective-C selectors specially, because one reference can
// cover several non-contiguous tokens.
void highlightObjCSelector(const ArrayRef<SourceLocation> &Locs, bool Decl,
bool Class, bool DefaultLibrary) {
HighlightingKind Kind =
Class ? HighlightingKind::StaticMethod : HighlightingKind::Method;
for (SourceLocation Part : Locs) {
auto &Tok =
H.addToken(Part, Kind).addModifier(HighlightingModifier::ClassScope);
if (Decl)
if (Class)
if (DefaultLibrary)
bool VisitObjCMethodDecl(ObjCMethodDecl *OMD) {
llvm::SmallVector<SourceLocation> Locs;
highlightObjCSelector(Locs, /*Decl=*/true, OMD->isClassMethod(),
return true;
bool VisitObjCMessageExpr(ObjCMessageExpr *OME) {
llvm::SmallVector<SourceLocation> Locs;
bool DefaultLibrary = false;
if (ObjCMethodDecl *OMD = OME->getMethodDecl())
DefaultLibrary = isDefaultLibrary(OMD);
highlightObjCSelector(Locs, /*Decl=*/false, OME->isClassMessage(),
return true;
// Objective-C allows you to use property syntax `self.prop` as sugar for
// `[self prop]` and `[self setProp:]` when there's no explicit `@property`
// for `prop` as well as for class properties. We treat this like a property
// even though semantically it's equivalent to a method expression.
void highlightObjCImplicitPropertyRef(const ObjCMethodDecl *OMD,
SourceLocation Loc) {
auto &Tok = H.addToken(Loc, HighlightingKind::Field)
if (OMD->isClassMethod())
if (isDefaultLibrary(OMD))
bool VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *OPRE) {
// We need to handle implicit properties here since they will appear to
// reference `ObjCMethodDecl` via an implicit `ObjCMessageExpr`, so normal
// highlighting will not work.
if (!OPRE->isImplicitProperty())
return true;
// A single property expr can reference both a getter and setter, but we can
// only provide a single semantic token, so prefer the getter. In most cases
// the end result should be the same, although it's technically possible
// that the user defines a setter for a system SDK.
if (OPRE->isMessagingGetter()) {
return true;
if (OPRE->isMessagingSetter()) {
return true;
bool VisitOverloadExpr(OverloadExpr *E) {
if (!E->decls().empty())
return true; // handled by findExplicitReferences.
auto &Tok = H.addToken(E->getNameLoc(), HighlightingKind::Unknown)
if (llvm::isa<UnresolvedMemberExpr>(E))
// other case is UnresolvedLookupExpr, scope is unknown.
return true;
bool VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E) {
H.addToken(E->getMemberNameInfo().getLoc(), HighlightingKind::Unknown)
return true;
bool VisitDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E) {
H.addToken(E->getNameInfo().getLoc(), HighlightingKind::Unknown)
return true;
bool VisitDependentNameTypeLoc(DependentNameTypeLoc L) {
H.addToken(L.getNameLoc(), HighlightingKind::Type)
return true;
bool VisitDependentTemplateSpecializationTypeLoc(
DependentTemplateSpecializationTypeLoc L) {
H.addToken(L.getTemplateNameLoc(), HighlightingKind::Type)
return true;
bool TraverseTemplateArgumentLoc(TemplateArgumentLoc L) {
// Handle template template arguments only (other arguments are handled by
// their Expr, TypeLoc etc values).
if (L.getArgument().getKind() != TemplateArgument::Template &&
L.getArgument().getKind() != TemplateArgument::TemplateExpansion)
return RecursiveASTVisitor::TraverseTemplateArgumentLoc(L);
TemplateName N = L.getArgument().getAsTemplateOrTemplatePattern();
switch (N.getKind()) {
case TemplateName::OverloadedTemplate:
// Template template params must always be class templates.
// Don't bother to try to work out the scope here.
H.addToken(L.getTemplateNameLoc(), HighlightingKind::Class);
case TemplateName::DependentTemplate:
case TemplateName::AssumedTemplate:
H.addToken(L.getTemplateNameLoc(), HighlightingKind::Class)
case TemplateName::Template:
case TemplateName::QualifiedTemplate:
case TemplateName::SubstTemplateTemplateParm:
case TemplateName::SubstTemplateTemplateParmPack:
// Names that could be resolved to a TemplateDecl are handled elsewhere.
return RecursiveASTVisitor::TraverseTemplateArgumentLoc(L);
// findExplicitReferences will walk nested-name-specifiers and
// find anything that can be resolved to a Decl. However, non-leaf
// components of nested-name-specifiers which are dependent names
// (kind "Identifier") cannot be resolved to a decl, so we visit
// them here.
bool TraverseNestedNameSpecifierLoc(NestedNameSpecifierLoc Q) {
if (NestedNameSpecifier *NNS = Q.getNestedNameSpecifier()) {
if (NNS->getKind() == NestedNameSpecifier::Identifier)
H.addToken(Q.getLocalBeginLoc(), HighlightingKind::Type)
return RecursiveASTVisitor::TraverseNestedNameSpecifierLoc(Q);
HighlightingsBuilder &H;
} // namespace
std::vector<HighlightingToken> getSemanticHighlightings(ParsedAST &AST) {
auto &C = AST.getASTContext();
// Add highlightings for AST nodes.
HighlightingsBuilder Builder(AST);
// Highlight 'decltype' and 'auto' as their underlying types.
// Highlight all decls and references coming from the AST.
[&](ReferenceLoc R) {
for (const NamedDecl *Decl : R.Targets) {
if (!canHighlightName(Decl->getDeclName()))
auto Kind = kindForDecl(Decl, AST.getHeuristicResolver());
if (!Kind)
auto &Tok = Builder.addToken(R.NameLoc, *Kind);
// The attribute tests don't want to look at the template.
if (auto *TD = dyn_cast<TemplateDecl>(Decl)) {
if (auto *Templated = TD->getTemplatedDecl())
Decl = Templated;
if (auto Mod = scopeModifier(Decl))
if (isConst(Decl))
if (isStatic(Decl))
if (isAbstract(Decl))
if (isVirtual(Decl))
if (isDependent(Decl))
if (isDefaultLibrary(Decl))
if (Decl->isDeprecated())
// Do not treat an UnresolvedUsingValueDecl as a declaration.
// It's more common to think of it as a reference to the
// underlying declaration.
if (R.IsDecl && !isa<UnresolvedUsingValueDecl>(Decl))
// Add highlightings for macro references.
auto AddMacro = [&](const MacroOccurrence &M) {
auto &T = Builder.addToken(M.Rng, HighlightingKind::Macro);
if (M.IsDefinition)
for (const auto &SIDToRefs : AST.getMacros().MacroRefs)
for (const auto &M : SIDToRefs.second)
for (const auto &M : AST.getMacros().UnknownMacros)
return std::move(Builder).collect(AST);
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, HighlightingKind K) {
switch (K) {
case HighlightingKind::Variable:
return OS << "Variable";
case HighlightingKind::LocalVariable:
return OS << "LocalVariable";
case HighlightingKind::Parameter:
return OS << "Parameter";
case HighlightingKind::Function:
return OS << "Function";
case HighlightingKind::Method:
return OS << "Method";
case HighlightingKind::StaticMethod:
return OS << "StaticMethod";
case HighlightingKind::Field:
return OS << "Field";
case HighlightingKind::StaticField:
return OS << "StaticField";
case HighlightingKind::Class:
return OS << "Class";
case HighlightingKind::Interface:
return OS << "Interface";
case HighlightingKind::Enum:
return OS << "Enum";
case HighlightingKind::EnumConstant:
return OS << "EnumConstant";
case HighlightingKind::Typedef:
return OS << "Typedef";
case HighlightingKind::Type:
return OS << "Type";
case HighlightingKind::Unknown:
return OS << "Unknown";
case HighlightingKind::Namespace:
return OS << "Namespace";
case HighlightingKind::TemplateParameter:
return OS << "TemplateParameter";
case HighlightingKind::Concept:
return OS << "Concept";
case HighlightingKind::Primitive:
return OS << "Primitive";
case HighlightingKind::Macro:
return OS << "Macro";
case HighlightingKind::InactiveCode:
return OS << "InactiveCode";
llvm_unreachable("invalid HighlightingKind");
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, HighlightingModifier K) {
switch (K) {
case HighlightingModifier::Declaration:
return OS << "decl"; // abbrevation for common case
return OS << toSemanticTokenModifier(K);
bool operator==(const HighlightingToken &L, const HighlightingToken &R) {
return std::tie(L.R, L.Kind, L.Modifiers) ==
std::tie(R.R, R.Kind, R.Modifiers);
bool operator<(const HighlightingToken &L, const HighlightingToken &R) {
return std::tie(L.R, L.Kind, R.Modifiers) <
std::tie(R.R, R.Kind, R.Modifiers);
toSemanticTokens(llvm::ArrayRef<HighlightingToken> Tokens) {
assert(std::is_sorted(Tokens.begin(), Tokens.end()));
std::vector<SemanticToken> Result;
const HighlightingToken *Last = nullptr;
for (const HighlightingToken &Tok : Tokens) {
SemanticToken &Out = Result.back();
// deltaStart/deltaLine are relative if possible.
if (Last) {
assert(Tok.R.start.line >= Last->R.start.line);
Out.deltaLine = Tok.R.start.line - Last->R.start.line;
if (Out.deltaLine == 0) {
assert(Tok.R.start.character >= Last->R.start.character);
Out.deltaStart = Tok.R.start.character - Last->R.start.character;
} else {
Out.deltaStart = Tok.R.start.character;
} else {
Out.deltaLine = Tok.R.start.line;
Out.deltaStart = Tok.R.start.character;
assert(Tok.R.end.line == Tok.R.start.line);
Out.length = Tok.R.end.character - Tok.R.start.character;
Out.tokenType = static_cast<unsigned>(Tok.Kind);
Out.tokenModifiers = Tok.Modifiers;
Last = &Tok;
return Result;
llvm::StringRef toSemanticTokenType(HighlightingKind Kind) {
switch (Kind) {
case HighlightingKind::Variable:
case HighlightingKind::LocalVariable:
case HighlightingKind::StaticField:
return "variable";
case HighlightingKind::Parameter:
return "parameter";
case HighlightingKind::Function:
return "function";
case HighlightingKind::Method:
return "method";
case HighlightingKind::StaticMethod:
// FIXME: better method with static modifier?
return "function";
case HighlightingKind::Field:
return "property";
case HighlightingKind::Class:
return "class";
case HighlightingKind::Interface:
return "interface";
case HighlightingKind::Enum:
return "enum";
case HighlightingKind::EnumConstant:
return "enumMember";
case HighlightingKind::Typedef:
case HighlightingKind::Type:
return "type";
case HighlightingKind::Unknown:
return "unknown"; // nonstandard
case HighlightingKind::Namespace:
return "namespace";
case HighlightingKind::TemplateParameter:
return "typeParameter";
case HighlightingKind::Concept:
return "concept"; // nonstandard
case HighlightingKind::Primitive:
return "type";
case HighlightingKind::Macro:
return "macro";
case HighlightingKind::InactiveCode:
return "comment";
llvm_unreachable("unhandled HighlightingKind");
llvm::StringRef toSemanticTokenModifier(HighlightingModifier Modifier) {
switch (Modifier) {
case HighlightingModifier::Declaration:
return "declaration";
case HighlightingModifier::Deprecated:
return "deprecated";
case HighlightingModifier::Readonly:
return "readonly";
case HighlightingModifier::Static:
return "static";
case HighlightingModifier::Deduced:
return "deduced"; // nonstandard
case HighlightingModifier::Abstract:
return "abstract";
case HighlightingModifier::Virtual:
return "virtual";
case HighlightingModifier::DependentName:
return "dependentName"; // nonstandard
case HighlightingModifier::DefaultLibrary:
return "defaultLibrary";
case HighlightingModifier::UsedAsMutableReference:
return "usedAsMutableReference"; // nonstandard
case HighlightingModifier::FunctionScope:
return "functionScope"; // nonstandard
case HighlightingModifier::ClassScope:
return "classScope"; // nonstandard
case HighlightingModifier::FileScope:
return "fileScope"; // nonstandard
case HighlightingModifier::GlobalScope:
return "globalScope"; // nonstandard
llvm_unreachable("unhandled HighlightingModifier");
diffTokens(llvm::ArrayRef<SemanticToken> Old,
llvm::ArrayRef<SemanticToken> New) {
// For now, just replace everything from the first-last modification.
// FIXME: use a real diff instead, this is bad with include-insertion.
unsigned Offset = 0;
while (!Old.empty() && !New.empty() && Old.front() == New.front()) {
Old = Old.drop_front();
New = New.drop_front();
while (!Old.empty() && !New.empty() && Old.back() == New.back()) {
Old = Old.drop_back();
New = New.drop_back();
if (Old.empty() && New.empty())
return {};
SemanticTokensEdit Edit;
Edit.startToken = Offset;
Edit.deleteTokens = Old.size();
Edit.tokens = New;
return {std::move(Edit)};
} // namespace clangd
} // namespace clang