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//===--- Symbol.h ------------------------------------------------*- 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 "SymbolID.h"
#include "SymbolLocation.h"
#include "SymbolOrigin.h"
#include "clang/Index/IndexSymbol.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/StringSaver.h"
namespace clang {
namespace clangd {
/// The class presents a C++ symbol, e.g. class, function.
/// WARNING: Symbols do not own much of their underlying data - typically
/// strings are owned by a SymbolSlab. They should be treated as non-owning
/// references. Copies are shallow.
/// When adding new unowned data fields to Symbol, remember to update:
/// - SymbolSlab::Builder in Index.cpp, to copy them to the slab's storage.
/// - mergeSymbol in Merge.cpp, to properly combine two Symbols.
/// A fully documented symbol can be split as:
/// size_type std::map<k, t>::count(const K& key) const
/// | Return | Scope |Name| Signature |
/// We split up these components to allow display flexibility later.
struct Symbol {
/// The ID of the symbol.
SymbolID ID;
/// The symbol information, like symbol kind.
index::SymbolInfo SymInfo = index::SymbolInfo();
/// The unqualified name of the symbol, e.g. "bar" (for ns::bar).
llvm::StringRef Name;
/// The containing namespace. e.g. "" (global), "ns::" (top-level namespace).
llvm::StringRef Scope;
/// The location of the symbol's definition, if one was found.
/// This just covers the symbol name (e.g. without class/function body).
SymbolLocation Definition;
/// The location of the preferred declaration of the symbol.
/// This just covers the symbol name.
/// This may be the same as Definition.
/// A C++ symbol may have multiple declarations, and we pick one to prefer.
/// * For classes, the canonical declaration should be the definition.
/// * For non-inline functions, the canonical declaration typically appears
/// in the ".h" file corresponding to the definition.
SymbolLocation CanonicalDeclaration;
/// The number of translation units that reference this symbol from their main
/// file. This number is only meaningful if aggregated in an index.
unsigned References = 0;
/// Where this symbol came from. Usually an index provides a constant value.
SymbolOrigin Origin = SymbolOrigin::Unknown;
/// A brief description of the symbol that can be appended in the completion
/// candidate list. For example, "(X x, Y y) const" is a function signature.
/// Only set when the symbol is indexed for completion.
llvm::StringRef Signature;
/// Argument list in human-readable format, will be displayed to help
/// disambiguate between different specializations of a template. Empty for
/// non-specializations. Example: "<int, bool, 3>"
llvm::StringRef TemplateSpecializationArgs;
/// What to insert when completing this symbol, after the symbol name.
/// This is in LSP snippet syntax (e.g. "({$0})" for a no-args function).
/// (When snippets are disabled, the symbol name alone is used).
/// Only set when the symbol is indexed for completion.
llvm::StringRef CompletionSnippetSuffix;
/// Documentation including comment for the symbol declaration.
llvm::StringRef Documentation;
/// Type when this symbol is used in an expression. (Short display form).
/// e.g. return type of a function, or type of a variable.
/// Only set when the symbol is indexed for completion.
llvm::StringRef ReturnType;
/// Raw representation of the OpaqueType of the symbol, used for scoring
/// purposes.
/// Only set when the symbol is indexed for completion.
llvm::StringRef Type;
struct IncludeHeaderWithReferences {
IncludeHeaderWithReferences() = default;
IncludeHeaderWithReferences(llvm::StringRef IncludeHeader,
unsigned References)
: IncludeHeader(IncludeHeader), References(References) {}
/// This can be either a URI of the header to be #include'd
/// for this symbol, or a literal header quoted with <> or "" that is
/// suitable to be included directly. When it is a URI, the exact #include
/// path needs to be calculated according to the URI scheme.
/// Note that the include header is a canonical include for the symbol and
/// can be different from FileURI in the CanonicalDeclaration.
llvm::StringRef IncludeHeader = "";
/// The number of translation units that reference this symbol and include
/// this header. This number is only meaningful if aggregated in an index.
unsigned References = 0;
/// One Symbol can potentially be included via different headers.
/// - If we haven't seen a definition, this covers all declarations.
/// - If we have seen a definition, this covers declarations visible from
/// any definition.
/// Only set when the symbol is indexed for completion.
llvm::SmallVector<IncludeHeaderWithReferences, 1> IncludeHeaders;
enum SymbolFlag : uint8_t {
None = 0,
/// Whether or not this symbol is meant to be used for the code completion.
/// See also isIndexedForCodeCompletion().
/// Note that we don't store completion information (signature, snippet,
/// type, includes) if the symbol is not indexed for code completion.
IndexedForCodeCompletion = 1 << 0,
/// Indicates if the symbol is deprecated.
Deprecated = 1 << 1,
/// Symbol is an implementation detail.
ImplementationDetail = 1 << 2,
/// Symbol is visible to other files (not e.g. a static helper function).
VisibleOutsideFile = 1 << 3,
SymbolFlag Flags = SymbolFlag::None;
/// FIXME: also add deprecation message and fixit?
inline Symbol::SymbolFlag operator|(Symbol::SymbolFlag A,
Symbol::SymbolFlag B) {
return static_cast<Symbol::SymbolFlag>(static_cast<uint8_t>(A) |
inline Symbol::SymbolFlag &operator|=(Symbol::SymbolFlag &A,
Symbol::SymbolFlag B) {
return A = A | B;
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Symbol &S);
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, Symbol::SymbolFlag);
/// Invokes Callback with each StringRef& contained in the Symbol.
/// Useful for deduplicating backing strings.
template <typename Callback> void visitStrings(Symbol &S, const Callback &CB) {
auto RawCharPointerCB = [&CB](const char *&P) {
llvm::StringRef S(P);
assert(![S.size()] && "Visited StringRef must be null-terminated");
P =;
for (auto &Include : S.IncludeHeaders)
/// Computes query-independent quality score for a Symbol.
/// This currently falls in the range [1, ln(#indexed documents)].
/// FIXME: this should probably be split into symbol -> signals
/// and signals -> score, so it can be reused for Sema completions.
float quality(const Symbol &S);
/// An immutable symbol container that stores a set of symbols.
/// The container will maintain the lifetime of the symbols.
class SymbolSlab {
using const_iterator = std::vector<Symbol>::const_iterator;
using iterator = const_iterator;
using value_type = Symbol;
SymbolSlab() = default;
const_iterator begin() const { return Symbols.begin(); }
const_iterator end() const { return Symbols.end(); }
const_iterator find(const SymbolID &SymID) const;
using size_type = size_t;
size_type size() const { return Symbols.size(); }
bool empty() const { return Symbols.empty(); }
// Estimates the total memory usage.
size_t bytes() const {
return sizeof(*this) + Arena.getTotalMemory() +
Symbols.capacity() * sizeof(Symbol);
/// SymbolSlab::Builder is a mutable container that can 'freeze' to
/// SymbolSlab. The frozen SymbolSlab will use less memory.
class Builder {
Builder() : UniqueStrings(Arena) {}
/// Adds a symbol, overwriting any existing one with the same ID.
/// This is a deep copy: underlying strings will be owned by the slab.
void insert(const Symbol &S);
/// Removes the symbol with an ID, if it exists.
void erase(const SymbolID &ID) { Symbols.erase(ID); }
/// Returns the symbol with an ID, if it exists. Valid until insert/remove.
const Symbol *find(const SymbolID &ID) {
auto I = Symbols.find(ID);
return I == Symbols.end() ? nullptr : &I->second;
/// Consumes the builder to finalize the slab.
SymbolSlab build() &&;
llvm::BumpPtrAllocator Arena;
/// Intern table for strings. Contents are on the arena.
llvm::UniqueStringSaver UniqueStrings;
/// Values are indices into Symbols vector.
llvm::DenseMap<SymbolID, Symbol> Symbols;
SymbolSlab(llvm::BumpPtrAllocator Arena, std::vector<Symbol> Symbols)
: Arena(std::move(Arena)), Symbols(std::move(Symbols)) {}
llvm::BumpPtrAllocator Arena; // Owns Symbol data that the Symbols do not.
std::vector<Symbol> Symbols; // Sorted by SymbolID to allow lookup.
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const SymbolSlab &Slab);
} // namespace clangd
} // namespace clang