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llvm-project/clang-tools-extra/clangd/Quality.cpp

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//===--- Quality.cpp ---------------------------------------------*- C++-*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Quality.h"
#include "AST.h"
#include "FileDistance.h"
#include "SourceCode.h"
#include "URI.h"
#include "index/Symbol.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclVisitor.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Sema/CodeCompleteConsumer.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cmath>
namespace clang {
namespace clangd {
static bool isReserved(llvm::StringRef Name) {
// FIXME: Should we exclude _Bool and others recognized by the standard?
return Name.size() >= 2 && Name[0] == '_' &&
(isUppercase(Name[1]) || Name[1] == '_');
}
static bool hasDeclInMainFile(const Decl &D) {
auto &SourceMgr = D.getASTContext().getSourceManager();
for (auto *Redecl : D.redecls()) {
if (isInsideMainFile(Redecl->getLocation(), SourceMgr))
return true;
}
return false;
}
static bool hasUsingDeclInMainFile(const CodeCompletionResult &R) {
const auto &Context = R.Declaration->getASTContext();
const auto &SourceMgr = Context.getSourceManager();
if (R.ShadowDecl) {
if (isInsideMainFile(R.ShadowDecl->getLocation(), SourceMgr))
return true;
}
return false;
}
static SymbolQualitySignals::SymbolCategory categorize(const NamedDecl &ND) {
if (const auto *FD = dyn_cast<FunctionDecl>(&ND)) {
if (FD->isOverloadedOperator())
return SymbolQualitySignals::Operator;
}
class Switch
: public ConstDeclVisitor<Switch, SymbolQualitySignals::SymbolCategory> {
public:
#define MAP(DeclType, Category) \
SymbolQualitySignals::SymbolCategory Visit##DeclType(const DeclType *) { \
return SymbolQualitySignals::Category; \
}
MAP(NamespaceDecl, Namespace);
MAP(NamespaceAliasDecl, Namespace);
MAP(TypeDecl, Type);
MAP(TypeAliasTemplateDecl, Type);
MAP(ClassTemplateDecl, Type);
MAP(CXXConstructorDecl, Constructor);
MAP(CXXDestructorDecl, Destructor);
MAP(ValueDecl, Variable);
MAP(VarTemplateDecl, Variable);
MAP(FunctionDecl, Function);
MAP(FunctionTemplateDecl, Function);
MAP(Decl, Unknown);
#undef MAP
};
return Switch().Visit(&ND);
}
static SymbolQualitySignals::SymbolCategory
categorize(const CodeCompletionResult &R) {
if (R.Declaration)
return categorize(*R.Declaration);
if (R.Kind == CodeCompletionResult::RK_Macro)
return SymbolQualitySignals::Macro;
// Everything else is a keyword or a pattern. Patterns are mostly keywords
// too, except a few which we recognize by cursor kind.
switch (R.CursorKind) {
case CXCursor_CXXMethod:
return SymbolQualitySignals::Function;
case CXCursor_ModuleImportDecl:
return SymbolQualitySignals::Namespace;
case CXCursor_MacroDefinition:
return SymbolQualitySignals::Macro;
case CXCursor_TypeRef:
return SymbolQualitySignals::Type;
case CXCursor_MemberRef:
return SymbolQualitySignals::Variable;
case CXCursor_Constructor:
return SymbolQualitySignals::Constructor;
default:
return SymbolQualitySignals::Keyword;
}
}
static SymbolQualitySignals::SymbolCategory
categorize(const index::SymbolInfo &D) {
switch (D.Kind) {
case index::SymbolKind::Namespace:
case index::SymbolKind::NamespaceAlias:
return SymbolQualitySignals::Namespace;
case index::SymbolKind::Macro:
return SymbolQualitySignals::Macro;
case index::SymbolKind::Enum:
case index::SymbolKind::Struct:
case index::SymbolKind::Class:
case index::SymbolKind::Protocol:
case index::SymbolKind::Extension:
case index::SymbolKind::Union:
case index::SymbolKind::TypeAlias:
case index::SymbolKind::TemplateTypeParm:
case index::SymbolKind::TemplateTemplateParm:
return SymbolQualitySignals::Type;
case index::SymbolKind::Function:
case index::SymbolKind::ClassMethod:
case index::SymbolKind::InstanceMethod:
case index::SymbolKind::StaticMethod:
case index::SymbolKind::InstanceProperty:
case index::SymbolKind::ClassProperty:
case index::SymbolKind::StaticProperty:
case index::SymbolKind::ConversionFunction:
return SymbolQualitySignals::Function;
case index::SymbolKind::Destructor:
return SymbolQualitySignals::Destructor;
case index::SymbolKind::Constructor:
return SymbolQualitySignals::Constructor;
case index::SymbolKind::Variable:
case index::SymbolKind::Field:
case index::SymbolKind::EnumConstant:
case index::SymbolKind::Parameter:
case index::SymbolKind::NonTypeTemplateParm:
return SymbolQualitySignals::Variable;
case index::SymbolKind::Using:
case index::SymbolKind::Module:
case index::SymbolKind::Unknown:
return SymbolQualitySignals::Unknown;
}
llvm_unreachable("Unknown index::SymbolKind");
}
static bool isInstanceMember(const NamedDecl *ND) {
if (!ND)
return false;
if (const auto *TP = dyn_cast<FunctionTemplateDecl>(ND))
ND = TP->TemplateDecl::getTemplatedDecl();
if (const auto *CM = dyn_cast<CXXMethodDecl>(ND))
return !CM->isStatic();
return isa<FieldDecl>(ND); // Note that static fields are VarDecl.
}
static bool isInstanceMember(const index::SymbolInfo &D) {
switch (D.Kind) {
case index::SymbolKind::InstanceMethod:
case index::SymbolKind::InstanceProperty:
case index::SymbolKind::Field:
return true;
default:
return false;
}
}
void SymbolQualitySignals::merge(const CodeCompletionResult &SemaCCResult) {
Deprecated |= (SemaCCResult.Availability == CXAvailability_Deprecated);
Category = categorize(SemaCCResult);
if (SemaCCResult.Declaration) {
ImplementationDetail |= isImplementationDetail(SemaCCResult.Declaration);
if (auto *ID = SemaCCResult.Declaration->getIdentifier())
ReservedName = ReservedName || isReserved(ID->getName());
} else if (SemaCCResult.Kind == CodeCompletionResult::RK_Macro)
ReservedName = ReservedName || isReserved(SemaCCResult.Macro->getName());
}
void SymbolQualitySignals::merge(const Symbol &IndexResult) {
Deprecated |= (IndexResult.Flags & Symbol::Deprecated);
ImplementationDetail |= (IndexResult.Flags & Symbol::ImplementationDetail);
References = std::max(IndexResult.References, References);
Category = categorize(IndexResult.SymInfo);
ReservedName = ReservedName || isReserved(IndexResult.Name);
}
float SymbolQualitySignals::evaluate() const {
float Score = 1;
// This avoids a sharp gradient for tail symbols, and also neatly avoids the
// question of whether 0 references means a bad symbol or missing data.
if (References >= 10) {
// Use a sigmoid style boosting function, which flats out nicely for large
// numbers (e.g. 2.58 for 1M references).
// The following boosting function is equivalent to:
// m = 0.06
// f = 12.0
// boost = f * sigmoid(m * std::log(References)) - 0.5 * f + 0.59
// Sample data points: (10, 1.00), (100, 1.41), (1000, 1.82),
// (10K, 2.21), (100K, 2.58), (1M, 2.94)
float S = std::pow(References, -0.06);
Score *= 6.0 * (1 - S) / (1 + S) + 0.59;
}
if (Deprecated)
Score *= 0.1f;
if (ReservedName)
Score *= 0.1f;
if (ImplementationDetail)
Score *= 0.2f;
switch (Category) {
case Keyword: // Often relevant, but misses most signals.
Score *= 4; // FIXME: important keywords should have specific boosts.
break;
case Type:
case Function:
case Variable:
Score *= 1.1f;
break;
case Namespace:
Score *= 0.8f;
break;
case Macro:
case Destructor:
case Operator:
Score *= 0.5f;
break;
case Constructor: // No boost constructors so they are after class types.
case Unknown:
break;
}
return Score;
}
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
const SymbolQualitySignals &S) {
OS << llvm::formatv("=== Symbol quality: {0}\n", S.evaluate());
OS << llvm::formatv("\tReferences: {0}\n", S.References);
OS << llvm::formatv("\tDeprecated: {0}\n", S.Deprecated);
OS << llvm::formatv("\tReserved name: {0}\n", S.ReservedName);
OS << llvm::formatv("\tCategory: {0}\n", static_cast<int>(S.Category));
return OS;
}
static SymbolRelevanceSignals::AccessibleScope
computeScope(const NamedDecl *D) {
// Injected "Foo" within the class "Foo" has file scope, not class scope.
const DeclContext *DC = D->getDeclContext();
if (auto *R = dyn_cast_or_null<RecordDecl>(D))
if (R->isInjectedClassName())
DC = DC->getParent();
// Class constructor should have the same scope as the class.
if (isa<CXXConstructorDecl>(D))
DC = DC->getParent();
bool InClass = false;
for (; !DC->isFileContext(); DC = DC->getParent()) {
if (DC->isFunctionOrMethod())
return SymbolRelevanceSignals::FunctionScope;
InClass = InClass || DC->isRecord();
}
if (InClass)
return SymbolRelevanceSignals::ClassScope;
// ExternalLinkage threshold could be tweaked, e.g. module-visible as global.
// Avoid caching linkage if it may change after enclosing code completion.
if (hasUnstableLinkage(D) || D->getLinkageInternal() < ExternalLinkage)
return SymbolRelevanceSignals::FileScope;
return SymbolRelevanceSignals::GlobalScope;
}
void SymbolRelevanceSignals::merge(const Symbol &IndexResult) {
SymbolURI = IndexResult.CanonicalDeclaration.FileURI;
SymbolScope = IndexResult.Scope;
IsInstanceMember |= isInstanceMember(IndexResult.SymInfo);
if (!(IndexResult.Flags & Symbol::VisibleOutsideFile)) {
Scope = AccessibleScope::FileScope;
}
}
void SymbolRelevanceSignals::merge(const CodeCompletionResult &SemaCCResult) {
if (SemaCCResult.Availability == CXAvailability_NotAvailable ||
SemaCCResult.Availability == CXAvailability_NotAccessible)
Forbidden = true;
if (SemaCCResult.Declaration) {
SemaSaysInScope = true;
// We boost things that have decls in the main file. We give a fixed score
// for all other declarations in sema as they are already included in the
// translation unit.
float DeclProximity = (hasDeclInMainFile(*SemaCCResult.Declaration) ||
hasUsingDeclInMainFile(SemaCCResult))
? 1.0
: 0.6;
SemaFileProximityScore = std::max(DeclProximity, SemaFileProximityScore);
IsInstanceMember |= isInstanceMember(SemaCCResult.Declaration);
InBaseClass |= SemaCCResult.InBaseClass;
}
// Declarations are scoped, others (like macros) are assumed global.
if (SemaCCResult.Declaration)
Scope = std::min(Scope, computeScope(SemaCCResult.Declaration));
NeedsFixIts = !SemaCCResult.FixIts.empty();
}
static std::pair<float, unsigned> uriProximity(llvm::StringRef SymbolURI,
URIDistance *D) {
if (!D || SymbolURI.empty())
return {0.f, 0u};
unsigned Distance = D->distance(SymbolURI);
// Assume approximately default options are used for sensible scoring.
return {std::exp(Distance * -0.4f / FileDistanceOptions().UpCost), Distance};
}
static float scopeBoost(ScopeDistance &Distance,
llvm::Optional<llvm::StringRef> SymbolScope) {
if (!SymbolScope)
return 1;
auto D = Distance.distance(*SymbolScope);
if (D == FileDistance::Unreachable)
return 0.6f;
return std::max(0.65, 2.0 * std::pow(0.6, D / 2.0));
}
static llvm::Optional<llvm::StringRef>
wordMatching(llvm::StringRef Name, const llvm::StringSet<> *ContextWords) {
if (ContextWords)
for (const auto& Word : ContextWords->keys())
if (Name.contains_lower(Word))
return Word;
return llvm::None;
}
float SymbolRelevanceSignals::evaluate() const {
float Score = 1;
if (Forbidden)
return 0;
Score *= NameMatch;
// File proximity scores are [0,1] and we translate them into a multiplier in
// the range from 1 to 3.
Score *= 1 + 2 * std::max(uriProximity(SymbolURI, FileProximityMatch).first,
SemaFileProximityScore);
if (ScopeProximityMatch)
// Use a constant scope boost for sema results, as scopes of sema results
// can be tricky (e.g. class/function scope). Set to the max boost as we
// don't load top-level symbols from the preamble and sema results are
// always in the accessible scope.
Score *=
SemaSaysInScope ? 2.0 : scopeBoost(*ScopeProximityMatch, SymbolScope);
if (wordMatching(Name, ContextWords))
Score *= 1.5;
// Symbols like local variables may only be referenced within their scope.
// Conversely if we're in that scope, it's likely we'll reference them.
if (Query == CodeComplete) {
// The narrower the scope where a symbol is visible, the more likely it is
// to be relevant when it is available.
switch (Scope) {
case GlobalScope:
break;
case FileScope:
Score *= 1.5f;
break;
case ClassScope:
Score *= 2;
break;
case FunctionScope:
Score *= 4;
break;
}
} else {
// For non-completion queries, the wider the scope where a symbol is
// visible, the more likely it is to be relevant.
switch (Scope) {
case GlobalScope:
break;
case FileScope:
Score *= 0.5f;
break;
default:
// TODO: Handle other scopes as we start to use them for index results.
break;
}
}
if (TypeMatchesPreferred)
Score *= 5.0;
// Penalize non-instance members when they are accessed via a class instance.
if (!IsInstanceMember &&
(Context == CodeCompletionContext::CCC_DotMemberAccess ||
Context == CodeCompletionContext::CCC_ArrowMemberAccess)) {
Score *= 0.2f;
}
if (InBaseClass)
Score *= 0.5f;
// Penalize for FixIts.
if (NeedsFixIts)
Score *= 0.5f;
return Score;
}
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
const SymbolRelevanceSignals &S) {
OS << llvm::formatv("=== Symbol relevance: {0}\n", S.evaluate());
OS << llvm::formatv("\tName: {0}\n", S.Name);
OS << llvm::formatv("\tName match: {0}\n", S.NameMatch);
if (S.ContextWords)
OS << llvm::formatv(
"\tMatching context word: {0}\n",
wordMatching(S.Name, S.ContextWords).getValueOr("<none>"));
OS << llvm::formatv("\tForbidden: {0}\n", S.Forbidden);
OS << llvm::formatv("\tNeedsFixIts: {0}\n", S.NeedsFixIts);
OS << llvm::formatv("\tIsInstanceMember: {0}\n", S.IsInstanceMember);
OS << llvm::formatv("\tContext: {0}\n", getCompletionKindString(S.Context));
OS << llvm::formatv("\tQuery type: {0}\n", static_cast<int>(S.Query));
OS << llvm::formatv("\tScope: {0}\n", static_cast<int>(S.Scope));
OS << llvm::formatv("\tSymbol URI: {0}\n", S.SymbolURI);
OS << llvm::formatv("\tSymbol scope: {0}\n",
S.SymbolScope ? *S.SymbolScope : "<None>");
if (S.FileProximityMatch) {
auto Score = uriProximity(S.SymbolURI, S.FileProximityMatch);
OS << llvm::formatv("\tIndex URI proximity: {0} (distance={1})\n",
Score.first, Score.second);
}
OS << llvm::formatv("\tSema file proximity: {0}\n", S.SemaFileProximityScore);
OS << llvm::formatv("\tSema says in scope: {0}\n", S.SemaSaysInScope);
if (S.ScopeProximityMatch)
OS << llvm::formatv("\tIndex scope boost: {0}\n",
scopeBoost(*S.ScopeProximityMatch, S.SymbolScope));
OS << llvm::formatv(
"\tType matched preferred: {0} (Context type: {1}, Symbol type: {2}\n",
S.TypeMatchesPreferred, S.HadContextType, S.HadSymbolType);
return OS;
}
float evaluateSymbolAndRelevance(float SymbolQuality, float SymbolRelevance) {
return SymbolQuality * SymbolRelevance;
}
// Produces an integer that sorts in the same order as F.
// That is: a < b <==> encodeFloat(a) < encodeFloat(b).
static uint32_t encodeFloat(float F) {
static_assert(std::numeric_limits<float>::is_iec559, "");
constexpr uint32_t TopBit = ~(~uint32_t{0} >> 1);
// Get the bits of the float. Endianness is the same as for integers.
uint32_t U = llvm::FloatToBits(F);
// IEEE 754 floats compare like sign-magnitude integers.
if (U & TopBit) // Negative float.
return 0 - U; // Map onto the low half of integers, order reversed.
return U + TopBit; // Positive floats map onto the high half of integers.
}
std::string sortText(float Score, llvm::StringRef Name) {
// We convert -Score to an integer, and hex-encode for readability.
// Example: [0.5, "foo"] -> "41000000foo"
std::string S;
llvm::raw_string_ostream OS(S);
llvm::write_hex(OS, encodeFloat(-Score), llvm::HexPrintStyle::Lower,
/*Width=*/2 * sizeof(Score));
OS << Name;
OS.flush();
return S;
}
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
const SignatureQualitySignals &S) {
OS << llvm::formatv("=== Signature Quality:\n");
OS << llvm::formatv("\tNumber of parameters: {0}\n", S.NumberOfParameters);
OS << llvm::formatv("\tNumber of optional parameters: {0}\n",
S.NumberOfOptionalParameters);
OS << llvm::formatv("\tKind: {0}\n", S.Kind);
return OS;
}
} // namespace clangd
} // namespace clang
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