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      1 //===- CIndexUSR.cpp - Clang-C Source Indexing Library --------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file implements the generation and use of USRs from CXEntities.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "CIndexer.h"
     15 #include "CXCursor.h"
     16 #include "CXString.h"
     17 #include "clang/AST/DeclTemplate.h"
     18 #include "clang/AST/DeclVisitor.h"
     19 #include "clang/Frontend/ASTUnit.h"
     20 #include "clang/Lex/PreprocessingRecord.h"
     21 #include "llvm/ADT/SmallString.h"
     22 #include "llvm/Support/raw_ostream.h"
     23 
     24 using namespace clang;
     25 using namespace clang::cxstring;
     26 
     27 //===----------------------------------------------------------------------===//
     28 // USR generation.
     29 //===----------------------------------------------------------------------===//
     30 
     31 namespace {
     32 class USRGenerator : public DeclVisitor<USRGenerator> {
     33   OwningPtr<SmallString<128> > OwnedBuf;
     34   SmallVectorImpl<char> &Buf;
     35   llvm::raw_svector_ostream Out;
     36   bool IgnoreResults;
     37   ASTContext *Context;
     38   bool generatedLoc;
     39 
     40   llvm::DenseMap<const Type *, unsigned> TypeSubstitutions;
     41 
     42 public:
     43   explicit USRGenerator(ASTContext *Ctx = 0, SmallVectorImpl<char> *extBuf = 0)
     44   : OwnedBuf(extBuf ? 0 : new SmallString<128>()),
     45     Buf(extBuf ? *extBuf : *OwnedBuf.get()),
     46     Out(Buf),
     47     IgnoreResults(false),
     48     Context(Ctx),
     49     generatedLoc(false)
     50   {
     51     // Add the USR space prefix.
     52     Out << "c:";
     53   }
     54 
     55   StringRef str() {
     56     return Out.str();
     57   }
     58 
     59   USRGenerator* operator->() { return this; }
     60 
     61   template <typename T>
     62   llvm::raw_svector_ostream &operator<<(const T &x) {
     63     Out << x;
     64     return Out;
     65   }
     66 
     67   bool ignoreResults() const { return IgnoreResults; }
     68 
     69   // Visitation methods from generating USRs from AST elements.
     70   void VisitDeclContext(DeclContext *D);
     71   void VisitFieldDecl(FieldDecl *D);
     72   void VisitFunctionDecl(FunctionDecl *D);
     73   void VisitNamedDecl(NamedDecl *D);
     74   void VisitNamespaceDecl(NamespaceDecl *D);
     75   void VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
     76   void VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
     77   void VisitClassTemplateDecl(ClassTemplateDecl *D);
     78   void VisitObjCContainerDecl(ObjCContainerDecl *CD);
     79   void VisitObjCMethodDecl(ObjCMethodDecl *MD);
     80   void VisitObjCPropertyDecl(ObjCPropertyDecl *D);
     81   void VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D);
     82   void VisitTagDecl(TagDecl *D);
     83   void VisitTypedefDecl(TypedefDecl *D);
     84   void VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
     85   void VisitVarDecl(VarDecl *D);
     86   void VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
     87   void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
     88   void VisitLinkageSpecDecl(LinkageSpecDecl *D) {
     89     IgnoreResults = true;
     90   }
     91   void VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
     92     IgnoreResults = true;
     93   }
     94   void VisitUsingDecl(UsingDecl *D) {
     95     IgnoreResults = true;
     96   }
     97   void VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
     98     IgnoreResults = true;
     99   }
    100   void VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D) {
    101     IgnoreResults = true;
    102   }
    103 
    104   /// Generate the string component containing the location of the
    105   ///  declaration.
    106   bool GenLoc(const Decl *D);
    107 
    108   /// String generation methods used both by the visitation methods
    109   /// and from other clients that want to directly generate USRs.  These
    110   /// methods do not construct complete USRs (which incorporate the parents
    111   /// of an AST element), but only the fragments concerning the AST element
    112   /// itself.
    113 
    114   /// Generate a USR for an Objective-C class.
    115   void GenObjCClass(StringRef cls);
    116   /// Generate a USR for an Objective-C class category.
    117   void GenObjCCategory(StringRef cls, StringRef cat);
    118   /// Generate a USR fragment for an Objective-C instance variable.  The
    119   /// complete USR can be created by concatenating the USR for the
    120   /// encompassing class with this USR fragment.
    121   void GenObjCIvar(StringRef ivar);
    122   /// Generate a USR fragment for an Objective-C method.
    123   void GenObjCMethod(StringRef sel, bool isInstanceMethod);
    124   /// Generate a USR fragment for an Objective-C property.
    125   void GenObjCProperty(StringRef prop);
    126   /// Generate a USR for an Objective-C protocol.
    127   void GenObjCProtocol(StringRef prot);
    128 
    129   void VisitType(QualType T);
    130   void VisitTemplateParameterList(const TemplateParameterList *Params);
    131   void VisitTemplateName(TemplateName Name);
    132   void VisitTemplateArgument(const TemplateArgument &Arg);
    133 
    134   /// Emit a Decl's name using NamedDecl::printName() and return true if
    135   ///  the decl had no name.
    136   bool EmitDeclName(const NamedDecl *D);
    137 };
    138 
    139 } // end anonymous namespace
    140 
    141 //===----------------------------------------------------------------------===//
    142 // Generating USRs from ASTS.
    143 //===----------------------------------------------------------------------===//
    144 
    145 bool USRGenerator::EmitDeclName(const NamedDecl *D) {
    146   Out.flush();
    147   const unsigned startSize = Buf.size();
    148   D->printName(Out);
    149   Out.flush();
    150   const unsigned endSize = Buf.size();
    151   return startSize == endSize;
    152 }
    153 
    154 static bool InAnonymousNamespace(const Decl *D) {
    155   if (const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(D->getDeclContext()))
    156     return ND->isAnonymousNamespace();
    157   return false;
    158 }
    159 
    160 static inline bool ShouldGenerateLocation(const NamedDecl *D) {
    161   return D->getLinkage() != ExternalLinkage && !InAnonymousNamespace(D);
    162 }
    163 
    164 void USRGenerator::VisitDeclContext(DeclContext *DC) {
    165   if (NamedDecl *D = dyn_cast<NamedDecl>(DC))
    166     Visit(D);
    167 }
    168 
    169 void USRGenerator::VisitFieldDecl(FieldDecl *D) {
    170   // The USR for an ivar declared in a class extension is based on the
    171   // ObjCInterfaceDecl, not the ObjCCategoryDecl.
    172   if (ObjCInterfaceDecl *ID = Context->getObjContainingInterface(D))
    173     Visit(ID);
    174   else
    175     VisitDeclContext(D->getDeclContext());
    176   Out << (isa<ObjCIvarDecl>(D) ? "@" : "@FI@");
    177   if (EmitDeclName(D)) {
    178     // Bit fields can be anonymous.
    179     IgnoreResults = true;
    180     return;
    181   }
    182 }
    183 
    184 void USRGenerator::VisitFunctionDecl(FunctionDecl *D) {
    185   if (ShouldGenerateLocation(D) && GenLoc(D))
    186     return;
    187 
    188   VisitDeclContext(D->getDeclContext());
    189   if (FunctionTemplateDecl *FunTmpl = D->getDescribedFunctionTemplate()) {
    190     Out << "@FT@";
    191     VisitTemplateParameterList(FunTmpl->getTemplateParameters());
    192   } else
    193     Out << "@F@";
    194   D->printName(Out);
    195 
    196   ASTContext &Ctx = *Context;
    197   if (!Ctx.getLangOpts().CPlusPlus || D->isExternC())
    198     return;
    199 
    200   if (const TemplateArgumentList *
    201         SpecArgs = D->getTemplateSpecializationArgs()) {
    202     Out << '<';
    203     for (unsigned I = 0, N = SpecArgs->size(); I != N; ++I) {
    204       Out << '#';
    205       VisitTemplateArgument(SpecArgs->get(I));
    206     }
    207     Out << '>';
    208   }
    209 
    210   // Mangle in type information for the arguments.
    211   for (FunctionDecl::param_iterator I = D->param_begin(), E = D->param_end();
    212        I != E; ++I) {
    213     Out << '#';
    214     if (ParmVarDecl *PD = *I)
    215       VisitType(PD->getType());
    216   }
    217   if (D->isVariadic())
    218     Out << '.';
    219   Out << '#';
    220   if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) {
    221     if (MD->isStatic())
    222       Out << 'S';
    223     if (unsigned quals = MD->getTypeQualifiers())
    224       Out << (char)('0' + quals);
    225   }
    226 }
    227 
    228 void USRGenerator::VisitNamedDecl(NamedDecl *D) {
    229   VisitDeclContext(D->getDeclContext());
    230   Out << "@";
    231 
    232   if (EmitDeclName(D)) {
    233     // The string can be empty if the declaration has no name; e.g., it is
    234     // the ParmDecl with no name for declaration of a function pointer type,
    235     // e.g.: void  (*f)(void *);
    236     // In this case, don't generate a USR.
    237     IgnoreResults = true;
    238   }
    239 }
    240 
    241 void USRGenerator::VisitVarDecl(VarDecl *D) {
    242   // VarDecls can be declared 'extern' within a function or method body,
    243   // but their enclosing DeclContext is the function, not the TU.  We need
    244   // to check the storage class to correctly generate the USR.
    245   if (ShouldGenerateLocation(D) && GenLoc(D))
    246     return;
    247 
    248   VisitDeclContext(D->getDeclContext());
    249 
    250   // Variables always have simple names.
    251   StringRef s = D->getName();
    252 
    253   // The string can be empty if the declaration has no name; e.g., it is
    254   // the ParmDecl with no name for declaration of a function pointer type, e.g.:
    255   //    void  (*f)(void *);
    256   // In this case, don't generate a USR.
    257   if (s.empty())
    258     IgnoreResults = true;
    259   else
    260     Out << '@' << s;
    261 }
    262 
    263 void USRGenerator::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
    264   GenLoc(D);
    265   return;
    266 }
    267 
    268 void USRGenerator::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
    269   GenLoc(D);
    270   return;
    271 }
    272 
    273 void USRGenerator::VisitNamespaceDecl(NamespaceDecl *D) {
    274   if (D->isAnonymousNamespace()) {
    275     Out << "@aN";
    276     return;
    277   }
    278 
    279   VisitDeclContext(D->getDeclContext());
    280   if (!IgnoreResults)
    281     Out << "@N@" << D->getName();
    282 }
    283 
    284 void USRGenerator::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
    285   VisitFunctionDecl(D->getTemplatedDecl());
    286 }
    287 
    288 void USRGenerator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
    289   VisitTagDecl(D->getTemplatedDecl());
    290 }
    291 
    292 void USRGenerator::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
    293   VisitDeclContext(D->getDeclContext());
    294   if (!IgnoreResults)
    295     Out << "@NA@" << D->getName();
    296 }
    297 
    298 void USRGenerator::VisitObjCMethodDecl(ObjCMethodDecl *D) {
    299   DeclContext *container = D->getDeclContext();
    300   if (ObjCProtocolDecl *pd = dyn_cast<ObjCProtocolDecl>(container)) {
    301     Visit(pd);
    302   }
    303   else {
    304     // The USR for a method declared in a class extension or category is based on
    305     // the ObjCInterfaceDecl, not the ObjCCategoryDecl.
    306     ObjCInterfaceDecl *ID = D->getClassInterface();
    307     if (!ID) {
    308       IgnoreResults = true;
    309       return;
    310     }
    311     Visit(ID);
    312   }
    313   // Ideally we would use 'GenObjCMethod', but this is such a hot path
    314   // for Objective-C code that we don't want to use
    315   // DeclarationName::getAsString().
    316   Out << (D->isInstanceMethod() ? "(im)" : "(cm)");
    317   DeclarationName N(D->getSelector());
    318   N.printName(Out);
    319 }
    320 
    321 void USRGenerator::VisitObjCContainerDecl(ObjCContainerDecl *D) {
    322   switch (D->getKind()) {
    323     default:
    324       llvm_unreachable("Invalid ObjC container.");
    325     case Decl::ObjCInterface:
    326     case Decl::ObjCImplementation:
    327       GenObjCClass(D->getName());
    328       break;
    329     case Decl::ObjCCategory: {
    330       ObjCCategoryDecl *CD = cast<ObjCCategoryDecl>(D);
    331       ObjCInterfaceDecl *ID = CD->getClassInterface();
    332       if (!ID) {
    333         // Handle invalid code where the @interface might not
    334         // have been specified.
    335         // FIXME: We should be able to generate this USR even if the
    336         // @interface isn't available.
    337         IgnoreResults = true;
    338         return;
    339       }
    340       // Specially handle class extensions, which are anonymous categories.
    341       // We want to mangle in the location to uniquely distinguish them.
    342       if (CD->IsClassExtension()) {
    343         Out << "objc(ext)" << ID->getName() << '@';
    344         GenLoc(CD);
    345       }
    346       else
    347         GenObjCCategory(ID->getName(), CD->getName());
    348 
    349       break;
    350     }
    351     case Decl::ObjCCategoryImpl: {
    352       ObjCCategoryImplDecl *CD = cast<ObjCCategoryImplDecl>(D);
    353       ObjCInterfaceDecl *ID = CD->getClassInterface();
    354       if (!ID) {
    355         // Handle invalid code where the @interface might not
    356         // have been specified.
    357         // FIXME: We should be able to generate this USR even if the
    358         // @interface isn't available.
    359         IgnoreResults = true;
    360         return;
    361       }
    362       GenObjCCategory(ID->getName(), CD->getName());
    363       break;
    364     }
    365     case Decl::ObjCProtocol:
    366       GenObjCProtocol(cast<ObjCProtocolDecl>(D)->getName());
    367       break;
    368   }
    369 }
    370 
    371 void USRGenerator::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
    372   // The USR for a property declared in a class extension or category is based
    373   // on the ObjCInterfaceDecl, not the ObjCCategoryDecl.
    374   if (ObjCInterfaceDecl *ID = Context->getObjContainingInterface(D))
    375     Visit(ID);
    376   else
    377     Visit(cast<Decl>(D->getDeclContext()));
    378   GenObjCProperty(D->getName());
    379 }
    380 
    381 void USRGenerator::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
    382   if (ObjCPropertyDecl *PD = D->getPropertyDecl()) {
    383     VisitObjCPropertyDecl(PD);
    384     return;
    385   }
    386 
    387   IgnoreResults = true;
    388 }
    389 
    390 void USRGenerator::VisitTagDecl(TagDecl *D) {
    391   // Add the location of the tag decl to handle resolution across
    392   // translation units.
    393   if (ShouldGenerateLocation(D) && GenLoc(D))
    394     return;
    395 
    396   D = D->getCanonicalDecl();
    397   VisitDeclContext(D->getDeclContext());
    398 
    399   bool AlreadyStarted = false;
    400   if (CXXRecordDecl *CXXRecord = dyn_cast<CXXRecordDecl>(D)) {
    401     if (ClassTemplateDecl *ClassTmpl = CXXRecord->getDescribedClassTemplate()) {
    402       AlreadyStarted = true;
    403 
    404       switch (D->getTagKind()) {
    405       case TTK_Struct: Out << "@ST"; break;
    406       case TTK_Class:  Out << "@CT"; break;
    407       case TTK_Union:  Out << "@UT"; break;
    408       case TTK_Enum: llvm_unreachable("enum template");
    409       }
    410       VisitTemplateParameterList(ClassTmpl->getTemplateParameters());
    411     } else if (ClassTemplatePartialSpecializationDecl *PartialSpec
    412                 = dyn_cast<ClassTemplatePartialSpecializationDecl>(CXXRecord)) {
    413       AlreadyStarted = true;
    414 
    415       switch (D->getTagKind()) {
    416       case TTK_Struct: Out << "@SP"; break;
    417       case TTK_Class:  Out << "@CP"; break;
    418       case TTK_Union:  Out << "@UP"; break;
    419       case TTK_Enum: llvm_unreachable("enum partial specialization");
    420       }
    421       VisitTemplateParameterList(PartialSpec->getTemplateParameters());
    422     }
    423   }
    424 
    425   if (!AlreadyStarted) {
    426     switch (D->getTagKind()) {
    427       case TTK_Struct: Out << "@S"; break;
    428       case TTK_Class:  Out << "@C"; break;
    429       case TTK_Union:  Out << "@U"; break;
    430       case TTK_Enum:   Out << "@E"; break;
    431     }
    432   }
    433 
    434   Out << '@';
    435   Out.flush();
    436   assert(Buf.size() > 0);
    437   const unsigned off = Buf.size() - 1;
    438 
    439   if (EmitDeclName(D)) {
    440     if (const TypedefNameDecl *TD = D->getTypedefNameForAnonDecl()) {
    441       Buf[off] = 'A';
    442       Out << '@' << *TD;
    443     }
    444     else
    445       Buf[off] = 'a';
    446   }
    447 
    448   // For a class template specialization, mangle the template arguments.
    449   if (ClassTemplateSpecializationDecl *Spec
    450                               = dyn_cast<ClassTemplateSpecializationDecl>(D)) {
    451     const TemplateArgumentList &Args = Spec->getTemplateInstantiationArgs();
    452     Out << '>';
    453     for (unsigned I = 0, N = Args.size(); I != N; ++I) {
    454       Out << '#';
    455       VisitTemplateArgument(Args.get(I));
    456     }
    457   }
    458 }
    459 
    460 void USRGenerator::VisitTypedefDecl(TypedefDecl *D) {
    461   if (ShouldGenerateLocation(D) && GenLoc(D))
    462     return;
    463   DeclContext *DC = D->getDeclContext();
    464   if (NamedDecl *DCN = dyn_cast<NamedDecl>(DC))
    465     Visit(DCN);
    466   Out << "@T@";
    467   Out << D->getName();
    468 }
    469 
    470 void USRGenerator::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
    471   GenLoc(D);
    472   return;
    473 }
    474 
    475 bool USRGenerator::GenLoc(const Decl *D) {
    476   if (generatedLoc)
    477     return IgnoreResults;
    478   generatedLoc = true;
    479 
    480   // Guard against null declarations in invalid code.
    481   if (!D) {
    482     IgnoreResults = true;
    483     return true;
    484   }
    485 
    486   // Use the location of canonical decl.
    487   D = D->getCanonicalDecl();
    488 
    489   const SourceManager &SM = Context->getSourceManager();
    490   SourceLocation L = D->getLocStart();
    491   if (L.isInvalid()) {
    492     IgnoreResults = true;
    493     return true;
    494   }
    495   L = SM.getExpansionLoc(L);
    496   const std::pair<FileID, unsigned> &Decomposed = SM.getDecomposedLoc(L);
    497   const FileEntry *FE = SM.getFileEntryForID(Decomposed.first);
    498   if (FE) {
    499     Out << llvm::sys::path::filename(FE->getName());
    500   }
    501   else {
    502     // This case really isn't interesting.
    503     IgnoreResults = true;
    504     return true;
    505   }
    506   // Use the offest into the FileID to represent the location.  Using
    507   // a line/column can cause us to look back at the original source file,
    508   // which is expensive.
    509   Out << '@' << Decomposed.second;
    510   return IgnoreResults;
    511 }
    512 
    513 void USRGenerator::VisitType(QualType T) {
    514   // This method mangles in USR information for types.  It can possibly
    515   // just reuse the naming-mangling logic used by codegen, although the
    516   // requirements for USRs might not be the same.
    517   ASTContext &Ctx = *Context;
    518 
    519   do {
    520     T = Ctx.getCanonicalType(T);
    521     Qualifiers Q = T.getQualifiers();
    522     unsigned qVal = 0;
    523     if (Q.hasConst())
    524       qVal |= 0x1;
    525     if (Q.hasVolatile())
    526       qVal |= 0x2;
    527     if (Q.hasRestrict())
    528       qVal |= 0x4;
    529     if(qVal)
    530       Out << ((char) ('0' + qVal));
    531 
    532     // Mangle in ObjC GC qualifiers?
    533 
    534     if (const PackExpansionType *Expansion = T->getAs<PackExpansionType>()) {
    535       Out << 'P';
    536       T = Expansion->getPattern();
    537     }
    538 
    539     if (const BuiltinType *BT = T->getAs<BuiltinType>()) {
    540       unsigned char c = '\0';
    541       switch (BT->getKind()) {
    542         case BuiltinType::Void:
    543           c = 'v'; break;
    544         case BuiltinType::Bool:
    545           c = 'b'; break;
    546         case BuiltinType::Char_U:
    547         case BuiltinType::UChar:
    548           c = 'c'; break;
    549         case BuiltinType::Char16:
    550           c = 'q'; break;
    551         case BuiltinType::Char32:
    552           c = 'w'; break;
    553         case BuiltinType::UShort:
    554           c = 's'; break;
    555         case BuiltinType::UInt:
    556           c = 'i'; break;
    557         case BuiltinType::ULong:
    558           c = 'l'; break;
    559         case BuiltinType::ULongLong:
    560           c = 'k'; break;
    561         case BuiltinType::UInt128:
    562           c = 'j'; break;
    563         case BuiltinType::Char_S:
    564         case BuiltinType::SChar:
    565           c = 'C'; break;
    566         case BuiltinType::WChar_S:
    567         case BuiltinType::WChar_U:
    568           c = 'W'; break;
    569         case BuiltinType::Short:
    570           c = 'S'; break;
    571         case BuiltinType::Int:
    572           c = 'I'; break;
    573         case BuiltinType::Long:
    574           c = 'L'; break;
    575         case BuiltinType::LongLong:
    576           c = 'K'; break;
    577         case BuiltinType::Int128:
    578           c = 'J'; break;
    579         case BuiltinType::Half:
    580           c = 'h'; break;
    581         case BuiltinType::Float:
    582           c = 'f'; break;
    583         case BuiltinType::Double:
    584           c = 'd'; break;
    585         case BuiltinType::LongDouble:
    586           c = 'D'; break;
    587         case BuiltinType::NullPtr:
    588           c = 'n'; break;
    589 #define BUILTIN_TYPE(Id, SingletonId)
    590 #define PLACEHOLDER_TYPE(Id, SingletonId) case BuiltinType::Id:
    591 #include "clang/AST/BuiltinTypes.def"
    592         case BuiltinType::Dependent:
    593           IgnoreResults = true;
    594           return;
    595         case BuiltinType::ObjCId:
    596           c = 'o'; break;
    597         case BuiltinType::ObjCClass:
    598           c = 'O'; break;
    599         case BuiltinType::ObjCSel:
    600           c = 'e'; break;
    601       }
    602       Out << c;
    603       return;
    604     }
    605 
    606     // If we have already seen this (non-built-in) type, use a substitution
    607     // encoding.
    608     llvm::DenseMap<const Type *, unsigned>::iterator Substitution
    609       = TypeSubstitutions.find(T.getTypePtr());
    610     if (Substitution != TypeSubstitutions.end()) {
    611       Out << 'S' << Substitution->second << '_';
    612       return;
    613     } else {
    614       // Record this as a substitution.
    615       unsigned Number = TypeSubstitutions.size();
    616       TypeSubstitutions[T.getTypePtr()] = Number;
    617     }
    618 
    619     if (const PointerType *PT = T->getAs<PointerType>()) {
    620       Out << '*';
    621       T = PT->getPointeeType();
    622       continue;
    623     }
    624     if (const ReferenceType *RT = T->getAs<ReferenceType>()) {
    625       Out << '&';
    626       T = RT->getPointeeType();
    627       continue;
    628     }
    629     if (const FunctionProtoType *FT = T->getAs<FunctionProtoType>()) {
    630       Out << 'F';
    631       VisitType(FT->getResultType());
    632       for (FunctionProtoType::arg_type_iterator
    633             I = FT->arg_type_begin(), E = FT->arg_type_end(); I!=E; ++I) {
    634         VisitType(*I);
    635       }
    636       if (FT->isVariadic())
    637         Out << '.';
    638       return;
    639     }
    640     if (const BlockPointerType *BT = T->getAs<BlockPointerType>()) {
    641       Out << 'B';
    642       T = BT->getPointeeType();
    643       continue;
    644     }
    645     if (const ComplexType *CT = T->getAs<ComplexType>()) {
    646       Out << '<';
    647       T = CT->getElementType();
    648       continue;
    649     }
    650     if (const TagType *TT = T->getAs<TagType>()) {
    651       Out << '$';
    652       VisitTagDecl(TT->getDecl());
    653       return;
    654     }
    655     if (const TemplateTypeParmType *TTP = T->getAs<TemplateTypeParmType>()) {
    656       Out << 't' << TTP->getDepth() << '.' << TTP->getIndex();
    657       return;
    658     }
    659     if (const TemplateSpecializationType *Spec
    660                                     = T->getAs<TemplateSpecializationType>()) {
    661       Out << '>';
    662       VisitTemplateName(Spec->getTemplateName());
    663       Out << Spec->getNumArgs();
    664       for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
    665         VisitTemplateArgument(Spec->getArg(I));
    666       return;
    667     }
    668 
    669     // Unhandled type.
    670     Out << ' ';
    671     break;
    672   } while (true);
    673 }
    674 
    675 void USRGenerator::VisitTemplateParameterList(
    676                                          const TemplateParameterList *Params) {
    677   if (!Params)
    678     return;
    679   Out << '>' << Params->size();
    680   for (TemplateParameterList::const_iterator P = Params->begin(),
    681                                           PEnd = Params->end();
    682        P != PEnd; ++P) {
    683     Out << '#';
    684     if (isa<TemplateTypeParmDecl>(*P)) {
    685       if (cast<TemplateTypeParmDecl>(*P)->isParameterPack())
    686         Out<< 'p';
    687       Out << 'T';
    688       continue;
    689     }
    690 
    691     if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(*P)) {
    692       if (NTTP->isParameterPack())
    693         Out << 'p';
    694       Out << 'N';
    695       VisitType(NTTP->getType());
    696       continue;
    697     }
    698 
    699     TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(*P);
    700     if (TTP->isParameterPack())
    701       Out << 'p';
    702     Out << 't';
    703     VisitTemplateParameterList(TTP->getTemplateParameters());
    704   }
    705 }
    706 
    707 void USRGenerator::VisitTemplateName(TemplateName Name) {
    708   if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
    709     if (TemplateTemplateParmDecl *TTP
    710                               = dyn_cast<TemplateTemplateParmDecl>(Template)) {
    711       Out << 't' << TTP->getDepth() << '.' << TTP->getIndex();
    712       return;
    713     }
    714 
    715     Visit(Template);
    716     return;
    717   }
    718 
    719   // FIXME: Visit dependent template names.
    720 }
    721 
    722 void USRGenerator::VisitTemplateArgument(const TemplateArgument &Arg) {
    723   switch (Arg.getKind()) {
    724   case TemplateArgument::Null:
    725     break;
    726 
    727   case TemplateArgument::Declaration:
    728     if (Decl *D = Arg.getAsDecl())
    729       Visit(D);
    730     break;
    731 
    732   case TemplateArgument::TemplateExpansion:
    733     Out << 'P'; // pack expansion of...
    734     // Fall through
    735   case TemplateArgument::Template:
    736     VisitTemplateName(Arg.getAsTemplateOrTemplatePattern());
    737     break;
    738 
    739   case TemplateArgument::Expression:
    740     // FIXME: Visit expressions.
    741     break;
    742 
    743   case TemplateArgument::Pack:
    744     Out << 'p' << Arg.pack_size();
    745     for (TemplateArgument::pack_iterator P = Arg.pack_begin(), PEnd = Arg.pack_end();
    746          P != PEnd; ++P)
    747       VisitTemplateArgument(*P);
    748     break;
    749 
    750   case TemplateArgument::Type:
    751     VisitType(Arg.getAsType());
    752     break;
    753 
    754   case TemplateArgument::Integral:
    755     Out << 'V';
    756     VisitType(Arg.getIntegralType());
    757     Out << *Arg.getAsIntegral();
    758     break;
    759   }
    760 }
    761 
    762 //===----------------------------------------------------------------------===//
    763 // General purpose USR generation methods.
    764 //===----------------------------------------------------------------------===//
    765 
    766 void USRGenerator::GenObjCClass(StringRef cls) {
    767   Out << "objc(cs)" << cls;
    768 }
    769 
    770 void USRGenerator::GenObjCCategory(StringRef cls, StringRef cat) {
    771   Out << "objc(cy)" << cls << '@' << cat;
    772 }
    773 
    774 void USRGenerator::GenObjCIvar(StringRef ivar) {
    775   Out << '@' << ivar;
    776 }
    777 
    778 void USRGenerator::GenObjCMethod(StringRef meth, bool isInstanceMethod) {
    779   Out << (isInstanceMethod ? "(im)" : "(cm)") << meth;
    780 }
    781 
    782 void USRGenerator::GenObjCProperty(StringRef prop) {
    783   Out << "(py)" << prop;
    784 }
    785 
    786 void USRGenerator::GenObjCProtocol(StringRef prot) {
    787   Out << "objc(pl)" << prot;
    788 }
    789 
    790 //===----------------------------------------------------------------------===//
    791 // API hooks.
    792 //===----------------------------------------------------------------------===//
    793 
    794 static inline StringRef extractUSRSuffix(StringRef s) {
    795   return s.startswith("c:") ? s.substr(2) : "";
    796 }
    797 
    798 bool cxcursor::getDeclCursorUSR(const Decl *D, SmallVectorImpl<char> &Buf) {
    799   // Don't generate USRs for things with invalid locations.
    800   if (!D || D->getLocStart().isInvalid())
    801     return true;
    802 
    803   // Check if the cursor has 'NoLinkage'.
    804   if (const NamedDecl *ND = dyn_cast<NamedDecl>(D))
    805     switch (ND->getLinkage()) {
    806       case ExternalLinkage:
    807         // Generate USRs for all entities with external linkage.
    808         break;
    809       case NoLinkage:
    810       case UniqueExternalLinkage:
    811         // We allow enums, typedefs, and structs that have no linkage to
    812         // have USRs that are anchored to the file they were defined in
    813         // (e.g., the header).  This is a little gross, but in principal
    814         // enums/anonymous structs/etc. defined in a common header file
    815         // are referred to across multiple translation units.
    816         if (isa<TagDecl>(ND) || isa<TypedefDecl>(ND) ||
    817             isa<EnumConstantDecl>(ND) || isa<FieldDecl>(ND) ||
    818             isa<VarDecl>(ND) || isa<NamespaceDecl>(ND))
    819           break;
    820         // Fall-through.
    821       case InternalLinkage:
    822         if (isa<FunctionDecl>(ND))
    823           break;
    824     }
    825 
    826   {
    827     USRGenerator UG(&D->getASTContext(), &Buf);
    828     UG->Visit(const_cast<Decl*>(D));
    829 
    830     if (UG->ignoreResults())
    831       return true;
    832   }
    833 
    834   return false;
    835 }
    836 
    837 extern "C" {
    838 
    839 CXString clang_getCursorUSR(CXCursor C) {
    840   const CXCursorKind &K = clang_getCursorKind(C);
    841 
    842   if (clang_isDeclaration(K)) {
    843     Decl *D = cxcursor::getCursorDecl(C);
    844     if (!D)
    845       return createCXString("");
    846 
    847     CXTranslationUnit TU = cxcursor::getCursorTU(C);
    848     if (!TU)
    849       return createCXString("");
    850 
    851     CXStringBuf *buf = cxstring::getCXStringBuf(TU);
    852     if (!buf)
    853       return createCXString("");
    854 
    855     bool Ignore = cxcursor::getDeclCursorUSR(D, buf->Data);
    856     if (Ignore) {
    857       disposeCXStringBuf(buf);
    858       return createCXString("");
    859     }
    860 
    861     // Return the C-string, but don't make a copy since it is already in
    862     // the string buffer.
    863     buf->Data.push_back('\0');
    864     return createCXString(buf);
    865   }
    866 
    867   if (K == CXCursor_MacroDefinition) {
    868     CXTranslationUnit TU = cxcursor::getCursorTU(C);
    869     if (!TU)
    870       return createCXString("");
    871 
    872     CXStringBuf *buf = cxstring::getCXStringBuf(TU);
    873     if (!buf)
    874       return createCXString("");
    875 
    876     {
    877       USRGenerator UG(&cxcursor::getCursorASTUnit(C)->getASTContext(),
    878                       &buf->Data);
    879       UG << "macro@"
    880         << cxcursor::getCursorMacroDefinition(C)->getName()->getNameStart();
    881     }
    882     buf->Data.push_back('\0');
    883     return createCXString(buf);
    884   }
    885 
    886   return createCXString("");
    887 }
    888 
    889 CXString clang_constructUSR_ObjCIvar(const char *name, CXString classUSR) {
    890   USRGenerator UG;
    891   UG << extractUSRSuffix(clang_getCString(classUSR));
    892   UG->GenObjCIvar(name);
    893   return createCXString(UG.str(), true);
    894 }
    895 
    896 CXString clang_constructUSR_ObjCMethod(const char *name,
    897                                        unsigned isInstanceMethod,
    898                                        CXString classUSR) {
    899   USRGenerator UG;
    900   UG << extractUSRSuffix(clang_getCString(classUSR));
    901   UG->GenObjCMethod(name, isInstanceMethod);
    902   return createCXString(UG.str(), true);
    903 }
    904 
    905 CXString clang_constructUSR_ObjCClass(const char *name) {
    906   USRGenerator UG;
    907   UG->GenObjCClass(name);
    908   return createCXString(UG.str(), true);
    909 }
    910 
    911 CXString clang_constructUSR_ObjCProtocol(const char *name) {
    912   USRGenerator UG;
    913   UG->GenObjCProtocol(name);
    914   return createCXString(UG.str(), true);
    915 }
    916 
    917 CXString clang_constructUSR_ObjCCategory(const char *class_name,
    918                                          const char *category_name) {
    919   USRGenerator UG;
    920   UG->GenObjCCategory(class_name, category_name);
    921   return createCXString(UG.str(), true);
    922 }
    923 
    924 CXString clang_constructUSR_ObjCProperty(const char *property,
    925                                          CXString classUSR) {
    926   USRGenerator UG;
    927   UG << extractUSRSuffix(clang_getCString(classUSR));
    928   UG->GenObjCProperty(property);
    929   return createCXString(UG.str(), true);
    930 }
    931 
    932 } // end extern "C"
    933