C++ Twine::isTriviallyEmpty方法代码示例

void InitHeaderSearch::AddPath(const Twine &Path,
                               IncludeDirGroup Group, bool isCXXAware,
                               bool isUserSupplied, bool isFramework,
                               bool IgnoreSysRoot) {
  assert(!Path.isTriviallyEmpty() && "can't handle empty path here");
  FileManager &FM = Headers.getFileMgr();

  // Compute the actual path, taking into consideration -isysroot.
  SmallString<256> MappedPathStorage;
  StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);

  // Handle isysroot.
  if ((Group == System || Group == CXXSystem) && !IgnoreSysRoot &&
#if defined(_WIN32)
      !MappedPathStr.empty() &&
      llvm::sys::path::is_separator(MappedPathStr[0]) &&
#else
      llvm::sys::path::is_absolute(MappedPathStr) &&
#endif
      IsNotEmptyOrRoot) {
    MappedPathStorage.clear();
    MappedPathStr =
      (IncludeSysroot + Path).toStringRef(MappedPathStorage);
  }

  // Compute the DirectoryLookup type.
  SrcMgr::CharacteristicKind Type;
  if (Group == Quoted || Group == Angled || Group == IndexHeaderMap)
    Type = SrcMgr::C_User;
  else if (isCXXAware)
    Type = SrcMgr::C_System;
  else
    Type = SrcMgr::C_ExternCSystem;


  // If the directory exists, add it.
  if (const DirectoryEntry *DE = FM.getDirectory(MappedPathStr)) {
    IncludePath.push_back(std::make_pair(Group, DirectoryLookup(DE, Type,
                          isUserSupplied, isFramework)));
    return;
  }

  // Check to see if this is an apple-style headermap (which are not allowed to
  // be frameworks).
  if (!isFramework) {
    if (const FileEntry *FE = FM.getFile(MappedPathStr)) {
      if (const HeaderMap *HM = Headers.CreateHeaderMap(FE)) {
        // It is a headermap, add it to the search path.
        IncludePath.push_back(std::make_pair(Group, DirectoryLookup(HM, Type,
                              isUserSupplied, Group == IndexHeaderMap)));
        return;
      }
    }
  }

  if (Verbose)
    llvm::errs() << "ignoring nonexistent directory \""
                 << MappedPathStr << "\"\n";
}

void Value::setName(const Twine &NewName) {
  // Fast path for common IRBuilder case of setName("") when there is no name.
  if (NewName.isTriviallyEmpty() && !hasName())
    return;

  SmallString<256> NameData;
  NewName.toVector(NameData);

  const char *NameStr = NameData.data();
  unsigned NameLen = NameData.size();

  // Name isn't changing?
  if (getName() == StringRef(NameStr, NameLen))
    return;

  assert(getType() != Type::getVoidTy(getContext()) &&
         "Cannot assign a name to void values!");

  // Get the symbol table to update for this object.
  ValueSymbolTable *ST;
  if (getSymTab(this, ST))
    return;  // Cannot set a name on this value (e.g. constant).

  if (!ST) { // No symbol table to update?  Just do the change.
    if (NameLen == 0) {
      // Free the name for this value.
      Name->Destroy();
      Name = 0;
      return;
    }

    if (Name)
      Name->Destroy();

    // NOTE: Could optimize for the case the name is shrinking to not deallocate
    // then reallocated.

    // Create the new name.
    Name = ValueName::Create(NameStr, NameStr+NameLen);
    Name->setValue(this);
    return;
  }

  // NOTE: Could optimize for the case the name is shrinking to not deallocate
  // then reallocated.
  if (hasName()) {
    // Remove old name.
    ST->removeValueName(Name);
    Name->Destroy();
    Name = 0;

    if (NameLen == 0)
      return;
  }

  // Name is changing to something new.
  Name = ST->createValueName(StringRef(NameStr, NameLen), this);
}

void Value::setName(const Twine &NewName) {
  assert(SubclassID != MDStringVal &&
         "Cannot set the name of MDString with this method!");

  // Fast path for common IRBuilder case of setName("") when there is no name.
  if (NewName.isTriviallyEmpty() && !hasName())
    return;

  SmallString<256> NameData;
  StringRef NameRef = NewName.toStringRef(NameData);

  // Name isn't changing?
  if (getName() == NameRef)
    return;

  assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");

  // Get the symbol table to update for this object.
  ValueSymbolTable *ST;
  if (getSymTab(this, ST))
    return;  // Cannot set a name on this value (e.g. constant).

  if (!ST) { // No symbol table to update?  Just do the change.
    if (NameRef.empty()) {
      // Free the name for this value.
      Name->Destroy();
      Name = 0;
      return;
    }

    if (Name)
      Name->Destroy();

    // NOTE: Could optimize for the case the name is shrinking to not deallocate
    // then reallocated.

    // Create the new name.
    Name = ValueName::Create(NameRef.begin(), NameRef.end());
    Name->setValue(this);
    return;
  }

  // NOTE: Could optimize for the case the name is shrinking to not deallocate
  // then reallocated.
  if (hasName()) {
    // Remove old name.
    ST->removeValueName(Name);
    Name->Destroy();
    Name = 0;

    if (NameRef.empty())
      return;
  }

  // Name is changing to something new.
  Name = ST->createValueName(NameRef, this);
}

void Attributes::addComment(const Twine &Comment) {
  if (!Comment.isTriviallyEmpty()) {
    if (Comments.empty())
      Comments = " // ";
    else
      Comments += ", ";
    Comments += Comment.str();
  }
}

void Value::setNameImpl(const Twine &NewName) {
  // Fast-path: LLVMContext can be set to strip out non-GlobalValue names
  if (getContext().shouldDiscardValueNames() && !isa<GlobalValue>(this))
    return;

  // Fast path for common IRBuilder case of setName("") when there is no name.
  if (NewName.isTriviallyEmpty() && !hasName())
    return;

  SmallString<256> NameData;
  StringRef NameRef = NewName.toStringRef(NameData);
  assert(NameRef.find_first_of(0) == StringRef::npos &&
         "Null bytes are not allowed in names");

  // Name isn't changing?
  if (getName() == NameRef)
    return;

  assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");

  // Get the symbol table to update for this object.
  ValueSymbolTable *ST;
  if (getSymTab(this, ST))
    return;  // Cannot set a name on this value (e.g. constant).

  if (!ST) { // No symbol table to update?  Just do the change.
    if (NameRef.empty()) {
      // Free the name for this value.
      destroyValueName();
      return;
    }

    // NOTE: Could optimize for the case the name is shrinking to not deallocate
    // then reallocated.
    destroyValueName();

    // Create the new name.
    setValueName(ValueName::Create(NameRef));
    getValueName()->setValue(this);
    return;
  }

  // NOTE: Could optimize for the case the name is shrinking to not deallocate
  // then reallocated.
  if (hasName()) {
    // Remove old name.
    ST->removeValueName(getValueName());
    destroyValueName();

    if (NameRef.empty())
      return;
  }

  // Name is changing to something new.
  setValueName(ST->createValueName(NameRef, this));
}

void append(SmallVectorImpl<char> &path, Style style, const Twine &a,
            const Twine &b, const Twine &c, const Twine &d) {
  SmallString<32> a_storage;
  SmallString<32> b_storage;
  SmallString<32> c_storage;
  SmallString<32> d_storage;

  SmallVector<StringRef, 4> components;
  if (!a.isTriviallyEmpty()) components.push_back(a.toStringRef(a_storage));
  if (!b.isTriviallyEmpty()) components.push_back(b.toStringRef(b_storage));
  if (!c.isTriviallyEmpty()) components.push_back(c.toStringRef(c_storage));
  if (!d.isTriviallyEmpty()) components.push_back(d.toStringRef(d_storage));

  for (auto &component : components) {
    bool path_has_sep =
        !path.empty() && is_separator(path[path.size() - 1], style);
    bool component_has_sep =
        !component.empty() && is_separator(component[0], style);
    bool is_root_name = has_root_name(component, style);

    if (path_has_sep) {
      // Strip separators from beginning of component.
      size_t loc = component.find_first_not_of(separators(style));
      StringRef c = component.substr(loc);

      // Append it.
      path.append(c.begin(), c.end());
      continue;
    }

    if (!component_has_sep && !(path.empty() || is_root_name)) {
      // Add a separator.
      path.push_back(preferred_separator(style));
    }

    path.append(component.begin(), component.end());
  }
}

void Attributes::add(const Twine &Name, const Twine &Value,
                     const Twine &Comment) {
  std::string A = Name.str();
  A += "=\"";
  A += Value.str();
  A += "\"";
  Attrs.push_back(A);
  if (!Comment.isTriviallyEmpty()) {
    if (Comments.empty())
      Comments = " // ";
    else
      Comments += ", ";
    Comments += Comment.str();
  }
}

bool InitHeaderSearch::AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
                                       bool isFramework) {
  assert(!Path.isTriviallyEmpty() && "can't handle empty path here");

  FileManager &FM = Headers.getFileMgr();
  SmallString<256> MappedPathStorage;
  StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);

  // Compute the DirectoryLookup type.
  SrcMgr::CharacteristicKind Type;
  if (Group == Quoted || Group == Angled || Group == IndexHeaderMap) {
    Type = SrcMgr::C_User;
  } else if (Group == ExternCSystem) {
    Type = SrcMgr::C_ExternCSystem;
  } else {
    Type = SrcMgr::C_System;
  }

  // If the directory exists, add it.
  if (const DirectoryEntry *DE = FM.getDirectory(MappedPathStr)) {
    IncludePath.push_back(
      std::make_pair(Group, DirectoryLookup(DE, Type, isFramework)));
    return true;
  }

  // Check to see if this is an apple-style headermap (which are not allowed to
  // be frameworks).
  if (!isFramework) {
    if (const FileEntry *FE = FM.getFile(MappedPathStr)) {
      if (const HeaderMap *HM = Headers.CreateHeaderMap(FE)) {
        // It is a headermap, add it to the search path.
        IncludePath.push_back(
          std::make_pair(Group,
                         DirectoryLookup(HM, Type, Group == IndexHeaderMap)));
        return true;
      }
    }
  }

  if (Verbose)
    llvm::errs() << "ignoring nonexistent directory \""
                 << MappedPathStr << "\"\n";
  return false;
}

void Value::setName(const Twine &NewName) {
  assert(SubclassID != MDStringVal &&
         "Cannot set the name of MDString with this method!");

  // Fast path for common IRBuilder case of setName("") when there is no name.
  if (NewName.isTriviallyEmpty() && !hasName())
    return;

  SmallString<256> NameData;
  StringRef NameRef = NewName.toStringRef(NameData);
  assert(NameRef.find_first_of(0) == StringRef::npos &&
         "Null bytes are not allowed in names");

  // Name isn't changing?
  if (getName() == NameRef)
    return;

  assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");

  // Get the symbol table to update for this object.
  ValueSymbolTable *ST;
  if (getSymTab(this, ST))
    return;  // Cannot set a name on this value (e.g. constant).

  if (Function *F = dyn_cast<Function>(this))
    getContext().pImpl->IntrinsicIDCache.erase(F);

  if (!ST) { // No symbol table to update?  Just do the change.
    if (NameRef.empty()) {
      // Free the name for this value.
      Name->Destroy();
      Name = nullptr;
      return;
    }

    if (Name)
      Name->Destroy();

    // NOTE: Could optimize for the case the name is shrinking to not deallocate
    // then reallocated.

    // Create the new name.
    Name = ValueName::Create(NameRef);
    Name->setValue(this);
    return;
  }

  // NOTE: Could optimize for the case the name is shrinking to not deallocate
  // then reallocated.
  if (hasName()) {
    // Remove old name.
    ST->removeValueName(Name);
    Name->Destroy();
    Name = nullptr;

    if (NameRef.empty())
      return;
  }

  // Name is changing to something new.
  Name = ST->createValueName(NameRef, this);
}