C++ StringRef::startswith_lower方法代码示例

size_t StringRef::find_lower(StringRef Str, size_t From) const {
  StringRef This = substr(From);
  while (This.size() >= Str.size()) {
    if (This.startswith_lower(Str))
      return From;
    This = This.drop_front();
    ++From;
  }
  return npos;
}

/// \returns Matched size. 0 means no match.
static unsigned matchOption(const OptTable::Info *I, StringRef Str,
                            bool IgnoreCase) {
  for (const char * const *Pre = I->Prefixes; *Pre != nullptr; ++Pre) {
    StringRef Prefix(*Pre);
    if (Str.startswith(Prefix)) {
      StringRef Rest = Str.substr(Prefix.size());
      bool Matched = IgnoreCase
          ? Rest.startswith_lower(I->Name)
          : Rest.startswith(I->Name);
      if (Matched)
        return Prefix.size() + StringRef(I->Name).size();
    }
  }
  return 0;
}

/// Match a word within a name to a word within a type.
static bool matchNameWordToTypeWord(StringRef nameWord, StringRef typeWord) {
  // If the name word is longer, there's no match.
  if (nameWord.size() > typeWord.size()) return false;

  // If the name word is shorter, try for a partial match.
  if (nameWord.size() < typeWord.size()) {
    // We can match the suffix of the type so long as everything preceding the
    // match is neither a lowercase letter nor a '_'. This ignores type
    // prefixes for acronyms, e.g., the 'NS' in 'NSURL'.
    if (typeWord.endswith_lower(nameWord) && 
        !clang::isLowercase(typeWord[typeWord.size()-nameWord.size()])) {
      // Check that everything preceding the match is neither a lowercase letter
      // nor a '_'.
      for (unsigned i = 0, n = nameWord.size(); i != n; ++i) {
        if (clang::isLowercase(typeWord[i]) || typeWord[i] == '_') return false;
      }

      return true;
    }

    // We can match a prefix so long as everything following the match is
    // a number.
    if (typeWord.startswith_lower(nameWord)) {
      for (unsigned i = nameWord.size(), n = typeWord.size(); i != n; ++i) {
        if (!clang::isDigit(typeWord[i])) return false;
      }

      return true;
    }

    return false;
  }

  // Check for an exact match.
  return nameWord.equals_lower(typeWord);
}

static bool isAutorelease(const FunctionDecl *FD, StringRef FName) {
  return FName.startswith_lower("autorelease") ||
         FName.endswith_lower("autorelease");
}

static bool isRetain(const FunctionDecl *FD, StringRef FName) {
  return FName.startswith_lower("retain") || FName.endswith_lower("retain");
}

bool MSP430AsmParser::parseJccInstruction(ParseInstructionInfo &Info,
                                          StringRef Name, SMLoc NameLoc,
                                          OperandVector &Operands) {
  if (!Name.startswith_lower("j"))
    return true;

  auto CC = Name.drop_front().lower();
  unsigned CondCode;
  if (CC == "ne" || CC == "nz")
    CondCode = MSP430CC::COND_NE;
  else if (CC == "eq" || CC == "z")
    CondCode = MSP430CC::COND_E;
  else if (CC == "lo" || CC == "nc")
    CondCode = MSP430CC::COND_LO;
  else if (CC == "hs" || CC == "c")
    CondCode = MSP430CC::COND_HS;
  else if (CC == "n")
    CondCode = MSP430CC::COND_N;
  else if (CC == "ge")
    CondCode = MSP430CC::COND_GE;
  else if (CC == "l")
    CondCode = MSP430CC::COND_L;
  else if (CC == "mp")
    CondCode = MSP430CC::COND_NONE;
  else
    return Error(NameLoc, "unknown instruction");

  if (CondCode == (unsigned)MSP430CC::COND_NONE)
    Operands.push_back(MSP430Operand::CreateToken("jmp", NameLoc));
  else {
    Operands.push_back(MSP430Operand::CreateToken("j", NameLoc));
    const MCExpr *CCode = MCConstantExpr::create(CondCode, getContext());
    Operands.push_back(MSP430Operand::CreateImm(CCode, SMLoc(), SMLoc()));
  }

  // Skip optional '$' sign.
  if (getLexer().getKind() == AsmToken::Dollar)
    getLexer().Lex(); // Eat '$'

  const MCExpr *Val;
  SMLoc ExprLoc = getLexer().getLoc();
  if (getParser().parseExpression(Val))
    return Error(ExprLoc, "expected expression operand");

  int64_t Res;
  if (Val->evaluateAsAbsolute(Res))
    if (Res < -512 || Res > 511)
      return Error(ExprLoc, "invalid jump offset");

  Operands.push_back(MSP430Operand::CreateImm(Val, ExprLoc,
    getLexer().getLoc()));

  if (getLexer().isNot(AsmToken::EndOfStatement)) {
    SMLoc Loc = getLexer().getLoc();
    getParser().eatToEndOfStatement();
    return Error(Loc, "unexpected token");
  }

  getParser().Lex(); // Consume the EndOfStatement.
  return false;
}