llvm-project/llvm/lib/Support/StringRef.cpp

//===-- StringRef.cpp - Lightweight String References ---------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/StringRef.h"
using namespace llvm;

// MSVC emits references to this into the translation units which reference it.
#ifndef _MSC_VER
const size_t StringRef::npos;
#endif

//===----------------------------------------------------------------------===//
// String Searching
//===----------------------------------------------------------------------===//


/// find - Search for the first string \arg Str in the string.
///
/// \return - The index of the first occurence of \arg Str, or npos if not
/// found.
size_t StringRef::find(const StringRef &Str) const {
  size_t N = Str.size();
  if (N > Length)
    return npos;
  for (size_t i = 0, e = Length - N + 1; i != e; ++i)
    if (substr(i, N).equals(Str))
      return i;
  return npos;
}

/// rfind - Search for the last string \arg Str in the string.
///
/// \return - The index of the last occurence of \arg Str, or npos if not
/// found.
size_t StringRef::rfind(const StringRef &Str) const {
  size_t N = Str.size();
  if (N > Length)
    return npos;
  for (size_t i = Length - N + 1, e = 0; i != e;) {
    --i;
    if (substr(i, N).equals(Str))
      return i;
  }
  return npos;
}

/// find_first_of - Find the first character from the string 'Chars' in the
/// current string or return npos if not in string.
StringRef::size_type StringRef::find_first_of(StringRef Chars) const {
  for (size_type i = 0, e = Length; i != e; ++i)
    if (Chars.find(Data[i]) != npos)
      return i;
  return npos;
}

/// find_first_not_of - Find the first character in the string that is not
/// in the string 'Chars' or return npos if all are in string. Same as find.
StringRef::size_type StringRef::find_first_not_of(StringRef Chars) const {
  for (size_type i = 0, e = Length; i != e; ++i)
    if (Chars.find(Data[i]) == npos)
      return i;
  return npos;
}


//===----------------------------------------------------------------------===//
// Helpful Algorithms
//===----------------------------------------------------------------------===//

/// count - Return the number of non-overlapped occurrences of \arg Str in
/// the string.
size_t StringRef::count(const StringRef &Str) const {
  size_t Count = 0;
  size_t N = Str.size();
  if (N > Length)
    return 0;
  for (size_t i = 0, e = Length - N + 1; i != e; ++i)
    if (substr(i, N).equals(Str))
      ++Count;
  return Count;
}

/// GetAsUnsignedInteger - Workhorse method that converts a integer character
/// sequence of radix up to 36 to an unsigned long long value.
static bool GetAsUnsignedInteger(StringRef Str, unsigned Radix,
                                 unsigned long long &Result) {
  // Autosense radix if not specified.
  if (Radix == 0) {
    if (Str.startswith("0x")) {
      Str = Str.substr(2);
      Radix = 16;
    } else if (Str.startswith("0b")) {
      Str = Str.substr(2);
      Radix = 2;
    } else if (Str.startswith("0"))
      Radix = 8;
    else
      Radix = 10;
  }
  
  // Empty strings (after the radix autosense) are invalid.
  if (Str.empty()) return true;
  
  // Parse all the bytes of the string given this radix.  Watch for overflow.
  Result = 0;
  while (!Str.empty()) {
    unsigned CharVal;
    if (Str[0] >= '0' && Str[0] <= '9')
      CharVal = Str[0]-'0';
    else if (Str[0] >= 'a' && Str[0] <= 'z')
      CharVal = Str[0]-'a'+10;
    else if (Str[0] >= 'A' && Str[0] <= 'Z')
      CharVal = Str[0]-'A'+10;
    else
      return true;
    
    // If the parsed value is larger than the integer radix, the string is
    // invalid.
    if (CharVal >= Radix)
      return true;
    
    // Add in this character.
    unsigned long long PrevResult = Result;
    Result = Result*Radix+CharVal;
    
    // Check for overflow.
    if (Result < PrevResult)
      return true;

    Str = Str.substr(1);
  }
  
  return false;
}

bool StringRef::getAsInteger(unsigned Radix, unsigned long long &Result) const {
  return GetAsUnsignedInteger(*this, Radix, Result);
}


bool StringRef::getAsInteger(unsigned Radix, long long &Result) const {
  unsigned long long ULLVal;
  
  // Handle positive strings first.
  if (empty() || front() != '-') {
    if (GetAsUnsignedInteger(*this, Radix, ULLVal) ||
        // Check for value so large it overflows a signed value.
        (long long)ULLVal < 0)
      return true;
    Result = ULLVal;
    return false;
  }
  
  // Get the positive part of the value.
  if (GetAsUnsignedInteger(substr(1), Radix, ULLVal) ||
      // Reject values so large they'd overflow as negative signed, but allow
      // "-0".  This negates the unsigned so that the negative isn't undefined
      // on signed overflow.
      (long long)-ULLVal > 0)
    return true;
  
  Result = -ULLVal;
  return false;
}

bool StringRef::getAsInteger(unsigned Radix, int &Result) const {
  long long Val;
  if (getAsInteger(Radix, Val) ||
      (int)Val != Val)
    return true;
  Result = Val;
  return false;
}

bool StringRef::getAsInteger(unsigned Radix, unsigned &Result) const {
  unsigned long long Val;
  if (getAsInteger(Radix, Val) ||
      (unsigned)Val != Val)
    return true;
  Result = Val;
  return false;
}