//===-- StringRef.cpp - Lightweight String References ---------------------===//

//

// 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 "llvm/ADT/StringRef.h"

#include "llvm/ADT/APFloat.h"

#include "llvm/ADT/APInt.h"

#include "llvm/ADT/Hashing.h"

#include "llvm/ADT/StringExtras.h"

#include "llvm/ADT/edit_distance.h"

#include "llvm/Support/Error.h"

#include <bitset>

using namespace llvm;

// MSVC emits references to this into the translation units which reference it.

#ifndef _MSC_VER

constexpr size_t StringRef::npos;

#endif

// strncasecmp() is not available on non-POSIX systems, so define an

// alternative function here.

static int ascii_strncasecmp(const char *LHS, const char *RHS, size_t Length) {

  for (size_t I = 0; I < Length; ++I) {

    unsigned char LHC = toLower(LHS[I]);

    unsigned char RHC = toLower(RHS[I]);

    if (LHC != RHC)

      return LHC < RHC ? -1 : 1;

  }

  return 0;

}

/// compare_lower - Compare strings, ignoring case.

int StringRef::compare_lower(StringRef RHS) const {

  if (int Res = ascii_strncasecmp(Data, RHS.Data, std::min(Length, RHS.Length)))

    return Res;

  if (Length == RHS.Length)

    return 0;

  return Length < RHS.Length ? -1 : 1;

}

/// Check if this string starts with the given \p Prefix, ignoring case.

bool StringRef::startswith_lower(StringRef Prefix) const {

  return Length >= Prefix.Length &&

      ascii_strncasecmp(Data, Prefix.Data, Prefix.Length) == 0;

}

/// Check if this string ends with the given \p Suffix, ignoring case.

bool StringRef::endswith_lower(StringRef Suffix) const {

  return Length >= Suffix.Length &&

      ascii_strncasecmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;

}

size_t StringRef::find_lower(char C, size_t From) const {

  char L = toLower(C);

  return find_if([L](char D) { return toLower(D) == L; }, From);

}

/// compare_numeric - Compare strings, handle embedded numbers.

int StringRef::compare_numeric(StringRef RHS) const {

  for (size_t I = 0, E = std::min(Length, RHS.Length); I != E; ++I) {

    // Check for sequences of digits.

    if (isDigit(Data[I]) && isDigit(RHS.Data[I])) {

      // The longer sequence of numbers is considered larger.

      // This doesn't really handle prefixed zeros well.

      size_t J;

      for (J = I + 1; J != E + 1; ++J) {

        bool ld = J < Length && isDigit(Data[J]);

        bool rd = J < RHS.Length && isDigit(RHS.Data[J]);

        if (ld != rd)

          return rd ? -1 : 1;

        if (!rd)

          break;

      }

      // The two number sequences have the same length (J-I), just memcmp them.

      if (int Res = compareMemory(Data + I, RHS.Data + I, J - I))

        return Res < 0 ? -1 : 1;

      // Identical number sequences, continue search after the numbers.

      I = J - 1;

      continue;

    }

    if (Data[I] != RHS.Data[I])

      return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1;

  }

  if (Length == RHS.Length)

    return 0;

  return Length < RHS.Length ? -1 : 1;

}

// Compute the edit distance between the two given strings.

unsigned StringRef::edit_distance(llvm::StringRef Other,

                                  bool AllowReplacements,

                                  unsigned MaxEditDistance) const {

  return llvm::ComputeEditDistance(

      makeArrayRef(data(), size()),

      makeArrayRef(Other.data(), Other.size()),

      AllowReplacements, MaxEditDistance);

}

//===----------------------------------------------------------------------===//

// String Operations

//===----------------------------------------------------------------------===//

std::string StringRef::lower() const {

  return std::string(map_iterator(begin(), toLower),

                     map_iterator(end(), toLower));

}

std::string StringRef::upper() const {

  return std::string(map_iterator(begin(), toUpper),

                     map_iterator(end(), toUpper));

}

//===----------------------------------------------------------------------===//

// String Searching

//===----------------------------------------------------------------------===//

/// find - Search for the first string \arg Str in the string.

///

/// \return - The index of the first occurrence of \arg Str, or npos if not

/// found.

size_t StringRef::find(StringRef Str, size_t From) const {

  if (From > Length)

    return npos;

  const char *Start = Data + From;

  size_t Size = Length - From;

  const char *Needle = Str.data();

  size_t N = Str.size();

  if (N == 0)

    return From;

  if (Size < N)

    return npos;

  if (N == 1) {

    const char *Ptr = (const char *)::memchr(Start, Needle[0], Size);

    return Ptr == nullptr ? npos : Ptr - Data;

  }

  const char *Stop = Start + (Size - N + 1);

  // For short haystacks or unsupported needles fall back to the naive algorithm

  if (Size < 16 || N > 255) {

    do {

      if (std::memcmp(Start, Needle, N) == 0)

        return Start - Data;

      ++Start;

    } while (Start < Stop);

    return npos;

  }

  // Build the bad char heuristic table, with uint8_t to reduce cache thrashing.

  uint8_t BadCharSkip[256];

  std::memset(BadCharSkip, N, 256);

  for (unsigned i = 0; i != N-1; ++i)

    BadCharSkip[(uint8_t)Str[i]] = N-1-i;

  do {

    uint8_t Last = Start[N - 1];

    if (LLVM_UNLIKELY(Last == (uint8_t)Needle[N - 1]))

      if (std::memcmp(Start, Needle, N - 1) == 0)

        return Start - Data;

    // Otherwise skip the appropriate number of bytes.

    Start += BadCharSkip[Last];

  } while (Start < Stop);

  return npos;

}

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;

}

size_t StringRef::rfind_lower(char C, size_t From) const {

  From = std::min(From, Length);

  size_t i = From;

  while (i != 0) {

    --i;

    if (toLower(Data[i]) == toLower(C))

      return i;

  }

  return npos;

}

/// rfind - Search for the last string \arg Str in the string.

///

/// \return - The index of the last occurrence of \arg Str, or npos if not

/// found.

size_t StringRef::rfind(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;

}

size_t StringRef::rfind_lower(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_lower(Str))

      return i;

  }

  return npos;

}

/// find_first_of - Find the first character in the string that is in \arg

/// Chars, or npos if not found.

///

/// Note: O(size() + Chars.size())

StringRef::size_type StringRef::find_first_of(StringRef Chars,

                                              size_t From) const {

  std::bitset<1 << CHAR_BIT> CharBits;

  for (size_type i = 0; i != Chars.size(); ++i)

    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = std::min(From, Length), e = Length; i != e; ++i)

    if (CharBits.test((unsigned char)Data[i]))

      return i;

  return npos;

}

/// find_first_not_of - Find the first character in the string that is not

/// \arg C or npos if not found.

StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {

  for (size_type i = std::min(From, Length), e = Length; i != e; ++i)

    if (Data[i] != C)

      return i;

  return npos;

}

/// find_first_not_of - Find the first character in the string that is not

/// in the string \arg Chars, or npos if not found.

///

/// Note: O(size() + Chars.size())

StringRef::size_type StringRef::find_first_not_of(StringRef Chars,

                                                  size_t From) const {

  std::bitset<1 << CHAR_BIT> CharBits;

  for (size_type i = 0; i != Chars.size(); ++i)

    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = std::min(From, Length), e = Length; i != e; ++i)

    if (!CharBits.test((unsigned char)Data[i]))

      return i;

  return npos;

}

/// find_last_of - Find the last character in the string that is in \arg C,

/// or npos if not found.

///

/// Note: O(size() + Chars.size())

StringRef::size_type StringRef::find_last_of(StringRef Chars,

                                             size_t From) const {

  std::bitset<1 << CHAR_BIT> CharBits;

  for (size_type i = 0; i != Chars.size(); ++i)

    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)

    if (CharBits.test((unsigned char)Data[i]))

      return i;

  return npos;

}

/// find_last_not_of - Find the last character in the string that is not

/// \arg C, or npos if not found.

StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const {

  for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)

    if (Data[i] != C)

      return i;

  return npos;

}

/// find_last_not_of - Find the last character in the string that is not in

/// \arg Chars, or npos if not found.

///

/// Note: O(size() + Chars.size())

StringRef::size_type StringRef::find_last_not_of(StringRef Chars,

                                                 size_t From) const {

  std::bitset<1 << CHAR_BIT> CharBits;

  for (size_type i = 0, e = Chars.size(); i != e; ++i)

    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)

    if (!CharBits.test((unsigned char)Data[i]))

      return i;

  return npos;

}

void StringRef::split(SmallVectorImpl<StringRef> &A,

                      StringRef Separator, int MaxSplit,

                      bool KeepEmpty) const {

  StringRef S = *this;

  // Count down from MaxSplit. When MaxSplit is -1, this will just split

  // "forever". This doesn't support splitting more than 2^31 times

  // intentionally; if we ever want that we can make MaxSplit a 64-bit integer

  // but that seems unlikely to be useful.

  while (MaxSplit-- != 0) {

    size_t Idx = S.find(Separator);

    if (Idx == npos)

      break;

    // Push this split.

    if (KeepEmpty || Idx > 0)

      A.push_back(S.slice(0, Idx));

    // Jump forward.

    S = S.slice(Idx + Separator.size(), npos);

  }

  // Push the tail.

  if (KeepEmpty || !S.empty())

    A.push_back(S);

}

void StringRef::split(SmallVectorImpl<StringRef> &A, char Separator,

                      int MaxSplit, bool KeepEmpty) const {

  StringRef S = *this;

  // Count down from MaxSplit. When MaxSplit is -1, this will just split

  // "forever". This doesn't support splitting more than 2^31 times

  // intentionally; if we ever want that we can make MaxSplit a 64-bit integer

  // but that seems unlikely to be useful.

  while (MaxSplit-- != 0) {

    size_t Idx = S.find(Separator);

    if (Idx == npos)

      break;

    // Push this split.

    if (KeepEmpty || Idx > 0)

      A.push_back(S.slice(0, Idx));

    // Jump forward.

    S = S.slice(Idx + 1, npos);

  }

  // Push the tail.

  if (KeepEmpty || !S.empty())

    A.push_back(S);

}

//===----------------------------------------------------------------------===//

// Helpful Algorithms

//===----------------------------------------------------------------------===//

/// count - Return the number of non-overlapped occurrences of \arg Str in

/// the string.

size_t StringRef::count(StringRef Str) const {

  size_t Count = 0;

  size_t N = Str.size();

  if (!N || N > Length)

    return 0;

  for (size_t i = 0, e = Length - N + 1; i < e;) {

    if (substr(i, N).equals(Str)) {

      ++Count;

      i += N;

    }

    else

      ++i;

  }

  return Count;

}

static unsigned GetAutoSenseRadix(StringRef &Str) {

  if (Str.empty())

    return 10;

  if (Str.startswith("0x") || Str.startswith("0X")) {

    Str = Str.substr(2);

    return 16;

  }

  if (Str.startswith("0b") || Str.startswith("0B")) {

    Str = Str.substr(2);

    return 2;

  }

  if (Str.startswith("0o")) {

    Str = Str.substr(2);

    return 8;

  }

  if (Str[0] == '0' && Str.size() > 1 && isDigit(Str[1])) {

    Str = Str.substr(1);

    return 8;

  }

  return 10;

}

bool llvm::consumeUnsignedInteger(StringRef &Str, unsigned Radix,

                                  unsigned long long &Result) {

  // Autosense radix if not specified.

  if (Radix == 0)

    Radix = GetAutoSenseRadix(Str);

  // 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.

  StringRef Str2 = Str;

  Result = 0;

  while (!Str2.empty()) {

    unsigned CharVal;

    if (Str2[0] >= '0' && Str2[0] <= '9')

      CharVal = Str2[0] - '0';

    else if (Str2[0] >= 'a' && Str2[0] <= 'z')

      CharVal = Str2[0] - 'a' + 10;

    else if (Str2[0] >= 'A' && Str2[0] <= 'Z')

      CharVal = Str2[0] - 'A' + 10;

    else

      break;

    // If the parsed value is larger than the integer radix, we cannot

    // consume any more characters.

    if (CharVal >= Radix)

      break;

    // Add in this character.

    unsigned long long PrevResult = Result;

    Result = Result * Radix + CharVal;

    // Check for overflow by shifting back and seeing if bits were lost.

    if (Result / Radix < PrevResult)

      return true;

    Str2 = Str2.substr(1);

  }

  // We consider the operation a failure if no characters were consumed

  // successfully.

  if (Str.size() == Str2.size())

    return true;

  Str = Str2;

  return false;

}

bool llvm::consumeSignedInteger(StringRef &Str, unsigned Radix,

                                long long &Result) {

  unsigned long long ULLVal;

  // Handle positive strings first.

  if (Str.empty() || Str.front() != '-') {

    if (consumeUnsignedInteger(Str, 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.

  StringRef Str2 = Str.drop_front(1);

  if (consumeUnsignedInteger(Str2, 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;

  Str = Str2;

  Result = -ULLVal;

  return false;

}

/// GetAsUnsignedInteger - Workhorse method that converts a integer character

/// sequence of radix up to 36 to an unsigned long long value.

bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix,

                                unsigned long long &Result) {

  if (consumeUnsignedInteger(Str, Radix, Result))

    return true;

  // For getAsUnsignedInteger, we require the whole string to be consumed or

  // else we consider it a failure.

  return !Str.empty();

}

bool llvm::getAsSignedInteger(StringRef Str, unsigned Radix,

                              long long &Result) {

  if (consumeSignedInteger(Str, Radix, Result))

    return true;

  // For getAsSignedInteger, we require the whole string to be consumed or else

  // we consider it a failure.

  return !Str.empty();

}

bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {

  StringRef Str = *this;

  // Autosense radix if not specified.

  if (Radix == 0)

    Radix = GetAutoSenseRadix(Str);

  assert(Radix > 1 && Radix <= 36);

  // Empty strings (after the radix autosense) are invalid.

  if (Str.empty()) return true;

  // Skip leading zeroes.  This can be a significant improvement if

  // it means we don't need > 64 bits.

  while (!Str.empty() && Str.front() == '0')

    Str = Str.substr(1);

  // If it was nothing but zeroes....

  if (Str.empty()) {

    Result = APInt(64, 0);

    return false;

  }

  // (Over-)estimate the required number of bits.

  unsigned Log2Radix = 0;

  while ((1U << Log2Radix) < Radix) Log2Radix++;

  bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);

  unsigned BitWidth = Log2Radix * Str.size();

  if (BitWidth < Result.getBitWidth())

    BitWidth = Result.getBitWidth(); // don't shrink the result

  else if (BitWidth > Result.getBitWidth())

    Result = Result.zext(BitWidth);

  APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix

  if (!IsPowerOf2Radix) {

    // These must have the same bit-width as Result.

    RadixAP = APInt(BitWidth, Radix);

    CharAP = APInt(BitWidth, 0);

  }

  // Parse all the bytes of the string given this radix.

  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.

    if (IsPowerOf2Radix) {

      Result <<= Log2Radix;

      Result |= CharVal;

    } else {

      Result *= RadixAP;

      CharAP = CharVal;

      Result += CharAP;

    }

    Str = Str.substr(1);

  }

  return false;

}

bool StringRef::getAsDouble(double &Result, bool AllowInexact) const {

  APFloat F(0.0);

  auto StatusOrErr = F.convertFromString(*this, APFloat::rmNearestTiesToEven);

  if (errorToBool(StatusOrErr.takeError()))

    return true;

  APFloat::opStatus Status = *StatusOrErr;

  if (Status != APFloat::opOK) {

    if (!AllowInexact || !(Status & APFloat::opInexact))

      return true;

  }

  Result = F.convertToDouble();

  return false;

}

// Implementation of StringRef hashing.

hash_code llvm::hash_value(StringRef S) {

  return hash_combine_range(S.begin(), S.end());

}