StringExtras.h

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//===- llvm/ADT/StringExtras.h - Useful string functions --------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains some functions that are useful when dealing with strings.
///
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_ADT_STRINGEXTRAS_H
#define LLVM_ADT_STRINGEXTRAS_H
 
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <iterator>
#include <string>
#include <utility>
 
namespace llvm {
 
class raw_ostream;
 
/// hexdigit - Return the hexadecimal character for the
/// given number \p X (which should be less than 16).
inline char hexdigit(unsigned X, bool LowerCase = false) {
  assert(X < 16);
  static const char LUT[] = "0123456789ABCDEF";
  const uint8_t Offset = LowerCase ? 32 : 0;
  return LUT[X] | Offset;
}
 
/// Given an array of c-style strings terminated by a null pointer, construct
/// a vector of StringRefs representing the same strings without the terminating
/// null string.
inline std::vector<StringRef> toStringRefArray(const char *const *Strings) {
  std::vector<StringRef> Result;
  while (*Strings)
    Result.push_back(*Strings++);
  return Result;
}
 
/// Construct a string ref from a boolean.
inline StringRef toStringRef(bool B) { return StringRef(B ? "true" : "false"); }
 
/// Construct a string ref from an array ref of unsigned chars.
inline StringRef toStringRef(ArrayRef<uint8_t> Input) {
  return StringRef(reinterpret_cast<const char *>(Input.begin()), Input.size());
}
inline StringRef toStringRef(ArrayRef<char> Input) {
  return StringRef(Input.begin(), Input.size());
}
 
/// Construct a string ref from an array ref of unsigned chars.
template <class CharT = uint8_t>
inline ArrayRef<CharT> arrayRefFromStringRef(StringRef Input) {
  static_assert(std::is_same<CharT, char>::value ||
                    std::is_same<CharT, unsigned char>::value ||
                    std::is_same<CharT, signed char>::value,
                "Expected byte type");
  return ArrayRef<CharT>(reinterpret_cast<const CharT *>(Input.data()),
                         Input.size());
}
 
/// Interpret the given character \p C as a hexadecimal digit and return its
/// value.
///
/// If \p C is not a valid hex digit, -1U is returned.
inline unsigned hexDigitValue(char C) {
  /* clang-format off */
  static const int16_t LUT[256] = {
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1,  // '0'..'9'
    -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 'A'..'F'
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 'a'..'f'
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  };
  /* clang-format on */
  return LUT[static_cast<unsigned char>(C)];
}
 
/// Checks if character \p C is one of the 10 decimal digits.
inline bool isDigit(char C) { return C >= '0' && C <= '9'; }
 
/// Checks if character \p C is a hexadecimal numeric character.
inline bool isHexDigit(char C) { return hexDigitValue(C) != ~0U; }
 
/// Checks if character \p C is a lowercase letter as classified by "C" locale.
inline bool isLower(char C) { return 'a' <= C && C <= 'z'; }
 
/// Checks if character \p C is a uppercase letter as classified by "C" locale.
inline bool isUpper(char C) { return 'A' <= C && C <= 'Z'; }
 
/// Checks if character \p C is a valid letter as classified by "C" locale.
inline bool isAlpha(char C) { return isLower(C) || isUpper(C); }
 
/// Checks whether character \p C is either a decimal digit or an uppercase or
/// lowercase letter as classified by "C" locale.
inline bool isAlnum(char C) { return isAlpha(C) || isDigit(C); }
 
/// Checks whether character \p C is valid ASCII (high bit is zero).
inline bool isASCII(char C) { return static_cast<unsigned char>(C) <= 127; }
 
/// Checks whether all characters in S are ASCII.
inline bool isASCII(llvm::StringRef S) {
  for (char C : S)
    if (LLVM_UNLIKELY(!isASCII(C)))
      return false;
  return true;
}
 
/// Checks whether character \p C is printable.
///
/// Locale-independent version of the C standard library isprint whose results
/// may differ on different platforms.
inline bool isPrint(char C) {
  unsigned char UC = static_cast<unsigned char>(C);
  return (0x20 <= UC) && (UC <= 0x7E);
}
 
/// Checks whether character \p C is whitespace in the "C" locale.
///
/// Locale-independent version of the C standard library isspace.
inline bool isSpace(char C) {
  return C == ' ' || C == '\f' || C == '\n' || C == '\r' || C == '\t' ||
         C == '\v';
}
 
/// Returns the corresponding lowercase character if \p x is uppercase.
inline char toLower(char x) {
  if (isUpper(x))
    return x - 'A' + 'a';
  return x;
}
 
/// Returns the corresponding uppercase character if \p x is lowercase.
inline char toUpper(char x) {
  if (isLower(x))
    return x - 'a' + 'A';
  return x;
}
 
inline std::string utohexstr(uint64_t X, bool LowerCase = false,
                             unsigned Width = 0) {
  char Buffer[17];
  char *BufPtr = std::end(Buffer);
 
  if (X == 0) *--BufPtr = '0';
 
  for (unsigned i = 0; Width ? (i < Width) : X; ++i) {
    unsigned char Mod = static_cast<unsigned char>(X) & 15;
    *--BufPtr = hexdigit(Mod, LowerCase);
    X >>= 4;
  }
 
  return std::string(BufPtr, std::end(Buffer));
}
 
/// Convert buffer \p Input to its hexadecimal representation.
/// The returned string is double the size of \p Input.
inline void toHex(ArrayRef<uint8_t> Input, bool LowerCase,
                  SmallVectorImpl<char> &Output) {
  const size_t Length = Input.size();
  Output.resize_for_overwrite(Length * 2);
 
  for (size_t i = 0; i < Length; i++) {
    const uint8_t c = Input[i];
    Output[i * 2    ] = hexdigit(c >> 4, LowerCase);
    Output[i * 2 + 1] = hexdigit(c & 15, LowerCase);
  }
}
 
inline std::string toHex(ArrayRef<uint8_t> Input, bool LowerCase = false) {
  SmallString<16> Output;
  toHex(Input, LowerCase, Output);
  return std::string(Output);
}
 
inline std::string toHex(StringRef Input, bool LowerCase = false) {
  return toHex(arrayRefFromStringRef(Input), LowerCase);
}
 
/// Store the binary representation of the two provided values, \p MSB and
/// \p LSB, that make up the nibbles of a hexadecimal digit. If \p MSB or \p LSB
/// do not correspond to proper nibbles of a hexadecimal digit, this method
/// returns false. Otherwise, returns true.
inline bool tryGetHexFromNibbles(char MSB, char LSB, uint8_t &Hex) {
  unsigned U1 = hexDigitValue(MSB);
  unsigned U2 = hexDigitValue(LSB);
  if (U1 == ~0U || U2 == ~0U)
    return false;
 
  Hex = static_cast<uint8_t>((U1 << 4) | U2);
  return true;
}
 
/// Return the binary representation of the two provided values, \p MSB and
/// \p LSB, that make up the nibbles of a hexadecimal digit.
inline uint8_t hexFromNibbles(char MSB, char LSB) {
  uint8_t Hex = 0;
  bool GotHex = tryGetHexFromNibbles(MSB, LSB, Hex);
  (void)GotHex;
  assert(GotHex && "MSB and/or LSB do not correspond to hex digits");
  return Hex;
}
 
/// Convert hexadecimal string \p Input to its binary representation and store
/// the result in \p Output. Returns true if the binary representation could be
/// converted from the hexadecimal string. Returns false if \p Input contains
/// non-hexadecimal digits. The output string is half the size of \p Input.
inline bool tryGetFromHex(StringRef Input, std::string &Output) {
  if (Input.empty())
    return true;
 
  // If the input string is not properly aligned on 2 nibbles we pad out the
  // front with a 0 prefix; e.g. `ABC` -> `0ABC`.
  Output.resize((Input.size() + 1) / 2);
  char *OutputPtr = const_cast<char *>(Output.data());
  if (Input.size() % 2 == 1) {
    uint8_t Hex = 0;
    if (!tryGetHexFromNibbles('0', Input.front(), Hex))
      return false;
    *OutputPtr++ = Hex;
    Input = Input.drop_front();
  }
 
  // Convert the nibble pairs (e.g. `9C`) into bytes (0x9C).
  // With the padding above we know the input is aligned and the output expects
  // exactly half as many bytes as nibbles in the input.
  size_t InputSize = Input.size();
  assert(InputSize % 2 == 0);
  const char *InputPtr = Input.data();
  for (size_t OutputIndex = 0; OutputIndex < InputSize / 2; ++OutputIndex) {
    uint8_t Hex = 0;
    if (!tryGetHexFromNibbles(InputPtr[OutputIndex * 2 + 0], // MSB
                              InputPtr[OutputIndex * 2 + 1], // LSB
                              Hex))
      return false;
    OutputPtr[OutputIndex] = Hex;
  }
  return true;
}
 
/// Convert hexadecimal string \p Input to its binary representation.
/// The return string is half the size of \p Input.
inline std::string fromHex(StringRef Input) {
  std::string Hex;
  bool GotHex = tryGetFromHex(Input, Hex);
  (void)GotHex;
  assert(GotHex && "Input contains non hex digits");
  return Hex;
}
 
/// Convert the string \p S to an integer of the specified type using
/// the radix \p Base.  If \p Base is 0, auto-detects the radix.
/// Returns true if the number was successfully converted, false otherwise.
template <typename N> bool to_integer(StringRef S, N &Num, unsigned Base = 0) {
  return !S.getAsInteger(Base, Num);
}
 
namespace detail {
template <typename N>
inline bool to_float(const Twine &T, N &Num, N (*StrTo)(const char *, char **)) {
  SmallString<32> Storage;
  StringRef S = T.toNullTerminatedStringRef(Storage);
  char *End;
  N Temp = StrTo(S.data(), &End);
  if (*End != '\0')
    return false;
  Num = Temp;
  return true;
}
}
 
inline bool to_float(const Twine &T, float &Num) {
  return detail::to_float(T, Num, strtof);
}
 
inline bool to_float(const Twine &T, double &Num) {
  return detail::to_float(T, Num, strtod);
}
 
inline bool to_float(const Twine &T, long double &Num) {
  return detail::to_float(T, Num, strtold);
}
 
inline std::string utostr(uint64_t X, bool isNeg = false) {
  char Buffer[21];
  char *BufPtr = std::end(Buffer);
 
  if (X == 0) *--BufPtr = '0';  // Handle special case...
 
  while (X) {
    *--BufPtr = '0' + char(X % 10);
    X /= 10;
  }
 
  if (isNeg) *--BufPtr = '-';   // Add negative sign...
  return std::string(BufPtr, std::end(Buffer));
}
 
inline std::string itostr(int64_t X) {
  if (X < 0)
    return utostr(static_cast<uint64_t>(1) + ~static_cast<uint64_t>(X), true);
  else
    return utostr(static_cast<uint64_t>(X));
}
 
inline std::string toString(const APInt &I, unsigned Radix, bool Signed,
                            bool formatAsCLiteral = false) {
  SmallString<40> S;
  I.toString(S, Radix, Signed, formatAsCLiteral);
  return std::string(S.str());
}
 
inline std::string toString(const APSInt &I, unsigned Radix) {
  return toString(I, Radix, I.isSigned());
}
 
/// StrInStrNoCase - Portable version of strcasestr.  Locates the first
/// occurrence of string 's1' in string 's2', ignoring case.  Returns
/// the offset of s2 in s1 or npos if s2 cannot be found.
StringRef::size_type StrInStrNoCase(StringRef s1, StringRef s2);
 
/// getToken - This function extracts one token from source, ignoring any
/// leading characters that appear in the Delimiters string, and ending the
/// token at any of the characters that appear in the Delimiters string.  If
/// there are no tokens in the source string, an empty string is returned.
/// The function returns a pair containing the extracted token and the
/// remaining tail string.
std::pair<StringRef, StringRef> getToken(StringRef Source,
                                         StringRef Delimiters = " \t\n\v\f\r");
 
/// SplitString - Split up the specified string according to the specified
/// delimiters, appending the result fragments to the output list.
void SplitString(StringRef Source,
                 SmallVectorImpl<StringRef> &OutFragments,
                 StringRef Delimiters = " \t\n\v\f\r");
 
/// Returns the English suffix for an ordinal integer (-st, -nd, -rd, -th).
inline StringRef getOrdinalSuffix(unsigned Val) {
  // It is critically important that we do this perfectly for
  // user-written sequences with over 100 elements.
  switch (Val % 100) {
  case 11:
  case 12:
  case 13:
    return "th";
  default:
    switch (Val % 10) {
      case 1: return "st";
      case 2: return "nd";
      case 3: return "rd";
      default: return "th";
    }
  }
}
 
/// Print each character of the specified string, escaping it if it is not
/// printable or if it is an escape char.
void printEscapedString(StringRef Name, raw_ostream &Out);
 
/// Print each character of the specified string, escaping HTML special
/// characters.
void printHTMLEscaped(StringRef String, raw_ostream &Out);
 
/// printLowerCase - Print each character as lowercase if it is uppercase.
void printLowerCase(StringRef String, raw_ostream &Out);
 
/// Converts a string from camel-case to snake-case by replacing all uppercase
/// letters with '_' followed by the letter in lowercase, except if the
/// uppercase letter is the first character of the string.
std::string convertToSnakeFromCamelCase(StringRef input);
 
/// Converts a string from snake-case to camel-case by replacing all occurrences
/// of '_' followed by a lowercase letter with the letter in uppercase.
/// Optionally allow capitalization of the first letter (if it is a lowercase
/// letter)
std::string convertToCamelFromSnakeCase(StringRef input,
                                        bool capitalizeFirst = false);
 
namespace detail {
 
template <typename IteratorT>
inline std::string join_impl(IteratorT Begin, IteratorT End,
                             StringRef Separator, std::input_iterator_tag) {
  std::string S;
  if (Begin == End)
    return S;
 
  S += (*Begin);
  while (++Begin != End) {
    S += Separator;
    S += (*Begin);
  }
  return S;
}
 
template <typename IteratorT>
inline std::string join_impl(IteratorT Begin, IteratorT End,
                             StringRef Separator, std::forward_iterator_tag) {
  std::string S;
  if (Begin == End)
    return S;
 
  size_t Len = (std::distance(Begin, End) - 1) * Separator.size();
  for (IteratorT I = Begin; I != End; ++I)
    Len += StringRef(*I).size();
  S.reserve(Len);
  size_t PrevCapacity = S.capacity();
  (void)PrevCapacity;
  S += (*Begin);
  while (++Begin != End) {
    S += Separator;
    S += (*Begin);
  }
  assert(PrevCapacity == S.capacity() && "String grew during building");
  return S;
}
 
template <typename Sep>
inline void join_items_impl(std::string &Result, Sep Separator) {}
 
template <typename Sep, typename Arg>
inline void join_items_impl(std::string &Result, Sep Separator,
                            const Arg &Item) {
  Result += Item;
}
 
template <typename Sep, typename Arg1, typename... Args>
inline void join_items_impl(std::string &Result, Sep Separator, const Arg1 &A1,
                            Args &&... Items) {
  Result += A1;
  Result += Separator;
  join_items_impl(Result, Separator, std::forward<Args>(Items)...);
}
 
inline size_t join_one_item_size(char) { return 1; }
inline size_t join_one_item_size(const char *S) { return S ? ::strlen(S) : 0; }
 
template <typename T> inline size_t join_one_item_size(const T &Str) {
  return Str.size();
}
 
template <typename... Args> inline size_t join_items_size(Args &&...Items) {
  return (0 + ... + join_one_item_size(std::forward<Args>(Items)));
}
 
} // end namespace detail
 
/// Joins the strings in the range [Begin, End), adding Separator between
/// the elements.
template <typename IteratorT>
inline std::string join(IteratorT Begin, IteratorT End, StringRef Separator) {
  using tag = typename std::iterator_traits<IteratorT>::iterator_category;
  return detail::join_impl(Begin, End, Separator, tag());
}
 
/// Joins the strings in the range [R.begin(), R.end()), adding Separator
/// between the elements.
template <typename Range>
inline std::string join(Range &&R, StringRef Separator) {
  return join(R.begin(), R.end(), Separator);
}
 
/// Joins the strings in the parameter pack \p Items, adding \p Separator
/// between the elements.  All arguments must be implicitly convertible to
/// std::string, or there should be an overload of std::string::operator+=()
/// that accepts the argument explicitly.
template <typename Sep, typename... Args>
inline std::string join_items(Sep Separator, Args &&... Items) {
  std::string Result;
  if (sizeof...(Items) == 0)
    return Result;
 
  size_t NS = detail::join_one_item_size(Separator);
  size_t NI = detail::join_items_size(std::forward<Args>(Items)...);
  Result.reserve(NI + (sizeof...(Items) - 1) * NS + 1);
  detail::join_items_impl(Result, Separator, std::forward<Args>(Items)...);
  return Result;
}
 
/// A helper class to return the specified delimiter string after the first
/// invocation of operator StringRef().  Used to generate a comma-separated
/// list from a loop like so:
///
/// \code
///   ListSeparator LS;
///   for (auto &I : C)
///     OS << LS << I.getName();
/// \end
class ListSeparator {
  bool First = true;
  StringRef Separator;
 
public:
  ListSeparator(StringRef Separator = ", ") : Separator(Separator) {}
  operator StringRef() {
    if (First) {
      First = false;
      return {};
    }
    return Separator;
  }
};
 
/// A forward iterator over partitions of string over a separator.
class SplittingIterator
    : public iterator_facade_base<SplittingIterator, std::forward_iterator_tag,
                                  StringRef> {
  char SeparatorStorage;
  StringRef Current;
  StringRef Next;
  StringRef Separator;
 
public:
  SplittingIterator(StringRef Str, StringRef Separator)
      : Next(Str), Separator(Separator) {
    ++*this;
  }
 
  SplittingIterator(StringRef Str, char Separator)
      : SeparatorStorage(Separator), Next(Str),
        Separator(&SeparatorStorage, 1) {
    ++*this;
  }
 
  SplittingIterator(const SplittingIterator &R)
      : SeparatorStorage(R.SeparatorStorage), Current(R.Current), Next(R.Next),
        Separator(R.Separator) {
    if (R.Separator.data() == &R.SeparatorStorage)
      Separator = StringRef(&SeparatorStorage, 1);
  }
 
  SplittingIterator &operator=(const SplittingIterator &R) {
    if (this == &R)
      return *this;
 
    SeparatorStorage = R.SeparatorStorage;
    Current = R.Current;
    Next = R.Next;
    Separator = R.Separator;
    if (R.Separator.data() == &R.SeparatorStorage)
      Separator = StringRef(&SeparatorStorage, 1);
    return *this;
  }
 
  bool operator==(const SplittingIterator &R) const {
    assert(Separator == R.Separator);
    return Current.data() == R.Current.data();
  }
 
  const StringRef &operator*() const { return Current; }
 
  StringRef &operator*() { return Current; }
 
  SplittingIterator &operator++() {
    std::tie(Current, Next) = Next.split(Separator);
    return *this;
  }
};
 
/// Split the specified string over a separator and return a range-compatible
/// iterable over its partitions.  Used to permit conveniently iterating
/// over separated strings like so:
///
/// \code
///   for (StringRef x : llvm::split("foo,bar,baz", ","))
///     ...;
/// \end
///
/// Note that the passed string must remain valid throuhgout lifetime
/// of the iterators.
inline iterator_range<SplittingIterator> split(StringRef Str, StringRef Separator) {
  return {SplittingIterator(Str, Separator),
          SplittingIterator(StringRef(), Separator)};
}
 
inline iterator_range<SplittingIterator> split(StringRef Str, char Separator) {
  return {SplittingIterator(Str, Separator),
          SplittingIterator(StringRef(), Separator)};
}
 
} // end namespace llvm
 
#endif // LLVM_ADT_STRINGEXTRAS_H