Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- StringRef.h - Constant String Reference Wrapper ----------*- 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

//

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

#ifndef LLVM_ADT_STRINGREF_H

#define LLVM_ADT_STRINGREF_H

#include "llvm/ADT/DenseMapInfo.h"

#include "llvm/ADT/STLFunctionalExtras.h"

#include "llvm/ADT/iterator_range.h"

#include "llvm/Support/Compiler.h"

#include <algorithm>

#include <cassert>

#include <cstddef>

#include <cstring>

#include <limits>

#include <string>

#include <string_view>

#include <type_traits>

#include <utility>

namespace llvm {

  class APInt;

  class hash_code;

  template <typename T> class SmallVectorImpl;

  class StringRef;

  /// Helper functions for StringRef::getAsInteger.

  bool getAsUnsignedInteger(StringRef Str, unsigned Radix,

                            unsigned long long &Result);

  bool getAsSignedInteger(StringRef Str, unsigned Radix, long long &Result);

  bool consumeUnsignedInteger(StringRef &Str, unsigned Radix,

                              unsigned long long &Result);

  bool consumeSignedInteger(StringRef &Str, unsigned Radix, long long &Result);

  /// StringRef - Represent a constant reference to a string, i.e. a character

  /// array and a length, which need not be null terminated.

  ///

  /// This class does not own the string data, it is expected to be used in

  /// situations where the character data resides in some other buffer, whose

  /// lifetime extends past that of the StringRef. For this reason, it is not in

  /// general safe to store a StringRef.

  class LLVM_GSL_POINTER StringRef {

  public:

    static constexpr size_t npos = ~size_t(0);

    using iterator = const char *;

    using const_iterator = const char *;

    using size_type = size_t;

  private:

    /// The start of the string, in an external buffer.

    const char *Data = nullptr;

    /// The length of the string.

    size_t Length = 0;

    // Workaround memcmp issue with null pointers (undefined behavior)

    // by providing a specialized version

    static int compareMemory(const char *Lhs, const char *Rhs, size_t Length) {

      if (Length == 0) { return 0; }

      return ::memcmp(Lhs,Rhs,Length);

    }

  public:

    /// @name Constructors

    /// @{

    /// Construct an empty string ref.

    /*implicit*/ StringRef() = default;

    /// Disable conversion from nullptr.  This prevents things like

    /// if (S == nullptr)

    StringRef(std::nullptr_t) = delete;

    /// Construct a string ref from a cstring.

    /*implicit*/ constexpr StringRef(const char *Str)

        : Data(Str), Length(Str ?

    // GCC 7 doesn't have constexpr char_traits. Fall back to __builtin_strlen.

#if defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE < 8

                                __builtin_strlen(Str)

#else

                                std::char_traits<char>::length(Str)

#endif

                                : 0) {

    }

    /// Construct a string ref from a pointer and length.

    /*implicit*/ constexpr StringRef(const char *data, size_t length)

        : Data(data), Length(length) {}

    /// Construct a string ref from an std::string.

    /*implicit*/ StringRef(const std::string &Str)

      : Data(Str.data()), Length(Str.length()) {}

    /// Construct a string ref from an std::string_view.

    /*implicit*/ constexpr StringRef(std::string_view Str)

        : Data(Str.data()), Length(Str.size()) {}

    /// @}

    /// @name Iterators

    /// @{

    iterator begin() const { return Data; }

    iterator end() const { return Data + Length; }

    const unsigned char *bytes_begin() const {

      return reinterpret_cast<const unsigned char *>(begin());

    }

    const unsigned char *bytes_end() const {

      return reinterpret_cast<const unsigned char *>(end());

    }

    iterator_range<const unsigned char *> bytes() const {

      return make_range(bytes_begin(), bytes_end());

    }

    /// @}

    /// @name String Operations

    /// @{

    /// data - Get a pointer to the start of the string (which may not be null

    /// terminated).

    [[nodiscard]] const char *data() const { return Data; }

    /// empty - Check if the string is empty.

    [[nodiscard]] constexpr bool empty() const { return Length == 0; }

    /// size - Get the string size.

    [[nodiscard]] constexpr size_t size() const { return Length; }

    /// front - Get the first character in the string.

    [[nodiscard]] char front() const {

      assert(!empty());

      return Data[0];

    }

    /// back - Get the last character in the string.

    [[nodiscard]] char back() const {

      assert(!empty());

      return Data[Length-1];

    }

    // copy - Allocate copy in Allocator and return StringRef to it.

    template <typename Allocator>

    [[nodiscard]] StringRef copy(Allocator &A) const {

      // Don't request a length 0 copy from the allocator.

      if (empty())

        return StringRef();

      char *S = A.template Allocate<char>(Length);

      std::copy(begin(), end(), S);

      return StringRef(S, Length);

    }

    /// equals - Check for string equality, this is more efficient than

    /// compare() when the relative ordering of inequal strings isn't needed.

    [[nodiscard]] bool equals(StringRef RHS) const {

      return (Length == RHS.Length &&

              compareMemory(Data, RHS.Data, RHS.Length) == 0);

    }

    /// Check for string equality, ignoring case.

    [[nodiscard]] bool equals_insensitive(StringRef RHS) const {

      return Length == RHS.Length && compare_insensitive(RHS) == 0;

    }

    /// compare - Compare two strings; the result is negative, zero, or positive

    /// if this string is lexicographically less than, equal to, or greater than

    /// the \p RHS.

    [[nodiscard]] int compare(StringRef RHS) const {

      // Check the prefix for a mismatch.

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

        return Res < 0 ? -1 : 1;

      // Otherwise the prefixes match, so we only need to check the lengths.

      if (Length == RHS.Length)

        return 0;

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

    }

    /// Compare two strings, ignoring case.

    [[nodiscard]] int compare_insensitive(StringRef RHS) const;

    /// compare_numeric - Compare two strings, treating sequences of digits as

    /// numbers.

    [[nodiscard]] int compare_numeric(StringRef RHS) const;

    /// Determine the edit distance between this string and another

    /// string.

    ///

    /// \param Other the string to compare this string against.

    ///

    /// \param AllowReplacements whether to allow character

    /// replacements (change one character into another) as a single

    /// operation, rather than as two operations (an insertion and a

    /// removal).

    ///

    /// \param MaxEditDistance If non-zero, the maximum edit distance that

    /// this routine is allowed to compute. If the edit distance will exceed

    /// that maximum, returns \c MaxEditDistance+1.

    ///

    /// \returns the minimum number of character insertions, removals,

    /// or (if \p AllowReplacements is \c true) replacements needed to

    /// transform one of the given strings into the other. If zero,

    /// the strings are identical.

    [[nodiscard]] unsigned edit_distance(StringRef Other,

                                         bool AllowReplacements = true,

                                         unsigned MaxEditDistance = 0) const;

    [[nodiscard]] unsigned

    edit_distance_insensitive(StringRef Other, bool AllowReplacements = true,

                              unsigned MaxEditDistance = 0) const;

    /// str - Get the contents as an std::string.

    [[nodiscard]] std::string str() const {

      if (!Data) return std::string();

      return std::string(Data, Length);

    }

    /// @}

    /// @name Operator Overloads

    /// @{

    [[nodiscard]] char operator[](size_t Index) const {

      assert(Index < Length && "Invalid index!");

      return Data[Index];

    }

    /// Disallow accidental assignment from a temporary std::string.

    ///

    /// The declaration here is extra complicated so that `stringRef = {}`

    /// and `stringRef = "abc"` continue to select the move assignment operator.

    template <typename T>

    std::enable_if_t<std::is_same<T, std::string>::value, StringRef> &

    operator=(T &&Str) = delete;

    /// @}

    /// @name Type Conversions

    /// @{

    operator std::string_view() const {

      return std::string_view(data(), size());

    }

    /// @}

    /// @name String Predicates

    /// @{

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

    [[nodiscard]] bool starts_with(StringRef Prefix) const {

      return Length >= Prefix.Length &&

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

    }

    [[nodiscard]] bool startswith(StringRef Prefix) const {

      return starts_with(Prefix);

    }

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

    [[nodiscard]] bool starts_with_insensitive(StringRef Prefix) const;

    [[nodiscard]] bool startswith_insensitive(StringRef Prefix) const {

      return starts_with_insensitive(Prefix);

    }

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

    [[nodiscard]] bool ends_with(StringRef Suffix) const {

      return Length >= Suffix.Length &&

             compareMemory(end() - Suffix.Length, Suffix.Data, Suffix.Length) ==

                 0;

    }

    [[nodiscard]] bool endswith(StringRef Suffix) const {

      return ends_with(Suffix);

    }

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

    [[nodiscard]] bool ends_with_insensitive(StringRef Suffix) const;

    [[nodiscard]] bool endswith_insensitive(StringRef Suffix) const {

      return ends_with_insensitive(Suffix);

    }

    /// @}

    /// @name String Searching

    /// @{

    /// Search for the first character \p C in the string.

    ///

    /// \returns The index of the first occurrence of \p C, or npos if not

    /// found.

    [[nodiscard]] size_t find(char C, size_t From = 0) const {

      return std::string_view(*this).find(C, From);

    }

    /// Search for the first character \p C in the string, ignoring case.

    ///

    /// \returns The index of the first occurrence of \p C, or npos if not

    /// found.

    [[nodiscard]] size_t find_insensitive(char C, size_t From = 0) const;

    /// Search for the first character satisfying the predicate \p F

    ///

    /// \returns The index of the first character satisfying \p F starting from

    /// \p From, or npos if not found.

    [[nodiscard]] size_t find_if(function_ref<bool(char)> F,

                                 size_t From = 0) const {

      StringRef S = drop_front(From);

      while (!S.empty()) {

        if (F(S.front()))

          return size() - S.size();

        S = S.drop_front();

      }

      return npos;

    }

    /// Search for the first character not satisfying the predicate \p F

    ///

    /// \returns The index of the first character not satisfying \p F starting

    /// from \p From, or npos if not found.

    [[nodiscard]] size_t find_if_not(function_ref<bool(char)> F,

                                     size_t From = 0) const {

      return find_if([F](char c) { return !F(c); }, From);

    }

    /// Search for the first string \p Str in the string.

    ///

    /// \returns The index of the first occurrence of \p Str, or npos if not

    /// found.

    [[nodiscard]] size_t find(StringRef Str, size_t From = 0) const;

    /// Search for the first string \p Str in the string, ignoring case.

    ///

    /// \returns The index of the first occurrence of \p Str, or npos if not

    /// found.

    [[nodiscard]] size_t find_insensitive(StringRef Str, size_t From = 0) const;

    /// Search for the last character \p C in the string.

    ///

    /// \returns The index of the last occurrence of \p C, or npos if not

    /// found.

    [[nodiscard]] size_t rfind(char C, size_t From = npos) const {

      From = std::min(From, Length);

      size_t i = From;

      while (i != 0) {

        --i;

        if (Data[i] == C)

          return i;

      }

      return npos;

    }

    /// Search for the last character \p C in the string, ignoring case.

    ///

    /// \returns The index of the last occurrence of \p C, or npos if not

    /// found.

    [[nodiscard]] size_t rfind_insensitive(char C, size_t From = npos) const;

    /// Search for the last string \p Str in the string.

    ///

    /// \returns The index of the last occurrence of \p Str, or npos if not

    /// found.

    [[nodiscard]] size_t rfind(StringRef Str) const;

    /// Search for the last string \p Str in the string, ignoring case.

    ///

    /// \returns The index of the last occurrence of \p Str, or npos if not

    /// found.

    [[nodiscard]] size_t rfind_insensitive(StringRef Str) const;

    /// Find the first character in the string that is \p C, or npos if not

    /// found. Same as find.

    [[nodiscard]] size_t find_first_of(char C, size_t From = 0) const {

      return find(C, From);

    }

    /// Find the first character in the string that is in \p Chars, or npos if

    /// not found.

    ///

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

    [[nodiscard]] size_t find_first_of(StringRef Chars, size_t From = 0) const;

    /// Find the first character in the string that is not \p C or npos if not

    /// found.

    [[nodiscard]] size_t find_first_not_of(char C, size_t From = 0) const;

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

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

    ///

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

    [[nodiscard]] size_t find_first_not_of(StringRef Chars,

                                           size_t From = 0) const;

    /// Find the last character in the string that is \p C, or npos if not

    /// found.

    [[nodiscard]] size_t find_last_of(char C, size_t From = npos) const {

      return rfind(C, From);

    }

    /// Find the last character in the string that is in \p C, or npos if not

    /// found.

    ///

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

    [[nodiscard]] size_t find_last_of(StringRef Chars,

                                      size_t From = npos) const;

    /// Find the last character in the string that is not \p C, or npos if not

    /// found.

    [[nodiscard]] size_t find_last_not_of(char C, size_t From = npos) const;

    /// Find the last character in the string that is not in \p Chars, or

    /// npos if not found.

    ///

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

    [[nodiscard]] size_t find_last_not_of(StringRef Chars,

                                          size_t From = npos) const;

    /// Return true if the given string is a substring of *this, and false

    /// otherwise.

    [[nodiscard]] bool contains(StringRef Other) const {

      return find(Other) != npos;

    }

    /// Return true if the given character is contained in *this, and false

    /// otherwise.

    [[nodiscard]] bool contains(char C) const {

      return find_first_of(C) != npos;

    }

    /// Return true if the given string is a substring of *this, and false

    /// otherwise.

    [[nodiscard]] bool contains_insensitive(StringRef Other) const {

      return find_insensitive(Other) != npos;

    }

    /// Return true if the given character is contained in *this, and false

    /// otherwise.

    [[nodiscard]] bool contains_insensitive(char C) const {

      return find_insensitive(C) != npos;

    }

    /// @}

    /// @name Helpful Algorithms

    /// @{

    /// Return the number of occurrences of \p C in the string.

    [[nodiscard]] size_t count(char C) const {

      size_t Count = 0;

      for (size_t i = 0, e = Length; i != e; ++i)

        if (Data[i] == C)

          ++Count;

      return Count;

    }

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

    /// the string.

    size_t count(StringRef Str) const;

    /// Parse the current string as an integer of the specified radix.  If

    /// \p Radix is specified as zero, this does radix autosensing using

    /// extended C rules: 0 is octal, 0x is hex, 0b is binary.

    ///

    /// If the string is invalid or if only a subset of the string is valid,

    /// this returns true to signify the error.  The string is considered

    /// erroneous if empty or if it overflows T.

    template <typename T> bool getAsInteger(unsigned Radix, T &Result) const {

      if constexpr (std::numeric_limits<T>::is_signed) {

        long long LLVal;

        if (getAsSignedInteger(*this, Radix, LLVal) ||

            static_cast<T>(LLVal) != LLVal)

          return true;

        Result = LLVal;

      } else {

        unsigned long long ULLVal;

        // The additional cast to unsigned long long is required to avoid the

        // Visual C++ warning C4805: '!=' : unsafe mix of type 'bool' and type

        // 'unsigned __int64' when instantiating getAsInteger with T = bool.

        if (getAsUnsignedInteger(*this, Radix, ULLVal) ||

            static_cast<unsigned long long>(static_cast<T>(ULLVal)) != ULLVal)

          return true;

        Result = ULLVal;

      }

      return false;

    }

    /// Parse the current string as an integer of the specified radix.  If

    /// \p Radix is specified as zero, this does radix autosensing using

    /// extended C rules: 0 is octal, 0x is hex, 0b is binary.

    ///

    /// If the string does not begin with a number of the specified radix,

    /// this returns true to signify the error. The string is considered

    /// erroneous if empty or if it overflows T.

    /// The portion of the string representing the discovered numeric value

    /// is removed from the beginning of the string.

    template <typename T> bool consumeInteger(unsigned Radix, T &Result) {

      if constexpr (std::numeric_limits<T>::is_signed) {

        long long LLVal;

        if (consumeSignedInteger(*this, Radix, LLVal) ||

            static_cast<long long>(static_cast<T>(LLVal)) != LLVal)

          return true;

        Result = LLVal;

      } else {

        unsigned long long ULLVal;

        if (consumeUnsignedInteger(*this, Radix, ULLVal) ||

            static_cast<unsigned long long>(static_cast<T>(ULLVal)) != ULLVal)

          return true;

        Result = ULLVal;

      }

      return false;

    }

    /// Parse the current string as an integer of the specified \p Radix, or of

    /// an autosensed radix if the \p Radix given is 0.  The current value in

    /// \p Result is discarded, and the storage is changed to be wide enough to

    /// store the parsed integer.

    ///

    /// \returns true if the string does not solely consist of a valid

    /// non-empty number in the appropriate base.

    ///

    /// APInt::fromString is superficially similar but assumes the

    /// string is well-formed in the given radix.

    bool getAsInteger(unsigned Radix, APInt &Result) const;

    /// Parse the current string as an IEEE double-precision floating

    /// point value.  The string must be a well-formed double.

    ///

    /// If \p AllowInexact is false, the function will fail if the string

    /// cannot be represented exactly.  Otherwise, the function only fails

    /// in case of an overflow or underflow, or an invalid floating point

    /// representation.

    bool getAsDouble(double &Result, bool AllowInexact = true) const;

    /// @}

    /// @name String Operations

    /// @{

    // Convert the given ASCII string to lowercase.

    [[nodiscard]] std::string lower() const;

    /// Convert the given ASCII string to uppercase.

    [[nodiscard]] std::string upper() const;

    /// @}

    /// @name Substring Operations

    /// @{

    /// Return a reference to the substring from [Start, Start + N).

    ///

    /// \param Start The index of the starting character in the substring; if

    /// the index is npos or greater than the length of the string then the

    /// empty substring will be returned.

    ///

    /// \param N The number of characters to included in the substring. If N

    /// exceeds the number of characters remaining in the string, the string

    /// suffix (starting with \p Start) will be returned.

    [[nodiscard]] constexpr StringRef substr(size_t Start,

                                             size_t N = npos) const {

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

      return StringRef(Data + Start, std::min(N, Length - Start));

    }

    /// Return a StringRef equal to 'this' but with only the first \p N

    /// elements remaining.  If \p N is greater than the length of the

    /// string, the entire string is returned.

    [[nodiscard]] StringRef take_front(size_t N = 1) const {

      if (N >= size())

        return *this;

      return drop_back(size() - N);

    }

    /// Return a StringRef equal to 'this' but with only the last \p N

    /// elements remaining.  If \p N is greater than the length of the

    /// string, the entire string is returned.

    [[nodiscard]] StringRef take_back(size_t N = 1) const {

      if (N >= size())

        return *this;

      return drop_front(size() - N);

    }

    /// Return the longest prefix of 'this' such that every character

    /// in the prefix satisfies the given predicate.

    [[nodiscard]] StringRef take_while(function_ref<bool(char)> F) const {

      return substr(0, find_if_not(F));

    }

    /// Return the longest prefix of 'this' such that no character in

    /// the prefix satisfies the given predicate.

    [[nodiscard]] StringRef take_until(function_ref<bool(char)> F) const {

      return substr(0, find_if(F));

    }

    /// Return a StringRef equal to 'this' but with the first \p N elements

    /// dropped.

    [[nodiscard]] StringRef drop_front(size_t N = 1) const {

      assert(size() >= N && "Dropping more elements than exist");

      return substr(N);

    }

    /// Return a StringRef equal to 'this' but with the last \p N elements

    /// dropped.

    [[nodiscard]] StringRef drop_back(size_t N = 1) const {

      assert(size() >= N && "Dropping more elements than exist");

      return substr(0, size()-N);

    }

    /// Return a StringRef equal to 'this', but with all characters satisfying

    /// the given predicate dropped from the beginning of the string.

    [[nodiscard]] StringRef drop_while(function_ref<bool(char)> F) const {

      return substr(find_if_not(F));

    }

    /// Return a StringRef equal to 'this', but with all characters not

    /// satisfying the given predicate dropped from the beginning of the string.

    [[nodiscard]] StringRef drop_until(function_ref<bool(char)> F) const {

      return substr(find_if(F));

    }

    /// Returns true if this StringRef has the given prefix and removes that

    /// prefix.

    bool consume_front(StringRef Prefix) {

      if (!starts_with(Prefix))

        return false;

      *this = drop_front(Prefix.size());

      return true;

    }

    /// Returns true if this StringRef has the given prefix, ignoring case,

    /// and removes that prefix.

    bool consume_front_insensitive(StringRef Prefix) {

      if (!startswith_insensitive(Prefix))

        return false;

      *this = drop_front(Prefix.size());

      return true;

    }

    /// Returns true if this StringRef has the given suffix and removes that

    /// suffix.

    bool consume_back(StringRef Suffix) {

      if (!ends_with(Suffix))

        return false;

      *this = drop_back(Suffix.size());

      return true;

    }

    /// Returns true if this StringRef has the given suffix, ignoring case,

    /// and removes that suffix.

    bool consume_back_insensitive(StringRef Suffix) {

      if (!endswith_insensitive(Suffix))

        return false;

      *this = drop_back(Suffix.size());

      return true;

    }

    /// Return a reference to the substring from [Start, End).

    ///

    /// \param Start The index of the starting character in the substring; if

    /// the index is npos or greater than the length of the string then the

    /// empty substring will be returned.

    ///

    /// \param End The index following the last character to include in the

    /// substring. If this is npos or exceeds the number of characters

    /// remaining in the string, the string suffix (starting with \p Start)

    /// will be returned. If this is less than \p Start, an empty string will

    /// be returned.

    [[nodiscard]] StringRef slice(size_t Start, size_t End) const {

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

      End = std::min(std::max(Start, End), Length);

      return StringRef(Data + Start, End - Start);

    }

    /// Split into two substrings around the first occurrence of a separator

    /// character.

    ///

    /// If \p Separator is in the string, then the result is a pair (LHS, RHS)

    /// such that (*this == LHS + Separator + RHS) is true and RHS is

    /// maximal. If \p Separator is not in the string, then the result is a

    /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").

    ///

    /// \param Separator The character to split on.

    /// \returns The split substrings.

    [[nodiscard]] std::pair<StringRef, StringRef> split(char Separator) const {

      return split(StringRef(&Separator, 1));

    }

    /// Split into two substrings around the first occurrence of a separator

    /// string.

    ///

    /// If \p Separator is in the string, then the result is a pair (LHS, RHS)

    /// such that (*this == LHS + Separator + RHS) is true and RHS is

    /// maximal. If \p Separator is not in the string, then the result is a

    /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").

    ///

    /// \param Separator - The string to split on.

    /// \return - The split substrings.

    [[nodiscard]] std::pair<StringRef, StringRef>

    split(StringRef Separator) const {

      size_t Idx = find(Separator);

      if (Idx == npos)

        return std::make_pair(*this, StringRef());

      return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));

    }

    /// Split into two substrings around the last occurrence of a separator

    /// string.

    ///

    /// If \p Separator is in the string, then the result is a pair (LHS, RHS)

    /// such that (*this == LHS + Separator + RHS) is true and RHS is

    /// minimal. If \p Separator is not in the string, then the result is a

    /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").

    ///

    /// \param Separator - The string to split on.

    /// \return - The split substrings.

    [[nodiscard]] std::pair<StringRef, StringRef>

    rsplit(StringRef Separator) const {

      size_t Idx = rfind(Separator);

      if (Idx == npos)

        return std::make_pair(*this, StringRef());

      return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));

    }

    /// Split into substrings around the occurrences of a separator string.

    ///

    /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most

    /// \p MaxSplit splits are done and consequently <= \p MaxSplit + 1

    /// elements are added to A.

    /// If \p KeepEmpty is false, empty strings are not added to \p A. They

    /// still count when considering \p MaxSplit

    /// An useful invariant is that

    /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true

    ///

    /// \param A - Where to put the substrings.

    /// \param Separator - The string to split on.

    /// \param MaxSplit - The maximum number of times the string is split.

    /// \param KeepEmpty - True if empty substring should be added.

    void split(SmallVectorImpl<StringRef> &A,

               StringRef Separator, int MaxSplit = -1,

               bool KeepEmpty = true) const;

    /// Split into substrings around the occurrences of a separator character.

    ///

    /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most

    /// \p MaxSplit splits are done and consequently <= \p MaxSplit + 1

    /// elements are added to A.

    /// If \p KeepEmpty is false, empty strings are not added to \p A. They

    /// still count when considering \p MaxSplit

    /// An useful invariant is that

    /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true

    ///

    /// \param A - Where to put the substrings.

    /// \param Separator - The string to split on.

    /// \param MaxSplit - The maximum number of times the string is split.

    /// \param KeepEmpty - True if empty substring should be added.

    void split(SmallVectorImpl<StringRef> &A, char Separator, int MaxSplit = -1,

               bool KeepEmpty = true) const;

    /// Split into two substrings around the last occurrence of a separator

    /// character.

    ///

    /// If \p Separator is in the string, then the result is a pair (LHS, RHS)

    /// such that (*this == LHS + Separator + RHS) is true and RHS is

    /// minimal. If \p Separator is not in the string, then the result is a

    /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").

    ///

    /// \param Separator - The character to split on.

    /// \return - The split substrings.

    [[nodiscard]] std::pair<StringRef, StringRef> rsplit(char Separator) const {

      return rsplit(StringRef(&Separator, 1));

    }

    /// Return string with consecutive \p Char characters starting from the

    /// the left removed.

    [[nodiscard]] StringRef ltrim(char Char) const {

      return drop_front(std::min(Length, find_first_not_of(Char)));

    }

    /// Return string with consecutive characters in \p Chars starting from

    /// the left removed.

    [[nodiscard]] StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const {

      return drop_front(std::min(Length, find_first_not_of(Chars)));

    }

    /// Return string with consecutive \p Char characters starting from the

    /// right removed.

    [[nodiscard]] StringRef rtrim(char Char) const {

      return drop_back(Length - std::min(Length, find_last_not_of(Char) + 1));