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283 lines
8.5 KiB
C++
283 lines
8.5 KiB
C++
//===--- StringRef.h - Constant String Reference Wrapper --------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_STRINGREF_H
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#define LLVM_ADT_STRINGREF_H
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#include <algorithm>
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#include <cassert>
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#include <cstring>
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#include <string>
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namespace llvm {
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/// StringRef - Represent a constant reference to a string, i.e. a character
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/// array and a length, which need not be null terminated.
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///
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/// This class does not own the string data, it is expected to be used in
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/// situations where the character data resides in some other buffer, whose
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/// lifetime extends past that of the StringRef. For this reason, it is not in
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/// general safe to store a StringRef.
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class StringRef {
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public:
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typedef const char *iterator;
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static const size_t npos = ~size_t(0);
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private:
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/// The start of the string, in an external buffer.
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const char *Data;
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/// The length of the string.
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size_t Length;
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public:
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/// @name Constructors
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/// @{
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/// Construct an empty string ref.
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/*implicit*/ StringRef() : Data(0), Length(0) {}
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/// Construct a string ref from a cstring.
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/*implicit*/ StringRef(const char *Str)
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: Data(Str), Length(::strlen(Str)) {}
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/// Construct a string ref from a pointer and length.
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/*implicit*/ StringRef(const char *_Data, unsigned _Length)
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: Data(_Data), Length(_Length) {}
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/// Construct a string ref from an std::string.
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/*implicit*/ StringRef(const std::string &Str)
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: Data(Str.c_str()), Length(Str.length()) {}
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/// @}
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/// @name Iterators
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/// @{
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iterator begin() const { return Data; }
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iterator end() const { return Data + Length; }
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/// @}
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/// @name String Operations
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/// @{
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/// data - Get a pointer to the start of the string (which may not be null
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/// terminated).
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const char *data() const { return Data; }
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/// empty - Check if the string is empty.
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bool empty() const { return Length == 0; }
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/// size - Get the string size.
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size_t size() const { return Length; }
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/// front - Get the first character in the string.
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char front() const {
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assert(!empty());
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return Data[0];
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}
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/// back - Get the last character in the string.
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char back() const {
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assert(!empty());
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return Data[Length-1];
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}
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/// equals - Check for string equality, this is more efficient than
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/// compare() when the relative ordering of inequal strings isn't needed.
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bool equals(const StringRef &RHS) const {
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return (Length == RHS.Length &&
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memcmp(Data, RHS.Data, RHS.Length) == 0);
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}
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/// compare - Compare two strings; the result is -1, 0, or 1 if this string
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/// is lexicographically less than, equal to, or greater than the \arg RHS.
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int compare(const StringRef &RHS) const {
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// Check the prefix for a mismatch.
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if (int Res = memcmp(Data, RHS.Data, std::min(Length, RHS.Length)))
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return Res < 0 ? -1 : 1;
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// Otherwise the prefixes match, so we only need to check the lengths.
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if (Length == RHS.Length)
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return 0;
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return Length < RHS.Length ? -1 : 1;
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}
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/// str - Get the contents as an std::string.
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std::string str() const { return std::string(Data, Length); }
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/// @}
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/// @name Operator Overloads
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/// @{
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char operator[](size_t Index) const {
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assert(Index < Length && "Invalid index!");
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return Data[Index];
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}
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/// @}
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/// @name Type Conversions
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/// @{
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operator std::string() const {
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return str();
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}
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/// @}
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/// @name String Predicates
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/// @{
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/// startswith - Check if this string starts with the given \arg Prefix.
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bool startswith(const StringRef &Prefix) const {
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return substr(0, Prefix.Length).equals(Prefix);
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}
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/// endswith - Check if this string ends with the given \arg Suffix.
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bool endswith(const StringRef &Suffix) const {
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return slice(size() - Suffix.Length, size()).equals(Suffix);
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}
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/// @}
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/// @name String Searching
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/// @{
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/// find - Search for the character \arg C in the string.
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///
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/// \return - The index of the first occurence of \arg C, or npos if not
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/// found.
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size_t find(char C) const {
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for (size_t i = 0, e = Length; i != e; ++i)
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if (Data[i] == C)
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return i;
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return npos;
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}
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/// find - Search for the string \arg Str in the string.
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///
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/// \return - The index of the first occurence of \arg Str, or npos if not
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/// found.
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size_t find(const StringRef &Str) const {
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size_t N = Str.size();
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if (N > Length)
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return npos;
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for (size_t i = 0, e = Length - N + 1; i != e; ++i)
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if (substr(i, N).equals(Str))
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return i;
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return npos;
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}
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/// count - Return the number of occurrences of \arg C in the string.
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size_t count(char C) const {
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size_t Count = 0;
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for (size_t i = 0, e = Length; i != e; ++i)
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if (Data[i] == C)
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++Count;
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return Count;
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}
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/// count - Return the number of non-overlapped occurrences of \arg Str in
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/// the string.
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size_t count(const StringRef &Str) const {
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size_t Count = 0;
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size_t N = Str.size();
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if (N > Length)
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return 0;
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for (size_t i = 0, e = Length - N + 1; i != e; ++i)
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if (substr(i, N).equals(Str))
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++Count;
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return Count;
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}
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/// @}
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/// @name Substring Operations
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/// @{
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/// substr - Return a reference to the substring from [Start, Start + N).
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///
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/// \param Start - The index of the starting character in the substring; if
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/// the index is npos or greater than the length of the string then the
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/// empty substring will be returned.
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///
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/// \param N - The number of characters to included in the substring. If N
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/// exceeds the number of characters remaining in the string, the string
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/// suffix (starting with \arg Start) will be returned.
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StringRef substr(size_t Start, size_t N = npos) const {
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Start = std::min(Start, Length);
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return StringRef(Data + Start, std::min(N, Length - Start));
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}
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/// slice - Return a reference to the substring from [Start, End).
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///
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/// \param Start - The index of the starting character in the substring; if
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/// the index is npos or greater than the length of the string then the
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/// empty substring will be returned.
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///
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/// \param End - The index following the last character to include in the
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/// substring. If this is npos, or less than \arg Start, or exceeds the
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/// number of characters remaining in the string, the string suffix
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/// (starting with \arg Start) will be returned.
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StringRef slice(size_t Start, size_t End) const {
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Start = std::min(Start, Length);
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End = std::min(std::max(Start, End), Length);
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return StringRef(Data + Start, End - Start);
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}
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/// split - Split into two substrings around the first occurence of a
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/// separator character.
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///
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/// If \arg Separator is in the string, then the result is a pair (LHS, RHS)
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/// such that (*this == LHS + Separator + RHS) is true and RHS is
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/// maximal. If \arg Separator is not in the string, then the result is a
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/// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
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///
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/// \param Separator - The character to split on.
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/// \return - The split substrings.
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std::pair<StringRef, StringRef> split(char Separator) const {
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size_t Idx = find(Separator);
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if (Idx == npos)
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return std::make_pair(*this, StringRef());
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return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
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}
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/// @}
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};
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/// @name StringRef Comparison Operators
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/// @{
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inline bool operator==(const StringRef &LHS, const StringRef &RHS) {
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return LHS.equals(RHS);
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}
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inline bool operator!=(const StringRef &LHS, const StringRef &RHS) {
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return !(LHS == RHS);
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}
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inline bool operator<(const StringRef &LHS, const StringRef &RHS) {
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return LHS.compare(RHS) == -1;
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}
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inline bool operator<=(const StringRef &LHS, const StringRef &RHS) {
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return LHS.compare(RHS) != 1;
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}
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inline bool operator>(const StringRef &LHS, const StringRef &RHS) {
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return LHS.compare(RHS) == 1;
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}
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inline bool operator>=(const StringRef &LHS, const StringRef &RHS) {
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return LHS.compare(RHS) != -1;
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}
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/// @}
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}
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#endif
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