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443 lines
15 KiB
C++
443 lines
15 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 <cassert>
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#include <cstring>
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#include <utility>
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#include <string>
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namespace llvm {
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template<typename T>
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class SmallVectorImpl;
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class APInt;
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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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typedef const char *const_iterator;
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static const size_t npos = ~size_t(0);
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typedef size_t size_type;
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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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// Workaround PR5482: nearly all gcc 4.x miscompile StringRef and std::min()
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// Changing the arg of min to be an integer, instead of a reference to an
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// integer works around this bug.
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static size_t min(size_t a, size_t b) { return a < b ? a : b; }
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static size_t max(size_t a, size_t b) { return a > b ? a : b; }
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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, size_t 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.data()), 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(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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/// equals_lower - Check for string equality, ignoring case.
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bool equals_lower(StringRef RHS) const {
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return Length == RHS.Length && compare_lower(RHS) == 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(StringRef RHS) const {
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// Check the prefix for a mismatch.
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if (int Res = memcmp(Data, RHS.Data, 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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/// compare_lower - Compare two strings, ignoring case.
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int compare_lower(StringRef RHS) const;
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/// compare_numeric - Compare two strings, treating sequences of digits as
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/// numbers.
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int compare_numeric(StringRef RHS) const;
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/// \brief Determine the edit distance between this string and another
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/// string.
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///
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/// \param Other the string to compare this string against.
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///
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/// \param AllowReplacements whether to allow character
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/// replacements (change one character into another) as a single
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/// operation, rather than as two operations (an insertion and a
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/// removal).
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///
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/// \param MaxEditDistance If non-zero, the maximum edit distance that
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/// this routine is allowed to compute. If the edit distance will exceed
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/// that maximum, returns \c MaxEditDistance+1.
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///
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/// \returns the minimum number of character insertions, removals,
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/// or (if \p AllowReplacements is \c true) replacements needed to
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/// transform one of the given strings into the other. If zero,
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/// the strings are identical.
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unsigned edit_distance(StringRef Other, bool AllowReplacements = true,
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unsigned MaxEditDistance = 0);
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/// str - Get the contents as an std::string.
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std::string str() const {
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if (Data == 0) return std::string();
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return std::string(Data, Length);
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}
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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(StringRef Prefix) const {
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return Length >= Prefix.Length &&
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memcmp(Data, Prefix.Data, Prefix.Length) == 0;
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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(StringRef Suffix) const {
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return Length >= Suffix.Length &&
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memcmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
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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 first character \arg C in the string.
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///
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/// \return - The index of the first occurrence of \arg C, or npos if not
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/// found.
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size_t find(char C, size_t From = 0) const {
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for (size_t i = min(From, Length), 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 first string \arg Str in the string.
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///
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/// \return - The index of the first occurrence of \arg Str, or npos if not
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/// found.
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size_t find(StringRef Str, size_t From = 0) const;
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/// rfind - Search for the last character \arg C in the string.
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///
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/// \return - The index of the last occurrence of \arg C, or npos if not
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/// found.
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size_t rfind(char C, size_t From = npos) const {
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From = min(From, Length);
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size_t i = From;
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while (i != 0) {
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--i;
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if (Data[i] == C)
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return i;
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}
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return npos;
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}
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/// rfind - Search for the last string \arg Str in the string.
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///
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/// \return - The index of the last occurrence of \arg Str, or npos if not
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/// found.
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size_t rfind(StringRef Str) const;
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/// find_first_of - Find the first character in the string that is \arg C,
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/// or npos if not found. Same as find.
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size_type find_first_of(char C, size_t From = 0) const {
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return find(C, From);
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}
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/// find_first_of - Find the first character in the string that is in \arg
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/// Chars, or npos if not found.
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///
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/// Note: O(size() + Chars.size())
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size_type find_first_of(StringRef Chars, size_t From = 0) const;
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/// find_first_not_of - Find the first character in the string that is not
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/// \arg C or npos if not found.
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size_type find_first_not_of(char C, size_t From = 0) const;
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/// find_first_not_of - Find the first character in the string that is not
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/// in the string \arg Chars, or npos if not found.
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///
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/// Note: O(size() + Chars.size())
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size_type find_first_not_of(StringRef Chars, size_t From = 0) const;
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/// @}
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/// @name Helpful Algorithms
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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(StringRef Str) const;
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/// getAsInteger - Parse the current string as an integer of the specified
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/// radix. If Radix is specified as zero, this does radix autosensing using
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/// extended C rules: 0 is octal, 0x is hex, 0b is binary.
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///
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/// If the string is invalid or if only a subset of the string is valid,
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/// this returns true to signify the error. The string is considered
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/// erroneous if empty.
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///
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bool getAsInteger(unsigned Radix, long long &Result) const;
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bool getAsInteger(unsigned Radix, unsigned long long &Result) const;
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bool getAsInteger(unsigned Radix, int &Result) const;
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bool getAsInteger(unsigned Radix, unsigned &Result) const;
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// TODO: Provide overloads for int/unsigned that check for overflow.
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/// getAsInteger - Parse the current string as an integer of the
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/// specified radix, or of an autosensed radix if the radix given
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/// is 0. The current value in Result is discarded, and the
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/// storage is changed to be wide enough to store the parsed
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/// integer.
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///
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/// Returns true if the string does not solely consist of a valid
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/// non-empty number in the appropriate base.
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///
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/// APInt::fromString is superficially similar but assumes the
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/// string is well-formed in the given radix.
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bool getAsInteger(unsigned Radix, APInt &Result) const;
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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 = min(Start, Length);
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return StringRef(Data + Start, 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 = min(Start, Length);
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End = min(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 occurrence 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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/// split - Split into two substrings around the first occurrence of a
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/// separator string.
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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 string to split on.
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/// \return - The split substrings.
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std::pair<StringRef, StringRef> split(StringRef 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 + Separator.size(), npos));
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}
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/// split - Split into substrings around the occurrences of a separator
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/// string.
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///
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/// Each substring is stored in \arg A. If \arg MaxSplit is >= 0, at most
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/// \arg MaxSplit splits are done and consequently <= \arg MaxSplit
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/// elements are added to A.
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/// If \arg KeepEmpty is false, empty strings are not added to \arg A. They
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/// still count when considering \arg MaxSplit
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/// An useful invariant is that
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/// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true
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///
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/// \param A - Where to put the substrings.
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/// \param Separator - The string to split on.
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/// \param MaxSplit - The maximum number of times the string is split.
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/// \param KeepEmpty - True if empty substring should be added.
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void split(SmallVectorImpl<StringRef> &A,
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StringRef Separator, int MaxSplit = -1,
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bool KeepEmpty = true) const;
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/// rsplit - Split into two substrings around the last occurrence 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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/// minimal. 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> rsplit(char Separator) const {
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size_t Idx = rfind(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==(StringRef LHS, StringRef RHS) {
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return LHS.equals(RHS);
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}
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inline bool operator!=(StringRef LHS, StringRef RHS) {
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return !(LHS == RHS);
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}
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inline bool operator<(StringRef LHS, StringRef RHS) {
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return LHS.compare(RHS) == -1;
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}
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inline bool operator<=(StringRef LHS, StringRef RHS) {
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return LHS.compare(RHS) != 1;
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}
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inline bool operator>(StringRef LHS, StringRef RHS) {
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return LHS.compare(RHS) == 1;
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}
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inline bool operator>=(StringRef LHS, 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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