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llvm-mirror/include/llvm/ADT/StringRef.h
Zachary Turner c6ee90568e [StringRef] Add enable-if to StringLiteral.
to prevent StringLiteral from being created with a non-literal
char array, clang has a macro enable_if() that can be used
in such a way as to guarantee that the constructor is disabled
unless the length fo the string can be computed at compile time.

This only works on clang, but at least it should allow bots
to catch abuse of StringLiteral.

Differential Revision: https://reviews.llvm.org/D27780

llvm-svn: 289853
2016-12-15 19:02:43 +00:00

901 lines
30 KiB
C++

//===--- StringRef.h - Constant String Reference Wrapper --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_STRINGREF_H
#define LLVM_ADT_STRINGREF_H
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Support/Compiler.h"
#include <algorithm>
#include <cassert>
#include <cstring>
#include <limits>
#include <string>
#include <utility>
namespace llvm {
template <typename T>
class SmallVectorImpl;
class APInt;
class hash_code;
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 StringRef {
public:
typedef const char *iterator;
typedef const char *const_iterator;
static const size_t npos = ~size_t(0);
typedef size_t size_type;
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
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_ATTRIBUTE_ALWAYS_INLINE
/*implicit*/ StringRef(const char *Str)
: Data(Str), Length(Str ? ::strlen(Str) : 0) {}
/// Construct a string ref from a pointer and length.
LLVM_ATTRIBUTE_ALWAYS_INLINE
/*implicit*/ constexpr StringRef(const char *data, size_t length)
: Data(data), Length(length) {}
/// Construct a string ref from an std::string.
LLVM_ATTRIBUTE_ALWAYS_INLINE
/*implicit*/ StringRef(const std::string &Str)
: Data(Str.data()), Length(Str.length()) {}
static StringRef withNullAsEmpty(const char *data) {
return StringRef(data ? data : "");
}
/// @}
/// @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).
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
const char *data() const { return Data; }
/// empty - Check if the string is empty.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool empty() const { return Length == 0; }
/// size - Get the string size.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
size_t size() const { return Length; }
/// front - Get the first character in the string.
LLVM_NODISCARD
char front() const {
assert(!empty());
return Data[0];
}
/// back - Get the last character in the string.
LLVM_NODISCARD
char back() const {
assert(!empty());
return Data[Length-1];
}
// copy - Allocate copy in Allocator and return StringRef to it.
template <typename Allocator>
LLVM_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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool equals(StringRef RHS) const {
return (Length == RHS.Length &&
compareMemory(Data, RHS.Data, RHS.Length) == 0);
}
/// equals_lower - Check for string equality, ignoring case.
LLVM_NODISCARD
bool equals_lower(StringRef RHS) const {
return Length == RHS.Length && compare_lower(RHS) == 0;
}
/// compare - Compare two strings; the result is -1, 0, or 1 if this string
/// is lexicographically less than, equal to, or greater than the \p RHS.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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_lower - Compare two strings, ignoring case.
LLVM_NODISCARD
int compare_lower(StringRef RHS) const;
/// compare_numeric - Compare two strings, treating sequences of digits as
/// numbers.
LLVM_NODISCARD
int compare_numeric(StringRef RHS) const;
/// \brief 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.
LLVM_NODISCARD
unsigned edit_distance(StringRef Other, bool AllowReplacements = true,
unsigned MaxEditDistance = 0) const;
/// str - Get the contents as an std::string.
LLVM_NODISCARD
std::string str() const {
if (!Data) return std::string();
return std::string(Data, Length);
}
/// @}
/// @name Operator Overloads
/// @{
LLVM_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>
typename std::enable_if<std::is_same<T, std::string>::value,
StringRef>::type &
operator=(T &&Str) = delete;
/// @}
/// @name Type Conversions
/// @{
operator std::string() const {
return str();
}
/// @}
/// @name String Predicates
/// @{
/// Check if this string starts with the given \p Prefix.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool startswith(StringRef Prefix) const {
return Length >= Prefix.Length &&
compareMemory(Data, Prefix.Data, Prefix.Length) == 0;
}
/// Check if this string starts with the given \p Prefix, ignoring case.
LLVM_NODISCARD
bool startswith_lower(StringRef Prefix) const;
/// Check if this string ends with the given \p Suffix.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool endswith(StringRef Suffix) const {
return Length >= Suffix.Length &&
compareMemory(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
}
/// Check if this string ends with the given \p Suffix, ignoring case.
LLVM_NODISCARD
bool endswith_lower(StringRef Suffix) const;
/// @}
/// @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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
size_t find(char C, size_t From = 0) const {
size_t FindBegin = std::min(From, Length);
if (FindBegin < Length) { // Avoid calling memchr with nullptr.
// Just forward to memchr, which is faster than a hand-rolled loop.
if (const void *P = ::memchr(Data + FindBegin, C, Length - FindBegin))
return static_cast<const char *>(P) - Data;
}
return npos;
}
/// 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.
LLVM_NODISCARD
size_t find_lower(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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_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.
LLVM_NODISCARD
size_t find_lower(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.
LLVM_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.
LLVM_NODISCARD
size_t rfind_lower(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.
LLVM_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.
LLVM_NODISCARD
size_t rfind_lower(StringRef Str) const;
/// Find the first character in the string that is \p C, or npos if not
/// found. Same as find.
LLVM_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())
LLVM_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.
LLVM_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())
LLVM_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.
LLVM_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())
LLVM_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.
LLVM_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())
LLVM_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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool contains(StringRef Other) const { return find(Other) != npos; }
/// Return true if the given character is contained in *this, and false
/// otherwise.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool contains_lower(StringRef Other) const {
return find_lower(Other) != npos;
}
/// Return true if the given character is contained in *this, and false
/// otherwise.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool contains_lower(char C) const { return find_lower(C) != npos; }
/// @}
/// @name Helpful Algorithms
/// @{
/// Return the number of occurrences of \p C in the string.
LLVM_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>
typename std::enable_if<std::numeric_limits<T>::is_signed, bool>::type
getAsInteger(unsigned Radix, T &Result) const {
long long LLVal;
if (getAsSignedInteger(*this, Radix, LLVal) ||
static_cast<T>(LLVal) != LLVal)
return true;
Result = LLVal;
return false;
}
template <typename T>
typename std::enable_if<!std::numeric_limits<T>::is_signed, bool>::type
getAsInteger(unsigned Radix, T &Result) const {
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>
typename std::enable_if<std::numeric_limits<T>::is_signed, bool>::type
consumeInteger(unsigned Radix, T &Result) {
long long LLVal;
if (consumeSignedInteger(*this, Radix, LLVal) ||
static_cast<long long>(static_cast<T>(LLVal)) != LLVal)
return true;
Result = LLVal;
return false;
}
template <typename T>
typename std::enable_if<!std::numeric_limits<T>::is_signed, bool>::type
consumeInteger(unsigned Radix, T &Result) {
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;
/// @}
/// @name String Operations
/// @{
// Convert the given ASCII string to lowercase.
LLVM_NODISCARD
std::string lower() const;
/// Convert the given ASCII string to uppercase.
LLVM_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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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 first \p N
/// elements remaining. If \p N is greater than the length of the
/// string, the entire string is returned.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool consume_front(StringRef Prefix) {
if (!startswith(Prefix))
return false;
*this = drop_front(Prefix.size());
return true;
}
/// Returns true if this StringRef has the given suffix and removes that
/// suffix.
LLVM_ATTRIBUTE_ALWAYS_INLINE
bool consume_back(StringRef Suffix) {
if (!endswith(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.
LLVM_NODISCARD
LLVM_ATTRIBUTE_ALWAYS_INLINE
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.
LLVM_NODISCARD
std::pair<StringRef, StringRef> split(char 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+1, npos));
}
/// 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.
LLVM_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 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.
LLVM_NODISCARD
std::pair<StringRef, StringRef> rsplit(char 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+1, npos));
}
/// Return string with consecutive \p Char characters starting from the
/// the left removed.
LLVM_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.
LLVM_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.
LLVM_NODISCARD
StringRef rtrim(char Char) const {
return drop_back(Length - std::min(Length, find_last_not_of(Char) + 1));
}
/// Return string with consecutive characters in \p Chars starting from
/// the right removed.
LLVM_NODISCARD
StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const {
return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1));
}
/// Return string with consecutive \p Char characters starting from the
/// left and right removed.
LLVM_NODISCARD
StringRef trim(char Char) const {
return ltrim(Char).rtrim(Char);
}
/// Return string with consecutive characters in \p Chars starting from
/// the left and right removed.
LLVM_NODISCARD
StringRef trim(StringRef Chars = " \t\n\v\f\r") const {
return ltrim(Chars).rtrim(Chars);
}
/// @}
};
/// A wrapper around a string literal that serves as a proxy for constructing
/// global tables of StringRefs with the length computed at compile time.
/// In order to avoid the invocation of a global constructor, StringLiteral
/// should *only* be used in a constexpr context, as such:
///
/// constexpr StringLiteral S("test");
///
class StringLiteral : public StringRef {
public:
template <size_t N>
constexpr StringLiteral(const char (&Str)[N])
#if __has_attribute(enable_if)
__attribute((enable_if(__builtin_strlen(Str) == N - 1,
"invalid string literal")))
#endif
: StringRef(Str, N - 1) {
}
};
/// @name StringRef Comparison Operators
/// @{
LLVM_ATTRIBUTE_ALWAYS_INLINE
inline bool operator==(StringRef LHS, StringRef RHS) {
return LHS.equals(RHS);
}
LLVM_ATTRIBUTE_ALWAYS_INLINE
inline bool operator!=(StringRef LHS, StringRef RHS) { return !(LHS == RHS); }
inline bool operator<(StringRef LHS, StringRef RHS) {
return LHS.compare(RHS) == -1;
}
inline bool operator<=(StringRef LHS, StringRef RHS) {
return LHS.compare(RHS) != 1;
}
inline bool operator>(StringRef LHS, StringRef RHS) {
return LHS.compare(RHS) == 1;
}
inline bool operator>=(StringRef LHS, StringRef RHS) {
return LHS.compare(RHS) != -1;
}
inline std::string &operator+=(std::string &buffer, StringRef string) {
return buffer.append(string.data(), string.size());
}
/// @}
/// \brief Compute a hash_code for a StringRef.
LLVM_NODISCARD
hash_code hash_value(StringRef S);
// StringRefs can be treated like a POD type.
template <typename T> struct isPodLike;
template <> struct isPodLike<StringRef> { static const bool value = true; };
}
#endif