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| Current File : //usr/src/contrib/llvm/include/llvm/ADT/StringRef.h |
//===--- 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/Support/type_traits.h"
#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);
/// 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;
/// The length of the string.
size_t Length;
// Workaround PR5482: nearly all gcc 4.x miscompile StringRef and std::min()
// Changing the arg of min to be an integer, instead of a reference to an
// integer works around this bug.
static size_t min(size_t a, size_t b) { return a < b ? a : b; }
static size_t max(size_t a, size_t b) { return a > b ? a : b; }
// 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() : Data(0), Length(0) {}
/// Construct a string ref from a cstring.
/*implicit*/ StringRef(const char *Str)
: Data(Str) {
assert(Str && "StringRef cannot be built from a NULL argument");
Length = ::strlen(Str); // invoking strlen(NULL) is undefined behavior
}
/// Construct a string ref from a pointer and length.
/*implicit*/ StringRef(const char *data, size_t length)
: Data(data), Length(length) {
assert((data || length == 0) &&
"StringRef cannot be built from a NULL argument with non-null length");
}
/// Construct a string ref from an std::string.
/*implicit*/ StringRef(const std::string &Str)
: Data(Str.data()), Length(Str.length()) {}
/// @}
/// @name Iterators
/// @{
iterator begin() const { return Data; }
iterator end() const { return Data + Length; }
/// @}
/// @name String Operations
/// @{
/// data - Get a pointer to the start of the string (which may not be null
/// terminated).
const char *data() const { return Data; }
/// empty - Check if the string is empty.
bool empty() const { return Length == 0; }
/// size - Get the string size.
size_t size() const { return Length; }
/// front - Get the first character in the string.
char front() const {
assert(!empty());
return Data[0];
}
/// back - Get the last character in the string.
char back() const {
assert(!empty());
return Data[Length-1];
}
/// equals - Check for string equality, this is more efficient than
/// compare() when the relative ordering of inequal strings isn't needed.
bool equals(StringRef RHS) const {
return (Length == RHS.Length &&
compareMemory(Data, RHS.Data, RHS.Length) == 0);
}
/// equals_lower - Check for string equality, ignoring case.
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 \arg RHS.
int compare(StringRef RHS) const {
// Check the prefix for a mismatch.
if (int Res = compareMemory(Data, RHS.Data, 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.
int compare_lower(StringRef RHS) const;
/// compare_numeric - Compare two strings, treating sequences of digits as
/// numbers.
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.
unsigned edit_distance(StringRef Other, bool AllowReplacements = true,
unsigned MaxEditDistance = 0);
/// str - Get the contents as an std::string.
std::string str() const {
if (Data == 0) return std::string();
return std::string(Data, Length);
}
/// @}
/// @name Operator Overloads
/// @{
char operator[](size_t Index) const {
assert(Index < Length && "Invalid index!");
return Data[Index];
}
/// @}
/// @name Type Conversions
/// @{
operator std::string() const {
return str();
}
/// @}
/// @name String Predicates
/// @{
/// startswith - Check if this string starts with the given \arg Prefix.
bool startswith(StringRef Prefix) const {
return Length >= Prefix.Length &&
compareMemory(Data, Prefix.Data, Prefix.Length) == 0;
}
/// endswith - Check if this string ends with the given \arg Suffix.
bool endswith(StringRef Suffix) const {
return Length >= Suffix.Length &&
compareMemory(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
}
/// @}
/// @name String Searching
/// @{
/// find - Search for the first character \arg C in the string.
///
/// \return - The index of the first occurrence of \arg C, or npos if not
/// found.
size_t find(char C, size_t From = 0) const {
for (size_t i = min(From, Length), e = Length; i != e; ++i)
if (Data[i] == C)
return i;
return npos;
}
/// find - Search for the first string \arg Str in the string.
///
/// \return - The index of the first occurrence of \arg Str, or npos if not
/// found.
size_t find(StringRef Str, size_t From = 0) const;
/// rfind - Search for the last character \arg C in the string.
///
/// \return - The index of the last occurrence of \arg C, or npos if not
/// found.
size_t rfind(char C, size_t From = npos) const {
From = min(From, Length);
size_t i = From;
while (i != 0) {
--i;
if (Data[i] == C)
return i;
}
return npos;
}
/// rfind - Search for the last string \arg Str in the string.
///
/// \return - The index of the last occurrence of \arg Str, or npos if not
/// found.
size_t rfind(StringRef Str) const;
/// find_first_of - Find the first character in the string that is \arg C,
/// or npos if not found. Same as find.
size_type find_first_of(char C, size_t From = 0) const {
return find(C, From);
}
/// find_first_of - Find the first character in the string that is in \arg
/// Chars, or npos if not found.
///
/// Note: O(size() + Chars.size())
size_type find_first_of(StringRef Chars, size_t From = 0) const;
/// find_first_not_of - Find the first character in the string that is not
/// \arg C or npos if not found.
size_type find_first_not_of(char C, size_t From = 0) const;
/// find_first_not_of - Find the first character in the string that is not
/// in the string \arg Chars, or npos if not found.
///
/// Note: O(size() + Chars.size())
size_type find_first_not_of(StringRef Chars, size_t From = 0) const;
/// find_last_of - Find the last character in the string that is \arg C, or
/// npos if not found.
size_type find_last_of(char C, size_t From = npos) const {
return rfind(C, From);
}
/// find_last_of - Find the last character in the string that is in \arg C,
/// or npos if not found.
///
/// Note: O(size() + Chars.size())
size_type find_last_of(StringRef Chars, size_t From = npos) const;
/// @}
/// @name Helpful Algorithms
/// @{
/// count - Return the number of occurrences of \arg C in the string.
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;
}
/// count - Return the number of non-overlapped occurrences of \arg Str in
/// the string.
size_t count(StringRef Str) const;
/// getAsInteger - Parse the current string as an integer of the specified
/// radix. If 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 enable_if_c<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 enable_if_c<!std::numeric_limits<T>::is_signed, bool>::type
getAsInteger(unsigned Radix, T &Result) const {
unsigned long long ULLVal;
if (getAsUnsignedInteger(*this, Radix, ULLVal) ||
static_cast<T>(ULLVal) != ULLVal)
return true;
Result = ULLVal;
return false;
}
/// getAsInteger - Parse the current string as an integer of the
/// specified radix, or of an autosensed radix if the radix given
/// is 0. The current value in 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
/// @{
// lower - Convert the given ASCII string to lowercase.
std::string lower() const;
/// upper - Convert the given ASCII string to uppercase.
std::string upper() const;
/// @}
/// @name Substring Operations
/// @{
/// substr - 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 \arg Start) will be returned.
StringRef substr(size_t Start, size_t N = npos) const {
Start = min(Start, Length);
return StringRef(Data + Start, min(N, Length - Start));
}
/// drop_front - Return a StringRef equal to 'this' but with the first
/// elements dropped.
StringRef drop_front(unsigned N = 1) const {
assert(size() >= N && "Dropping more elements than exist");
return substr(N);
}
/// drop_back - Return a StringRef equal to 'this' but with the last
/// elements dropped.
StringRef drop_back(unsigned N = 1) const {
assert(size() >= N && "Dropping more elements than exist");
return substr(0, size()-N);
}
/// slice - 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 less than \arg Start, or exceeds the
/// number of characters remaining in the string, the string suffix
/// (starting with \arg Start) will be returned.
StringRef slice(size_t Start, size_t End) const {
Start = min(Start, Length);
End = min(max(Start, End), Length);
return StringRef(Data + Start, End - Start);
}
/// split - Split into two substrings around the first occurrence of a
/// separator character.
///
/// If \arg 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 \arg 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.
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 - Split into two substrings around the first occurrence of a
/// separator string.
///
/// If \arg 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 \arg 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.
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 - Split into substrings around the occurrences of a separator
/// string.
///
/// Each substring is stored in \arg A. If \arg MaxSplit is >= 0, at most
/// \arg MaxSplit splits are done and consequently <= \arg MaxSplit
/// elements are added to A.
/// If \arg KeepEmpty is false, empty strings are not added to \arg A. They
/// still count when considering \arg 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;
/// rsplit - Split into two substrings around the last occurrence of a
/// separator character.
///
/// If \arg 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 \arg 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.
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));
}
/// @}
};
/// @name StringRef Comparison Operators
/// @{
inline bool operator==(StringRef LHS, StringRef RHS) {
return LHS.equals(RHS);
}
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, llvm::StringRef string) {
return buffer.append(string.data(), string.size());
}
/// @}
/// \brief Compute a hash_code for a StringRef.
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