llvm-project/llvm/lib/Support/StringRef.cpp

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//===-- StringRef.cpp - Lightweight String References ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/edit_distance.h"
#include <bitset>
using namespace llvm;
// MSVC emits references to this into the translation units which reference it.
#ifndef _MSC_VER
const size_t StringRef::npos;
#endif
static char ascii_tolower(char x) {
if (x >= 'A' && x <= 'Z')
return x - 'A' + 'a';
return x;
}
static char ascii_toupper(char x) {
if (x >= 'a' && x <= 'z')
return x - 'a' + 'A';
return x;
}
static bool ascii_isdigit(char x) {
return x >= '0' && x <= '9';
}
/// compare_lower - Compare strings, ignoring case.
int StringRef::compare_lower(StringRef RHS) const {
for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
unsigned char LHC = ascii_tolower(Data[I]);
unsigned char RHC = ascii_tolower(RHS.Data[I]);
if (LHC != RHC)
return LHC < RHC ? -1 : 1;
}
if (Length == RHS.Length)
return 0;
return Length < RHS.Length ? -1 : 1;
}
/// compare_numeric - Compare strings, handle embedded numbers.
int StringRef::compare_numeric(StringRef RHS) const {
for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
// Check for sequences of digits.
if (ascii_isdigit(Data[I]) && ascii_isdigit(RHS.Data[I])) {
// The longer sequence of numbers is considered larger.
// This doesn't really handle prefixed zeros well.
size_t J;
for (J = I + 1; J != E + 1; ++J) {
bool ld = J < Length && ascii_isdigit(Data[J]);
bool rd = J < RHS.Length && ascii_isdigit(RHS.Data[J]);
if (ld != rd)
return rd ? -1 : 1;
if (!rd)
break;
}
// The two number sequences have the same length (J-I), just memcmp them.
if (int Res = compareMemory(Data + I, RHS.Data + I, J - I))
return Res < 0 ? -1 : 1;
// Identical number sequences, continue search after the numbers.
I = J - 1;
continue;
}
if (Data[I] != RHS.Data[I])
return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1;
}
if (Length == RHS.Length)
return 0;
return Length < RHS.Length ? -1 : 1;
}
// Compute the edit distance between the two given strings.
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unsigned StringRef::edit_distance(llvm::StringRef Other,
bool AllowReplacements,
unsigned MaxEditDistance) const {
return llvm::ComputeEditDistance(
llvm::ArrayRef<char>(data(), size()),
llvm::ArrayRef<char>(Other.data(), Other.size()),
AllowReplacements, MaxEditDistance);
}
//===----------------------------------------------------------------------===//
// String Operations
//===----------------------------------------------------------------------===//
std::string StringRef::lower() const {
std::string Result(size(), char());
for (size_type i = 0, e = size(); i != e; ++i) {
Result[i] = ascii_tolower(Data[i]);
}
return Result;
}
std::string StringRef::upper() const {
std::string Result(size(), char());
for (size_type i = 0, e = size(); i != e; ++i) {
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Result[i] = ascii_toupper(Data[i]);
}
return Result;
}
//===----------------------------------------------------------------------===//
// String Searching
//===----------------------------------------------------------------------===//
/// 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 StringRef::find(StringRef Str, size_t From) const {
size_t N = Str.size();
if (N > Length)
return npos;
// For short haystacks or unsupported needles fall back to the naive algorithm
if (Length < 16 || N > 255 || N == 0) {
for (size_t e = Length - N + 1, i = min(From, e); i != e; ++i)
if (substr(i, N).equals(Str))
return i;
return npos;
}
if (From >= Length)
return npos;
// Build the bad char heuristic table, with uint8_t to reduce cache thrashing.
uint8_t BadCharSkip[256];
std::memset(BadCharSkip, N, 256);
for (unsigned i = 0; i != N-1; ++i)
BadCharSkip[(uint8_t)Str[i]] = N-1-i;
unsigned Len = Length-From, Pos = From;
while (Len >= N) {
if (substr(Pos, N).equals(Str)) // See if this is the correct substring.
return Pos;
// Otherwise skip the appropriate number of bytes.
uint8_t Skip = BadCharSkip[(uint8_t)(*this)[Pos+N-1]];
Len -= Skip;
Pos += Skip;
}
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 StringRef::rfind(StringRef Str) const {
size_t N = Str.size();
if (N > Length)
return npos;
for (size_t i = Length - N + 1, e = 0; i != e;) {
--i;
if (substr(i, N).equals(Str))
return i;
}
return npos;
}
/// 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())
StringRef::size_type StringRef::find_first_of(StringRef Chars,
size_t From) const {
std::bitset<1 << CHAR_BIT> CharBits;
for (size_type i = 0; i != Chars.size(); ++i)
CharBits.set((unsigned char)Chars[i]);
for (size_type i = min(From, Length), e = Length; i != e; ++i)
if (CharBits.test((unsigned char)Data[i]))
return i;
return npos;
}
/// find_first_not_of - Find the first character in the string that is not
/// \arg C or npos if not found.
StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
for (size_type i = min(From, Length), e = Length; i != e; ++i)
if (Data[i] != C)
return i;
return npos;
}
/// 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())
StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
size_t From) const {
std::bitset<1 << CHAR_BIT> CharBits;
for (size_type i = 0; i != Chars.size(); ++i)
CharBits.set((unsigned char)Chars[i]);
for (size_type i = min(From, Length), e = Length; i != e; ++i)
if (!CharBits.test((unsigned char)Data[i]))
return i;
return npos;
}
/// 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())
StringRef::size_type StringRef::find_last_of(StringRef Chars,
size_t From) const {
std::bitset<1 << CHAR_BIT> CharBits;
for (size_type i = 0; i != Chars.size(); ++i)
CharBits.set((unsigned char)Chars[i]);
for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
if (CharBits.test((unsigned char)Data[i]))
return i;
return npos;
}
/// find_last_not_of - Find the last character in the string that is not
/// \arg C, or npos if not found.
StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const {
for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
if (Data[i] != C)
return i;
return npos;
}
/// find_last_not_of - Find the last character in the string that is not in
/// \arg Chars, or npos if not found.
///
/// Note: O(size() + Chars.size())
StringRef::size_type StringRef::find_last_not_of(StringRef Chars,
size_t From) const {
std::bitset<1 << CHAR_BIT> CharBits;
for (size_type i = 0, e = Chars.size(); i != e; ++i)
CharBits.set((unsigned char)Chars[i]);
for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
if (!CharBits.test((unsigned char)Data[i]))
return i;
return npos;
}
void StringRef::split(SmallVectorImpl<StringRef> &A,
StringRef Separators, int MaxSplit,
bool KeepEmpty) const {
StringRef rest = *this;
// rest.data() is used to distinguish cases like "a," that splits into
// "a" + "" and "a" that splits into "a" + 0.
for (int splits = 0;
rest.data() != NULL && (MaxSplit < 0 || splits < MaxSplit);
++splits) {
std::pair<StringRef, StringRef> p = rest.split(Separators);
if (KeepEmpty || p.first.size() != 0)
A.push_back(p.first);
rest = p.second;
}
// If we have a tail left, add it.
if (rest.data() != NULL && (rest.size() != 0 || KeepEmpty))
A.push_back(rest);
}
//===----------------------------------------------------------------------===//
// Helpful Algorithms
//===----------------------------------------------------------------------===//
/// count - Return the number of non-overlapped occurrences of \arg Str in
/// the string.
size_t StringRef::count(StringRef Str) const {
size_t Count = 0;
size_t N = Str.size();
if (N > Length)
return 0;
for (size_t i = 0, e = Length - N + 1; i != e; ++i)
if (substr(i, N).equals(Str))
++Count;
return Count;
}
static unsigned GetAutoSenseRadix(StringRef &Str) {
if (Str.startswith("0x")) {
Str = Str.substr(2);
return 16;
}
if (Str.startswith("0b")) {
Str = Str.substr(2);
return 2;
}
if (Str.startswith("0o")) {
Str = Str.substr(2);
return 8;
}
if (Str.startswith("0"))
return 8;
return 10;
}
/// GetAsUnsignedInteger - Workhorse method that converts a integer character
/// sequence of radix up to 36 to an unsigned long long value.
bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix,
unsigned long long &Result) {
// Autosense radix if not specified.
if (Radix == 0)
Radix = GetAutoSenseRadix(Str);
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// Empty strings (after the radix autosense) are invalid.
if (Str.empty()) return true;
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// Parse all the bytes of the string given this radix. Watch for overflow.
Result = 0;
while (!Str.empty()) {
unsigned CharVal;
if (Str[0] >= '0' && Str[0] <= '9')
CharVal = Str[0]-'0';
else if (Str[0] >= 'a' && Str[0] <= 'z')
CharVal = Str[0]-'a'+10;
else if (Str[0] >= 'A' && Str[0] <= 'Z')
CharVal = Str[0]-'A'+10;
else
return true;
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// If the parsed value is larger than the integer radix, the string is
// invalid.
if (CharVal >= Radix)
return true;
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// Add in this character.
unsigned long long PrevResult = Result;
Result = Result*Radix+CharVal;
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// Check for overflow by shifting back and seeing if bits were lost.
if (Result/Radix < PrevResult)
return true;
Str = Str.substr(1);
}
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return false;
}
bool llvm::getAsSignedInteger(StringRef Str, unsigned Radix,
long long &Result) {
unsigned long long ULLVal;
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// Handle positive strings first.
if (Str.empty() || Str.front() != '-') {
if (getAsUnsignedInteger(Str, Radix, ULLVal) ||
// Check for value so large it overflows a signed value.
(long long)ULLVal < 0)
return true;
Result = ULLVal;
return false;
}
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// Get the positive part of the value.
if (getAsUnsignedInteger(Str.substr(1), Radix, ULLVal) ||
// Reject values so large they'd overflow as negative signed, but allow
// "-0". This negates the unsigned so that the negative isn't undefined
// on signed overflow.
(long long)-ULLVal > 0)
return true;
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Result = -ULLVal;
return false;
}
bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
StringRef Str = *this;
// Autosense radix if not specified.
if (Radix == 0)
Radix = GetAutoSenseRadix(Str);
assert(Radix > 1 && Radix <= 36);
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// Empty strings (after the radix autosense) are invalid.
if (Str.empty()) return true;
// Skip leading zeroes. This can be a significant improvement if
// it means we don't need > 64 bits.
while (!Str.empty() && Str.front() == '0')
Str = Str.substr(1);
// If it was nothing but zeroes....
if (Str.empty()) {
Result = APInt(64, 0);
return false;
}
// (Over-)estimate the required number of bits.
unsigned Log2Radix = 0;
while ((1U << Log2Radix) < Radix) Log2Radix++;
bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);
unsigned BitWidth = Log2Radix * Str.size();
if (BitWidth < Result.getBitWidth())
BitWidth = Result.getBitWidth(); // don't shrink the result
else if (BitWidth > Result.getBitWidth())
Result = Result.zext(BitWidth);
APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
if (!IsPowerOf2Radix) {
// These must have the same bit-width as Result.
RadixAP = APInt(BitWidth, Radix);
CharAP = APInt(BitWidth, 0);
}
// Parse all the bytes of the string given this radix.
Result = 0;
while (!Str.empty()) {
unsigned CharVal;
if (Str[0] >= '0' && Str[0] <= '9')
CharVal = Str[0]-'0';
else if (Str[0] >= 'a' && Str[0] <= 'z')
CharVal = Str[0]-'a'+10;
else if (Str[0] >= 'A' && Str[0] <= 'Z')
CharVal = Str[0]-'A'+10;
else
return true;
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// If the parsed value is larger than the integer radix, the string is
// invalid.
if (CharVal >= Radix)
return true;
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// Add in this character.
if (IsPowerOf2Radix) {
Result <<= Log2Radix;
Result |= CharVal;
} else {
Result *= RadixAP;
CharAP = CharVal;
Result += CharAP;
}
Str = Str.substr(1);
}
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return false;
}
// Implementation of StringRef hashing.
hash_code llvm::hash_value(StringRef S) {
return hash_combine_range(S.begin(), S.end());
}