StringExtras.h

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//===- llvm/ADT/StringExtras.h - Useful string functions --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains some functions that are useful when dealing with strings.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_STRINGEXTRAS_H
#define LLVM_ADT_STRINGEXTRAS_H

#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <iterator>
#include <string>
#include <utility>

namespace llvm {

class raw_ostream;

/// hexdigit - Return the hexadecimal character for the
/// given number \p X (which should be less than 16).
inlinechar hexdigit(unsignedX, bool LowerCase = false) {
assert(X < 16);
staticconstcharLUT[] = "0123456789ABCDEF";
constuint8_tOffset = LowerCase ? 32 : 0;
returnLUT[X] | Offset;
}

/// Given an array of c-style strings terminated by a null pointer, construct
/// a vector of StringRefs representing the same strings without the terminating
/// null string.
inline std::vector<StringRef> toStringRefArray(constchar *const *Strings) {
 std::vector<StringRef> Result;
while (*Strings)
Result.push_back(*Strings++);
returnResult;
}

/// Construct a string ref from a boolean.
inline StringRef toStringRef(boolB) { return StringRef(B ? "true" : "false"); }

/// Construct a string ref from an array ref of unsigned chars.
inline StringRef toStringRef(ArrayRef<uint8_t> Input) {
return StringRef(reinterpret_cast<const char *>(Input.begin()), Input.size());
}
inline StringRef toStringRef(ArrayRef<char> Input) {
return StringRef(Input.begin(), Input.size());
}

/// Construct a string ref from an array ref of unsigned chars.
template <class CharT = uint8_t>
inline ArrayRef<CharT> arrayRefFromStringRef(StringRef Input) {
static_assert(std::is_same<CharT, char>::value ||
 std::is_same<CharT, unsigned char>::value ||
 std::is_same<CharT, signed char>::value,
"Expected byte type");
return ArrayRef<CharT>(reinterpret_cast<const CharT *>(Input.data()),
 Input.size());
}

/// Interpret the given character \p C as a hexadecimal digit and return its
/// value.
///
/// If \p C is not a valid hex digit, -1U is returned.
inlineunsigned hexDigitValue(charC) {
/* clang-format off */
staticconst int16_t LUT[256] = {
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, // '0'..'9'
 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 'A'..'F'
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 'a'..'f'
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 };
/* clang-format on */
returnLUT[static_cast<unsignedchar>(C)];
}

/// Checks if character \p C is one of the 10 decimal digits.
inlineboolisDigit(charC) { returnC >= '0' && C <= '9'; }

/// Checks if character \p C is a hexadecimal numeric character.
inlineboolisHexDigit(charC) { return hexDigitValue(C) != ~0U; }

/// Checks if character \p C is a lowercase letter as classified by "C" locale.
inlineboolisLower(charC) { return'a' <= C && C <= 'z'; }

/// Checks if character \p C is a uppercase letter as classified by "C" locale.
inlineboolisUpper(charC) { return'A' <= C && C <= 'Z'; }

/// Checks if character \p C is a valid letter as classified by "C" locale.
inlinebool isAlpha(charC) { returnisLower(C) || isUpper(C); }

/// Checks whether character \p C is either a decimal digit or an uppercase or
/// lowercase letter as classified by "C" locale.
inlinebool isAlnum(charC) { return isAlpha(C) || isDigit(C); }

/// Checks whether character \p C is valid ASCII (high bit is zero).
inlinebool isASCII(charC) { returnstatic_cast<unsignedchar>(C) <= 127; }

/// Checks whether all characters in S are ASCII.
inlinebool isASCII(llvm::StringRef S) {
for (charC : S)
if (LLVM_UNLIKELY(!isASCII(C)))
returnfalse;
returntrue;
}

/// Checks whether character \p C is printable.
///
/// Locale-independent version of the C standard library isprint whose results
/// may differ on different platforms.
inlineboolisPrint(charC) {
unsignedchar UC = static_cast<unsignedchar>(C);
return (0x20 <= UC) && (UC <= 0x7E);
}

/// Checks whether character \p C is a punctuation character.
///
/// Locale-independent version of the C standard library ispunct. The list of
/// punctuation characters can be found in the documentation of std::ispunct:
/// https://en.cppreference.com/w/cpp/string/byte/ispunct.
inlinebool isPunct(charC) {
staticconstexprStringLiteral Punctuations =
 R"(!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~)";
return Punctuations.contains(C);
}

/// Checks whether character \p C is whitespace in the "C" locale.
///
/// Locale-independent version of the C standard library isspace.
inlinebool isSpace(charC) {
returnC == ' ' || C == '\f' || C == '\n' || C == '\r' || C == '\t' ||
C == '\v';
}

/// Returns the corresponding lowercase character if \p x is uppercase.
inlinechar toLower(char x) {
if (isUpper(x))
returnx - 'A' + 'a';
returnx;
}

/// Returns the corresponding uppercase character if \p x is lowercase.
inlinechar toUpper(char x) {
if (isLower(x))
returnx - 'a' + 'A';
returnx;
}

inline std::string utohexstr(uint64_tX, bool LowerCase = false,
unsigned Width = 0) {
char Buffer[17];
char *BufPtr = std::end(Buffer);

if (X == 0) *--BufPtr = '0';

for (unsigned i = 0; Width ? (i < Width) : X; ++i) {
unsignedcharMod = static_cast<unsignedchar>(X) & 15;
 *--BufPtr = hexdigit(Mod, LowerCase);
X >>= 4;
 }

return std::string(BufPtr, std::end(Buffer));
}

/// Convert buffer \p Input to its hexadecimal representation.
/// The returned string is double the size of \p Input.
inlinevoid toHex(ArrayRef<uint8_t> Input, bool LowerCase,
 SmallVectorImpl<char> &Output) {
constsize_tLength = Input.size();
 Output.resize_for_overwrite(Length * 2);

for (size_t i = 0; i < Length; i++) {
constuint8_t c = Input[i];
 Output[i * 2 ] = hexdigit(c >> 4, LowerCase);
 Output[i * 2 + 1] = hexdigit(c & 15, LowerCase);
 }
}

inline std::string toHex(ArrayRef<uint8_t> Input, bool LowerCase = false) {
 SmallString<16> Output;
 toHex(Input, LowerCase, Output);
return std::string(Output);
}

inline std::string toHex(StringRef Input, bool LowerCase = false) {
return toHex(arrayRefFromStringRef(Input), LowerCase);
}

/// Store the binary representation of the two provided values, \p MSB and
/// \p LSB, that make up the nibbles of a hexadecimal digit. If \p MSB or \p LSB
/// do not correspond to proper nibbles of a hexadecimal digit, this method
/// returns false. Otherwise, returns true.
inlinebool tryGetHexFromNibbles(char MSB, char LSB, uint8_t &Hex) {
unsigned U1 = hexDigitValue(MSB);
unsigned U2 = hexDigitValue(LSB);
if (U1 == ~0U || U2 == ~0U)
returnfalse;

 Hex = static_cast<uint8_t>((U1 << 4) | U2);
returntrue;
}

/// Return the binary representation of the two provided values, \p MSB and
/// \p LSB, that make up the nibbles of a hexadecimal digit.
inlineuint8_t hexFromNibbles(char MSB, char LSB) {
uint8_t Hex = 0;
bool GotHex = tryGetHexFromNibbles(MSB, LSB, Hex);
 (void)GotHex;
assert(GotHex && "MSB and/or LSB do not correspond to hex digits");
return Hex;
}

/// Convert hexadecimal string \p Input to its binary representation and store
/// the result in \p Output. Returns true if the binary representation could be
/// converted from the hexadecimal string. Returns false if \p Input contains
/// non-hexadecimal digits. The output string is half the size of \p Input.
inlinebool tryGetFromHex(StringRef Input, std::string &Output) {
if (Input.empty())
returntrue;

// If the input string is not properly aligned on 2 nibbles we pad out the
// front with a 0 prefix; e.g. `ABC` -> `0ABC`.
 Output.resize((Input.size() + 1) / 2);
char *OutputPtr = const_cast<char *>(Output.data());
if (Input.size() % 2 == 1) {
uint8_t Hex = 0;
if (!tryGetHexFromNibbles('0', Input.front(), Hex))
returnfalse;
 *OutputPtr++ = Hex;
 Input = Input.drop_front();
 }

// Convert the nibble pairs (e.g. `9C`) into bytes (0x9C).
// With the padding above we know the input is aligned and the output expects
// exactly half as many bytes as nibbles in the input.
size_t InputSize = Input.size();
assert(InputSize % 2 == 0);
constchar *InputPtr = Input.data();
for (size_t OutputIndex = 0; OutputIndex < InputSize / 2; ++OutputIndex) {
uint8_t Hex = 0;
if (!tryGetHexFromNibbles(InputPtr[OutputIndex * 2 + 0], // MSB
 InputPtr[OutputIndex * 2 + 1], // LSB
 Hex))
returnfalse;
 OutputPtr[OutputIndex] = Hex;
 }
returntrue;
}

/// Convert hexadecimal string \p Input to its binary representation.
/// The return string is half the size of \p Input.
inline std::string fromHex(StringRef Input) {
 std::string Hex;
bool GotHex = tryGetFromHex(Input, Hex);
 (void)GotHex;
assert(GotHex && "Input contains non hex digits");
return Hex;
}

/// Convert the string \p S to an integer of the specified type using
/// the radix \p Base. If \p Base is 0, auto-detects the radix.
/// Returns true if the number was successfully converted, false otherwise.
template <typename N> bool to_integer(StringRef S, N &Num, unsignedBase = 0) {
return !S.getAsInteger(Base, Num);
}

namespace detail {
template <typename N>
inlinebool to_float(const Twine &T, N &Num, N (*StrTo)(constchar *, char **)) {
 SmallString<32> Storage;
 StringRef S = T.toNullTerminatedStringRef(Storage);
char *End;
N Temp = StrTo(S.data(), &End);
if (*End != '\0')
returnfalse;
 Num = Temp;
returntrue;
}
}

inlinebool to_float(const Twine &T, float &Num) {
return detail::to_float(T, Num, strtof);
}

inlinebool to_float(const Twine &T, double &Num) {
return detail::to_float(T, Num, strtod);
}

inlinebool to_float(const Twine &T, longdouble &Num) {
return detail::to_float(T, Num, strtold);
}

inline std::string utostr(uint64_tX, boolisNeg = false) {
char Buffer[21];
char *BufPtr = std::end(Buffer);

if (X == 0) *--BufPtr = '0'; // Handle special case...

while (X) {
 *--BufPtr = '0' + char(X % 10);
X /= 10;
 }

if (isNeg) *--BufPtr = '-'; // Add negative sign...
return std::string(BufPtr, std::end(Buffer));
}

inline std::string itostr(int64_t X) {
if (X < 0)
return utostr(static_cast<uint64_t>(1) + ~static_cast<uint64_t>(X), true);
else
return utostr(static_cast<uint64_t>(X));
}

inline std::string toString(const APInt &I, unsigned Radix, boolSigned,
bool formatAsCLiteral = false,
bool UpperCase = true,
bool InsertSeparators = false) {
 SmallString<40> S;
I.toString(S, Radix, Signed, formatAsCLiteral, UpperCase, InsertSeparators);
return std::string(S);
}

inline std::string toString(const APSInt &I, unsigned Radix) {
returntoString(I, Radix, I.isSigned());
}

/// StrInStrNoCase - Portable version of strcasestr. Locates the first
/// occurrence of string 's1' in string 's2', ignoring case. Returns
/// the offset of s2 in s1 or npos if s2 cannot be found.
StringRef::size_type StrInStrNoCase(StringRef s1, StringRef s2);

/// getToken - This function extracts one token from source, ignoring any
/// leading characters that appear in the Delimiters string, and ending the
/// token at any of the characters that appear in the Delimiters string. If
/// there are no tokens in the source string, an empty string is returned.
/// The function returns a pair containing the extracted token and the
/// remaining tail string.
std::pair<StringRef, StringRef> getToken(StringRef Source,
 StringRef Delimiters = " \t\n\v\f\r");

/// SplitString - Split up the specified string according to the specified
/// delimiters, appending the result fragments to the output list.
void SplitString(StringRef Source,
 SmallVectorImpl<StringRef> &OutFragments,
 StringRef Delimiters = " \t\n\v\f\r");

/// Returns the English suffix for an ordinal integer (-st, -nd, -rd, -th).
inline StringRef getOrdinalSuffix(unsigned Val) {
// It is critically important that we do this perfectly for
// user-written sequences with over 100 elements.
switch (Val % 100) {
case 11:
case 12:
case 13:
return"th";
default:
switch (Val % 10) {
case 1: return"st";
case 2: return"nd";
case 3: return"rd";
default: return"th";
 }
 }
}

/// Print each character of the specified string, escaping it if it is not
/// printable or if it is an escape char.
void printEscapedString(StringRef Name, raw_ostream &Out);

/// Print each character of the specified string, escaping HTML special
/// characters.
void printHTMLEscaped(StringRef String, raw_ostream &Out);

/// printLowerCase - Print each character as lowercase if it is uppercase.
void printLowerCase(StringRef String, raw_ostream &Out);

/// Converts a string from camel-case to snake-case by replacing all uppercase
/// letters with '_' followed by the letter in lowercase, except if the
/// uppercase letter is the first character of the string.
std::string convertToSnakeFromCamelCase(StringRef input);

/// Converts a string from snake-case to camel-case by replacing all occurrences
/// of '_' followed by a lowercase letter with the letter in uppercase.
/// Optionally allow capitalization of the first letter (if it is a lowercase
/// letter)
std::string convertToCamelFromSnakeCase(StringRef input,
bool capitalizeFirst = false);

namespace detail {

template <typename IteratorT>
inline std::string join_impl(IteratorT Begin, IteratorT End,
 StringRef Separator, std::input_iterator_tag) {
 std::string S;
if (Begin == End)
return S;

 S += (*Begin);
while (++Begin != End) {
 S += Separator;
 S += (*Begin);
 }
return S;
}

template <typename IteratorT>
inline std::string join_impl(IteratorT Begin, IteratorT End,
 StringRef Separator, std::forward_iterator_tag) {
 std::string S;
if (Begin == End)
return S;

size_tLen = (std::distance(Begin, End) - 1) * Separator.size();
for (IteratorT I = Begin; I != End; ++I)
 Len += StringRef(*I).size();
 S.reserve(Len);
size_t PrevCapacity = S.capacity();
 (void)PrevCapacity;
 S += (*Begin);
while (++Begin != End) {
 S += Separator;
 S += (*Begin);
 }
assert(PrevCapacity == S.capacity() && "String grew during building");
return S;
}

template <typename Sep>
inlinevoid join_items_impl(std::string &Result, Sep Separator) {}

template <typename Sep, typename Arg>
inlinevoid join_items_impl(std::string &Result, Sep Separator,
const Arg &Item) {
Result += Item;
}

template <typename Sep, typename Arg1, typename... Args>
inlinevoid join_items_impl(std::string &Result, Sep Separator, const Arg1 &A1,
 Args &&... Items) {
Result += A1;
Result += Separator;
 join_items_impl(Result, Separator, std::forward<Args>(Items)...);
}

inlinesize_t join_one_item_size(char) { return 1; }
inlinesize_t join_one_item_size(constchar *S) { return S ? ::strlen(S) : 0; }

template <typename T> inlinesize_t join_one_item_size(constT &Str) {
return Str.size();
}

template <typename... Args> inlinesize_t join_items_size(Args &&...Items) {
return (0 + ... + join_one_item_size(std::forward<Args>(Items)));
}

} // end namespace detail

/// Joins the strings in the range [Begin, End), adding Separator between
/// the elements.
template <typename IteratorT>
inline std::string join(IteratorT Begin, IteratorT End, StringRef Separator) {
using tag = typename std::iterator_traits<IteratorT>::iterator_category;
return detail::join_impl(Begin, End, Separator, tag());
}

/// Joins the strings in the range [R.begin(), R.end()), adding Separator
/// between the elements.
template <typename Range>
inline std::string join(Range &&R, StringRef Separator) {
return join(R.begin(), R.end(), Separator);
}

/// Joins the strings in the parameter pack \p Items, adding \p Separator
/// between the elements. All arguments must be implicitly convertible to
/// std::string, or there should be an overload of std::string::operator+=()
/// that accepts the argument explicitly.
template <typename Sep, typename... Args>
inline std::string join_items(Sep Separator, Args &&... Items) {
 std::string Result;
if (sizeof...(Items) == 0)
returnResult;

size_t NS = detail::join_one_item_size(Separator);
size_t NI = detail::join_items_size(std::forward<Args>(Items)...);
Result.reserve(NI + (sizeof...(Items) - 1) * NS + 1);
 detail::join_items_impl(Result, Separator, std::forward<Args>(Items)...);
returnResult;
}

/// A helper class to return the specified delimiter string after the first
/// invocation of operator StringRef(). Used to generate a comma-separated
/// list from a loop like so:
///
/// \code
/// ListSeparator LS;
/// for (auto &I : C)
/// OS << LS << I.getName();
/// \end
class ListSeparator {
boolFirst = true;
 StringRef Separator;

public:
 ListSeparator(StringRef Separator = ", ") : Separator(Separator) {}
operator StringRef() {
if (First) {
First = false;
return {};
 }
return Separator;
 }
};

/// A forward iterator over partitions of string over a separator.
class SplittingIterator
 : public iterator_facade_base<SplittingIterator, std::forward_iterator_tag,
 StringRef> {
char SeparatorStorage;
 StringRef Current;
 StringRef Next;
 StringRef Separator;

public:
 SplittingIterator(StringRef Str, StringRef Separator)
 : Next(Str), Separator(Separator) {
 ++*this;
 }

 SplittingIterator(StringRef Str, char Separator)
 : SeparatorStorage(Separator), Next(Str),
 Separator(&SeparatorStorage, 1) {
 ++*this;
 }

 SplittingIterator(const SplittingIterator &R)
 : SeparatorStorage(R.SeparatorStorage), Current(R.Current), Next(R.Next),
 Separator(R.Separator) {
if (R.Separator.data() == &R.SeparatorStorage)
 Separator = StringRef(&SeparatorStorage, 1);
 }

 SplittingIterator &operator=(const SplittingIterator &R) {
if (this == &R)
return *this;

 SeparatorStorage = R.SeparatorStorage;
 Current = R.Current;
 Next = R.Next;
 Separator = R.Separator;
if (R.Separator.data() == &R.SeparatorStorage)
 Separator = StringRef(&SeparatorStorage, 1);
return *this;
 }

booloperator==(const SplittingIterator &R) const {
assert(Separator == R.Separator);
return Current.data() == R.Current.data();
 }

const StringRef &operator*() const { return Current; }

 StringRef &operator*() { return Current; }

 SplittingIterator &operator++() {
 std::tie(Current, Next) = Next.split(Separator);
return *this;
 }
};

/// Split the specified string over a separator and return a range-compatible
/// iterable over its partitions. Used to permit conveniently iterating
/// over separated strings like so:
///
/// \code
/// for (StringRef x : llvm::split("foo,bar,baz", ","))
/// ...;
/// \end
///
/// Note that the passed string must remain valid throuhgout lifetime
/// of the iterators.
inline iterator_range<SplittingIterator> split(StringRef Str, StringRef Separator) {
return {SplittingIterator(Str, Separator),
 SplittingIterator(StringRef(), Separator)};
}

inline iterator_range<SplittingIterator> split(StringRef Str, char Separator) {
return {SplittingIterator(Str, Separator),
 SplittingIterator(StringRef(), Separator)};
}

} // end namespace llvm

#endif // LLVM_ADT_STRINGEXTRAS_H