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//===--- Utility.h ----------------------------------------------*- 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 
// 
//===----------------------------------------------------------------------===// 
// 
// Provide some utility classes for use in the demangler(s). 
// 
//===----------------------------------------------------------------------===// 
 
#ifndef DEMANGLE_UTILITY_H 
#define DEMANGLE_UTILITY_H 
 
#include "StringView.h" 
#include <cstdint> 
#include <cstdlib> 
#include <cstring> 
#include <iterator> 
#include <limits> 
 
DEMANGLE_NAMESPACE_BEGIN 
 
// Stream that AST nodes write their string representation into after the AST 
// has been parsed. 
class OutputBuffer {
  char *Buffer = nullptr; 
  size_t CurrentPosition = 0; 
  size_t BufferCapacity = 0; 
 
  // Ensure there is at least n more positions in buffer. 
  void grow(size_t N) { 
    if (N + CurrentPosition >= BufferCapacity) { 
      BufferCapacity *= 2; 
      if (BufferCapacity < N + CurrentPosition) 
        BufferCapacity = N + CurrentPosition; 
      Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity)); 
      if (Buffer == nullptr) 
        std::terminate(); 
    } 
  } 
 
  void writeUnsigned(uint64_t N, bool isNeg = false) { 
    // Handle special case... 
    if (N == 0) { 
      *this << '0'; 
      return; 
    } 
 
    char Temp[21]; 
    char *TempPtr = std::end(Temp); 
 
    while (N) { 
      *--TempPtr = char('0' + N % 10); 
      N /= 10; 
    } 
 
    // Add negative sign... 
    if (isNeg) 
      *--TempPtr = '-'; 
    this->operator<<(StringView(TempPtr, std::end(Temp))); 
  } 
 
public: 
  OutputBuffer(char *StartBuf, size_t Size)
      : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {} 
  OutputBuffer() = default;
  void reset(char *Buffer_, size_t BufferCapacity_) { 
    CurrentPosition = 0; 
    Buffer = Buffer_; 
    BufferCapacity = BufferCapacity_; 
  } 
 
  /// If a ParameterPackExpansion (or similar type) is encountered, the offset 
  /// into the pack that we're currently printing. 
  unsigned CurrentPackIndex = std::numeric_limits<unsigned>::max(); 
  unsigned CurrentPackMax = std::numeric_limits<unsigned>::max(); 
 
  OutputBuffer &operator+=(StringView R) {
    size_t Size = R.size(); 
    if (Size == 0) 
      return *this; 
    grow(Size); 
    std::memmove(Buffer + CurrentPosition, R.begin(), Size); 
    CurrentPosition += Size; 
    return *this; 
  } 
 
  OutputBuffer &operator+=(char C) {
    grow(1); 
    Buffer[CurrentPosition++] = C; 
    return *this; 
  } 
 
  OutputBuffer &operator<<(StringView R) { return (*this += R); }
 
  OutputBuffer prepend(StringView R) {
    size_t Size = R.size();
 
    grow(Size);
    std::memmove(Buffer + Size, Buffer, CurrentPosition);
    std::memcpy(Buffer, R.begin(), Size);
    CurrentPosition += Size;

    return *this;
  }

  OutputBuffer &operator<<(char C) { return (*this += C); }

  OutputBuffer &operator<<(long long N) {
    if (N < 0) 
      writeUnsigned(static_cast<unsigned long long>(-N), true); 
    else 
      writeUnsigned(static_cast<unsigned long long>(N)); 
    return *this; 
  } 
 
  OutputBuffer &operator<<(unsigned long long N) {
    writeUnsigned(N, false); 
    return *this; 
  } 
 
  OutputBuffer &operator<<(long N) {
    return this->operator<<(static_cast<long long>(N)); 
  } 
 
  OutputBuffer &operator<<(unsigned long N) {
    return this->operator<<(static_cast<unsigned long long>(N)); 
  } 
 
  OutputBuffer &operator<<(int N) {
    return this->operator<<(static_cast<long long>(N)); 
  } 
 
  OutputBuffer &operator<<(unsigned int N) {
    return this->operator<<(static_cast<unsigned long long>(N)); 
  } 
 
  void insert(size_t Pos, const char *S, size_t N) {
    assert(Pos <= CurrentPosition);
    if (N == 0)
      return;
    grow(N);
    std::memmove(Buffer + Pos + N, Buffer + Pos, CurrentPosition - Pos);
    std::memcpy(Buffer + Pos, S, N);
    CurrentPosition += N;
  }

  size_t getCurrentPosition() const { return CurrentPosition; } 
  void setCurrentPosition(size_t NewPos) { CurrentPosition = NewPos; } 
 
  char back() const { 
    return CurrentPosition ? Buffer[CurrentPosition - 1] : '\0'; 
  } 
 
  bool empty() const { return CurrentPosition == 0; } 
 
  char *getBuffer() { return Buffer; } 
  char *getBufferEnd() { return Buffer + CurrentPosition - 1; } 
  size_t getBufferCapacity() const { return BufferCapacity; } 
}; 
 
template <class T> class SwapAndRestore { 
  T &Restore; 
  T OriginalValue; 
  bool ShouldRestore = true; 
 
public: 
  SwapAndRestore(T &Restore_) : SwapAndRestore(Restore_, Restore_) {} 
 
  SwapAndRestore(T &Restore_, T NewVal) 
      : Restore(Restore_), OriginalValue(Restore) { 
    Restore = std::move(NewVal); 
  } 
  ~SwapAndRestore() { 
    if (ShouldRestore) 
      Restore = std::move(OriginalValue); 
  } 
 
  void shouldRestore(bool ShouldRestore_) { ShouldRestore = ShouldRestore_; } 
 
  void restoreNow(bool Force) { 
    if (!Force && !ShouldRestore) 
      return; 
 
    Restore = std::move(OriginalValue); 
    ShouldRestore = false; 
  } 
 
  SwapAndRestore(const SwapAndRestore &) = delete; 
  SwapAndRestore &operator=(const SwapAndRestore &) = delete; 
}; 
 
inline bool initializeOutputBuffer(char *Buf, size_t *N, OutputBuffer &OB,
                                   size_t InitSize) { 
  size_t BufferSize; 
  if (Buf == nullptr) { 
    Buf = static_cast<char *>(std::malloc(InitSize)); 
    if (Buf == nullptr) 
      return false; 
    BufferSize = InitSize; 
  } else 
    BufferSize = *N; 
 
  OB.reset(Buf, BufferSize);
  return true; 
} 
 
DEMANGLE_NAMESPACE_END 
 
#endif