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externals/demangle/llvm/Demangle/Utility.h

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+//===--- Utility.h -------------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-FileCopyrightText: Part of the LLVM Project
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Provide some utility classes for use in the demangler.
+// There are two copies of this file in the source tree.  The one in libcxxabi
+// is the original and the one in llvm is the copy.  Use cp-to-llvm.sh to update
+// the copy.  See README.txt for more details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_UTILITY_H
+#define DEMANGLE_UTILITY_H
+
+#include "DemangleConfig.h"
+
+#include <array>
+#include <cassert>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <exception>
+#include <limits>
+#include <string_view>
+
+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 are at least N more positions in the buffer.
+  void grow(size_t N) {
+    size_t Need = N + CurrentPosition;
+    if (Need > BufferCapacity) {
+      // Reduce the number of reallocations, with a bit of hysteresis. The
+      // number here is chosen so the first allocation will more-than-likely not
+      // allocate more than 1K.
+      Need += 1024 - 32;
+      BufferCapacity *= 2;
+      if (BufferCapacity < Need)
+        BufferCapacity = Need;
+      Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity));
+      if (Buffer == nullptr)
+        std::terminate();
+    }
+  }
+
+  OutputBuffer &writeUnsigned(uint64_t N, bool isNeg = false) {
+    std::array<char, 21> Temp;
+    char *TempPtr = Temp.data() + Temp.size();
+
+    // Output at least one character.
+    do {
+      *--TempPtr = char('0' + N % 10);
+      N /= 10;
+    } while (N);
+
+    // Add negative sign.
+    if (isNeg)
+      *--TempPtr = '-';
+
+    return operator+=(
+        std::string_view(TempPtr, Temp.data() + Temp.size() - TempPtr));
+  }
+
+public:
+  OutputBuffer(char *StartBuf, size_t Size)
+      : Buffer(StartBuf), BufferCapacity(Size) {}
+  OutputBuffer(char *StartBuf, size_t *SizePtr)
+      : OutputBuffer(StartBuf, StartBuf ? *SizePtr : 0) {}
+  OutputBuffer() = default;
+  // Non-copyable
+  OutputBuffer(const OutputBuffer &) = delete;
+  OutputBuffer &operator=(const OutputBuffer &) = delete;
+
+  operator std::string_view() const {
+    return std::string_view(Buffer, CurrentPosition);
+  }
+
+  /// 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();
+
+  /// When zero, we're printing template args and '>' needs to be parenthesized.
+  /// Use a counter so we can simply increment inside parentheses.
+  unsigned GtIsGt = 1;
+
+  bool isGtInsideTemplateArgs() const { return GtIsGt == 0; }
+
+  void printOpen(char Open = '(') {
+    GtIsGt++;
+    *this += Open;
+  }
+  void printClose(char Close = ')') {
+    GtIsGt--;
+    *this += Close;
+  }
+
+  OutputBuffer &operator+=(std::string_view R) {
+    if (size_t Size = R.size()) {
+      grow(Size);
+      std::memcpy(Buffer + CurrentPosition, &*R.begin(), Size);
+      CurrentPosition += Size;
+    }
+    return *this;
+  }
+
+  OutputBuffer &operator+=(char C) {
+    grow(1);
+    Buffer[CurrentPosition++] = C;
+    return *this;
+  }
+
+  OutputBuffer &prepend(std::string_view 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<<(std::string_view R) { return (*this += R); }
+
+  OutputBuffer &operator<<(char C) { return (*this += C); }
+
+  OutputBuffer &operator<<(long long N) {
+    return writeUnsigned(static_cast<unsigned long long>(std::abs(N)), N < 0);
+  }
+
+  OutputBuffer &operator<<(unsigned long long N) {
+    return writeUnsigned(N, false);
+  }
+
+  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 {
+    assert(CurrentPosition);
+    return Buffer[CurrentPosition - 1];
+  }
+
+  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 ScopedOverride {
+  T &Loc;
+  T Original;
+
+public:
+  ScopedOverride(T &Loc_) : ScopedOverride(Loc_, Loc_) {}
+
+  ScopedOverride(T &Loc_, T NewVal) : Loc(Loc_), Original(Loc_) {
+    Loc_ = std::move(NewVal);
+  }
+  ~ScopedOverride() { Loc = std::move(Original); }
+
+  ScopedOverride(const ScopedOverride &) = delete;
+  ScopedOverride &operator=(const ScopedOverride &) = delete;
+};
+
+DEMANGLE_NAMESPACE_END
+
+#endif