raw_ostream.h

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//===--- raw_ostream.h - Raw output stream ----------------------*- 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
//
//===----------------------------------------------------------------------===//
//
// This file defines the raw_ostream class.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_RAW_OSTREAM_H
#define LLVM_SUPPORT_RAW_OSTREAM_H

#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/DataTypes.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <optional>
#include <string>
#include <string_view>
#include <system_error>
#include <type_traits>

namespace llvm {

class Duration;
class formatv_object_base;
class format_object_base;
class FormattedString;
class FormattedNumber;
class FormattedBytes;
template <class T> class [[nodiscard]] Expected;

namespace sys {
namespace fs {
enumFileAccess : unsigned;
enumOpenFlags : unsigned;
enumCreationDisposition : unsigned;
class FileLocker;
} // end namespace fs
} // end namespace sys

/// This class implements an extremely fast bulk output stream that can *only*
/// output to a stream. It does not support seeking, reopening, rewinding, line
/// buffered disciplines etc. It is a simple buffer that outputs
/// a chunk at a time.
class raw_ostream {
public:
// Class kinds to support LLVM-style RTTI.
enum classOStreamKind {
OK_OStream,
OK_FDStream,
OK_SVecStream,
 };

private:
OStreamKind Kind;

 /// The buffer is handled in such a way that the buffer is
 /// uninitialized, unbuffered, or out of space when OutBufCur >=
 /// OutBufEnd. Thus a single comparison suffices to determine if we
 /// need to take the slow path to write a single character.
 ///
 /// The buffer is in one of three states:
 /// 1. Unbuffered (BufferMode == Unbuffered)
 /// 1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
 /// 2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
 /// OutBufEnd - OutBufStart >= 1).
 ///
 /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
 /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
 /// managed by the subclass.
 ///
 /// If a subclass installs an external buffer using SetBuffer then it can wait
 /// for a \see write_impl() call to handle the data which has been put into
 /// this buffer.
char *OutBufStart, *OutBufEnd, *OutBufCur;
bool ColorEnabled = false;

enum class BufferKind {
 Unbuffered = 0,
 InternalBuffer,
 ExternalBuffer
 } BufferMode;

public:
// color order matches ANSI escape sequence, don't change
enum classColors {
BLACK = 0,
RED,
GREEN,
YELLOW,
BLUE,
MAGENTA,
CYAN,
WHITE,
BRIGHT_BLACK,
BRIGHT_RED,
BRIGHT_GREEN,
BRIGHT_YELLOW,
BRIGHT_BLUE,
BRIGHT_MAGENTA,
BRIGHT_CYAN,
BRIGHT_WHITE,
SAVEDCOLOR,
RESET,
 };

staticconstexprColorsBLACK = Colors::BLACK;
staticconstexprColorsRED = Colors::RED;
staticconstexprColorsGREEN = Colors::GREEN;
staticconstexprColorsYELLOW = Colors::YELLOW;
staticconstexprColorsBLUE = Colors::BLUE;
staticconstexprColorsMAGENTA = Colors::MAGENTA;
staticconstexprColorsCYAN = Colors::CYAN;
staticconstexprColorsWHITE = Colors::WHITE;
staticconstexprColorsBRIGHT_BLACK = Colors::BRIGHT_BLACK;
staticconstexprColorsBRIGHT_RED = Colors::BRIGHT_RED;
staticconstexprColorsBRIGHT_GREEN = Colors::BRIGHT_GREEN;
staticconstexprColorsBRIGHT_YELLOW = Colors::BRIGHT_YELLOW;
staticconstexprColorsBRIGHT_BLUE = Colors::BRIGHT_BLUE;
staticconstexprColorsBRIGHT_MAGENTA = Colors::BRIGHT_MAGENTA;
staticconstexprColorsBRIGHT_CYAN = Colors::BRIGHT_CYAN;
staticconstexprColorsBRIGHT_WHITE = Colors::BRIGHT_WHITE;
staticconstexprColorsSAVEDCOLOR = Colors::SAVEDCOLOR;
staticconstexprColorsRESET = Colors::RESET;

explicitraw_ostream(bool unbuffered = false,
OStreamKind K = OStreamKind::OK_OStream)
 : Kind(K), BufferMode(unbuffered ? BufferKind::Unbuffered
 : BufferKind::InternalBuffer) {
// Start out ready to flush.
 OutBufStart = OutBufEnd = OutBufCur = nullptr;
 }

raw_ostream(constraw_ostream &) = delete;
voidoperator=(constraw_ostream &) = delete;

virtual~raw_ostream();

 /// tell - Return the current offset with the file.
uint64_ttell() const { return current_pos() + GetNumBytesInBuffer(); }

OStreamKindget_kind() const { return Kind; }

//===--------------------------------------------------------------------===//
// Configuration Interface
//===--------------------------------------------------------------------===//

 /// If possible, pre-allocate \p ExtraSize bytes for stream data.
 /// i.e. it extends internal buffers to keep additional ExtraSize bytes.
 /// So that the stream could keep at least tell() + ExtraSize bytes
 /// without re-allocations. reserveExtraSpace() does not change
 /// the size/data of the stream.
virtualvoidreserveExtraSpace(uint64_t ExtraSize) { (void)ExtraSize; }

 /// Set the stream to be buffered, with an automatically determined buffer
 /// size.
voidSetBuffered();

 /// Set the stream to be buffered, using the specified buffer size.
voidSetBufferSize(size_tSize) {
flush();
 SetBufferAndMode(newchar[Size], Size, BufferKind::InternalBuffer);
 }

size_tGetBufferSize() const {
// If we're supposed to be buffered but haven't actually gotten around
// to allocating the buffer yet, return the value that would be used.
if (BufferMode != BufferKind::Unbuffered && OutBufStart == nullptr)
returnpreferred_buffer_size();

// Otherwise just return the size of the allocated buffer.
return OutBufEnd - OutBufStart;
 }

 /// Set the stream to be unbuffered. When unbuffered, the stream will flush
 /// after every write. This routine will also flush the buffer immediately
 /// when the stream is being set to unbuffered.
voidSetUnbuffered() {
flush();
 SetBufferAndMode(nullptr, 0, BufferKind::Unbuffered);
 }

size_tGetNumBytesInBuffer() const {
return OutBufCur - OutBufStart;
 }

//===--------------------------------------------------------------------===//
// Data Output Interface
//===--------------------------------------------------------------------===//

voidflush() {
if (OutBufCur != OutBufStart)
 flush_nonempty();
 }

raw_ostream &operator<<(charC) {
if (OutBufCur >= OutBufEnd)
returnwrite(C);
 *OutBufCur++ = C;
return *this;
 }

raw_ostream &operator<<(unsignedcharC) {
if (OutBufCur >= OutBufEnd)
returnwrite(C);
 *OutBufCur++ = C;
return *this;
 }

raw_ostream &operator<<(signedcharC) {
if (OutBufCur >= OutBufEnd)
returnwrite(C);
 *OutBufCur++ = C;
return *this;
 }

raw_ostream &operator<<(StringRef Str) {
// Inline fast path, particularly for strings with a known length.
size_tSize = Str.size();

// Make sure we can use the fast path.
if (Size > (size_t)(OutBufEnd - OutBufCur))
returnwrite(Str.data(), Size);

if (Size) {
 memcpy(OutBufCur, Str.data(), Size);
 OutBufCur += Size;
 }
return *this;
 }

#if defined(__cpp_char8_t)
// When using `char8_t *` integers or pointers are written to the ostream
// instead of UTF-8 code as one might expect. This might lead to unexpected
// behavior, especially as `u8""` literals are of type `char8_t*` instead of
// type `char_t*` from C++20 onwards. Thus we disallow using them with
// raw_ostreams.
// If you have u8"" literals to stream, you can rewrite them as ordinary
// literals with escape sequences
// e.g. replace `u8"\u00a0"` by `"\xc2\xa0"`
// or use `reinterpret_cast`:
// e.g. replace `u8"\u00a0"` by `reinterpret_cast<const char *>(u8"\u00a0")`
raw_ostream &operator<<(constchar8_t *Str) = delete;
#endif

raw_ostream &operator<<(constchar *Str) {
// Inline fast path, particularly for constant strings where a sufficiently
// smart compiler will simplify strlen.

return this->operator<<(StringRef(Str));
 }

raw_ostream &operator<<(const std::string &Str) {
// Avoid the fast path, it would only increase code size for a marginal win.
returnwrite(Str.data(), Str.length());
 }

raw_ostream &operator<<(const std::string_view &Str) {
returnwrite(Str.data(), Str.length());
 }

raw_ostream &operator<<(constSmallVectorImpl<char> &Str) {
returnwrite(Str.data(), Str.size());
 }

raw_ostream &operator<<(unsignedlongN);
raw_ostream &operator<<(longN);
raw_ostream &operator<<(unsignedlonglongN);
raw_ostream &operator<<(longlongN);
raw_ostream &operator<<(constvoid *P);

raw_ostream &operator<<(unsignedintN) {
return this->operator<<(static_cast<unsigned long>(N));
 }

raw_ostream &operator<<(intN) {
return this->operator<<(static_cast<long>(N));
 }

raw_ostream &operator<<(doubleN);

 /// Output \p N in hexadecimal, without any prefix or padding.
raw_ostream &write_hex(unsignedlonglongN);

// Change the foreground color of text.
raw_ostream &operator<<(ColorsC);

 /// Output a formatted UUID with dash separators.
using uuid_t = uint8_t[16];
raw_ostream &write_uuid(constuuid_tUUID);

 /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't
 /// satisfy llvm::isPrint into an escape sequence.
raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);

raw_ostream &write(unsignedcharC);
raw_ostream &write(constchar *Ptr, size_tSize);

// Formatted output, see the format() function in Support/Format.h.
raw_ostream &operator<<(constformat_object_base &Fmt);

// Formatted output, see the leftJustify() function in Support/Format.h.
raw_ostream &operator<<(constFormattedString &);

// Formatted output, see the formatHex() function in Support/Format.h.
raw_ostream &operator<<(constFormattedNumber &);

// Formatted output, see the formatv() function in Support/FormatVariadic.h.
raw_ostream &operator<<(constformatv_object_base &);

// Formatted output, see the format_bytes() function in Support/Format.h.
raw_ostream &operator<<(constFormattedBytes &);

 /// indent - Insert 'NumSpaces' spaces.
raw_ostream &indent(unsigned NumSpaces);

 /// write_zeros - Insert 'NumZeros' nulls.
raw_ostream &write_zeros(unsigned NumZeros);

 /// Changes the foreground color of text that will be output from this point
 /// forward.
 /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
 /// change only the bold attribute, and keep colors untouched
 /// @param Bold bold/brighter text, default false
 /// @param BG if true change the background, default: change foreground
 /// @returns itself so it can be used within << invocations
virtualraw_ostream &changeColor(enumColors Color, bool Bold = false,
bool BG = false);

 /// Resets the colors to terminal defaults. Call this when you are done
 /// outputting colored text, or before program exit.
virtualraw_ostream &resetColor();

 /// Reverses the foreground and background colors.
virtualraw_ostream &reverseColor();

 /// This function determines if this stream is connected to a "tty" or
 /// "console" window. That is, the output would be displayed to the user
 /// rather than being put on a pipe or stored in a file.
virtualboolis_displayed() const { returnfalse; }

 /// This function determines if this stream is displayed and supports colors.
 /// The result is unaffected by calls to enable_color().
virtualboolhas_colors() const { returnis_displayed(); }

// Enable or disable colors. Once enable_colors(false) is called,
// changeColor() has no effect until enable_colors(true) is called.
virtualvoidenable_colors(bool enable) { ColorEnabled = enable; }

boolcolors_enabled() const { return ColorEnabled; }

//===--------------------------------------------------------------------===//
// Subclass Interface
//===--------------------------------------------------------------------===//

private:
 /// The is the piece of the class that is implemented by subclasses. This
 /// writes the \p Size bytes starting at
 /// \p Ptr to the underlying stream.
 ///
 /// This function is guaranteed to only be called at a point at which it is
 /// safe for the subclass to install a new buffer via SetBuffer.
 ///
 /// \param Ptr The start of the data to be written. For buffered streams this
 /// is guaranteed to be the start of the buffer.
 ///
 /// \param Size The number of bytes to be written.
 ///
 /// \invariant { Size > 0 }
virtualvoid write_impl(constchar *Ptr, size_tSize) = 0;

 /// Return the current position within the stream, not counting the bytes
 /// currently in the buffer.
virtualuint64_t current_pos() const = 0;

protected:
 /// Use the provided buffer as the raw_ostream buffer. This is intended for
 /// use only by subclasses which can arrange for the output to go directly
 /// into the desired output buffer, instead of being copied on each flush.
voidSetBuffer(char *BufferStart, size_tSize) {
 SetBufferAndMode(BufferStart, Size, BufferKind::ExternalBuffer);
 }

 /// Return an efficient buffer size for the underlying output mechanism.
virtualsize_tpreferred_buffer_size() const;

 /// Return the beginning of the current stream buffer, or 0 if the stream is
 /// unbuffered.
constchar *getBufferStart() const { return OutBufStart; }

//===--------------------------------------------------------------------===//
// Private Interface
//===--------------------------------------------------------------------===//
private:
 /// Install the given buffer and mode.
void SetBufferAndMode(char *BufferStart, size_tSize, BufferKind Mode);

 /// Flush the current buffer, which is known to be non-empty. This outputs the
 /// currently buffered data and resets the buffer to empty.
void flush_nonempty();

 /// Copy data into the buffer. Size must not be greater than the number of
 /// unused bytes in the buffer.
void copy_to_buffer(constchar *Ptr, size_tSize);

 /// Compute whether colors should be used and do the necessary work such as
 /// flushing. The result is affected by calls to enable_color().
bool prepare_colors();

virtualvoid anchor();
};

/// Call the appropriate insertion operator, given an rvalue reference to a
/// raw_ostream object and return a stream of the same type as the argument.
template <typename OStream, typename T>
std::enable_if_t<!std::is_reference_v<OStream> &&
 std::is_base_of_v<raw_ostream, OStream>,
 OStream &&>
operator<<(OStream &&OS, constT &Value) {
OS << Value;
return std::move(OS);
}

/// An abstract base class for streams implementations that also support a
/// pwrite operation. This is useful for code that can mostly stream out data,
/// but needs to patch in a header that needs to know the output size.
class raw_pwrite_stream : publicraw_ostream {
virtualvoid pwrite_impl(constchar *Ptr, size_tSize, uint64_tOffset) = 0;
void anchor() override;

public:
explicitraw_pwrite_stream(bool Unbuffered = false,
OStreamKind K = OStreamKind::OK_OStream)
 : raw_ostream(Unbuffered, K) {}
voidpwrite(constchar *Ptr, size_tSize, uint64_tOffset) {
#ifndef NDEBUG
uint64_t Pos = tell();
// /dev/null always reports a pos of 0, so we cannot perform this check
// in that case.
if (Pos)
assert(Size + Offset <= Pos && "We don't support extending the stream");
#endif
 pwrite_impl(Ptr, Size, Offset);
 }
};

//===----------------------------------------------------------------------===//
// File Output Streams
//===----------------------------------------------------------------------===//

/// A raw_ostream that writes to a file descriptor.
///
class raw_fd_ostream : publicraw_pwrite_stream {
int FD;
bool ShouldClose;
bool SupportsSeeking = false;
bool IsRegularFile = false;
mutable std::optional<bool> HasColors;

 /// Optional stream this stream is tied to. If this stream is written to, the
 /// tied-to stream will be flushed first.
raw_ostream *TiedStream = nullptr;

#ifdef _WIN32
 /// True if this fd refers to a Windows console device. Mintty and other
 /// terminal emulators are TTYs, but they are not consoles.
bool IsWindowsConsole = false;
#endif

 std::error_code EC;

uint64_t pos = 0;

 /// See raw_ostream::write_impl.
void write_impl(constchar *Ptr, size_tSize) override;

void pwrite_impl(constchar *Ptr, size_tSize, uint64_tOffset) override;

 /// Return the current position within the stream, not counting the bytes
 /// currently in the buffer.
uint64_t current_pos() const override { return pos; }

 /// Determine an efficient buffer size.
size_t preferred_buffer_size() const override;

void anchor() override;

protected:
 /// Set the flag indicating that an output error has been encountered.
voiderror_detected(std::error_code EC) { this->EC = EC; }

 /// Return the file descriptor.
intget_fd() const { return FD; }

// Update the file position by increasing \p Delta.
voidinc_pos(uint64_t Delta) { pos += Delta; }

public:
 /// Open the specified file for writing. If an error occurs, information
 /// about the error is put into EC, and the stream should be immediately
 /// destroyed;
 /// \p Flags allows optional flags to control how the file will be opened.
 ///
 /// As a special case, if Filename is "-", then the stream will use
 /// STDOUT_FILENO instead of opening a file. This will not close the stdout
 /// descriptor.
raw_fd_ostream(StringRef Filename, std::error_code &EC);
raw_fd_ostream(StringRef Filename, std::error_code &EC,
sys::fs::CreationDisposition Disp);
raw_fd_ostream(StringRef Filename, std::error_code &EC,
sys::fs::FileAccessAccess);
raw_fd_ostream(StringRef Filename, std::error_code &EC,
sys::fs::OpenFlags Flags);
raw_fd_ostream(StringRef Filename, std::error_code &EC,
sys::fs::CreationDisposition Disp, sys::fs::FileAccessAccess,
sys::fs::OpenFlags Flags);

 /// FD is the file descriptor that this writes to. If ShouldClose is true,
 /// this closes the file when the stream is destroyed. If FD is for stdout or
 /// stderr, it will not be closed.
raw_fd_ostream(int fd, bool shouldClose, bool unbuffered = false,
OStreamKind K = OStreamKind::OK_OStream);

~raw_fd_ostream() override;

 /// Manually flush the stream and close the file. Note that this does not call
 /// fsync.
voidclose();

boolsupportsSeeking() const { return SupportsSeeking; }

boolisRegularFile() const { return IsRegularFile; }

 /// Flushes the stream and repositions the underlying file descriptor position
 /// to the offset specified from the beginning of the file.
uint64_tseek(uint64_t off);

boolis_displayed() const override;

boolhas_colors() const override;

 /// Tie this stream to the specified stream. Replaces any existing tied-to
 /// stream. Specifying a nullptr unties the stream. This is intended for to
 /// tie errs() to outs(), so that outs() is flushed whenever something is
 /// written to errs(), preventing weird and hard-to-test output when stderr
 /// is redirected to stdout.
voidtie(raw_ostream *TieTo) { TiedStream = TieTo; }

 std::error_code error() const { return EC; }

 /// Return the value of the flag in this raw_fd_ostream indicating whether an
 /// output error has been encountered.
 /// This doesn't implicitly flush any pending output. Also, it doesn't
 /// guarantee to detect all errors unless the stream has been closed.
boolhas_error() const { returnbool(EC); }

 /// Set the flag read by has_error() to false. If the error flag is set at the
 /// time when this raw_ostream's destructor is called, report_fatal_error is
 /// called to report the error. Use clear_error() after handling the error to
 /// avoid this behavior.
 ///
 /// "Errors should never pass silently.
 /// Unless explicitly silenced."
 /// - from The Zen of Python, by Tim Peters
 ///
voidclear_error() { EC = std::error_code(); }

 /// Locks the underlying file.
 ///
 /// @returns RAII object that releases the lock upon leaving the scope, if the
 /// locking was successful. Otherwise returns corresponding
 /// error code.
 ///
 /// The function blocks the current thread until the lock become available or
 /// error occurs.
 ///
 /// Possible use of this function may be as follows:
 ///
 /// @code{.cpp}
 /// if (auto L = stream.lock()) {
 /// // ... do action that require file to be locked.
 /// } else {
 /// handleAllErrors(std::move(L.takeError()), [&](ErrorInfoBase &EIB) {
 /// // ... handle lock error.
 /// });
 /// }
 /// @endcode
 [[nodiscard]] Expected<sys::fs::FileLocker>lock();

 /// Tries to lock the underlying file within the specified period.
 ///
 /// @returns RAII object that releases the lock upon leaving the scope, if the
 /// locking was successful. Otherwise returns corresponding
 /// error code.
 ///
 /// It is used as @ref lock.
 [[nodiscard]] Expected<sys::fs::FileLocker>
tryLockFor(Durationconst &Timeout);
};

/// This returns a reference to a raw_fd_ostream for standard output. Use it
/// like: outs() << "foo" << "bar";
raw_fd_ostream &outs();

/// This returns a reference to a raw_ostream for standard error.
/// Use it like: errs() << "foo" << "bar";
/// By default, the stream is tied to stdout to ensure stdout is flushed before
/// stderr is written, to ensure the error messages are written in their
/// expected place.
raw_fd_ostream &errs();

/// This returns a reference to a raw_ostream which simply discards output.
raw_ostream &nulls();

//===----------------------------------------------------------------------===//
// File Streams
//===----------------------------------------------------------------------===//

/// A raw_ostream of a file for reading/writing/seeking.
///
class raw_fd_stream : publicraw_fd_ostream {
public:
 /// Open the specified file for reading/writing/seeking. If an error occurs,
 /// information about the error is put into EC, and the stream should be
 /// immediately destroyed.
raw_fd_stream(StringRef Filename, std::error_code &EC);

raw_fd_stream(int fd, bool shouldClose);

 /// This reads the \p Size bytes into a buffer pointed by \p Ptr.
 ///
 /// \param Ptr The start of the buffer to hold data to be read.
 ///
 /// \param Size The number of bytes to be read.
 ///
 /// On success, the number of bytes read is returned, and the file position is
 /// advanced by this number. On error, -1 is returned, use error() to get the
 /// error code.
 ssize_t read(char *Ptr, size_tSize);

 /// Check if \p OS is a pointer of type raw_fd_stream*.
staticboolclassof(constraw_ostream *OS);
};

//===----------------------------------------------------------------------===//
// Output Stream Adaptors
//===----------------------------------------------------------------------===//

/// A raw_ostream that writes to an std::string. This is a simple adaptor
/// class. This class does not encounter output errors.
/// raw_string_ostream operates without a buffer, delegating all memory
/// management to the std::string. Thus the std::string is always up-to-date,
/// may be used directly and there is no need to call flush().
class raw_string_ostream : publicraw_ostream {
 std::string &OS;

 /// See raw_ostream::write_impl.
void write_impl(constchar *Ptr, size_tSize) override;

 /// Return the current position within the stream, not counting the bytes
 /// currently in the buffer.
uint64_t current_pos() const override { returnOS.size(); }

public:
explicitraw_string_ostream(std::string &O) : OS(O) {
SetUnbuffered();
 }

 /// Returns the string's reference. In most cases it is better to simply use
 /// the underlying std::string directly.
 /// TODO: Consider removing this API.
 std::string &str() { returnOS; }

voidreserveExtraSpace(uint64_t ExtraSize) override {
OS.reserve(tell() + ExtraSize);
 }
};

/// A raw_ostream that writes to an SmallVector or SmallString. This is a
/// simple adaptor class. This class does not encounter output errors.
/// raw_svector_ostream operates without a buffer, delegating all memory
/// management to the SmallString. Thus the SmallString is always up-to-date,
/// may be used directly and there is no need to call flush().
class raw_svector_ostream : publicraw_pwrite_stream {
SmallVectorImpl<char> &OS;

 /// See raw_ostream::write_impl.
void write_impl(constchar *Ptr, size_tSize) override;

void pwrite_impl(constchar *Ptr, size_tSize, uint64_tOffset) override;

 /// Return the current position within the stream.
uint64_t current_pos() const override;

public:
 /// Construct a new raw_svector_ostream.
 ///
 /// \param O The vector to write to; this should generally have at least 128
 /// bytes free to avoid any extraneous memory overhead.
explicitraw_svector_ostream(SmallVectorImpl<char> &O)
 : raw_pwrite_stream(false, raw_ostream::OStreamKind::OK_SVecStream),
OS(O) {
// FIXME: here and in a few other places, set directly to unbuffered in the
// ctor.
SetUnbuffered();
 }

~raw_svector_ostream() override = default;

voidflush() = delete;

 /// Return a StringRef for the vector contents.
StringRefstr() const { returnStringRef(OS.data(), OS.size()); }
SmallVectorImpl<char> &buffer() { returnOS; }

voidreserveExtraSpace(uint64_t ExtraSize) override {
OS.reserve(tell() + ExtraSize);
 }

staticboolclassof(constraw_ostream *OS);
};

/// A raw_ostream that discards all output.
class raw_null_ostream : publicraw_pwrite_stream {
 /// See raw_ostream::write_impl.
void write_impl(constchar *Ptr, size_tsize) override;
void pwrite_impl(constchar *Ptr, size_tSize, uint64_tOffset) override;

 /// Return the current position within the stream, not counting the bytes
 /// currently in the buffer.
uint64_t current_pos() const override;

public:
explicitraw_null_ostream() = default;
~raw_null_ostream() override;
};

class buffer_ostream : publicraw_svector_ostream {
raw_ostream &OS;
SmallVector<char, 0> Buffer;

void anchor() override;

public:
buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer), OS(OS) {}
~buffer_ostream() override { OS << str(); }
};

class buffer_unique_ostream : publicraw_svector_ostream {
 std::unique_ptr<raw_ostream> OS;
SmallVector<char, 0> Buffer;

void anchor() override;

public:
buffer_unique_ostream(std::unique_ptr<raw_ostream> OS)
 : raw_svector_ostream(Buffer), OS(std::move(OS)) {
// Turn off buffering on OS, which we now own, to avoid allocating a buffer
// when the destructor writes only to be immediately flushed again.
 this->OS->SetUnbuffered();
 }
~buffer_unique_ostream() override { *OS << str(); }
};

// Helper struct to add indentation to raw_ostream. Instead of
// OS.indent(6) << "more stuff";
// you can use
// OS << indent(6) << "more stuff";
// which has better ergonomics (and clang-formats better as well).
//
// If indentation is always in increments of a fixed value, you can use Scale
// to set that value once. So indent(1, 2) will add 2 spaces and
// indent(1,2) + 1 will add 4 spaces.
struct indent {
// Indentation is represented as `NumIndents` steps of size `Scale` each.
unsignedNumIndents;
unsignedScale;

explicitindent(unsignedNumIndents, unsignedScale = 1)
 : NumIndents(NumIndents), Scale(Scale) {}

// These arithmeric operators preserve scale.
voidoperator+=(unsignedN) { NumIndents += N; }
voidoperator-=(unsignedN) {
assert(NumIndents >= N && "Indentation underflow");
NumIndents -= N;
 }
indentoperator+(unsignedN) const { returnindent(NumIndents + N, Scale); }
indentoperator-(unsignedN) const {
assert(NumIndents >= N && "Indentation undeflow");
returnindent(NumIndents - N, Scale);
 }
indent &operator++() { // Prefix ++.
 ++NumIndents;
return *this;
 }
indentoperator++(int) { // Postfix ++.
indent Old = *this;
 ++NumIndents;
return Old;
 }
indent &operator--() { // Prefix --.
assert(NumIndents >= 1);
 --NumIndents;
return *this;
 }
indentoperator--(int) { // Postfix --.
indent Old = *this;
assert(NumIndents >= 1);
 --NumIndents;
return Old;
 }
indent &operator=(unsignedN) {
NumIndents = N;
return *this;
 }
};

inlineraw_ostream &operator<<(raw_ostream &OS, constindent &Indent) {
returnOS.indent(Indent.NumIndents * Indent.Scale);
}

class Error;

/// This helper creates an output stream and then passes it to \p Write.
/// The stream created is based on the specified \p OutputFileName:
/// llvm::outs for "-", raw_null_ostream for "/dev/null", and raw_fd_ostream
/// for other names. For raw_fd_ostream instances, the stream writes to
/// a temporary file. The final output file is atomically replaced with the
/// temporary file after the \p Write function is finished.
Error writeToOutput(StringRef OutputFileName,
 std::function<Error(raw_ostream &)> Write);

raw_ostream &operator<<(raw_ostream &OS, std::nullopt_t);

template <typename T, typename = decltype(std::declval<raw_ostream &>()
 << std::declval<const T &>())>
raw_ostream &operator<<(raw_ostream &OS, const std::optional<T> &O) {
if (O)
OS << *O;
else
OS << std::nullopt;
returnOS;
}

} // end namespace llvm

#endif // LLVM_SUPPORT_RAW_OSTREAM_H