1//===--- raw_ostream.h - Raw output stream ----------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the raw_ostream class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_SUPPORT_RAW_OSTREAM_H
14#define LLVM_SUPPORT_RAW_OSTREAM_H
15
16#include "llvm/ADT/SmallVector.h"
17#include "llvm/ADT/StringRef.h"
18#include "llvm/Support/DataTypes.h"
19#include <cassert>
20#include <cstddef>
21#include <cstdint>
22#include <cstring>
23#include <optional>
24#include <string>
25#include <string_view>
26#include <system_error>
27#include <type_traits>
28
29namespace llvm {
30
31class Duration;
32class formatv_object_base;
33class format_object_base;
34class FormattedString;
35class FormattedNumber;
36class FormattedBytes;
37template <class T> class [[nodiscard]] Expected;
38
39namespace sys {
40namespace fs {
41enum FileAccess : unsigned;
42enum OpenFlags : unsigned;
43enum CreationDisposition : unsigned;
44class FileLocker;
45} // end namespace fs
46} // end namespace sys
47
48/// This class implements an extremely fast bulk output stream that can *only*
49/// output to a stream. It does not support seeking, reopening, rewinding, line
50/// buffered disciplines etc. It is a simple buffer that outputs
51/// a chunk at a time.
52class raw_ostream {
53public:
54 // Class kinds to support LLVM-style RTTI.
55 enum class OStreamKind {
56 OK_OStream,
57 OK_FDStream,
58 };
59
60private:
61 OStreamKind Kind;
62
63 /// The buffer is handled in such a way that the buffer is
64 /// uninitialized, unbuffered, or out of space when OutBufCur >=
65 /// OutBufEnd. Thus a single comparison suffices to determine if we
66 /// need to take the slow path to write a single character.
67 ///
68 /// The buffer is in one of three states:
69 /// 1. Unbuffered (BufferMode == Unbuffered)
70 /// 1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
71 /// 2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
72 /// OutBufEnd - OutBufStart >= 1).
73 ///
74 /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
75 /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
76 /// managed by the subclass.
77 ///
78 /// If a subclass installs an external buffer using SetBuffer then it can wait
79 /// for a \see write_impl() call to handle the data which has been put into
80 /// this buffer.
81 char *OutBufStart, *OutBufEnd, *OutBufCur;
82 bool ColorEnabled = false;
83
84 /// Optional stream this stream is tied to. If this stream is written to, the
85 /// tied-to stream will be flushed first.
86 raw_ostream *TiedStream = nullptr;
87
88 enum class BufferKind {
89 Unbuffered = 0,
90 InternalBuffer,
91 ExternalBuffer
92 } BufferMode;
93
94public:
95 // color order matches ANSI escape sequence, don't change
96 enum class Colors {
97 BLACK = 0,
98 RED,
99 GREEN,
100 YELLOW,
101 BLUE,
102 MAGENTA,
103 CYAN,
104 WHITE,
105 SAVEDCOLOR,
106 RESET,
107 };
108
109 static constexpr Colors BLACK = Colors::BLACK;
110 static constexpr Colors RED = Colors::RED;
111 static constexpr Colors GREEN = Colors::GREEN;
112 static constexpr Colors YELLOW = Colors::YELLOW;
113 static constexpr Colors BLUE = Colors::BLUE;
114 static constexpr Colors MAGENTA = Colors::MAGENTA;
115 static constexpr Colors CYAN = Colors::CYAN;
116 static constexpr Colors WHITE = Colors::WHITE;
117 static constexpr Colors SAVEDCOLOR = Colors::SAVEDCOLOR;
118 static constexpr Colors RESET = Colors::RESET;
119
120 explicit raw_ostream(bool unbuffered = false,
121 OStreamKind K = OStreamKind::OK_OStream)
122 : Kind(K), BufferMode(unbuffered ? BufferKind::Unbuffered
123 : BufferKind::InternalBuffer) {
124 // Start out ready to flush.
125 OutBufStart = OutBufEnd = OutBufCur = nullptr;
126 }
127
128 raw_ostream(const raw_ostream &) = delete;
129 void operator=(const raw_ostream &) = delete;
130
131 virtual ~raw_ostream();
132
133 /// tell - Return the current offset with the file.
134 uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); }
135
136 OStreamKind get_kind() const { return Kind; }
137
138 //===--------------------------------------------------------------------===//
139 // Configuration Interface
140 //===--------------------------------------------------------------------===//
141
142 /// If possible, pre-allocate \p ExtraSize bytes for stream data.
143 /// i.e. it extends internal buffers to keep additional ExtraSize bytes.
144 /// So that the stream could keep at least tell() + ExtraSize bytes
145 /// without re-allocations. reserveExtraSpace() does not change
146 /// the size/data of the stream.
147 virtual void reserveExtraSpace(uint64_t ExtraSize) {}
148
149 /// Set the stream to be buffered, with an automatically determined buffer
150 /// size.
151 void SetBuffered();
152
153 /// Set the stream to be buffered, using the specified buffer size.
154 void SetBufferSize(size_t Size) {
155 flush();
156 SetBufferAndMode(BufferStart: new char[Size], Size, Mode: BufferKind::InternalBuffer);
157 }
158
159 size_t GetBufferSize() const {
160 // If we're supposed to be buffered but haven't actually gotten around
161 // to allocating the buffer yet, return the value that would be used.
162 if (BufferMode != BufferKind::Unbuffered && OutBufStart == nullptr)
163 return preferred_buffer_size();
164
165 // Otherwise just return the size of the allocated buffer.
166 return OutBufEnd - OutBufStart;
167 }
168
169 /// Set the stream to be unbuffered. When unbuffered, the stream will flush
170 /// after every write. This routine will also flush the buffer immediately
171 /// when the stream is being set to unbuffered.
172 void SetUnbuffered() {
173 flush();
174 SetBufferAndMode(BufferStart: nullptr, Size: 0, Mode: BufferKind::Unbuffered);
175 }
176
177 size_t GetNumBytesInBuffer() const {
178 return OutBufCur - OutBufStart;
179 }
180
181 //===--------------------------------------------------------------------===//
182 // Data Output Interface
183 //===--------------------------------------------------------------------===//
184
185 void flush() {
186 if (OutBufCur != OutBufStart)
187 flush_nonempty();
188 }
189
190 raw_ostream &operator<<(char C) {
191 if (OutBufCur >= OutBufEnd)
192 return write(C);
193 *OutBufCur++ = C;
194 return *this;
195 }
196
197 raw_ostream &operator<<(unsigned char C) {
198 if (OutBufCur >= OutBufEnd)
199 return write(C);
200 *OutBufCur++ = C;
201 return *this;
202 }
203
204 raw_ostream &operator<<(signed char C) {
205 if (OutBufCur >= OutBufEnd)
206 return write(C);
207 *OutBufCur++ = C;
208 return *this;
209 }
210
211 raw_ostream &operator<<(StringRef Str) {
212 // Inline fast path, particularly for strings with a known length.
213 size_t Size = Str.size();
214
215 // Make sure we can use the fast path.
216 if (Size > (size_t)(OutBufEnd - OutBufCur))
217 return write(Ptr: Str.data(), Size);
218
219 if (Size) {
220 memcpy(dest: OutBufCur, src: Str.data(), n: Size);
221 OutBufCur += Size;
222 }
223 return *this;
224 }
225
226#if defined(__cpp_char8_t)
227 // When using `char8_t *` integers or pointers are written to the ostream
228 // instead of UTF-8 code as one might expect. This might lead to unexpected
229 // behavior, especially as `u8""` literals are of type `char8_t*` instead of
230 // type `char_t*` from C++20 onwards. Thus we disallow using them with
231 // raw_ostreams.
232 // If you have u8"" literals to stream, you can rewrite them as ordinary
233 // literals with escape sequences
234 // e.g. replace `u8"\u00a0"` by `"\xc2\xa0"`
235 // or use `reinterpret_cast`:
236 // e.g. replace `u8"\u00a0"` by `reinterpret_cast<const char *>(u8"\u00a0")`
237 raw_ostream &operator<<(const char8_t *Str) = delete;
238#endif
239
240 raw_ostream &operator<<(const char *Str) {
241 // Inline fast path, particularly for constant strings where a sufficiently
242 // smart compiler will simplify strlen.
243
244 return this->operator<<(Str: StringRef(Str));
245 }
246
247 raw_ostream &operator<<(const std::string &Str) {
248 // Avoid the fast path, it would only increase code size for a marginal win.
249 return write(Ptr: Str.data(), Size: Str.length());
250 }
251
252 raw_ostream &operator<<(const std::string_view &Str) {
253 return write(Ptr: Str.data(), Size: Str.length());
254 }
255
256 raw_ostream &operator<<(const SmallVectorImpl<char> &Str) {
257 return write(Ptr: Str.data(), Size: Str.size());
258 }
259
260 raw_ostream &operator<<(unsigned long N);
261 raw_ostream &operator<<(long N);
262 raw_ostream &operator<<(unsigned long long N);
263 raw_ostream &operator<<(long long N);
264 raw_ostream &operator<<(const void *P);
265
266 raw_ostream &operator<<(unsigned int N) {
267 return this->operator<<(N: static_cast<unsigned long>(N));
268 }
269
270 raw_ostream &operator<<(int N) {
271 return this->operator<<(N: static_cast<long>(N));
272 }
273
274 raw_ostream &operator<<(double N);
275
276 /// Output \p N in hexadecimal, without any prefix or padding.
277 raw_ostream &write_hex(unsigned long long N);
278
279 // Change the foreground color of text.
280 raw_ostream &operator<<(Colors C);
281
282 /// Output a formatted UUID with dash separators.
283 using uuid_t = uint8_t[16];
284 raw_ostream &write_uuid(const uuid_t UUID);
285
286 /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't
287 /// satisfy llvm::isPrint into an escape sequence.
288 raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
289
290 raw_ostream &write(unsigned char C);
291 raw_ostream &write(const char *Ptr, size_t Size);
292
293 // Formatted output, see the format() function in Support/Format.h.
294 raw_ostream &operator<<(const format_object_base &Fmt);
295
296 // Formatted output, see the leftJustify() function in Support/Format.h.
297 raw_ostream &operator<<(const FormattedString &);
298
299 // Formatted output, see the formatHex() function in Support/Format.h.
300 raw_ostream &operator<<(const FormattedNumber &);
301
302 // Formatted output, see the formatv() function in Support/FormatVariadic.h.
303 raw_ostream &operator<<(const formatv_object_base &);
304
305 // Formatted output, see the format_bytes() function in Support/Format.h.
306 raw_ostream &operator<<(const FormattedBytes &);
307
308 /// indent - Insert 'NumSpaces' spaces.
309 raw_ostream &indent(unsigned NumSpaces);
310
311 /// write_zeros - Insert 'NumZeros' nulls.
312 raw_ostream &write_zeros(unsigned NumZeros);
313
314 /// Changes the foreground color of text that will be output from this point
315 /// forward.
316 /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
317 /// change only the bold attribute, and keep colors untouched
318 /// @param Bold bold/brighter text, default false
319 /// @param BG if true change the background, default: change foreground
320 /// @returns itself so it can be used within << invocations
321 virtual raw_ostream &changeColor(enum Colors Color, bool Bold = false,
322 bool BG = false);
323
324 /// Resets the colors to terminal defaults. Call this when you are done
325 /// outputting colored text, or before program exit.
326 virtual raw_ostream &resetColor();
327
328 /// Reverses the foreground and background colors.
329 virtual raw_ostream &reverseColor();
330
331 /// This function determines if this stream is connected to a "tty" or
332 /// "console" window. That is, the output would be displayed to the user
333 /// rather than being put on a pipe or stored in a file.
334 virtual bool is_displayed() const { return false; }
335
336 /// This function determines if this stream is displayed and supports colors.
337 /// The result is unaffected by calls to enable_color().
338 virtual bool has_colors() const { return is_displayed(); }
339
340 // Enable or disable colors. Once enable_colors(false) is called,
341 // changeColor() has no effect until enable_colors(true) is called.
342 virtual void enable_colors(bool enable) { ColorEnabled = enable; }
343
344 bool colors_enabled() const { return ColorEnabled; }
345
346 /// Tie this stream to the specified stream. Replaces any existing tied-to
347 /// stream. Specifying a nullptr unties the stream.
348 void tie(raw_ostream *TieTo) { TiedStream = TieTo; }
349
350 //===--------------------------------------------------------------------===//
351 // Subclass Interface
352 //===--------------------------------------------------------------------===//
353
354private:
355 /// The is the piece of the class that is implemented by subclasses. This
356 /// writes the \p Size bytes starting at
357 /// \p Ptr to the underlying stream.
358 ///
359 /// This function is guaranteed to only be called at a point at which it is
360 /// safe for the subclass to install a new buffer via SetBuffer.
361 ///
362 /// \param Ptr The start of the data to be written. For buffered streams this
363 /// is guaranteed to be the start of the buffer.
364 ///
365 /// \param Size The number of bytes to be written.
366 ///
367 /// \invariant { Size > 0 }
368 virtual void write_impl(const char *Ptr, size_t Size) = 0;
369
370 /// Return the current position within the stream, not counting the bytes
371 /// currently in the buffer.
372 virtual uint64_t current_pos() const = 0;
373
374protected:
375 /// Use the provided buffer as the raw_ostream buffer. This is intended for
376 /// use only by subclasses which can arrange for the output to go directly
377 /// into the desired output buffer, instead of being copied on each flush.
378 void SetBuffer(char *BufferStart, size_t Size) {
379 SetBufferAndMode(BufferStart, Size, Mode: BufferKind::ExternalBuffer);
380 }
381
382 /// Return an efficient buffer size for the underlying output mechanism.
383 virtual size_t preferred_buffer_size() const;
384
385 /// Return the beginning of the current stream buffer, or 0 if the stream is
386 /// unbuffered.
387 const char *getBufferStart() const { return OutBufStart; }
388
389 //===--------------------------------------------------------------------===//
390 // Private Interface
391 //===--------------------------------------------------------------------===//
392private:
393 /// Install the given buffer and mode.
394 void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
395
396 /// Flush the current buffer, which is known to be non-empty. This outputs the
397 /// currently buffered data and resets the buffer to empty.
398 void flush_nonempty();
399
400 /// Copy data into the buffer. Size must not be greater than the number of
401 /// unused bytes in the buffer.
402 void copy_to_buffer(const char *Ptr, size_t Size);
403
404 /// Compute whether colors should be used and do the necessary work such as
405 /// flushing. The result is affected by calls to enable_color().
406 bool prepare_colors();
407
408 /// Flush the tied-to stream (if present) and then write the required data.
409 void flush_tied_then_write(const char *Ptr, size_t Size);
410
411 virtual void anchor();
412};
413
414/// Call the appropriate insertion operator, given an rvalue reference to a
415/// raw_ostream object and return a stream of the same type as the argument.
416template <typename OStream, typename T>
417std::enable_if_t<!std::is_reference_v<OStream> &&
418 std::is_base_of_v<raw_ostream, OStream>,
419 OStream &&>
420operator<<(OStream &&OS, const T &Value) {
421 OS << Value;
422 return std::move(OS);
423}
424
425/// An abstract base class for streams implementations that also support a
426/// pwrite operation. This is useful for code that can mostly stream out data,
427/// but needs to patch in a header that needs to know the output size.
428class raw_pwrite_stream : public raw_ostream {
429 virtual void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) = 0;
430 void anchor() override;
431
432public:
433 explicit raw_pwrite_stream(bool Unbuffered = false,
434 OStreamKind K = OStreamKind::OK_OStream)
435 : raw_ostream(Unbuffered, K) {}
436 void pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
437#ifndef NDEBUG
438 uint64_t Pos = tell();
439 // /dev/null always reports a pos of 0, so we cannot perform this check
440 // in that case.
441 if (Pos)
442 assert(Size + Offset <= Pos && "We don't support extending the stream");
443#endif
444 pwrite_impl(Ptr, Size, Offset);
445 }
446};
447
448//===----------------------------------------------------------------------===//
449// File Output Streams
450//===----------------------------------------------------------------------===//
451
452/// A raw_ostream that writes to a file descriptor.
453///
454class raw_fd_ostream : public raw_pwrite_stream {
455 int FD;
456 bool ShouldClose;
457 bool SupportsSeeking = false;
458 bool IsRegularFile = false;
459 mutable std::optional<bool> HasColors;
460
461#ifdef _WIN32
462 /// True if this fd refers to a Windows console device. Mintty and other
463 /// terminal emulators are TTYs, but they are not consoles.
464 bool IsWindowsConsole = false;
465#endif
466
467 std::error_code EC;
468
469 uint64_t pos = 0;
470
471 /// See raw_ostream::write_impl.
472 void write_impl(const char *Ptr, size_t Size) override;
473
474 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
475
476 /// Return the current position within the stream, not counting the bytes
477 /// currently in the buffer.
478 uint64_t current_pos() const override { return pos; }
479
480 /// Determine an efficient buffer size.
481 size_t preferred_buffer_size() const override;
482
483 void anchor() override;
484
485protected:
486 /// Set the flag indicating that an output error has been encountered.
487 void error_detected(std::error_code EC) { this->EC = EC; }
488
489 /// Return the file descriptor.
490 int get_fd() const { return FD; }
491
492 // Update the file position by increasing \p Delta.
493 void inc_pos(uint64_t Delta) { pos += Delta; }
494
495public:
496 /// Open the specified file for writing. If an error occurs, information
497 /// about the error is put into EC, and the stream should be immediately
498 /// destroyed;
499 /// \p Flags allows optional flags to control how the file will be opened.
500 ///
501 /// As a special case, if Filename is "-", then the stream will use
502 /// STDOUT_FILENO instead of opening a file. This will not close the stdout
503 /// descriptor.
504 raw_fd_ostream(StringRef Filename, std::error_code &EC);
505 raw_fd_ostream(StringRef Filename, std::error_code &EC,
506 sys::fs::CreationDisposition Disp);
507 raw_fd_ostream(StringRef Filename, std::error_code &EC,
508 sys::fs::FileAccess Access);
509 raw_fd_ostream(StringRef Filename, std::error_code &EC,
510 sys::fs::OpenFlags Flags);
511 raw_fd_ostream(StringRef Filename, std::error_code &EC,
512 sys::fs::CreationDisposition Disp, sys::fs::FileAccess Access,
513 sys::fs::OpenFlags Flags);
514
515 /// FD is the file descriptor that this writes to. If ShouldClose is true,
516 /// this closes the file when the stream is destroyed. If FD is for stdout or
517 /// stderr, it will not be closed.
518 raw_fd_ostream(int fd, bool shouldClose, bool unbuffered = false,
519 OStreamKind K = OStreamKind::OK_OStream);
520
521 ~raw_fd_ostream() override;
522
523 /// Manually flush the stream and close the file. Note that this does not call
524 /// fsync.
525 void close();
526
527 bool supportsSeeking() const { return SupportsSeeking; }
528
529 bool isRegularFile() const { return IsRegularFile; }
530
531 /// Flushes the stream and repositions the underlying file descriptor position
532 /// to the offset specified from the beginning of the file.
533 uint64_t seek(uint64_t off);
534
535 bool is_displayed() const override;
536
537 bool has_colors() const override;
538
539 std::error_code error() const { return EC; }
540
541 /// Return the value of the flag in this raw_fd_ostream indicating whether an
542 /// output error has been encountered.
543 /// This doesn't implicitly flush any pending output. Also, it doesn't
544 /// guarantee to detect all errors unless the stream has been closed.
545 bool has_error() const { return bool(EC); }
546
547 /// Set the flag read by has_error() to false. If the error flag is set at the
548 /// time when this raw_ostream's destructor is called, report_fatal_error is
549 /// called to report the error. Use clear_error() after handling the error to
550 /// avoid this behavior.
551 ///
552 /// "Errors should never pass silently.
553 /// Unless explicitly silenced."
554 /// - from The Zen of Python, by Tim Peters
555 ///
556 void clear_error() { EC = std::error_code(); }
557
558 /// Locks the underlying file.
559 ///
560 /// @returns RAII object that releases the lock upon leaving the scope, if the
561 /// locking was successful. Otherwise returns corresponding
562 /// error code.
563 ///
564 /// The function blocks the current thread until the lock become available or
565 /// error occurs.
566 ///
567 /// Possible use of this function may be as follows:
568 ///
569 /// @code{.cpp}
570 /// if (auto L = stream.lock()) {
571 /// // ... do action that require file to be locked.
572 /// } else {
573 /// handleAllErrors(std::move(L.takeError()), [&](ErrorInfoBase &EIB) {
574 /// // ... handle lock error.
575 /// });
576 /// }
577 /// @endcode
578 [[nodiscard]] Expected<sys::fs::FileLocker> lock();
579
580 /// Tries to lock the underlying file within the specified period.
581 ///
582 /// @returns RAII object that releases the lock upon leaving the scope, if the
583 /// locking was successful. Otherwise returns corresponding
584 /// error code.
585 ///
586 /// It is used as @ref lock.
587 [[nodiscard]] Expected<sys::fs::FileLocker>
588 tryLockFor(Duration const &Timeout);
589};
590
591/// This returns a reference to a raw_fd_ostream for standard output. Use it
592/// like: outs() << "foo" << "bar";
593raw_fd_ostream &outs();
594
595/// This returns a reference to a raw_ostream for standard error.
596/// Use it like: errs() << "foo" << "bar";
597/// By default, the stream is tied to stdout to ensure stdout is flushed before
598/// stderr is written, to ensure the error messages are written in their
599/// expected place.
600raw_fd_ostream &errs();
601
602/// This returns a reference to a raw_ostream which simply discards output.
603raw_ostream &nulls();
604
605//===----------------------------------------------------------------------===//
606// File Streams
607//===----------------------------------------------------------------------===//
608
609/// A raw_ostream of a file for reading/writing/seeking.
610///
611class raw_fd_stream : public raw_fd_ostream {
612public:
613 /// Open the specified file for reading/writing/seeking. If an error occurs,
614 /// information about the error is put into EC, and the stream should be
615 /// immediately destroyed.
616 raw_fd_stream(StringRef Filename, std::error_code &EC);
617
618 /// This reads the \p Size bytes into a buffer pointed by \p Ptr.
619 ///
620 /// \param Ptr The start of the buffer to hold data to be read.
621 ///
622 /// \param Size The number of bytes to be read.
623 ///
624 /// On success, the number of bytes read is returned, and the file position is
625 /// advanced by this number. On error, -1 is returned, use error() to get the
626 /// error code.
627 ssize_t read(char *Ptr, size_t Size);
628
629 /// Check if \p OS is a pointer of type raw_fd_stream*.
630 static bool classof(const raw_ostream *OS);
631};
632
633//===----------------------------------------------------------------------===//
634// Output Stream Adaptors
635//===----------------------------------------------------------------------===//
636
637/// A raw_ostream that writes to an std::string. This is a simple adaptor
638/// class. This class does not encounter output errors.
639/// raw_string_ostream operates without a buffer, delegating all memory
640/// management to the std::string. Thus the std::string is always up-to-date,
641/// may be used directly and there is no need to call flush().
642class raw_string_ostream : public raw_ostream {
643 std::string &OS;
644
645 /// See raw_ostream::write_impl.
646 void write_impl(const char *Ptr, size_t Size) override;
647
648 /// Return the current position within the stream, not counting the bytes
649 /// currently in the buffer.
650 uint64_t current_pos() const override { return OS.size(); }
651
652public:
653 explicit raw_string_ostream(std::string &O) : OS(O) {
654 SetUnbuffered();
655 }
656
657 /// Returns the string's reference. In most cases it is better to simply use
658 /// the underlying std::string directly.
659 /// TODO: Consider removing this API.
660 std::string &str() { return OS; }
661
662 void reserveExtraSpace(uint64_t ExtraSize) override {
663 OS.reserve(res_arg: tell() + ExtraSize);
664 }
665};
666
667/// A raw_ostream that writes to an SmallVector or SmallString. This is a
668/// simple adaptor class. This class does not encounter output errors.
669/// raw_svector_ostream operates without a buffer, delegating all memory
670/// management to the SmallString. Thus the SmallString is always up-to-date,
671/// may be used directly and there is no need to call flush().
672class raw_svector_ostream : public raw_pwrite_stream {
673 SmallVectorImpl<char> &OS;
674
675 /// See raw_ostream::write_impl.
676 void write_impl(const char *Ptr, size_t Size) override;
677
678 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
679
680 /// Return the current position within the stream.
681 uint64_t current_pos() const override;
682
683public:
684 /// Construct a new raw_svector_ostream.
685 ///
686 /// \param O The vector to write to; this should generally have at least 128
687 /// bytes free to avoid any extraneous memory overhead.
688 explicit raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
689 SetUnbuffered();
690 }
691
692 ~raw_svector_ostream() override = default;
693
694 void flush() = delete;
695
696 /// Return a StringRef for the vector contents.
697 StringRef str() const { return StringRef(OS.data(), OS.size()); }
698
699 void reserveExtraSpace(uint64_t ExtraSize) override {
700 OS.reserve(N: tell() + ExtraSize);
701 }
702};
703
704/// A raw_ostream that discards all output.
705class raw_null_ostream : public raw_pwrite_stream {
706 /// See raw_ostream::write_impl.
707 void write_impl(const char *Ptr, size_t size) override;
708 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
709
710 /// Return the current position within the stream, not counting the bytes
711 /// currently in the buffer.
712 uint64_t current_pos() const override;
713
714public:
715 explicit raw_null_ostream() = default;
716 ~raw_null_ostream() override;
717};
718
719class buffer_ostream : public raw_svector_ostream {
720 raw_ostream &OS;
721 SmallVector<char, 0> Buffer;
722
723 void anchor() override;
724
725public:
726 buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer), OS(OS) {}
727 ~buffer_ostream() override { OS << str(); }
728};
729
730class buffer_unique_ostream : public raw_svector_ostream {
731 std::unique_ptr<raw_ostream> OS;
732 SmallVector<char, 0> Buffer;
733
734 void anchor() override;
735
736public:
737 buffer_unique_ostream(std::unique_ptr<raw_ostream> OS)
738 : raw_svector_ostream(Buffer), OS(std::move(OS)) {
739 // Turn off buffering on OS, which we now own, to avoid allocating a buffer
740 // when the destructor writes only to be immediately flushed again.
741 this->OS->SetUnbuffered();
742 }
743 ~buffer_unique_ostream() override { *OS << str(); }
744};
745
746class Error;
747
748/// This helper creates an output stream and then passes it to \p Write.
749/// The stream created is based on the specified \p OutputFileName:
750/// llvm::outs for "-", raw_null_ostream for "/dev/null", and raw_fd_ostream
751/// for other names. For raw_fd_ostream instances, the stream writes to
752/// a temporary file. The final output file is atomically replaced with the
753/// temporary file after the \p Write function is finished.
754Error writeToOutput(StringRef OutputFileName,
755 std::function<Error(raw_ostream &)> Write);
756
757raw_ostream &operator<<(raw_ostream &OS, std::nullopt_t);
758
759template <typename T, typename = decltype(std::declval<raw_ostream &>()
760 << std::declval<const T &>())>
761raw_ostream &operator<<(raw_ostream &OS, const std::optional<T> &O) {
762 if (O)
763 OS << *O;
764 else
765 OS << std::nullopt;
766 return OS;
767}
768
769} // end namespace llvm
770
771#endif // LLVM_SUPPORT_RAW_OSTREAM_H
772

source code of llvm/include/llvm/Support/raw_ostream.h