1 //===--- raw_ostream.h - Raw output stream ----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the raw_ostream class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SUPPORT_RAW_OSTREAM_H
15 #define LLVM_SUPPORT_RAW_OSTREAM_H
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringRef.h"
24 #include <system_error>
28 class formatv_object_base;
29 class format_object_base;
30 class FormattedString;
31 class FormattedNumber;
36 enum OpenFlags : unsigned;
38 } // end namespace sys
40 /// This class implements an extremely fast bulk output stream that can *only*
41 /// output to a stream. It does not support seeking, reopening, rewinding, line
42 /// buffered disciplines etc. It is a simple buffer that outputs
43 /// a chunk at a time.
46 /// The buffer is handled in such a way that the buffer is
47 /// uninitialized, unbuffered, or out of space when OutBufCur >=
48 /// OutBufEnd. Thus a single comparison suffices to determine if we
49 /// need to take the slow path to write a single character.
51 /// The buffer is in one of three states:
52 /// 1. Unbuffered (BufferMode == Unbuffered)
53 /// 1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
54 /// 2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
55 /// OutBufEnd - OutBufStart >= 1).
57 /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
58 /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
59 /// managed by the subclass.
61 /// If a subclass installs an external buffer using SetBuffer then it can wait
62 /// for a \see write_impl() call to handle the data which has been put into
64 char *OutBufStart, *OutBufEnd, *OutBufCur;
73 // color order matches ANSI escape sequence, don't change
86 explicit raw_ostream(bool unbuffered = false)
87 : BufferMode(unbuffered ? Unbuffered : InternalBuffer) {
88 // Start out ready to flush.
89 OutBufStart = OutBufEnd = OutBufCur = nullptr;
92 raw_ostream(const raw_ostream &) = delete;
93 void operator=(const raw_ostream &) = delete;
95 virtual ~raw_ostream();
97 /// tell - Return the current offset with the file.
98 uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); }
100 //===--------------------------------------------------------------------===//
101 // Configuration Interface
102 //===--------------------------------------------------------------------===//
104 /// Set the stream to be buffered, with an automatically determined buffer
108 /// Set the stream to be buffered, using the specified buffer size.
109 void SetBufferSize(size_t Size) {
111 SetBufferAndMode(new char[Size], Size, InternalBuffer);
114 size_t GetBufferSize() const {
115 // If we're supposed to be buffered but haven't actually gotten around
116 // to allocating the buffer yet, return the value that would be used.
117 if (BufferMode != Unbuffered && OutBufStart == nullptr)
118 return preferred_buffer_size();
120 // Otherwise just return the size of the allocated buffer.
121 return OutBufEnd - OutBufStart;
124 /// Set the stream to be unbuffered. When unbuffered, the stream will flush
125 /// after every write. This routine will also flush the buffer immediately
126 /// when the stream is being set to unbuffered.
127 void SetUnbuffered() {
129 SetBufferAndMode(nullptr, 0, Unbuffered);
132 size_t GetNumBytesInBuffer() const {
133 return OutBufCur - OutBufStart;
136 //===--------------------------------------------------------------------===//
137 // Data Output Interface
138 //===--------------------------------------------------------------------===//
141 if (OutBufCur != OutBufStart)
145 raw_ostream &operator<<(char C) {
146 if (OutBufCur >= OutBufEnd)
152 raw_ostream &operator<<(unsigned char C) {
153 if (OutBufCur >= OutBufEnd)
159 raw_ostream &operator<<(signed char C) {
160 if (OutBufCur >= OutBufEnd)
166 raw_ostream &operator<<(StringRef Str) {
167 // Inline fast path, particularly for strings with a known length.
168 size_t Size = Str.size();
170 // Make sure we can use the fast path.
171 if (Size > (size_t)(OutBufEnd - OutBufCur))
172 return write(Str.data(), Size);
175 memcpy(OutBufCur, Str.data(), Size);
181 raw_ostream &operator<<(const char *Str) {
182 // Inline fast path, particularly for constant strings where a sufficiently
183 // smart compiler will simplify strlen.
185 return this->operator<<(StringRef(Str));
188 raw_ostream &operator<<(const std::string &Str) {
189 // Avoid the fast path, it would only increase code size for a marginal win.
190 return write(Str.data(), Str.length());
193 raw_ostream &operator<<(const SmallVectorImpl<char> &Str) {
194 return write(Str.data(), Str.size());
197 raw_ostream &operator<<(unsigned long N);
198 raw_ostream &operator<<(long N);
199 raw_ostream &operator<<(unsigned long long N);
200 raw_ostream &operator<<(long long N);
201 raw_ostream &operator<<(const void *P);
203 raw_ostream &operator<<(unsigned int N) {
204 return this->operator<<(static_cast<unsigned long>(N));
207 raw_ostream &operator<<(int N) {
208 return this->operator<<(static_cast<long>(N));
211 raw_ostream &operator<<(double N);
213 /// Output \p N in hexadecimal, without any prefix or padding.
214 raw_ostream &write_hex(unsigned long long N);
216 /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't
217 /// satisfy std::isprint into an escape sequence.
218 raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
220 raw_ostream &write(unsigned char C);
221 raw_ostream &write(const char *Ptr, size_t Size);
223 // Formatted output, see the format() function in Support/Format.h.
224 raw_ostream &operator<<(const format_object_base &Fmt);
226 // Formatted output, see the leftJustify() function in Support/Format.h.
227 raw_ostream &operator<<(const FormattedString &);
229 // Formatted output, see the formatHex() function in Support/Format.h.
230 raw_ostream &operator<<(const FormattedNumber &);
232 // Formatted output, see the formatv() function in Support/FormatVariadic.h.
233 raw_ostream &operator<<(const formatv_object_base &);
235 // Formatted output, see the format_bytes() function in Support/Format.h.
236 raw_ostream &operator<<(const FormattedBytes &);
238 /// indent - Insert 'NumSpaces' spaces.
239 raw_ostream &indent(unsigned NumSpaces);
241 /// Changes the foreground color of text that will be output from this point
243 /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
244 /// change only the bold attribute, and keep colors untouched
245 /// @param Bold bold/brighter text, default false
246 /// @param BG if true change the background, default: change foreground
247 /// @returns itself so it can be used within << invocations
248 virtual raw_ostream &changeColor(enum Colors Color,
257 /// Resets the colors to terminal defaults. Call this when you are done
258 /// outputting colored text, or before program exit.
259 virtual raw_ostream &resetColor() { return *this; }
261 /// Reverses the foreground and background colors.
262 virtual raw_ostream &reverseColor() { return *this; }
264 /// This function determines if this stream is connected to a "tty" or
265 /// "console" window. That is, the output would be displayed to the user
266 /// rather than being put on a pipe or stored in a file.
267 virtual bool is_displayed() const { return false; }
269 /// This function determines if this stream is displayed and supports colors.
270 virtual bool has_colors() const { return is_displayed(); }
272 //===--------------------------------------------------------------------===//
273 // Subclass Interface
274 //===--------------------------------------------------------------------===//
277 /// The is the piece of the class that is implemented by subclasses. This
278 /// writes the \p Size bytes starting at
279 /// \p Ptr to the underlying stream.
281 /// This function is guaranteed to only be called at a point at which it is
282 /// safe for the subclass to install a new buffer via SetBuffer.
284 /// \param Ptr The start of the data to be written. For buffered streams this
285 /// is guaranteed to be the start of the buffer.
287 /// \param Size The number of bytes to be written.
289 /// \invariant { Size > 0 }
290 virtual void write_impl(const char *Ptr, size_t Size) = 0;
292 // An out of line virtual method to provide a home for the class vtable.
293 virtual void handle();
295 /// Return the current position within the stream, not counting the bytes
296 /// currently in the buffer.
297 virtual uint64_t current_pos() const = 0;
300 /// Use the provided buffer as the raw_ostream buffer. This is intended for
301 /// use only by subclasses which can arrange for the output to go directly
302 /// into the desired output buffer, instead of being copied on each flush.
303 void SetBuffer(char *BufferStart, size_t Size) {
304 SetBufferAndMode(BufferStart, Size, ExternalBuffer);
307 /// Return an efficient buffer size for the underlying output mechanism.
308 virtual size_t preferred_buffer_size() const;
310 /// Return the beginning of the current stream buffer, or 0 if the stream is
312 const char *getBufferStart() const { return OutBufStart; }
314 //===--------------------------------------------------------------------===//
316 //===--------------------------------------------------------------------===//
318 /// Install the given buffer and mode.
319 void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
321 /// Flush the current buffer, which is known to be non-empty. This outputs the
322 /// currently buffered data and resets the buffer to empty.
323 void flush_nonempty();
325 /// Copy data into the buffer. Size must not be greater than the number of
326 /// unused bytes in the buffer.
327 void copy_to_buffer(const char *Ptr, size_t Size);
330 /// An abstract base class for streams implementations that also support a
331 /// pwrite operation. This is useful for code that can mostly stream out data,
332 /// but needs to patch in a header that needs to know the output size.
333 class raw_pwrite_stream : public raw_ostream {
334 virtual void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) = 0;
337 explicit raw_pwrite_stream(bool Unbuffered = false)
338 : raw_ostream(Unbuffered) {}
339 void pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
341 uint64_t Pos = tell();
342 // /dev/null always reports a pos of 0, so we cannot perform this check
345 assert(Size + Offset <= Pos && "We don't support extending the stream");
347 pwrite_impl(Ptr, Size, Offset);
351 //===----------------------------------------------------------------------===//
352 // File Output Streams
353 //===----------------------------------------------------------------------===//
355 /// A raw_ostream that writes to a file descriptor.
357 class raw_fd_ostream : public raw_pwrite_stream {
361 /// Error This flag is true if an error of any kind has been detected.
367 bool SupportsSeeking;
369 /// See raw_ostream::write_impl.
370 void write_impl(const char *Ptr, size_t Size) override;
372 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
374 /// Return the current position within the stream, not counting the bytes
375 /// currently in the buffer.
376 uint64_t current_pos() const override { return pos; }
378 /// Determine an efficient buffer size.
379 size_t preferred_buffer_size() const override;
381 /// Set the flag indicating that an output error has been encountered.
382 void error_detected() { Error = true; }
385 /// Open the specified file for writing. If an error occurs, information
386 /// about the error is put into EC, and the stream should be immediately
388 /// \p Flags allows optional flags to control how the file will be opened.
390 /// As a special case, if Filename is "-", then the stream will use
391 /// STDOUT_FILENO instead of opening a file. Note that it will still consider
392 /// itself to own the file descriptor. In particular, it will close the
393 /// file descriptor when it is done (this is necessary to detect
395 raw_fd_ostream(StringRef Filename, std::error_code &EC,
396 sys::fs::OpenFlags Flags);
398 /// FD is the file descriptor that this writes to. If ShouldClose is true,
399 /// this closes the file when the stream is destroyed.
400 raw_fd_ostream(int fd, bool shouldClose, bool unbuffered=false);
402 ~raw_fd_ostream() override;
404 /// Manually flush the stream and close the file. Note that this does not call
408 bool supportsSeeking() { return SupportsSeeking; }
410 /// Flushes the stream and repositions the underlying file descriptor position
411 /// to the offset specified from the beginning of the file.
412 uint64_t seek(uint64_t off);
414 raw_ostream &changeColor(enum Colors colors, bool bold=false,
415 bool bg=false) override;
416 raw_ostream &resetColor() override;
418 raw_ostream &reverseColor() override;
420 bool is_displayed() const override;
422 bool has_colors() const override;
424 /// Return the value of the flag in this raw_fd_ostream indicating whether an
425 /// output error has been encountered.
426 /// This doesn't implicitly flush any pending output. Also, it doesn't
427 /// guarantee to detect all errors unless the stream has been closed.
428 bool has_error() const {
432 /// Set the flag read by has_error() to false. If the error flag is set at the
433 /// time when this raw_ostream's destructor is called, report_fatal_error is
434 /// called to report the error. Use clear_error() after handling the error to
435 /// avoid this behavior.
437 /// "Errors should never pass silently.
438 /// Unless explicitly silenced."
439 /// - from The Zen of Python, by Tim Peters
446 /// This returns a reference to a raw_ostream for standard output. Use it like:
447 /// outs() << "foo" << "bar";
450 /// This returns a reference to a raw_ostream for standard error. Use it like:
451 /// errs() << "foo" << "bar";
454 /// This returns a reference to a raw_ostream which simply discards output.
455 raw_ostream &nulls();
457 //===----------------------------------------------------------------------===//
458 // Output Stream Adaptors
459 //===----------------------------------------------------------------------===//
461 /// A raw_ostream that writes to an std::string. This is a simple adaptor
462 /// class. This class does not encounter output errors.
463 class raw_string_ostream : public raw_ostream {
466 /// See raw_ostream::write_impl.
467 void write_impl(const char *Ptr, size_t Size) override;
469 /// Return the current position within the stream, not counting the bytes
470 /// currently in the buffer.
471 uint64_t current_pos() const override { return OS.size(); }
474 explicit raw_string_ostream(std::string &O) : OS(O) {}
475 ~raw_string_ostream() override;
477 /// Flushes the stream contents to the target string and returns the string's
485 /// A raw_ostream that writes to an SmallVector or SmallString. This is a
486 /// simple adaptor class. This class does not encounter output errors.
487 /// raw_svector_ostream operates without a buffer, delegating all memory
488 /// management to the SmallString. Thus the SmallString is always up-to-date,
489 /// may be used directly and there is no need to call flush().
490 class raw_svector_ostream : public raw_pwrite_stream {
491 SmallVectorImpl<char> &OS;
493 /// See raw_ostream::write_impl.
494 void write_impl(const char *Ptr, size_t Size) override;
496 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
498 /// Return the current position within the stream.
499 uint64_t current_pos() const override;
502 /// Construct a new raw_svector_ostream.
504 /// \param O The vector to write to; this should generally have at least 128
505 /// bytes free to avoid any extraneous memory overhead.
506 explicit raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
510 ~raw_svector_ostream() override = default;
512 void flush() = delete;
514 /// Return a StringRef for the vector contents.
515 StringRef str() { return StringRef(OS.data(), OS.size()); }
518 /// A raw_ostream that discards all output.
519 class raw_null_ostream : public raw_pwrite_stream {
520 /// See raw_ostream::write_impl.
521 void write_impl(const char *Ptr, size_t size) override;
522 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
524 /// Return the current position within the stream, not counting the bytes
525 /// currently in the buffer.
526 uint64_t current_pos() const override;
529 explicit raw_null_ostream() = default;
530 ~raw_null_ostream() override;
533 class buffer_ostream : public raw_svector_ostream {
535 SmallVector<char, 0> Buffer;
538 buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer), OS(OS) {}
539 ~buffer_ostream() override { OS << str(); }
542 } // end namespace llvm
544 #endif // LLVM_SUPPORT_RAW_OSTREAM_H