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"
19 #include "llvm/Support/DataTypes.h"
20 #include <system_error>
23 class format_object_base;
24 class FormattedString;
25 class FormattedNumber;
27 template <typename T> class SmallVectorImpl;
31 enum OpenFlags : unsigned;
35 /// This class implements an extremely fast bulk output stream that can *only*
36 /// output to a stream. It does not support seeking, reopening, rewinding, line
37 /// buffered disciplines etc. It is a simple buffer that outputs
38 /// a chunk at a time.
41 void operator=(const raw_ostream &) = delete;
42 raw_ostream(const raw_ostream &) = delete;
44 /// The buffer is handled in such a way that the buffer is
45 /// uninitialized, unbuffered, or out of space when OutBufCur >=
46 /// OutBufEnd. Thus a single comparison suffices to determine if we
47 /// need to take the slow path to write a single character.
49 /// The buffer is in one of three states:
50 /// 1. Unbuffered (BufferMode == Unbuffered)
51 /// 1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
52 /// 2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
53 /// OutBufEnd - OutBufStart >= 1).
55 /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
56 /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
57 /// managed by the subclass.
59 /// If a subclass installs an external buffer using SetBuffer then it can wait
60 /// for a \see write_impl() call to handle the data which has been put into
62 char *OutBufStart, *OutBufEnd, *OutBufCur;
71 // color order matches ANSI escape sequence, don't change
84 explicit raw_ostream(bool unbuffered = false)
85 : BufferMode(unbuffered ? Unbuffered : InternalBuffer) {
86 // Start out ready to flush.
87 OutBufStart = OutBufEnd = OutBufCur = nullptr;
90 virtual ~raw_ostream();
92 /// tell - Return the current offset with the file.
93 uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); }
95 //===--------------------------------------------------------------------===//
96 // Configuration Interface
97 //===--------------------------------------------------------------------===//
99 /// Set the stream to be buffered, with an automatically determined buffer
103 /// Set the stream to be buffered, using the specified buffer size.
104 void SetBufferSize(size_t Size) {
106 SetBufferAndMode(new char[Size], Size, InternalBuffer);
109 size_t GetBufferSize() const {
110 // If we're supposed to be buffered but haven't actually gotten around
111 // to allocating the buffer yet, return the value that would be used.
112 if (BufferMode != Unbuffered && OutBufStart == nullptr)
113 return preferred_buffer_size();
115 // Otherwise just return the size of the allocated buffer.
116 return OutBufEnd - OutBufStart;
119 /// Set the stream to be unbuffered. When unbuffered, the stream will flush
120 /// after every write. This routine will also flush the buffer immediately
121 /// when the stream is being set to unbuffered.
122 void SetUnbuffered() {
124 SetBufferAndMode(nullptr, 0, Unbuffered);
127 size_t GetNumBytesInBuffer() const {
128 return OutBufCur - OutBufStart;
131 //===--------------------------------------------------------------------===//
132 // Data Output Interface
133 //===--------------------------------------------------------------------===//
136 if (OutBufCur != OutBufStart)
140 raw_ostream &operator<<(char C) {
141 if (OutBufCur >= OutBufEnd)
147 raw_ostream &operator<<(unsigned char C) {
148 if (OutBufCur >= OutBufEnd)
154 raw_ostream &operator<<(signed char C) {
155 if (OutBufCur >= OutBufEnd)
161 raw_ostream &operator<<(StringRef Str) {
162 // Inline fast path, particularly for strings with a known length.
163 size_t Size = Str.size();
165 // Make sure we can use the fast path.
166 if (Size > (size_t)(OutBufEnd - OutBufCur))
167 return write(Str.data(), Size);
170 memcpy(OutBufCur, Str.data(), Size);
176 raw_ostream &operator<<(const char *Str) {
177 // Inline fast path, particularly for constant strings where a sufficiently
178 // smart compiler will simplify strlen.
180 return this->operator<<(StringRef(Str));
183 raw_ostream &operator<<(const std::string &Str) {
184 // Avoid the fast path, it would only increase code size for a marginal win.
185 return write(Str.data(), Str.length());
188 raw_ostream &operator<<(const llvm::SmallVectorImpl<char> &Str) {
189 return write(Str.data(), Str.size());
192 raw_ostream &operator<<(unsigned long N);
193 raw_ostream &operator<<(long N);
194 raw_ostream &operator<<(unsigned long long N);
195 raw_ostream &operator<<(long long N);
196 raw_ostream &operator<<(const void *P);
197 raw_ostream &operator<<(unsigned int N) {
198 return this->operator<<(static_cast<unsigned long>(N));
201 raw_ostream &operator<<(int N) {
202 return this->operator<<(static_cast<long>(N));
205 raw_ostream &operator<<(double N);
207 /// Output \p N in hexadecimal, without any prefix or padding.
208 raw_ostream &write_hex(unsigned long long N);
210 /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't
211 /// satisfy std::isprint into an escape sequence.
212 raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
214 raw_ostream &write(unsigned char C);
215 raw_ostream &write(const char *Ptr, size_t Size);
217 // Formatted output, see the format() function in Support/Format.h.
218 raw_ostream &operator<<(const format_object_base &Fmt);
220 // Formatted output, see the leftJustify() function in Support/Format.h.
221 raw_ostream &operator<<(const FormattedString &);
223 // Formatted output, see the formatHex() function in Support/Format.h.
224 raw_ostream &operator<<(const FormattedNumber &);
226 // Formatted output, see the format_bytes() function in Support/Format.h.
227 raw_ostream &operator<<(const FormattedBytes &);
229 /// indent - Insert 'NumSpaces' spaces.
230 raw_ostream &indent(unsigned NumSpaces);
232 /// Changes the foreground color of text that will be output from this point
234 /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
235 /// change only the bold attribute, and keep colors untouched
236 /// @param Bold bold/brighter text, default false
237 /// @param BG if true change the background, default: change foreground
238 /// @returns itself so it can be used within << invocations
239 virtual raw_ostream &changeColor(enum Colors Color,
248 /// Resets the colors to terminal defaults. Call this when you are done
249 /// outputting colored text, or before program exit.
250 virtual raw_ostream &resetColor() { return *this; }
252 /// Reverses the foreground and background colors.
253 virtual raw_ostream &reverseColor() { return *this; }
255 /// This function determines if this stream is connected to a "tty" or
256 /// "console" window. That is, the output would be displayed to the user
257 /// rather than being put on a pipe or stored in a file.
258 virtual bool is_displayed() const { return false; }
260 /// This function determines if this stream is displayed and supports colors.
261 virtual bool has_colors() const { return is_displayed(); }
263 //===--------------------------------------------------------------------===//
264 // Subclass Interface
265 //===--------------------------------------------------------------------===//
268 /// The is the piece of the class that is implemented by subclasses. This
269 /// writes the \p Size bytes starting at
270 /// \p Ptr to the underlying stream.
272 /// This function is guaranteed to only be called at a point at which it is
273 /// safe for the subclass to install a new buffer via SetBuffer.
275 /// \param Ptr The start of the data to be written. For buffered streams this
276 /// is guaranteed to be the start of the buffer.
278 /// \param Size The number of bytes to be written.
280 /// \invariant { Size > 0 }
281 virtual void write_impl(const char *Ptr, size_t Size) = 0;
283 // An out of line virtual method to provide a home for the class vtable.
284 virtual void handle();
286 /// Return the current position within the stream, not counting the bytes
287 /// currently in the buffer.
288 virtual uint64_t current_pos() const = 0;
291 /// Use the provided buffer as the raw_ostream buffer. This is intended for
292 /// use only by subclasses which can arrange for the output to go directly
293 /// into the desired output buffer, instead of being copied on each flush.
294 void SetBuffer(char *BufferStart, size_t Size) {
295 SetBufferAndMode(BufferStart, Size, ExternalBuffer);
298 /// Return an efficient buffer size for the underlying output mechanism.
299 virtual size_t preferred_buffer_size() const;
301 /// Return the beginning of the current stream buffer, or 0 if the stream is
303 const char *getBufferStart() const { return OutBufStart; }
305 //===--------------------------------------------------------------------===//
307 //===--------------------------------------------------------------------===//
309 /// Install the given buffer and mode.
310 void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
312 /// Flush the current buffer, which is known to be non-empty. This outputs the
313 /// currently buffered data and resets the buffer to empty.
314 void flush_nonempty();
316 /// Copy data into the buffer. Size must not be greater than the number of
317 /// unused bytes in the buffer.
318 void copy_to_buffer(const char *Ptr, size_t Size);
321 /// An abstract base class for streams implementations that also support a
322 /// pwrite operation. This is useful for code that can mostly stream out data,
323 /// but needs to patch in a header that needs to know the output size.
324 class raw_pwrite_stream : public raw_ostream {
325 virtual void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) = 0;
328 explicit raw_pwrite_stream(bool Unbuffered = false)
329 : raw_ostream(Unbuffered) {}
330 void pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
332 uint64_t Pos = tell();
333 // /dev/null always reports a pos of 0, so we cannot perform this check
336 assert(Size + Offset <= Pos && "We don't support extending the stream");
338 pwrite_impl(Ptr, Size, Offset);
342 //===----------------------------------------------------------------------===//
343 // File Output Streams
344 //===----------------------------------------------------------------------===//
346 /// A raw_ostream that writes to a file descriptor.
348 class raw_fd_ostream : public raw_pwrite_stream {
352 /// Error This flag is true if an error of any kind has been detected.
358 bool SupportsSeeking;
360 /// See raw_ostream::write_impl.
361 void write_impl(const char *Ptr, size_t Size) override;
363 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
365 /// Return the current position within the stream, not counting the bytes
366 /// currently in the buffer.
367 uint64_t current_pos() const override { return pos; }
369 /// Determine an efficient buffer size.
370 size_t preferred_buffer_size() const override;
372 /// Set the flag indicating that an output error has been encountered.
373 void error_detected() { Error = true; }
376 /// Open the specified file for writing. If an error occurs, information
377 /// about the error is put into EC, and the stream should be immediately
379 /// \p Flags allows optional flags to control how the file will be opened.
381 /// As a special case, if Filename is "-", then the stream will use
382 /// STDOUT_FILENO instead of opening a file. Note that it will still consider
383 /// itself to own the file descriptor. In particular, it will close the
384 /// file descriptor when it is done (this is necessary to detect
386 raw_fd_ostream(StringRef Filename, std::error_code &EC,
387 sys::fs::OpenFlags Flags);
389 /// FD is the file descriptor that this writes to. If ShouldClose is true,
390 /// this closes the file when the stream is destroyed.
391 raw_fd_ostream(int fd, bool shouldClose, bool unbuffered=false);
393 ~raw_fd_ostream() override;
395 /// Manually flush the stream and close the file. Note that this does not call
399 bool supportsSeeking() { return SupportsSeeking; }
401 /// Flushes the stream and repositions the underlying file descriptor position
402 /// to the offset specified from the beginning of the file.
403 uint64_t seek(uint64_t off);
405 raw_ostream &changeColor(enum Colors colors, bool bold=false,
406 bool bg=false) override;
407 raw_ostream &resetColor() override;
409 raw_ostream &reverseColor() override;
411 bool is_displayed() const override;
413 bool has_colors() const override;
415 /// Return the value of the flag in this raw_fd_ostream indicating whether an
416 /// output error has been encountered.
417 /// This doesn't implicitly flush any pending output. Also, it doesn't
418 /// guarantee to detect all errors unless the stream has been closed.
419 bool has_error() const {
423 /// Set the flag read by has_error() to false. If the error flag is set at the
424 /// time when this raw_ostream's destructor is called, report_fatal_error is
425 /// called to report the error. Use clear_error() after handling the error to
426 /// avoid this behavior.
428 /// "Errors should never pass silently.
429 /// Unless explicitly silenced."
430 /// - from The Zen of Python, by Tim Peters
437 /// This returns a reference to a raw_ostream for standard output. Use it like:
438 /// outs() << "foo" << "bar";
441 /// This returns a reference to a raw_ostream for standard error. Use it like:
442 /// errs() << "foo" << "bar";
445 /// This returns a reference to a raw_ostream which simply discards output.
446 raw_ostream &nulls();
448 //===----------------------------------------------------------------------===//
449 // Output Stream Adaptors
450 //===----------------------------------------------------------------------===//
452 /// A raw_ostream that writes to an std::string. This is a simple adaptor
453 /// class. This class does not encounter output errors.
454 class raw_string_ostream : public raw_ostream {
457 /// See raw_ostream::write_impl.
458 void write_impl(const char *Ptr, size_t Size) override;
460 /// Return the current position within the stream, not counting the bytes
461 /// currently in the buffer.
462 uint64_t current_pos() const override { return OS.size(); }
465 explicit raw_string_ostream(std::string &O) : OS(O) {}
466 ~raw_string_ostream() override;
468 /// Flushes the stream contents to the target string and returns the string's
476 /// A raw_ostream that writes to an SmallVector or SmallString. This is a
477 /// simple adaptor class. This class does not encounter output errors.
478 /// raw_svector_ostream operates without a buffer, delegating all memory
479 /// management to the SmallString. Thus the SmallString is always up-to-date,
480 /// may be used directly and there is no need to call flush().
481 class raw_svector_ostream : public raw_pwrite_stream {
482 SmallVectorImpl<char> &OS;
484 /// See raw_ostream::write_impl.
485 void write_impl(const char *Ptr, size_t Size) override;
487 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
489 /// Return the current position within the stream.
490 uint64_t current_pos() const override;
493 /// Construct a new raw_svector_ostream.
495 /// \param O The vector to write to; this should generally have at least 128
496 /// bytes free to avoid any extraneous memory overhead.
497 explicit raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
500 ~raw_svector_ostream() override {}
502 void flush() = delete;
504 /// Return a StringRef for the vector contents.
505 StringRef str() { return StringRef(OS.data(), OS.size()); }
508 /// A raw_ostream that discards all output.
509 class raw_null_ostream : public raw_pwrite_stream {
510 /// See raw_ostream::write_impl.
511 void write_impl(const char *Ptr, size_t size) override;
512 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
514 /// Return the current position within the stream, not counting the bytes
515 /// currently in the buffer.
516 uint64_t current_pos() const override;
519 explicit raw_null_ostream() {}
520 ~raw_null_ostream() override;
523 class buffer_ostream : public raw_svector_ostream {
525 SmallVector<char, 0> Buffer;
528 buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer), OS(OS) {}
529 ~buffer_ostream() override { OS << str(); }
532 } // end llvm namespace
534 #endif // LLVM_SUPPORT_RAW_OSTREAM_H