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;
26 template <typename T> class SmallVectorImpl;
30 enum OpenFlags : unsigned;
34 /// This class implements an extremely fast bulk output stream that can *only*
35 /// output to a stream. It does not support seeking, reopening, rewinding, line
36 /// buffered disciplines etc. It is a simple buffer that outputs
37 /// a chunk at a time.
40 void operator=(const raw_ostream &) = delete;
41 raw_ostream(const raw_ostream &) = delete;
43 /// The buffer is handled in such a way that the buffer is
44 /// uninitialized, unbuffered, or out of space when OutBufCur >=
45 /// OutBufEnd. Thus a single comparison suffices to determine if we
46 /// need to take the slow path to write a single character.
48 /// The buffer is in one of three states:
49 /// 1. Unbuffered (BufferMode == Unbuffered)
50 /// 1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
51 /// 2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
52 /// OutBufEnd - OutBufStart >= 1).
54 /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
55 /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
56 /// managed by the subclass.
58 /// If a subclass installs an external buffer using SetBuffer then it can wait
59 /// for a \see write_impl() call to handle the data which has been put into
61 char *OutBufStart, *OutBufEnd, *OutBufCur;
70 // color order matches ANSI escape sequence, don't change
83 explicit raw_ostream(bool unbuffered = false)
84 : BufferMode(unbuffered ? Unbuffered : InternalBuffer) {
85 // Start out ready to flush.
86 OutBufStart = OutBufEnd = OutBufCur = nullptr;
89 virtual ~raw_ostream();
91 /// tell - Return the current offset with the file.
92 uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); }
94 //===--------------------------------------------------------------------===//
95 // Configuration Interface
96 //===--------------------------------------------------------------------===//
98 /// Set the stream to be buffered, with an automatically determined buffer
102 /// Set the stream to be buffered, using the specified buffer size.
103 void SetBufferSize(size_t Size) {
105 SetBufferAndMode(new char[Size], Size, InternalBuffer);
108 size_t GetBufferSize() const {
109 // If we're supposed to be buffered but haven't actually gotten around
110 // to allocating the buffer yet, return the value that would be used.
111 if (BufferMode != Unbuffered && OutBufStart == nullptr)
112 return preferred_buffer_size();
114 // Otherwise just return the size of the allocated buffer.
115 return OutBufEnd - OutBufStart;
118 /// Set the stream to be unbuffered. When unbuffered, the stream will flush
119 /// after every write. This routine will also flush the buffer immediately
120 /// when the stream is being set to unbuffered.
121 void SetUnbuffered() {
123 SetBufferAndMode(nullptr, 0, Unbuffered);
126 size_t GetNumBytesInBuffer() const {
127 return OutBufCur - OutBufStart;
130 //===--------------------------------------------------------------------===//
131 // Data Output Interface
132 //===--------------------------------------------------------------------===//
135 if (OutBufCur != OutBufStart)
139 raw_ostream &operator<<(char C) {
140 if (OutBufCur >= OutBufEnd)
146 raw_ostream &operator<<(unsigned char C) {
147 if (OutBufCur >= OutBufEnd)
153 raw_ostream &operator<<(signed char C) {
154 if (OutBufCur >= OutBufEnd)
160 raw_ostream &operator<<(StringRef Str) {
161 // Inline fast path, particularly for strings with a known length.
162 size_t Size = Str.size();
164 // Make sure we can use the fast path.
165 if (Size > (size_t)(OutBufEnd - OutBufCur))
166 return write(Str.data(), Size);
168 memcpy(OutBufCur, Str.data(), Size);
173 raw_ostream &operator<<(const char *Str) {
174 // Inline fast path, particularly for constant strings where a sufficiently
175 // smart compiler will simplify strlen.
177 return this->operator<<(StringRef(Str));
180 raw_ostream &operator<<(const std::string &Str) {
181 // Avoid the fast path, it would only increase code size for a marginal win.
182 return write(Str.data(), Str.length());
185 raw_ostream &operator<<(const llvm::SmallVectorImpl<char> &Str) {
186 return write(Str.data(), Str.size());
189 raw_ostream &operator<<(unsigned long N);
190 raw_ostream &operator<<(long N);
191 raw_ostream &operator<<(unsigned long long N);
192 raw_ostream &operator<<(long long N);
193 raw_ostream &operator<<(const void *P);
194 raw_ostream &operator<<(unsigned int N) {
195 return this->operator<<(static_cast<unsigned long>(N));
198 raw_ostream &operator<<(int N) {
199 return this->operator<<(static_cast<long>(N));
202 raw_ostream &operator<<(double N);
204 /// Output \p N in hexadecimal, without any prefix or padding.
205 raw_ostream &write_hex(unsigned long long N);
207 /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't
208 /// satisfy std::isprint into an escape sequence.
209 raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
211 raw_ostream &write(unsigned char C);
212 raw_ostream &write(const char *Ptr, size_t Size);
214 // Formatted output, see the format() function in Support/Format.h.
215 raw_ostream &operator<<(const format_object_base &Fmt);
217 // Formatted output, see the leftJustify() function in Support/Format.h.
218 raw_ostream &operator<<(const FormattedString &);
220 // Formatted output, see the formatHex() function in Support/Format.h.
221 raw_ostream &operator<<(const FormattedNumber &);
223 /// indent - Insert 'NumSpaces' spaces.
224 raw_ostream &indent(unsigned NumSpaces);
227 /// Changes the foreground color of text that will be output from this point
229 /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
230 /// change only the bold attribute, and keep colors untouched
231 /// @param Bold bold/brighter text, default false
232 /// @param BG if true change the background, default: change foreground
233 /// @returns itself so it can be used within << invocations
234 virtual raw_ostream &changeColor(enum Colors Color,
243 /// Resets the colors to terminal defaults. Call this when you are done
244 /// outputting colored text, or before program exit.
245 virtual raw_ostream &resetColor() { return *this; }
247 /// Reverses the forground and background colors.
248 virtual raw_ostream &reverseColor() { return *this; }
250 /// This function determines if this stream is connected to a "tty" or
251 /// "console" window. That is, the output would be displayed to the user
252 /// rather than being put on a pipe or stored in a file.
253 virtual bool is_displayed() const { return false; }
255 /// This function determines if this stream is displayed and supports colors.
256 virtual bool has_colors() const { return is_displayed(); }
258 //===--------------------------------------------------------------------===//
259 // Subclass Interface
260 //===--------------------------------------------------------------------===//
263 /// The is the piece of the class that is implemented by subclasses. This
264 /// writes the \p Size bytes starting at
265 /// \p Ptr to the underlying stream.
267 /// This function is guaranteed to only be called at a point at which it is
268 /// safe for the subclass to install a new buffer via SetBuffer.
270 /// \param Ptr The start of the data to be written. For buffered streams this
271 /// is guaranteed to be the start of the buffer.
273 /// \param Size The number of bytes to be written.
275 /// \invariant { Size > 0 }
276 virtual void write_impl(const char *Ptr, size_t Size) = 0;
278 // An out of line virtual method to provide a home for the class vtable.
279 virtual void handle();
281 /// Return the current position within the stream, not counting the bytes
282 /// currently in the buffer.
283 virtual uint64_t current_pos() const = 0;
286 /// Use the provided buffer as the raw_ostream buffer. This is intended for
287 /// use only by subclasses which can arrange for the output to go directly
288 /// into the desired output buffer, instead of being copied on each flush.
289 void SetBuffer(char *BufferStart, size_t Size) {
290 SetBufferAndMode(BufferStart, Size, ExternalBuffer);
293 /// Return an efficient buffer size for the underlying output mechanism.
294 virtual size_t preferred_buffer_size() const;
296 /// Return the beginning of the current stream buffer, or 0 if the stream is
298 const char *getBufferStart() const { return OutBufStart; }
300 //===--------------------------------------------------------------------===//
302 //===--------------------------------------------------------------------===//
304 /// Install the given buffer and mode.
305 void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
307 /// Flush the current buffer, which is known to be non-empty. This outputs the
308 /// currently buffered data and resets the buffer to empty.
309 void flush_nonempty();
311 /// Copy data into the buffer. Size must not be greater than the number of
312 /// unused bytes in the buffer.
313 void copy_to_buffer(const char *Ptr, size_t Size);
316 //===----------------------------------------------------------------------===//
317 // File Output Streams
318 //===----------------------------------------------------------------------===//
320 /// A raw_ostream that writes to a file descriptor.
322 class raw_fd_ostream : public raw_ostream {
326 /// Error This flag is true if an error of any kind has been detected.
330 /// Controls whether the stream should attempt to use atomic writes, when
332 bool UseAtomicWrites;
336 bool SupportsSeeking;
338 /// See raw_ostream::write_impl.
339 void write_impl(const char *Ptr, size_t Size) override;
341 /// Return the current position within the stream, not counting the bytes
342 /// currently in the buffer.
343 uint64_t current_pos() const override { return pos; }
345 /// Determine an efficient buffer size.
346 size_t preferred_buffer_size() const override;
348 /// Set the flag indicating that an output error has been encountered.
349 void error_detected() { Error = true; }
352 /// Open the specified file for writing. If an error occurs, information
353 /// about the error is put into EC, and the stream should be immediately
355 /// \p Flags allows optional flags to control how the file will be opened.
357 /// As a special case, if Filename is "-", then the stream will use
358 /// STDOUT_FILENO instead of opening a file. Note that it will still consider
359 /// itself to own the file descriptor. In particular, it will close the
360 /// file descriptor when it is done (this is necessary to detect
362 raw_fd_ostream(StringRef Filename, std::error_code &EC,
363 sys::fs::OpenFlags Flags);
365 /// FD is the file descriptor that this writes to. If ShouldClose is true,
366 /// this closes the file when the stream is destroyed.
367 raw_fd_ostream(int fd, bool shouldClose, bool unbuffered=false);
369 ~raw_fd_ostream() override;
371 /// Manually flush the stream and close the file. Note that this does not call
375 bool supportsSeeking() { return SupportsSeeking; }
377 /// Flushes the stream and repositions the underlying file descriptor position
378 /// to the offset specified from the beginning of the file.
379 uint64_t seek(uint64_t off);
381 /// Set the stream to attempt to use atomic writes for individual output
382 /// routines where possible.
384 /// Note that because raw_ostream's are typically buffered, this flag is only
385 /// sensible when used on unbuffered streams which will flush their output
387 void SetUseAtomicWrites(bool Value) {
388 UseAtomicWrites = Value;
391 raw_ostream &changeColor(enum Colors colors, bool bold=false,
392 bool bg=false) override;
393 raw_ostream &resetColor() override;
395 raw_ostream &reverseColor() override;
397 bool is_displayed() const override;
399 bool has_colors() const override;
401 /// Return the value of the flag in this raw_fd_ostream indicating whether an
402 /// output error has been encountered.
403 /// This doesn't implicitly flush any pending output. Also, it doesn't
404 /// guarantee to detect all errors unless the stream has been closed.
405 bool has_error() const {
409 /// Set the flag read by has_error() to false. If the error flag is set at the
410 /// time when this raw_ostream's destructor is called, report_fatal_error is
411 /// called to report the error. Use clear_error() after handling the error to
412 /// avoid this behavior.
414 /// "Errors should never pass silently.
415 /// Unless explicitly silenced."
416 /// - from The Zen of Python, by Tim Peters
423 /// This returns a reference to a raw_ostream for standard output. Use it like:
424 /// outs() << "foo" << "bar";
427 /// This returns a reference to a raw_ostream for standard error. Use it like:
428 /// errs() << "foo" << "bar";
431 /// This returns a reference to a raw_ostream which simply discards output.
432 raw_ostream &nulls();
434 //===----------------------------------------------------------------------===//
435 // Output Stream Adaptors
436 //===----------------------------------------------------------------------===//
438 /// A raw_ostream that writes to an std::string. This is a simple adaptor
439 /// class. This class does not encounter output errors.
440 class raw_string_ostream : public raw_ostream {
443 /// See raw_ostream::write_impl.
444 void write_impl(const char *Ptr, size_t Size) override;
446 /// Return the current position within the stream, not counting the bytes
447 /// currently in the buffer.
448 uint64_t current_pos() const override { return OS.size(); }
450 explicit raw_string_ostream(std::string &O) : OS(O) {}
451 ~raw_string_ostream() override;
453 /// Flushes the stream contents to the target string and returns the string's
461 /// A raw_ostream that writes to an SmallVector or SmallString. This is a
462 /// simple adaptor class. This class does not encounter output errors.
463 class raw_svector_ostream : public raw_ostream {
464 SmallVectorImpl<char> &OS;
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;
473 /// Construct a new raw_svector_ostream.
475 /// \param O The vector to write to; this should generally have at least 128
476 /// bytes free to avoid any extraneous memory overhead.
477 explicit raw_svector_ostream(SmallVectorImpl<char> &O);
478 ~raw_svector_ostream() override;
480 /// This is called when the SmallVector we're appending to is changed outside
481 /// of the raw_svector_ostream's control. It is only safe to do this if the
482 /// raw_svector_ostream has previously been flushed.
485 /// Flushes the stream contents to the target vector and return a StringRef
486 /// for the vector contents.
490 /// A raw_ostream that discards all output.
491 class raw_null_ostream : public raw_ostream {
492 /// See raw_ostream::write_impl.
493 void write_impl(const char *Ptr, size_t size) override;
495 /// Return the current position within the stream, not counting the bytes
496 /// currently in the buffer.
497 uint64_t current_pos() const override;
500 explicit raw_null_ostream() {}
501 ~raw_null_ostream() override;
504 } // end llvm namespace