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1 //===--- raw_ostream.h - Raw output stream ----------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file defines the raw_ostream class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_RAW_OSTREAM_H
15 #define LLVM_SUPPORT_RAW_OSTREAM_H
16 
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/Support/DataTypes.h"
19 
20 namespace llvm {
21   class format_object_base;
22   template <typename T>
23   class SmallVectorImpl;
24 
25 /// raw_ostream - This class implements an extremely fast bulk output stream
26 /// that can *only* output to a stream.  It does not support seeking, reopening,
27 /// rewinding, line buffered disciplines etc. It is a simple buffer that outputs
28 /// a chunk at a time.
29 class raw_ostream {
30 private:
31   // Do not implement. raw_ostream is noncopyable.
32   void operator=(const raw_ostream &);
33   raw_ostream(const raw_ostream &);
34 
35   /// The buffer is handled in such a way that the buffer is
36   /// uninitialized, unbuffered, or out of space when OutBufCur >=
37   /// OutBufEnd. Thus a single comparison suffices to determine if we
38   /// need to take the slow path to write a single character.
39   ///
40   /// The buffer is in one of three states:
41   ///  1. Unbuffered (BufferMode == Unbuffered)
42   ///  1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
43   ///  2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
44   ///               OutBufEnd - OutBufStart >= 1).
45   ///
46   /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
47   /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
48   /// managed by the subclass.
49   ///
50   /// If a subclass installs an external buffer using SetBuffer then it can wait
51   /// for a \see write_impl() call to handle the data which has been put into
52   /// this buffer.
53   char *OutBufStart, *OutBufEnd, *OutBufCur;
54 
55   enum BufferKind {
56     Unbuffered = 0,
57     InternalBuffer,
58     ExternalBuffer
59   } BufferMode;
60 
61 public:
62   // color order matches ANSI escape sequence, don't change
63   enum Colors {
64     BLACK=0,
65     RED,
66     GREEN,
67     YELLOW,
68     BLUE,
69     MAGENTA,
70     CYAN,
71     WHITE,
72     SAVEDCOLOR
73   };
74 
75   explicit raw_ostream(bool unbuffered=false)
76     : BufferMode(unbuffered ? Unbuffered : InternalBuffer) {
77     // Start out ready to flush.
78     OutBufStart = OutBufEnd = OutBufCur = 0;
79   }
80 
81   virtual ~raw_ostream();
82 
83   /// tell - Return the current offset with the file.
tell()84   uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); }
85 
86   //===--------------------------------------------------------------------===//
87   // Configuration Interface
88   //===--------------------------------------------------------------------===//
89 
90   /// SetBuffered - Set the stream to be buffered, with an automatically
91   /// determined buffer size.
92   void SetBuffered();
93 
94   /// SetBufferSize - Set the stream to be buffered, using the
95   /// specified buffer size.
SetBufferSize(size_t Size)96   void SetBufferSize(size_t Size) {
97     flush();
98     SetBufferAndMode(new char[Size], Size, InternalBuffer);
99   }
100 
GetBufferSize()101   size_t GetBufferSize() const {
102     // If we're supposed to be buffered but haven't actually gotten around
103     // to allocating the buffer yet, return the value that would be used.
104     if (BufferMode != Unbuffered && OutBufStart == 0)
105       return preferred_buffer_size();
106 
107     // Otherwise just return the size of the allocated buffer.
108     return OutBufEnd - OutBufStart;
109   }
110 
111   /// SetUnbuffered - Set the stream to be unbuffered. When
112   /// unbuffered, the stream will flush after every write. This routine
113   /// will also flush the buffer immediately when the stream is being
114   /// set to unbuffered.
SetUnbuffered()115   void SetUnbuffered() {
116     flush();
117     SetBufferAndMode(0, 0, Unbuffered);
118   }
119 
GetNumBytesInBuffer()120   size_t GetNumBytesInBuffer() const {
121     return OutBufCur - OutBufStart;
122   }
123 
124   //===--------------------------------------------------------------------===//
125   // Data Output Interface
126   //===--------------------------------------------------------------------===//
127 
flush()128   void flush() {
129     if (OutBufCur != OutBufStart)
130       flush_nonempty();
131   }
132 
133   raw_ostream &operator<<(char C) {
134     if (OutBufCur >= OutBufEnd)
135       return write(C);
136     *OutBufCur++ = C;
137     return *this;
138   }
139 
140   raw_ostream &operator<<(unsigned char C) {
141     if (OutBufCur >= OutBufEnd)
142       return write(C);
143     *OutBufCur++ = C;
144     return *this;
145   }
146 
147   raw_ostream &operator<<(signed char C) {
148     if (OutBufCur >= OutBufEnd)
149       return write(C);
150     *OutBufCur++ = C;
151     return *this;
152   }
153 
154   raw_ostream &operator<<(StringRef Str) {
155     // Inline fast path, particularly for strings with a known length.
156     size_t Size = Str.size();
157 
158     // Make sure we can use the fast path.
159     if (OutBufCur+Size > OutBufEnd)
160       return write(Str.data(), Size);
161 
162     memcpy(OutBufCur, Str.data(), Size);
163     OutBufCur += Size;
164     return *this;
165   }
166 
167   raw_ostream &operator<<(const char *Str) {
168     // Inline fast path, particularly for constant strings where a sufficiently
169     // smart compiler will simplify strlen.
170 
171     return this->operator<<(StringRef(Str));
172   }
173 
174   raw_ostream &operator<<(const std::string &Str) {
175     // Avoid the fast path, it would only increase code size for a marginal win.
176     return write(Str.data(), Str.length());
177   }
178 
179   raw_ostream &operator<<(unsigned long N);
180   raw_ostream &operator<<(long N);
181   raw_ostream &operator<<(unsigned long long N);
182   raw_ostream &operator<<(long long N);
183   raw_ostream &operator<<(const void *P);
184   raw_ostream &operator<<(unsigned int N) {
185     return this->operator<<(static_cast<unsigned long>(N));
186   }
187 
188   raw_ostream &operator<<(int N) {
189     return this->operator<<(static_cast<long>(N));
190   }
191 
192   raw_ostream &operator<<(double N);
193 
194   /// write_hex - Output \arg N in hexadecimal, without any prefix or padding.
195   raw_ostream &write_hex(unsigned long long N);
196 
197   /// write_escaped - Output \arg Str, turning '\\', '\t', '\n', '"', and
198   /// anything that doesn't satisfy std::isprint into an escape sequence.
199   raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
200 
201   raw_ostream &write(unsigned char C);
202   raw_ostream &write(const char *Ptr, size_t Size);
203 
204   // Formatted output, see the format() function in Support/Format.h.
205   raw_ostream &operator<<(const format_object_base &Fmt);
206 
207   /// indent - Insert 'NumSpaces' spaces.
208   raw_ostream &indent(unsigned NumSpaces);
209 
210 
211   /// Changes the foreground color of text that will be output from this point
212   /// forward.
213   /// @param colors ANSI color to use, the special SAVEDCOLOR can be used to
214   /// change only the bold attribute, and keep colors untouched
215   /// @param bold bold/brighter text, default false
216   /// @param bg if true change the background, default: change foreground
217   /// @returns itself so it can be used within << invocations
218   virtual raw_ostream &changeColor(enum Colors, bool = false, bool = false) {
219     return *this; }
220 
221   /// Resets the colors to terminal defaults. Call this when you are done
222   /// outputting colored text, or before program exit.
resetColor()223   virtual raw_ostream &resetColor() { return *this; }
224 
225   /// This function determines if this stream is connected to a "tty" or
226   /// "console" window. That is, the output would be displayed to the user
227   /// rather than being put on a pipe or stored in a file.
is_displayed()228   virtual bool is_displayed() const { return false; }
229 
230   //===--------------------------------------------------------------------===//
231   // Subclass Interface
232   //===--------------------------------------------------------------------===//
233 
234 private:
235   /// write_impl - The is the piece of the class that is implemented
236   /// by subclasses.  This writes the \args Size bytes starting at
237   /// \arg Ptr to the underlying stream.
238   ///
239   /// This function is guaranteed to only be called at a point at which it is
240   /// safe for the subclass to install a new buffer via SetBuffer.
241   ///
242   /// \arg Ptr - The start of the data to be written. For buffered streams this
243   /// is guaranteed to be the start of the buffer.
244   /// \arg Size - The number of bytes to be written.
245   ///
246   /// \invariant { Size > 0 }
247   virtual void write_impl(const char *Ptr, size_t Size) = 0;
248 
249   // An out of line virtual method to provide a home for the class vtable.
250   virtual void handle();
251 
252   /// current_pos - Return the current position within the stream, not
253   /// counting the bytes currently in the buffer.
254   virtual uint64_t current_pos() const = 0;
255 
256 protected:
257   /// SetBuffer - Use the provided buffer as the raw_ostream buffer. This is
258   /// intended for use only by subclasses which can arrange for the output to go
259   /// directly into the desired output buffer, instead of being copied on each
260   /// flush.
SetBuffer(char * BufferStart,size_t Size)261   void SetBuffer(char *BufferStart, size_t Size) {
262     SetBufferAndMode(BufferStart, Size, ExternalBuffer);
263   }
264 
265   /// preferred_buffer_size - Return an efficient buffer size for the
266   /// underlying output mechanism.
267   virtual size_t preferred_buffer_size() const;
268 
269   /// getBufferStart - Return the beginning of the current stream buffer, or 0
270   /// if the stream is unbuffered.
getBufferStart()271   const char *getBufferStart() const { return OutBufStart; }
272 
273   //===--------------------------------------------------------------------===//
274   // Private Interface
275   //===--------------------------------------------------------------------===//
276 private:
277   /// SetBufferAndMode - Install the given buffer and mode.
278   void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
279 
280   /// flush_nonempty - Flush the current buffer, which is known to be
281   /// non-empty. This outputs the currently buffered data and resets
282   /// the buffer to empty.
283   void flush_nonempty();
284 
285   /// copy_to_buffer - Copy data into the buffer. Size must not be
286   /// greater than the number of unused bytes in the buffer.
287   void copy_to_buffer(const char *Ptr, size_t Size);
288 };
289 
290 //===----------------------------------------------------------------------===//
291 // File Output Streams
292 //===----------------------------------------------------------------------===//
293 
294 /// raw_fd_ostream - A raw_ostream that writes to a file descriptor.
295 ///
296 class raw_fd_ostream : public raw_ostream {
297   int FD;
298   bool ShouldClose;
299 
300   /// Error This flag is true if an error of any kind has been detected.
301   ///
302   bool Error;
303 
304   /// Controls whether the stream should attempt to use atomic writes, when
305   /// possible.
306   bool UseAtomicWrites;
307 
308   uint64_t pos;
309 
310   /// write_impl - See raw_ostream::write_impl.
311   virtual void write_impl(const char *Ptr, size_t Size);
312 
313   /// current_pos - Return the current position within the stream, not
314   /// counting the bytes currently in the buffer.
current_pos()315   virtual uint64_t current_pos() const { return pos; }
316 
317   /// preferred_buffer_size - Determine an efficient buffer size.
318   virtual size_t preferred_buffer_size() const;
319 
320   /// error_detected - Set the flag indicating that an output error has
321   /// been encountered.
error_detected()322   void error_detected() { Error = true; }
323 
324 public:
325 
326   enum {
327     /// F_Excl - When opening a file, this flag makes raw_fd_ostream
328     /// report an error if the file already exists.
329     F_Excl  = 1,
330 
331     /// F_Append - When opening a file, if it already exists append to the
332     /// existing file instead of returning an error.  This may not be specified
333     /// with F_Excl.
334     F_Append = 2,
335 
336     /// F_Binary - The file should be opened in binary mode on platforms that
337     /// make this distinction.
338     F_Binary = 4
339   };
340 
341   /// raw_fd_ostream - Open the specified file for writing. If an error occurs,
342   /// information about the error is put into ErrorInfo, and the stream should
343   /// be immediately destroyed; the string will be empty if no error occurred.
344   /// This allows optional flags to control how the file will be opened.
345   ///
346   /// As a special case, if Filename is "-", then the stream will use
347   /// STDOUT_FILENO instead of opening a file. Note that it will still consider
348   /// itself to own the file descriptor. In particular, it will close the
349   /// file descriptor when it is done (this is necessary to detect
350   /// output errors).
351   raw_fd_ostream(const char *Filename, std::string &ErrorInfo,
352                  unsigned Flags = 0);
353 
354   /// raw_fd_ostream ctor - FD is the file descriptor that this writes to.  If
355   /// ShouldClose is true, this closes the file when the stream is destroyed.
356   raw_fd_ostream(int fd, bool shouldClose, bool unbuffered=false);
357 
358   ~raw_fd_ostream();
359 
360   /// close - Manually flush the stream and close the file.
361   /// Note that this does not call fsync.
362   void close();
363 
364   /// seek - Flushes the stream and repositions the underlying file descriptor
365   /// position to the offset specified from the beginning of the file.
366   uint64_t seek(uint64_t off);
367 
368   /// SetUseAtomicWrite - Set the stream to attempt to use atomic writes for
369   /// individual output routines where possible.
370   ///
371   /// Note that because raw_ostream's are typically buffered, this flag is only
372   /// sensible when used on unbuffered streams which will flush their output
373   /// immediately.
SetUseAtomicWrites(bool Value)374   void SetUseAtomicWrites(bool Value) {
375     UseAtomicWrites = Value;
376   }
377 
378   virtual raw_ostream &changeColor(enum Colors colors, bool bold=false,
379                                    bool bg=false);
380   virtual raw_ostream &resetColor();
381 
382   virtual bool is_displayed() const;
383 
384   /// has_error - Return the value of the flag in this raw_fd_ostream indicating
385   /// whether an output error has been encountered.
386   /// This doesn't implicitly flush any pending output.  Also, it doesn't
387   /// guarantee to detect all errors unless the the stream has been closed.
has_error()388   bool has_error() const {
389     return Error;
390   }
391 
392   /// clear_error - Set the flag read by has_error() to false. If the error
393   /// flag is set at the time when this raw_ostream's destructor is called,
394   /// report_fatal_error is called to report the error. Use clear_error()
395   /// after handling the error to avoid this behavior.
396   ///
397   ///   "Errors should never pass silently.
398   ///    Unless explicitly silenced."
399   ///      - from The Zen of Python, by Tim Peters
400   ///
clear_error()401   void clear_error() {
402     Error = false;
403   }
404 };
405 
406 /// outs() - This returns a reference to a raw_ostream for standard output.
407 /// Use it like: outs() << "foo" << "bar";
408 raw_ostream &outs();
409 
410 /// errs() - This returns a reference to a raw_ostream for standard error.
411 /// Use it like: errs() << "foo" << "bar";
412 raw_ostream &errs();
413 
414 /// nulls() - This returns a reference to a raw_ostream which simply discards
415 /// output.
416 raw_ostream &nulls();
417 
418 //===----------------------------------------------------------------------===//
419 // Output Stream Adaptors
420 //===----------------------------------------------------------------------===//
421 
422 /// raw_string_ostream - A raw_ostream that writes to an std::string.  This is a
423 /// simple adaptor class. This class does not encounter output errors.
424 class raw_string_ostream : public raw_ostream {
425   std::string &OS;
426 
427   /// write_impl - See raw_ostream::write_impl.
428   virtual void write_impl(const char *Ptr, size_t Size);
429 
430   /// current_pos - Return the current position within the stream, not
431   /// counting the bytes currently in the buffer.
current_pos()432   virtual uint64_t current_pos() const { return OS.size(); }
433 public:
raw_string_ostream(std::string & O)434   explicit raw_string_ostream(std::string &O) : OS(O) {}
435   ~raw_string_ostream();
436 
437   /// str - Flushes the stream contents to the target string and returns
438   ///  the string's reference.
str()439   std::string& str() {
440     flush();
441     return OS;
442   }
443 };
444 
445 /// raw_svector_ostream - A raw_ostream that writes to an SmallVector or
446 /// SmallString.  This is a simple adaptor class. This class does not
447 /// encounter output errors.
448 class raw_svector_ostream : public raw_ostream {
449   SmallVectorImpl<char> &OS;
450 
451   /// write_impl - See raw_ostream::write_impl.
452   virtual void write_impl(const char *Ptr, size_t Size);
453 
454   /// current_pos - Return the current position within the stream, not
455   /// counting the bytes currently in the buffer.
456   virtual uint64_t current_pos() const;
457 public:
458   /// Construct a new raw_svector_ostream.
459   ///
460   /// \arg O - The vector to write to; this should generally have at least 128
461   /// bytes free to avoid any extraneous memory overhead.
462   explicit raw_svector_ostream(SmallVectorImpl<char> &O);
463   ~raw_svector_ostream();
464 
465   /// resync - This is called when the SmallVector we're appending to is changed
466   /// outside of the raw_svector_ostream's control.  It is only safe to do this
467   /// if the raw_svector_ostream has previously been flushed.
468   void resync();
469 
470   /// str - Flushes the stream contents to the target vector and return a
471   /// StringRef for the vector contents.
472   StringRef str();
473 };
474 
475 /// raw_null_ostream - A raw_ostream that discards all output.
476 class raw_null_ostream : public raw_ostream {
477   /// write_impl - See raw_ostream::write_impl.
478   virtual void write_impl(const char *Ptr, size_t size);
479 
480   /// current_pos - Return the current position within the stream, not
481   /// counting the bytes currently in the buffer.
482   virtual uint64_t current_pos() const;
483 
484 public:
raw_null_ostream()485   explicit raw_null_ostream() {}
486   ~raw_null_ostream();
487 };
488 
489 } // end llvm namespace
490 
491 #endif
492