src/llvm/include/llvm/Support/raw_ostream.h

   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/Compiler.h"
  19 #include "llvm/Support/DataTypes.h"
  20 #include <system_error>
  21
  22 namespace llvm {
  23   class format_object_base;
  24   class FormattedString;
  25   class FormattedNumber;
  26   template <typename T>
  27   class SmallVectorImpl;
  28
  29   namespace sys {
  30     namespace fs {
  31       enum OpenFlags : unsigned;
  32     }
  33   }
  34
  35 /// raw_ostream - This class implements an extremely fast bulk output stream
  36 /// that can *only* output to a stream.  It does not support seeking, reopening,
  37 /// rewinding, line buffered disciplines etc. It is a simple buffer that outputs
  38 /// a chunk at a time.
  39 class raw_ostream {
  40 private:
  41   void operator=(const raw_ostream &) LLVM_DELETED_FUNCTION;
  42   raw_ostream(const raw_ostream &) LLVM_DELETED_FUNCTION;
  43
  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.
  48   ///
  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).
  54   ///
  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.
  58   ///
  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
  61   /// this buffer.
  62   char *OutBufStart, *OutBufEnd, *OutBufCur;
  63
  64   enum BufferKind {
  65     Unbuffered = 0,
  66     InternalBuffer,
  67     ExternalBuffer
  68   } BufferMode;
  69
  70 public:
  71   // color order matches ANSI escape sequence, don't change
  72   enum Colors {
  73     BLACK=0,
  74     RED,
  75     GREEN,
  76     YELLOW,
  77     BLUE,
  78     MAGENTA,
  79     CYAN,
  80     WHITE,
  81     SAVEDCOLOR
  82   };
  83
  84   explicit raw_ostream(bool unbuffered=false)
  85     : BufferMode(unbuffered ? Unbuffered : InternalBuffer) {
  86     // Start out ready to flush.
  87     OutBufStart = OutBufEnd = OutBufCur = nullptr;
  88   }
  89
  90   virtual ~raw_ostream();
  91
  92   /// tell - Return the current offset with the file.
  93   uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); }
  94
  95   //===--------------------------------------------------------------------===//
  96   // Configuration Interface
  97   //===--------------------------------------------------------------------===//
  98
  99   /// SetBuffered - Set the stream to be buffered, with an automatically
 100   /// determined buffer size.
 101   void SetBuffered();
 102
 103   /// SetBufferSize - Set the stream to be buffered, using the
 104   /// specified buffer size.
 105   void SetBufferSize(size_t Size) {
 106     flush();
 107     SetBufferAndMode(new char[Size], Size, InternalBuffer);
 108   }
 109
 110   size_t GetBufferSize() const {
 111     // If we're supposed to be buffered but haven't actually gotten around
 112     // to allocating the buffer yet, return the value that would be used.
 113     if (BufferMode != Unbuffered && OutBufStart == nullptr)
 114       return preferred_buffer_size();
 115
 116     // Otherwise just return the size of the allocated buffer.
 117     return OutBufEnd - OutBufStart;
 118   }
 119
 120   /// SetUnbuffered - Set the stream to be unbuffered. When
 121   /// unbuffered, the stream will flush after every write. This routine
 122   /// will also flush the buffer immediately when the stream is being
 123   /// set to unbuffered.
 124   void SetUnbuffered() {
 125     flush();
 126     SetBufferAndMode(nullptr, 0, Unbuffered);
 127   }
 128
 129   size_t GetNumBytesInBuffer() const {
 130     return OutBufCur - OutBufStart;
 131   }
 132
 133   //===--------------------------------------------------------------------===//
 134   // Data Output Interface
 135   //===--------------------------------------------------------------------===//
 136
 137   void flush() {
 138     if (OutBufCur != OutBufStart)
 139       flush_nonempty();
 140   }
 141
 142   raw_ostream &operator<<(char C) {
 143     if (OutBufCur >= OutBufEnd)
 144       return write(C);
 145     *OutBufCur++ = C;
 146     return *this;
 147   }
 148
 149   raw_ostream &operator<<(unsigned char C) {
 150     if (OutBufCur >= OutBufEnd)
 151       return write(C);
 152     *OutBufCur++ = C;
 153     return *this;
 154   }
 155
 156   raw_ostream &operator<<(signed char C) {
 157     if (OutBufCur >= OutBufEnd)
 158       return write(C);
 159     *OutBufCur++ = C;
 160     return *this;
 161   }
 162
 163   raw_ostream &operator<<(StringRef Str) {
 164     // Inline fast path, particularly for strings with a known length.
 165     size_t Size = Str.size();
 166
 167     // Make sure we can use the fast path.
 168     if (Size > (size_t)(OutBufEnd - OutBufCur))
 169       return write(Str.data(), Size);
 170
 171     memcpy(OutBufCur, Str.data(), Size);
 172     OutBufCur += Size;
 173     return *this;
 174   }
 175
 176   raw_ostream &operator<<(const char *Str) {
 177     // Inline fast path, particularly for constant strings where a sufficiently
 178     // smart compiler will simplify strlen.
 179
 180     return this->operator<<(StringRef(Str));
 181   }
 182
 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());
 186   }
 187
 188   raw_ostream &operator<<(unsigned long N);
 189   raw_ostream &operator<<(long N);
 190   raw_ostream &operator<<(unsigned long long N);
 191   raw_ostream &operator<<(long long N);
 192   raw_ostream &operator<<(const void *P);
 193   raw_ostream &operator<<(unsigned int N) {
 194     return this->operator<<(static_cast<unsigned long>(N));
 195   }
 196
 197   raw_ostream &operator<<(int N) {
 198     return this->operator<<(static_cast<long>(N));
 199   }
 200
 201   raw_ostream &operator<<(double N);
 202
 203   /// write_hex - Output \p N in hexadecimal, without any prefix or padding.
 204   raw_ostream &write_hex(unsigned long long N);
 205
 206   /// write_escaped - Output \p Str, turning '\\', '\t', '\n', '"', and
 207   /// anything that doesn't satisfy std::isprint into an escape sequence.
 208   raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
 209
 210   raw_ostream &write(unsigned char C);
 211   raw_ostream &write(const char *Ptr, size_t Size);
 212
 213   // Formatted output, see the format() function in Support/Format.h.
 214   raw_ostream &operator<<(const format_object_base &Fmt);
 215
 216   // Formatted output, see the leftJustify() function in Support/Format.h.
 217   raw_ostream &operator<<(const FormattedString &);
 218
 219   // Formatted output, see the formatHex() function in Support/Format.h.
 220   raw_ostream &operator<<(const FormattedNumber &);
 221
 222   /// indent - Insert 'NumSpaces' spaces.
 223   raw_ostream &indent(unsigned NumSpaces);
 224
 225
 226   /// Changes the foreground color of text that will be output from this point
 227   /// forward.
 228   /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
 229   /// change only the bold attribute, and keep colors untouched
 230   /// @param Bold bold/brighter text, default false
 231   /// @param BG if true change the background, default: change foreground
 232   /// @returns itself so it can be used within << invocations
 233   virtual raw_ostream &changeColor(enum Colors Color,
 234                                    bool Bold = false,
 235                                    bool BG = false) {
 236     (void)Color;
 237     (void)Bold;
 238     (void)BG;
 239     return *this;
 240   }
 241
 242   /// Resets the colors to terminal defaults. Call this when you are done
 243   /// outputting colored text, or before program exit.
 244   virtual raw_ostream &resetColor() { return *this; }
 245
 246   /// Reverses the forground and background colors.
 247   virtual raw_ostream &reverseColor() { return *this; }
 248
 249   /// This function determines if this stream is connected to a "tty" or
 250   /// "console" window. That is, the output would be displayed to the user
 251   /// rather than being put on a pipe or stored in a file.
 252   virtual bool is_displayed() const { return false; }
 253
 254   /// This function determines if this stream is displayed and supports colors.
 255   virtual bool has_colors() const { return is_displayed(); }
 256
 257   //===--------------------------------------------------------------------===//
 258   // Subclass Interface
 259   //===--------------------------------------------------------------------===//
 260
 261 private:
 262   /// write_impl - The is the piece of the class that is implemented
 263   /// by subclasses.  This writes the \p Size bytes starting at
 264   /// \p Ptr to the underlying stream.
 265   ///
 266   /// This function is guaranteed to only be called at a point at which it is
 267   /// safe for the subclass to install a new buffer via SetBuffer.
 268   ///
 269   /// \param Ptr The start of the data to be written. For buffered streams this
 270   /// is guaranteed to be the start of the buffer.
 271   ///
 272   /// \param Size The number of bytes to be written.
 273   ///
 274   /// \invariant { Size > 0 }
 275   virtual void write_impl(const char *Ptr, size_t Size) = 0;
 276
 277   // An out of line virtual method to provide a home for the class vtable.
 278   virtual void handle();
 279
 280   /// current_pos - Return the current position within the stream, not
 281   /// counting the bytes currently in the buffer.
 282   virtual uint64_t current_pos() const = 0;
 283
 284 protected:
 285   /// SetBuffer - Use the provided buffer as the raw_ostream buffer. This is
 286   /// intended for use only by subclasses which can arrange for the output to go
 287   /// directly into the desired output buffer, instead of being copied on each
 288   /// flush.
 289   void SetBuffer(char *BufferStart, size_t Size) {
 290     SetBufferAndMode(BufferStart, Size, ExternalBuffer);
 291   }
 292
 293   /// preferred_buffer_size - Return an efficient buffer size for the
 294   /// underlying output mechanism.
 295   virtual size_t preferred_buffer_size() const;
 296
 297   /// getBufferStart - Return the beginning of the current stream buffer, or 0
 298   /// if the stream is unbuffered.
 299   const char *getBufferStart() const { return OutBufStart; }
 300
 301   //===--------------------------------------------------------------------===//
 302   // Private Interface
 303   //===--------------------------------------------------------------------===//
 304 private:
 305   /// SetBufferAndMode - Install the given buffer and mode.
 306   void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
 307
 308   /// flush_nonempty - Flush the current buffer, which is known to be
 309   /// non-empty. This outputs the currently buffered data and resets
 310   /// the buffer to empty.
 311   void flush_nonempty();
 312
 313   /// copy_to_buffer - Copy data into the buffer. Size must not be
 314   /// greater than the number of unused bytes in the buffer.
 315   void copy_to_buffer(const char *Ptr, size_t Size);
 316 };
 317
 318 //===----------------------------------------------------------------------===//
 319 // File Output Streams
 320 //===----------------------------------------------------------------------===//
 321
 322 /// raw_fd_ostream - A raw_ostream that writes to a file descriptor.
 323 ///
 324 class raw_fd_ostream : public raw_ostream {
 325   int FD;
 326   bool ShouldClose;
 327
 328   /// Error This flag is true if an error of any kind has been detected.
 329   ///
 330   bool Error;
 331
 332   /// Controls whether the stream should attempt to use atomic writes, when
 333   /// possible.
 334   bool UseAtomicWrites;
 335
 336   uint64_t pos;
 337
 338   /// write_impl - See raw_ostream::write_impl.
 339   void write_impl(const char *Ptr, size_t Size) override;
 340
 341   /// current_pos - Return the current position within the stream, not
 342   /// counting the bytes currently in the buffer.
 343   uint64_t current_pos() const override { return pos; }
 344
 345   /// preferred_buffer_size - Determine an efficient buffer size.
 346   size_t preferred_buffer_size() const override;
 347
 348   /// error_detected - Set the flag indicating that an output error has
 349   /// been encountered.
 350   void error_detected() { Error = true; }
 351
 352 public:
 353   /// Open the specified file for writing. If an error occurs, information
 354   /// about the error is put into EC, and the stream should be immediately
 355   /// destroyed;
 356   /// \p Flags allows optional flags to control how the file will be opened.
 357   ///
 358   /// As a special case, if Filename is "-", then the stream will use
 359   /// STDOUT_FILENO instead of opening a file. Note that it will still consider
 360   /// itself to own the file descriptor. In particular, it will close the
 361   /// file descriptor when it is done (this is necessary to detect
 362   /// output errors).
 363   raw_fd_ostream(StringRef Filename, std::error_code &EC,
 364                  sys::fs::OpenFlags Flags);
 365
 366   /// raw_fd_ostream ctor - FD is the file descriptor that this writes to.  If
 367   /// ShouldClose is true, this closes the file when the stream is destroyed.
 368   raw_fd_ostream(int fd, bool shouldClose, bool unbuffered=false);
 369
 370   ~raw_fd_ostream();
 371
 372   /// close - Manually flush the stream and close the file.
 373   /// Note that this does not call fsync.
 374   void close();
 375
 376   /// seek - Flushes the stream and repositions the underlying file descriptor
 377   /// position to the offset specified from the beginning of the file.
 378   uint64_t seek(uint64_t off);
 379
 380   /// SetUseAtomicWrite - Set the stream to attempt to use atomic writes for
 381   /// individual output routines where possible.
 382   ///
 383   /// Note that because raw_ostream's are typically buffered, this flag is only
 384   /// sensible when used on unbuffered streams which will flush their output
 385   /// immediately.
 386   void SetUseAtomicWrites(bool Value) {
 387     UseAtomicWrites = Value;
 388   }
 389
 390   raw_ostream &changeColor(enum Colors colors, bool bold=false,
 391                            bool bg=false) override;
 392   raw_ostream &resetColor() override;
 393
 394   raw_ostream &reverseColor() override;
 395
 396   bool is_displayed() const override;
 397
 398   bool has_colors() const override;
 399
 400   /// has_error - Return the value of the flag in this raw_fd_ostream indicating
 401   /// whether an output error has been encountered.
 402   /// This doesn't implicitly flush any pending output.  Also, it doesn't
 403   /// guarantee to detect all errors unless the stream has been closed.
 404   bool has_error() const {
 405     return Error;
 406   }
 407
 408   /// clear_error - Set the flag read by has_error() to false. If the error
 409   /// flag is set at the time when this raw_ostream's destructor is called,
 410   /// report_fatal_error is called to report the error. Use clear_error()
 411   /// after handling the error to avoid this behavior.
 412   ///
 413   ///   "Errors should never pass silently.
 414   ///    Unless explicitly silenced."
 415   ///      - from The Zen of Python, by Tim Peters
 416   ///
 417   void clear_error() {
 418     Error = false;
 419   }
 420 };
 421
 422 /// outs() - This returns a reference to a raw_ostream for standard output.
 423 /// Use it like: outs() << "foo" << "bar";
 424 raw_ostream &outs();
 425
 426 /// errs() - This returns a reference to a raw_ostream for standard error.
 427 /// Use it like: errs() << "foo" << "bar";
 428 raw_ostream &errs();
 429
 430 /// nulls() - This returns a reference to a raw_ostream which simply discards
 431 /// output.
 432 raw_ostream &nulls();
 433
 434 //===----------------------------------------------------------------------===//
 435 // Output Stream Adaptors
 436 //===----------------------------------------------------------------------===//
 437
 438 /// raw_string_ostream - A raw_ostream that writes to an std::string.  This is a
 439 /// simple adaptor class. This class does not encounter output errors.
 440 class raw_string_ostream : public raw_ostream {
 441   std::string &OS;
 442
 443   /// write_impl - See raw_ostream::write_impl.
 444   void write_impl(const char *Ptr, size_t Size) override;
 445
 446   /// current_pos - Return the current position within the stream, not
 447   /// counting the bytes currently in the buffer.
 448   uint64_t current_pos() const override { return OS.size(); }
 449 public:
 450   explicit raw_string_ostream(std::string &O) : OS(O) {}
 451   ~raw_string_ostream();
 452
 453   /// str - Flushes the stream contents to the target string and returns
 454   ///  the string's reference.
 455   std::string& str() {
 456     flush();
 457     return OS;
 458   }
 459 };
 460
 461 /// raw_svector_ostream - A raw_ostream that writes to an SmallVector or
 462 /// SmallString.  This is a simple adaptor class. This class does not
 463 /// encounter output errors.
 464 class raw_svector_ostream : public raw_ostream {
 465   SmallVectorImpl<char> &OS;
 466
 467   /// write_impl - See raw_ostream::write_impl.
 468   void write_impl(const char *Ptr, size_t Size) override;
 469
 470   /// current_pos - Return the current position within the stream, not
 471   /// counting the bytes currently in the buffer.
 472   uint64_t current_pos() const override;
 473 public:
 474   /// Construct a new raw_svector_ostream.
 475   ///
 476   /// \param O The vector to write to; this should generally have at least 128
 477   /// bytes free to avoid any extraneous memory overhead.
 478   explicit raw_svector_ostream(SmallVectorImpl<char> &O);
 479   ~raw_svector_ostream();
 480
 481   /// resync - This is called when the SmallVector we're appending to is changed
 482   /// outside of the raw_svector_ostream's control.  It is only safe to do this
 483   /// if the raw_svector_ostream has previously been flushed.
 484   void resync();
 485
 486   /// str - Flushes the stream contents to the target vector and return a
 487   /// StringRef for the vector contents.
 488   StringRef str();
 489 };
 490
 491 /// raw_null_ostream - A raw_ostream that discards all output.
 492 class raw_null_ostream : public raw_ostream {
 493   /// write_impl - See raw_ostream::write_impl.
 494   void write_impl(const char *Ptr, size_t size) override;
 495
 496   /// current_pos - Return the current position within the stream, not
 497   /// counting the bytes currently in the buffer.
 498   uint64_t current_pos() const override;
 499
 500 public:
 501   explicit raw_null_ostream() {}
 502   ~raw_null_ostream();
 503 };
 504
 505 } // end llvm namespace
 506
 507 #endif