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/SmallVector.h" 18 #include "llvm/ADT/StringRef.h" 19 #include <cassert> 20 #include <cstddef> 21 #include <cstdint> 22 #include <cstring> 23 #include <string> 24 #include <system_error> 25 26 namespace llvm { 27 28 class formatv_object_base; 29 class format_object_base; 30 class FormattedString; 31 class FormattedNumber; 32 class FormattedBytes; 33 34 namespace sys { 35 namespace fs { 36 enum OpenFlags : unsigned; 37 } // end namespace fs 38 } // end namespace sys 39 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. 44 class raw_ostream { 45 private: 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. 50 /// 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). 56 /// 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. 60 /// 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 63 /// this buffer. 64 char *OutBufStart, *OutBufEnd, *OutBufCur; 65 66 enum BufferKind { 67 Unbuffered = 0, 68 InternalBuffer, 69 ExternalBuffer 70 } BufferMode; 71 72 public: 73 // color order matches ANSI escape sequence, don't change 74 enum Colors { 75 BLACK = 0, 76 RED, 77 GREEN, 78 YELLOW, 79 BLUE, 80 MAGENTA, 81 CYAN, 82 WHITE, 83 SAVEDCOLOR 84 }; 85 86 explicit raw_ostream(bool unbuffered = false) 87 : BufferMode(unbuffered ? Unbuffered : InternalBuffer) { 88 // Start out ready to flush. 89 OutBufStart = OutBufEnd = OutBufCur = nullptr; 90 } 91 92 raw_ostream(const raw_ostream &) = delete; 93 void operator=(const raw_ostream &) = delete; 94 95 virtual ~raw_ostream(); 96 97 /// tell - Return the current offset with the file. 98 uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); } 99 100 //===--------------------------------------------------------------------===// 101 // Configuration Interface 102 //===--------------------------------------------------------------------===// 103 104 /// Set the stream to be buffered, with an automatically determined buffer 105 /// size. 106 void SetBuffered(); 107 108 /// Set the stream to be buffered, using the specified buffer size. 109 void SetBufferSize(size_t Size) { 110 flush(); 111 SetBufferAndMode(new char[Size], Size, InternalBuffer); 112 } 113 114 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(); 119 120 // Otherwise just return the size of the allocated buffer. 121 return OutBufEnd - OutBufStart; 122 } 123 124 /// 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() { 128 flush(); 129 SetBufferAndMode(nullptr, 0, Unbuffered); 130 } 131 132 size_t GetNumBytesInBuffer() const { 133 return OutBufCur - OutBufStart; 134 } 135 136 //===--------------------------------------------------------------------===// 137 // Data Output Interface 138 //===--------------------------------------------------------------------===// 139 140 void flush() { 141 if (OutBufCur != OutBufStart) 142 flush_nonempty(); 143 } 144 145 raw_ostream &operator<<(char C) { 146 if (OutBufCur >= OutBufEnd) 147 return write(C); 148 *OutBufCur++ = C; 149 return *this; 150 } 151 152 raw_ostream &operator<<(unsigned char C) { 153 if (OutBufCur >= OutBufEnd) 154 return write(C); 155 *OutBufCur++ = C; 156 return *this; 157 } 158 159 raw_ostream &operator<<(signed char C) { 160 if (OutBufCur >= OutBufEnd) 161 return write(C); 162 *OutBufCur++ = C; 163 return *this; 164 } 165 166 raw_ostream &operator<<(StringRef Str) { 167 // Inline fast path, particularly for strings with a known length. 168 size_t Size = Str.size(); 169 170 // Make sure we can use the fast path. 171 if (Size > (size_t)(OutBufEnd - OutBufCur)) 172 return write(Str.data(), Size); 173 174 if (Size) { 175 memcpy(OutBufCur, Str.data(), Size); 176 OutBufCur += Size; 177 } 178 return *this; 179 } 180 181 raw_ostream &operator<<(const char *Str) { 182 // Inline fast path, particularly for constant strings where a sufficiently 183 // smart compiler will simplify strlen. 184 185 return this->operator<<(StringRef(Str)); 186 } 187 188 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()); 191 } 192 193 raw_ostream &operator<<(const SmallVectorImpl<char> &Str) { 194 return write(Str.data(), Str.size()); 195 } 196 197 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); 202 203 raw_ostream &operator<<(unsigned int N) { 204 return this->operator<<(static_cast<unsigned long>(N)); 205 } 206 207 raw_ostream &operator<<(int N) { 208 return this->operator<<(static_cast<long>(N)); 209 } 210 211 raw_ostream &operator<<(double N); 212 213 /// Output \p N in hexadecimal, without any prefix or padding. 214 raw_ostream &write_hex(unsigned long long N); 215 216 /// Output a formatted UUID with dash separators. 217 using uuid_t = uint8_t[16]; 218 raw_ostream &write_uuid(const uuid_t UUID); 219 220 /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't 221 /// satisfy std::isprint into an escape sequence. 222 raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false); 223 224 raw_ostream &write(unsigned char C); 225 raw_ostream &write(const char *Ptr, size_t Size); 226 227 // Formatted output, see the format() function in Support/Format.h. 228 raw_ostream &operator<<(const format_object_base &Fmt); 229 230 // Formatted output, see the leftJustify() function in Support/Format.h. 231 raw_ostream &operator<<(const FormattedString &); 232 233 // Formatted output, see the formatHex() function in Support/Format.h. 234 raw_ostream &operator<<(const FormattedNumber &); 235 236 // Formatted output, see the formatv() function in Support/FormatVariadic.h. 237 raw_ostream &operator<<(const formatv_object_base &); 238 239 // Formatted output, see the format_bytes() function in Support/Format.h. 240 raw_ostream &operator<<(const FormattedBytes &); 241 242 /// indent - Insert 'NumSpaces' spaces. 243 raw_ostream &indent(unsigned NumSpaces); 244 245 /// Changes the foreground color of text that will be output from this point 246 /// forward. 247 /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to 248 /// change only the bold attribute, and keep colors untouched 249 /// @param Bold bold/brighter text, default false 250 /// @param BG if true change the background, default: change foreground 251 /// @returns itself so it can be used within << invocations 252 virtual raw_ostream &changeColor(enum Colors Color, 253 bool Bold = false, 254 bool BG = false) { 255 (void)Color; 256 (void)Bold; 257 (void)BG; 258 return *this; 259 } 260 261 /// Resets the colors to terminal defaults. Call this when you are done 262 /// outputting colored text, or before program exit. 263 virtual raw_ostream &resetColor() { return *this; } 264 265 /// Reverses the foreground and background colors. 266 virtual raw_ostream &reverseColor() { return *this; } 267 268 /// This function determines if this stream is connected to a "tty" or 269 /// "console" window. That is, the output would be displayed to the user 270 /// rather than being put on a pipe or stored in a file. 271 virtual bool is_displayed() const { return false; } 272 273 /// This function determines if this stream is displayed and supports colors. 274 virtual bool has_colors() const { return is_displayed(); } 275 276 //===--------------------------------------------------------------------===// 277 // Subclass Interface 278 //===--------------------------------------------------------------------===// 279 280 private: 281 /// The is the piece of the class that is implemented by subclasses. This 282 /// writes the \p Size bytes starting at 283 /// \p Ptr to the underlying stream. 284 /// 285 /// This function is guaranteed to only be called at a point at which it is 286 /// safe for the subclass to install a new buffer via SetBuffer. 287 /// 288 /// \param Ptr The start of the data to be written. For buffered streams this 289 /// is guaranteed to be the start of the buffer. 290 /// 291 /// \param Size The number of bytes to be written. 292 /// 293 /// \invariant { Size > 0 } 294 virtual void write_impl(const char *Ptr, size_t Size) = 0; 295 296 // An out of line virtual method to provide a home for the class vtable. 297 virtual void handle(); 298 299 /// Return the current position within the stream, not counting the bytes 300 /// currently in the buffer. 301 virtual uint64_t current_pos() const = 0; 302 303 protected: 304 /// Use the provided buffer as the raw_ostream buffer. This is intended for 305 /// use only by subclasses which can arrange for the output to go directly 306 /// into the desired output buffer, instead of being copied on each flush. 307 void SetBuffer(char *BufferStart, size_t Size) { 308 SetBufferAndMode(BufferStart, Size, ExternalBuffer); 309 } 310 311 /// Return an efficient buffer size for the underlying output mechanism. 312 virtual size_t preferred_buffer_size() const; 313 314 /// Return the beginning of the current stream buffer, or 0 if the stream is 315 /// unbuffered. 316 const char *getBufferStart() const { return OutBufStart; } 317 318 //===--------------------------------------------------------------------===// 319 // Private Interface 320 //===--------------------------------------------------------------------===// 321 private: 322 /// Install the given buffer and mode. 323 void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode); 324 325 /// Flush the current buffer, which is known to be non-empty. This outputs the 326 /// currently buffered data and resets the buffer to empty. 327 void flush_nonempty(); 328 329 /// Copy data into the buffer. Size must not be greater than the number of 330 /// unused bytes in the buffer. 331 void copy_to_buffer(const char *Ptr, size_t Size); 332 }; 333 334 /// An abstract base class for streams implementations that also support a 335 /// pwrite operation. This is useful for code that can mostly stream out data, 336 /// but needs to patch in a header that needs to know the output size. 337 class raw_pwrite_stream : public raw_ostream { 338 virtual void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) = 0; 339 340 public: 341 explicit raw_pwrite_stream(bool Unbuffered = false) 342 : raw_ostream(Unbuffered) {} 343 void pwrite(const char *Ptr, size_t Size, uint64_t Offset) { 344 #ifndef NDBEBUG 345 uint64_t Pos = tell(); 346 // /dev/null always reports a pos of 0, so we cannot perform this check 347 // in that case. 348 if (Pos) 349 assert(Size + Offset <= Pos && "We don't support extending the stream"); 350 #endif 351 pwrite_impl(Ptr, Size, Offset); 352 } 353 }; 354 355 //===----------------------------------------------------------------------===// 356 // File Output Streams 357 //===----------------------------------------------------------------------===// 358 359 /// A raw_ostream that writes to a file descriptor. 360 /// 361 class raw_fd_ostream : public raw_pwrite_stream { 362 int FD; 363 bool ShouldClose; 364 365 /// Error This flag is true if an error of any kind has been detected. 366 /// 367 bool Error; 368 369 uint64_t pos; 370 371 bool SupportsSeeking; 372 373 /// See raw_ostream::write_impl. 374 void write_impl(const char *Ptr, size_t Size) override; 375 376 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override; 377 378 /// Return the current position within the stream, not counting the bytes 379 /// currently in the buffer. 380 uint64_t current_pos() const override { return pos; } 381 382 /// Determine an efficient buffer size. 383 size_t preferred_buffer_size() const override; 384 385 /// Set the flag indicating that an output error has been encountered. 386 void error_detected() { Error = true; } 387 388 public: 389 /// Open the specified file for writing. If an error occurs, information 390 /// about the error is put into EC, and the stream should be immediately 391 /// destroyed; 392 /// \p Flags allows optional flags to control how the file will be opened. 393 /// 394 /// As a special case, if Filename is "-", then the stream will use 395 /// STDOUT_FILENO instead of opening a file. This will not close the stdout 396 /// descriptor. 397 raw_fd_ostream(StringRef Filename, std::error_code &EC, 398 sys::fs::OpenFlags Flags); 399 400 /// FD is the file descriptor that this writes to. If ShouldClose is true, 401 /// this closes the file when the stream is destroyed. If FD is for stdout or 402 /// stderr, it will not be closed. 403 raw_fd_ostream(int fd, bool shouldClose, bool unbuffered=false); 404 405 ~raw_fd_ostream() override; 406 407 /// Manually flush the stream and close the file. Note that this does not call 408 /// fsync. 409 void close(); 410 411 bool supportsSeeking() { return SupportsSeeking; } 412 413 /// Flushes the stream and repositions the underlying file descriptor position 414 /// to the offset specified from the beginning of the file. 415 uint64_t seek(uint64_t off); 416 417 raw_ostream &changeColor(enum Colors colors, bool bold=false, 418 bool bg=false) override; 419 raw_ostream &resetColor() override; 420 421 raw_ostream &reverseColor() override; 422 423 bool is_displayed() const override; 424 425 bool has_colors() const override; 426 427 /// Return the value of the flag in this raw_fd_ostream indicating whether an 428 /// output error has been encountered. 429 /// This doesn't implicitly flush any pending output. Also, it doesn't 430 /// guarantee to detect all errors unless the stream has been closed. 431 bool has_error() const { 432 return Error; 433 } 434 435 /// Set the flag read by has_error() to false. If the error flag is set at the 436 /// time when this raw_ostream's destructor is called, report_fatal_error is 437 /// called to report the error. Use clear_error() after handling the error to 438 /// avoid this behavior. 439 /// 440 /// "Errors should never pass silently. 441 /// Unless explicitly silenced." 442 /// - from The Zen of Python, by Tim Peters 443 /// 444 void clear_error() { 445 Error = false; 446 } 447 }; 448 449 /// This returns a reference to a raw_ostream for standard output. Use it like: 450 /// outs() << "foo" << "bar"; 451 raw_ostream &outs(); 452 453 /// This returns a reference to a raw_ostream for standard error. Use it like: 454 /// errs() << "foo" << "bar"; 455 raw_ostream &errs(); 456 457 /// This returns a reference to a raw_ostream which simply discards output. 458 raw_ostream &nulls(); 459 460 //===----------------------------------------------------------------------===// 461 // Output Stream Adaptors 462 //===----------------------------------------------------------------------===// 463 464 /// A raw_ostream that writes to an std::string. This is a simple adaptor 465 /// class. This class does not encounter output errors. 466 class raw_string_ostream : public raw_ostream { 467 std::string &OS; 468 469 /// See raw_ostream::write_impl. 470 void write_impl(const char *Ptr, size_t Size) override; 471 472 /// Return the current position within the stream, not counting the bytes 473 /// currently in the buffer. 474 uint64_t current_pos() const override { return OS.size(); } 475 476 public: 477 explicit raw_string_ostream(std::string &O) : OS(O) {} 478 ~raw_string_ostream() override; 479 480 /// Flushes the stream contents to the target string and returns the string's 481 /// reference. 482 std::string& str() { 483 flush(); 484 return OS; 485 } 486 }; 487 488 /// A raw_ostream that writes to an SmallVector or SmallString. This is a 489 /// simple adaptor class. This class does not encounter output errors. 490 /// raw_svector_ostream operates without a buffer, delegating all memory 491 /// management to the SmallString. Thus the SmallString is always up-to-date, 492 /// may be used directly and there is no need to call flush(). 493 class raw_svector_ostream : public raw_pwrite_stream { 494 SmallVectorImpl<char> &OS; 495 496 /// See raw_ostream::write_impl. 497 void write_impl(const char *Ptr, size_t Size) override; 498 499 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override; 500 501 /// Return the current position within the stream. 502 uint64_t current_pos() const override; 503 504 public: 505 /// Construct a new raw_svector_ostream. 506 /// 507 /// \param O The vector to write to; this should generally have at least 128 508 /// bytes free to avoid any extraneous memory overhead. 509 explicit raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) { 510 SetUnbuffered(); 511 } 512 513 ~raw_svector_ostream() override = default; 514 515 void flush() = delete; 516 517 /// Return a StringRef for the vector contents. 518 StringRef str() { return StringRef(OS.data(), OS.size()); } 519 }; 520 521 /// A raw_ostream that discards all output. 522 class raw_null_ostream : public raw_pwrite_stream { 523 /// See raw_ostream::write_impl. 524 void write_impl(const char *Ptr, size_t size) override; 525 void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override; 526 527 /// Return the current position within the stream, not counting the bytes 528 /// currently in the buffer. 529 uint64_t current_pos() const override; 530 531 public: 532 explicit raw_null_ostream() = default; 533 ~raw_null_ostream() override; 534 }; 535 536 class buffer_ostream : public raw_svector_ostream { 537 raw_ostream &OS; 538 SmallVector<char, 0> Buffer; 539 540 public: 541 buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer), OS(OS) {} 542 ~buffer_ostream() override { OS << str(); } 543 }; 544 545 } // end namespace llvm 546 547 #endif // LLVM_SUPPORT_RAW_OSTREAM_H 548