lib/Support/raw_ostream.cpp

   1 //===--- raw_ostream.cpp - Implement the raw_ostream classes --------------===//
   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 implements support for bulk buffered stream output.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Support/raw_ostream.h"
  15 #include "llvm/Support/Format.h"
  16 #include "llvm/Support/Program.h"
  17 #include "llvm/Support/Process.h"
  18 #include "llvm/ADT/StringExtras.h"
  19 #include "llvm/ADT/SmallVector.h"
  20 #include "llvm/Config/config.h"
  21 #include "llvm/Support/Compiler.h"
  22 #include "llvm/Support/ErrorHandling.h"
  23 #include "llvm/ADT/STLExtras.h"
  24 #include <cctype>
  25 #include <cerrno>
  26 #include <sys/stat.h>
  27 #include <sys/types.h>
  28
  29 #if defined(HAVE_UNISTD_H)
  30 # include <unistd.h>
  31 #endif
  32 #if defined(HAVE_FCNTL_H)
  33 # include <fcntl.h>
  34 #endif
  35 #if defined(HAVE_SYS_UIO_H) && defined(HAVE_WRITEV)
  36 #  include <sys/uio.h>
  37 #endif
  38
  39 #if defined(__CYGWIN__)
  40 #include <io.h>
  41 #endif
  42
  43 #if defined(_MSC_VER)
  44 #include <io.h>
  45 #include <fcntl.h>
  46 #ifndef STDIN_FILENO
  47 # define STDIN_FILENO 0
  48 #endif
  49 #ifndef STDOUT_FILENO
  50 # define STDOUT_FILENO 1
  51 #endif
  52 #ifndef STDERR_FILENO
  53 # define STDERR_FILENO 2
  54 #endif
  55 #endif
  56
  57 using namespace llvm;
  58
  59 raw_ostream::~raw_ostream() {
  60   // raw_ostream's subclasses should take care to flush the buffer
  61   // in their destructors.
  62   assert(OutBufCur == OutBufStart &&
  63          "raw_ostream destructor called with non-empty buffer!");
  64
  65   if (BufferMode == InternalBuffer)
  66     delete [] OutBufStart;
  67 }
  68
  69 // An out of line virtual method to provide a home for the class vtable.
  70 void raw_ostream::handle() {}
  71
  72 size_t raw_ostream::preferred_buffer_size() const {
  73   // BUFSIZ is intended to be a reasonable default.
  74   return BUFSIZ;
  75 }
  76
  77 void raw_ostream::SetBuffered() {
  78   // Ask the subclass to determine an appropriate buffer size.
  79   if (size_t Size = preferred_buffer_size())
  80     SetBufferSize(Size);
  81   else
  82     // It may return 0, meaning this stream should be unbuffered.
  83     SetUnbuffered();
  84 }
  85
  86 void raw_ostream::SetBufferAndMode(char *BufferStart, size_t Size,
  87                                     BufferKind Mode) {
  88   assert(((Mode == Unbuffered && BufferStart == 0 && Size == 0) ||
  89           (Mode != Unbuffered && BufferStart && Size)) &&
  90          "stream must be unbuffered or have at least one byte");
  91   // Make sure the current buffer is free of content (we can't flush here; the
  92   // child buffer management logic will be in write_impl).
  93   assert(GetNumBytesInBuffer() == 0 && "Current buffer is non-empty!");
  94
  95   if (BufferMode == InternalBuffer)
  96     delete [] OutBufStart;
  97   OutBufStart = BufferStart;
  98   OutBufEnd = OutBufStart+Size;
  99   OutBufCur = OutBufStart;
 100   BufferMode = Mode;
 101
 102   assert(OutBufStart <= OutBufEnd && "Invalid size!");
 103 }
 104
 105 raw_ostream &raw_ostream::operator<<(unsigned long N) {
 106   // Zero is a special case.
 107   if (N == 0)
 108     return *this << '0';
 109
 110   char NumberBuffer[20];
 111   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
 112   char *CurPtr = EndPtr;
 113
 114   while (N) {
 115     *--CurPtr = '0' + char(N % 10);
 116     N /= 10;
 117   }
 118   return write(CurPtr, EndPtr-CurPtr);
 119 }
 120
 121 raw_ostream &raw_ostream::operator<<(long N) {
 122   if (N <  0) {
 123     *this << '-';
 124     N = -N;
 125   }
 126
 127   return this->operator<<(static_cast<unsigned long>(N));
 128 }
 129
 130 raw_ostream &raw_ostream::operator<<(unsigned long long N) {
 131   // Output using 32-bit div/mod when possible.
 132   if (N == static_cast<unsigned long>(N))
 133     return this->operator<<(static_cast<unsigned long>(N));
 134
 135   char NumberBuffer[20];
 136   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
 137   char *CurPtr = EndPtr;
 138
 139   while (N) {
 140     *--CurPtr = '0' + char(N % 10);
 141     N /= 10;
 142   }
 143   return write(CurPtr, EndPtr-CurPtr);
 144 }
 145
 146 raw_ostream &raw_ostream::operator<<(long long N) {
 147   if (N < 0) {
 148     *this << '-';
 149     // Avoid undefined behavior on INT64_MIN with a cast.
 150     N = -(unsigned long long)N;
 151   }
 152
 153   return this->operator<<(static_cast<unsigned long long>(N));
 154 }
 155
 156 raw_ostream &raw_ostream::write_hex(unsigned long long N) {
 157   // Zero is a special case.
 158   if (N == 0)
 159     return *this << '0';
 160
 161   char NumberBuffer[20];
 162   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
 163   char *CurPtr = EndPtr;
 164
 165   while (N) {
 166     uintptr_t x = N % 16;
 167     *--CurPtr = (x < 10 ? '0' + x : 'a' + x - 10);
 168     N /= 16;
 169   }
 170
 171   return write(CurPtr, EndPtr-CurPtr);
 172 }
 173
 174 raw_ostream &raw_ostream::write_escaped(StringRef Str,
 175                                         bool UseHexEscapes) {
 176   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 177     unsigned char c = Str[i];
 178
 179     switch (c) {
 180     case '\\':
 181       *this << '\\' << '\\';
 182       break;
 183     case '\t':
 184       *this << '\\' << 't';
 185       break;
 186     case '\n':
 187       *this << '\\' << 'n';
 188       break;
 189     case '"':
 190       *this << '\\' << '"';
 191       break;
 192     default:
 193       if (std::isprint(c)) {
 194         *this << c;
 195         break;
 196       }
 197
 198       // Write out the escaped representation.
 199       if (UseHexEscapes) {
 200         *this << '\\' << 'x';
 201         *this << hexdigit((c >> 4 & 0xF));
 202         *this << hexdigit((c >> 0) & 0xF);
 203       } else {
 204         // Always use a full 3-character octal escape.
 205         *this << '\\';
 206         *this << char('0' + ((c >> 6) & 7));
 207         *this << char('0' + ((c >> 3) & 7));
 208         *this << char('0' + ((c >> 0) & 7));
 209       }
 210     }
 211   }
 212
 213   return *this;
 214 }
 215
 216 raw_ostream &raw_ostream::operator<<(const void *P) {
 217   *this << '0' << 'x';
 218
 219   return write_hex((uintptr_t) P);
 220 }
 221
 222 raw_ostream &raw_ostream::operator<<(double N) {
 223 #ifdef _WIN32
 224   // On MSVCRT and compatible, output of %e is incompatible to Posix
 225   // by default. Number of exponent digits should be at least 2. "%+03d"
 226   // FIXME: Implement our formatter to here or Support/Format.h!
 227   int fpcl = _fpclass(N);
 228
 229   // negative zero
 230   if (fpcl == _FPCLASS_NZ)
 231     return *this << "-0.000000e+00";
 232
 233   char buf[16];
 234   unsigned len;
 235   len = snprintf(buf, sizeof(buf), "%e", N);
 236   if (len <= sizeof(buf) - 2) {
 237     if (len >= 5 && buf[len - 5] == 'e' && buf[len - 3] == '0') {
 238       int cs = buf[len - 4];
 239       if (cs == '+' || cs == '-') {
 240         int c1 = buf[len - 2];
 241         int c0 = buf[len - 1];
 242         if (isdigit(c1) && isdigit(c0)) {
 243           // Trim leading '0': "...e+012" -> "...e+12\0"
 244           buf[len - 3] = c1;
 245           buf[len - 2] = c0;
 246           buf[--len] = 0;
 247         }
 248       }
 249     }
 250     return this->operator<<(buf);
 251   }
 252 #endif
 253   return this->operator<<(format("%e", N));
 254 }
 255
 256
 257
 258 void raw_ostream::flush_nonempty() {
 259   assert(OutBufCur > OutBufStart && "Invalid call to flush_nonempty.");
 260   size_t Length = OutBufCur - OutBufStart;
 261   OutBufCur = OutBufStart;
 262   write_impl(OutBufStart, Length);
 263 }
 264
 265 raw_ostream &raw_ostream::write(unsigned char C) {
 266   // Group exceptional cases into a single branch.
 267   if (BUILTIN_EXPECT(OutBufCur >= OutBufEnd, false)) {
 268     if (BUILTIN_EXPECT(!OutBufStart, false)) {
 269       if (BufferMode == Unbuffered) {
 270         write_impl(reinterpret_cast<char*>(&C), 1);
 271         return *this;
 272       }
 273       // Set up a buffer and start over.
 274       SetBuffered();
 275       return write(C);
 276     }
 277
 278     flush_nonempty();
 279   }
 280
 281   *OutBufCur++ = C;
 282   return *this;
 283 }
 284
 285 raw_ostream &raw_ostream::write(const char *Ptr, size_t Size) {
 286   // Group exceptional cases into a single branch.
 287   if (BUILTIN_EXPECT(OutBufCur+Size > OutBufEnd, false)) {
 288     if (BUILTIN_EXPECT(!OutBufStart, false)) {
 289       if (BufferMode == Unbuffered) {
 290         write_impl(Ptr, Size);
 291         return *this;
 292       }
 293       // Set up a buffer and start over.
 294       SetBuffered();
 295       return write(Ptr, Size);
 296     }
 297
 298     size_t NumBytes = OutBufEnd - OutBufCur;
 299
 300     // If the buffer is empty at this point we have a string that is larger
 301     // than the buffer. Directly write the chunk that is a multiple of the
 302     // preferred buffer size and put the remainder in the buffer.
 303     if (BUILTIN_EXPECT(OutBufCur == OutBufStart, false)) {
 304       size_t BytesToWrite = Size - (Size % NumBytes);
 305       write_impl(Ptr, BytesToWrite);
 306       copy_to_buffer(Ptr + BytesToWrite, Size - BytesToWrite);
 307       return *this;
 308     }
 309
 310     // We don't have enough space in the buffer to fit the string in. Insert as
 311     // much as possible, flush and start over with the remainder.
 312     copy_to_buffer(Ptr, NumBytes);
 313     flush_nonempty();
 314     return write(Ptr + NumBytes, Size - NumBytes);
 315   }
 316
 317   copy_to_buffer(Ptr, Size);
 318
 319   return *this;
 320 }
 321
 322 void raw_ostream::copy_to_buffer(const char *Ptr, size_t Size) {
 323   assert(Size <= size_t(OutBufEnd - OutBufCur) && "Buffer overrun!");
 324
 325   // Handle short strings specially, memcpy isn't very good at very short
 326   // strings.
 327   switch (Size) {
 328   case 4: OutBufCur[3] = Ptr[3]; // FALL THROUGH
 329   case 3: OutBufCur[2] = Ptr[2]; // FALL THROUGH
 330   case 2: OutBufCur[1] = Ptr[1]; // FALL THROUGH
 331   case 1: OutBufCur[0] = Ptr[0]; // FALL THROUGH
 332   case 0: break;
 333   default:
 334     memcpy(OutBufCur, Ptr, Size);
 335     break;
 336   }
 337
 338   OutBufCur += Size;
 339 }
 340
 341 // Formatted output.
 342 raw_ostream &raw_ostream::operator<<(const format_object_base &Fmt) {
 343   // If we have more than a few bytes left in our output buffer, try
 344   // formatting directly onto its end.
 345   size_t NextBufferSize = 127;
 346   size_t BufferBytesLeft = OutBufEnd - OutBufCur;
 347   if (BufferBytesLeft > 3) {
 348     size_t BytesUsed = Fmt.print(OutBufCur, BufferBytesLeft);
 349
 350     // Common case is that we have plenty of space.
 351     if (BytesUsed <= BufferBytesLeft) {
 352       OutBufCur += BytesUsed;
 353       return *this;
 354     }
 355
 356     // Otherwise, we overflowed and the return value tells us the size to try
 357     // again with.
 358     NextBufferSize = BytesUsed;
 359   }
 360
 361   // If we got here, we didn't have enough space in the output buffer for the
 362   // string.  Try printing into a SmallVector that is resized to have enough
 363   // space.  Iterate until we win.
 364   SmallVector<char, 128> V;
 365
 366   while (1) {
 367     V.resize(NextBufferSize);
 368
 369     // Try formatting into the SmallVector.
 370     size_t BytesUsed = Fmt.print(V.data(), NextBufferSize);
 371
 372     // If BytesUsed fit into the vector, we win.
 373     if (BytesUsed <= NextBufferSize)
 374       return write(V.data(), BytesUsed);
 375
 376     // Otherwise, try again with a new size.
 377     assert(BytesUsed > NextBufferSize && "Didn't grow buffer!?");
 378     NextBufferSize = BytesUsed;
 379   }
 380 }
 381
 382 /// indent - Insert 'NumSpaces' spaces.
 383 raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
 384   static const char Spaces[] = "                                "
 385                                "                                "
 386                                "                ";
 387
 388   // Usually the indentation is small, handle it with a fastpath.
 389   if (NumSpaces < array_lengthof(Spaces))
 390     return write(Spaces, NumSpaces);
 391
 392   while (NumSpaces) {
 393     unsigned NumToWrite = std::min(NumSpaces,
 394                                    (unsigned)array_lengthof(Spaces)-1);
 395     write(Spaces, NumToWrite);
 396     NumSpaces -= NumToWrite;
 397   }
 398   return *this;
 399 }
 400
 401
 402 //===----------------------------------------------------------------------===//
 403 //  Formatted Output
 404 //===----------------------------------------------------------------------===//
 405
 406 // Out of line virtual method.
 407 void format_object_base::home() {
 408 }
 409
 410 //===----------------------------------------------------------------------===//
 411 //  raw_fd_ostream
 412 //===----------------------------------------------------------------------===//
 413
 414 /// raw_fd_ostream - Open the specified file for writing. If an error
 415 /// occurs, information about the error is put into ErrorInfo, and the
 416 /// stream should be immediately destroyed; the string will be empty
 417 /// if no error occurred.
 418 raw_fd_ostream::raw_fd_ostream(const char *Filename, std::string &ErrorInfo,
 419                                unsigned Flags)
 420   : Error(false), UseAtomicWrites(false), pos(0)
 421 {
 422   assert(Filename != 0 && "Filename is null");
 423   // Verify that we don't have both "append" and "excl".
 424   assert((!(Flags & F_Excl) || !(Flags & F_Append)) &&
 425          "Cannot specify both 'excl' and 'append' file creation flags!");
 426
 427   ErrorInfo.clear();
 428
 429   // Handle "-" as stdout. Note that when we do this, we consider ourself
 430   // the owner of stdout. This means that we can do things like close the
 431   // file descriptor when we're done and set the "binary" flag globally.
 432   if (Filename[0] == '-' && Filename[1] == 0) {
 433     FD = STDOUT_FILENO;
 434     // If user requested binary then put stdout into binary mode if
 435     // possible.
 436     if (Flags & F_Binary)
 437       sys::Program::ChangeStdoutToBinary();
 438     // Close stdout when we're done, to detect any output errors.
 439     ShouldClose = true;
 440     return;
 441   }
 442
 443   int OpenFlags = O_WRONLY|O_CREAT;
 444 #ifdef O_BINARY
 445   if (Flags & F_Binary)
 446     OpenFlags |= O_BINARY;
 447 #endif
 448
 449   if (Flags & F_Append)
 450     OpenFlags |= O_APPEND;
 451   else
 452     OpenFlags |= O_TRUNC;
 453   if (Flags & F_Excl)
 454     OpenFlags |= O_EXCL;
 455
 456   while ((FD = open(Filename, OpenFlags, 0664)) < 0) {
 457     if (errno != EINTR) {
 458       ErrorInfo = "Error opening output file '" + std::string(Filename) + "'";
 459       ShouldClose = false;
 460       return;
 461     }
 462   }
 463
 464   // Ok, we successfully opened the file, so it'll need to be closed.
 465   ShouldClose = true;
 466 }
 467
 468 /// raw_fd_ostream ctor - FD is the file descriptor that this writes to.  If
 469 /// ShouldClose is true, this closes the file when the stream is destroyed.
 470 raw_fd_ostream::raw_fd_ostream(int fd, bool shouldClose, bool unbuffered)
 471   : raw_ostream(unbuffered), FD(fd),
 472     ShouldClose(shouldClose), Error(false), UseAtomicWrites(false) {
 473 #ifdef O_BINARY
 474   // Setting STDOUT and STDERR to binary mode is necessary in Win32
 475   // to avoid undesirable linefeed conversion.
 476   if (fd == STDOUT_FILENO || fd == STDERR_FILENO)
 477     setmode(fd, O_BINARY);
 478 #endif
 479
 480   // Get the starting position.
 481   off_t loc = ::lseek(FD, 0, SEEK_CUR);
 482   if (loc == (off_t)-1)
 483     pos = 0;
 484   else
 485     pos = static_cast<uint64_t>(loc);
 486 }
 487
 488 raw_fd_ostream::~raw_fd_ostream() {
 489   if (FD >= 0) {
 490     flush();
 491     if (ShouldClose)
 492       while (::close(FD) != 0)
 493         if (errno != EINTR) {
 494           error_detected();
 495           break;
 496         }
 497   }
 498
 499 #ifdef __MINGW32__
 500   // On mingw, global dtors should not call exit().
 501   // report_fatal_error() invokes exit(). We know report_fatal_error()
 502   // might not write messages to stderr when any errors were detected
 503   // on FD == 2.
 504   if (FD == 2) return;
 505 #endif
 506
 507   // If there are any pending errors, report them now. Clients wishing
 508   // to avoid report_fatal_error calls should check for errors with
 509   // has_error() and clear the error flag with clear_error() before
 510   // destructing raw_ostream objects which may have errors.
 511   if (has_error())
 512     report_fatal_error("IO failure on output stream.");
 513 }
 514
 515
 516 void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
 517   assert(FD >= 0 && "File already closed.");
 518   pos += Size;
 519
 520   do {
 521     ssize_t ret;
 522
 523     // Check whether we should attempt to use atomic writes.
 524     if (BUILTIN_EXPECT(!UseAtomicWrites, true)) {
 525       ret = ::write(FD, Ptr, Size);
 526     } else {
 527       // Use ::writev() where available.
 528 #if defined(HAVE_WRITEV)
 529       struct iovec IOV = { (void*) Ptr, Size };
 530       ret = ::writev(FD, &IOV, 1);
 531 #else
 532       ret = ::write(FD, Ptr, Size);
 533 #endif
 534     }
 535
 536     if (ret < 0) {
 537       // If it's a recoverable error, swallow it and retry the write.
 538       //
 539       // Ideally we wouldn't ever see EAGAIN or EWOULDBLOCK here, since
 540       // raw_ostream isn't designed to do non-blocking I/O. However, some
 541       // programs, such as old versions of bjam, have mistakenly used
 542       // O_NONBLOCK. For compatibility, emulate blocking semantics by
 543       // spinning until the write succeeds. If you don't want spinning,
 544       // don't use O_NONBLOCK file descriptors with raw_ostream.
 545       if (errno == EINTR || errno == EAGAIN
 546 #ifdef EWOULDBLOCK
 547           || errno == EWOULDBLOCK
 548 #endif
 549           )
 550         continue;
 551
 552       // Otherwise it's a non-recoverable error. Note it and quit.
 553       error_detected();
 554       break;
 555     }
 556
 557     // The write may have written some or all of the data. Update the
 558     // size and buffer pointer to reflect the remainder that needs
 559     // to be written. If there are no bytes left, we're done.
 560     Ptr += ret;
 561     Size -= ret;
 562   } while (Size > 0);
 563 }
 564
 565 void raw_fd_ostream::close() {
 566   assert(ShouldClose);
 567   ShouldClose = false;
 568   flush();
 569   while (::close(FD) != 0)
 570     if (errno != EINTR) {
 571       error_detected();
 572       break;
 573     }
 574   FD = -1;
 575 }
 576
 577 uint64_t raw_fd_ostream::seek(uint64_t off) {
 578   flush();
 579   pos = ::lseek(FD, off, SEEK_SET);
 580   if (pos != off)
 581     error_detected();
 582   return pos;
 583 }
 584
 585 size_t raw_fd_ostream::preferred_buffer_size() const {
 586 #if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(__minix)
 587   // Windows and Minix have no st_blksize.
 588   assert(FD >= 0 && "File not yet open!");
 589   struct stat statbuf;
 590   if (fstat(FD, &statbuf) != 0)
 591     return 0;
 592
 593   // If this is a terminal, don't use buffering. Line buffering
 594   // would be a more traditional thing to do, but it's not worth
 595   // the complexity.
 596   if (S_ISCHR(statbuf.st_mode) && isatty(FD))
 597     return 0;
 598   // Return the preferred block size.
 599   return statbuf.st_blksize;
 600 #else
 601   return raw_ostream::preferred_buffer_size();
 602 #endif
 603 }
 604
 605 raw_ostream &raw_fd_ostream::changeColor(enum Colors colors, bool bold,
 606                                          bool bg) {
 607   if (sys::Process::ColorNeedsFlush())
 608     flush();
 609   const char *colorcode =
 610     (colors == SAVEDCOLOR) ? sys::Process::OutputBold(bg)
 611     : sys::Process::OutputColor(colors, bold, bg);
 612   if (colorcode) {
 613     size_t len = strlen(colorcode);
 614     write(colorcode, len);
 615     // don't account colors towards output characters
 616     pos -= len;
 617   }
 618   return *this;
 619 }
 620
 621 raw_ostream &raw_fd_ostream::resetColor() {
 622   if (sys::Process::ColorNeedsFlush())
 623     flush();
 624   const char *colorcode = sys::Process::ResetColor();
 625   if (colorcode) {
 626     size_t len = strlen(colorcode);
 627     write(colorcode, len);
 628     // don't account colors towards output characters
 629     pos -= len;
 630   }
 631   return *this;
 632 }
 633
 634 bool raw_fd_ostream::is_displayed() const {
 635   return sys::Process::FileDescriptorIsDisplayed(FD);
 636 }
 637
 638 //===----------------------------------------------------------------------===//
 639 //  outs(), errs(), nulls()
 640 //===----------------------------------------------------------------------===//
 641
 642 /// outs() - This returns a reference to a raw_ostream for standard output.
 643 /// Use it like: outs() << "foo" << "bar";
 644 raw_ostream &llvm::outs() {
 645   // Set buffer settings to model stdout behavior.
 646   // Delete the file descriptor when the program exists, forcing error
 647   // detection. If you don't want this behavior, don't use outs().
 648   static raw_fd_ostream S(STDOUT_FILENO, true);
 649   return S;
 650 }
 651
 652 /// errs() - This returns a reference to a raw_ostream for standard error.
 653 /// Use it like: errs() << "foo" << "bar";
 654 raw_ostream &llvm::errs() {
 655   // Set standard error to be unbuffered by default.
 656   static raw_fd_ostream S(STDERR_FILENO, false, true);
 657   return S;
 658 }
 659
 660 /// nulls() - This returns a reference to a raw_ostream which discards output.
 661 raw_ostream &llvm::nulls() {
 662   static raw_null_ostream S;
 663   return S;
 664 }
 665
 666
 667 //===----------------------------------------------------------------------===//
 668 //  raw_string_ostream
 669 //===----------------------------------------------------------------------===//
 670
 671 raw_string_ostream::~raw_string_ostream() {
 672   flush();
 673 }
 674
 675 void raw_string_ostream::write_impl(const char *Ptr, size_t Size) {
 676   OS.append(Ptr, Size);
 677 }
 678
 679 //===----------------------------------------------------------------------===//
 680 //  raw_svector_ostream
 681 //===----------------------------------------------------------------------===//
 682
 683 // The raw_svector_ostream implementation uses the SmallVector itself as the
 684 // buffer for the raw_ostream. We guarantee that the raw_ostream buffer is
 685 // always pointing past the end of the vector, but within the vector
 686 // capacity. This allows raw_ostream to write directly into the correct place,
 687 // and we only need to set the vector size when the data is flushed.
 688
 689 raw_svector_ostream::raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
 690   // Set up the initial external buffer. We make sure that the buffer has at
 691   // least 128 bytes free; raw_ostream itself only requires 64, but we want to
 692   // make sure that we don't grow the buffer unnecessarily on destruction (when
 693   // the data is flushed). See the FIXME below.
 694   OS.reserve(OS.size() + 128);
 695   SetBuffer(OS.end(), OS.capacity() - OS.size());
 696 }
 697
 698 raw_svector_ostream::~raw_svector_ostream() {
 699   // FIXME: Prevent resizing during this flush().
 700   flush();
 701 }
 702
 703 /// resync - This is called when the SmallVector we're appending to is changed
 704 /// outside of the raw_svector_ostream's control.  It is only safe to do this
 705 /// if the raw_svector_ostream has previously been flushed.
 706 void raw_svector_ostream::resync() {
 707   assert(GetNumBytesInBuffer() == 0 && "Didn't flush before mutating vector");
 708
 709   if (OS.capacity() - OS.size() < 64)
 710     OS.reserve(OS.capacity() * 2);
 711   SetBuffer(OS.end(), OS.capacity() - OS.size());
 712 }
 713
 714 void raw_svector_ostream::write_impl(const char *Ptr, size_t Size) {
 715   // If we're writing bytes from the end of the buffer into the smallvector, we
 716   // don't need to copy the bytes, just commit the bytes because they are
 717   // already in the right place.
 718   if (Ptr == OS.end()) {
 719     assert(OS.size() + Size <= OS.capacity() && "Invalid write_impl() call!");
 720     OS.set_size(OS.size() + Size);
 721   } else {
 722     assert(GetNumBytesInBuffer() == 0 &&
 723            "Should be writing from buffer if some bytes in it");
 724     // Otherwise, do copy the bytes.
 725     OS.append(Ptr, Ptr+Size);
 726   }
 727
 728   // Grow the vector if necessary.
 729   if (OS.capacity() - OS.size() < 64)
 730     OS.reserve(OS.capacity() * 2);
 731
 732   // Update the buffer position.
 733   SetBuffer(OS.end(), OS.capacity() - OS.size());
 734 }
 735
 736 uint64_t raw_svector_ostream::current_pos() const {
 737    return OS.size();
 738 }
 739
 740 StringRef raw_svector_ostream::str() {
 741   flush();
 742   return StringRef(OS.begin(), OS.size());
 743 }
 744
 745 //===----------------------------------------------------------------------===//
 746 //  raw_null_ostream
 747 //===----------------------------------------------------------------------===//
 748
 749 raw_null_ostream::~raw_null_ostream() {
 750 #ifndef NDEBUG
 751   // ~raw_ostream asserts that the buffer is empty. This isn't necessary
 752   // with raw_null_ostream, but it's better to have raw_null_ostream follow
 753   // the rules than to change the rules just for raw_null_ostream.
 754   flush();
 755 #endif
 756 }
 757
 758 void raw_null_ostream::write_impl(const char *Ptr, size_t Size) {
 759 }
 760
 761 uint64_t raw_null_ostream::current_pos() const {
 762   return 0;
 763 }