raw_ostream.h   [plain text]

//===--- raw_ostream.h - Raw output stream ----------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file defines the raw_ostream class.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_RAW_OSTREAM_H
#define LLVM_SUPPORT_RAW_OSTREAM_H

#include "llvm/ADT/StringExtras.h"
#include <cassert>
#include <cstring>
#include <string>
#include <iosfwd>

namespace llvm {
  class format_object_base;
  template <typename T>
  class SmallVectorImpl;

/// raw_ostream - This class implements an extremely fast bulk output stream
/// that can *only* output to a stream.  It does not support seeking, reopening,
/// rewinding, line buffered disciplines etc. It is a simple buffer that outputs
/// a chunk at a time.
class raw_ostream {
private:
  /// The buffer is handled in such a way that the buffer is
  /// uninitialized, unbuffered, or out of space when OutBufCur >=
  /// OutBufEnd. Thus a single comparison suffices to determine if we
  /// need to take the slow path to write a single character.
  ///
  /// The buffer is in one of three states:
  ///  1. Unbuffered (Unbuffered == true)
  ///  1. Uninitialized (Unbuffered == false && OutBufStart == 0).
  ///  2. Buffered (Unbuffered == false && OutBufStart != 0 &&
  ///               OutBufEnd - OutBufStart >= 64).
  char *OutBufStart, *OutBufEnd, *OutBufCur;
  bool Unbuffered;

public:
  explicit raw_ostream(bool unbuffered=false) : Unbuffered(unbuffered) {
    // Start out ready to flush.
    OutBufStart = OutBufEnd = OutBufCur = 0;
  }

  virtual ~raw_ostream() {
    delete [] OutBufStart;
  }

  /// tell - Return the current offset with the file.
  uint64_t tell() { return current_pos() + GetNumBytesInBuffer(); }

  //===--------------------------------------------------------------------===//
  // Configuration Interface
  //===--------------------------------------------------------------------===//

  /// SetBufferSize - Set the internal buffer size to the specified amount
  /// instead of the default.
  void SetBufferSize(unsigned Size=4096) {
    assert(Size >= 64 &&
           "Buffer size must be somewhat large for invariants to hold");
    flush();

    delete [] OutBufStart;
    OutBufStart = new char[Size];
    OutBufEnd = OutBufStart+Size;
    OutBufCur = OutBufStart;
    Unbuffered = false;
  }

  /// SetUnbuffered - Set the streams buffering status. When
  /// unbuffered the stream will flush after every write. This routine
  /// will also flush the buffer immediately when the stream is being
  /// set to unbuffered.
  void SetUnbuffered() {
    flush();
    
    delete [] OutBufStart;
    OutBufStart = OutBufEnd = OutBufCur = 0;
    Unbuffered = true;
  }

  unsigned GetNumBytesInBuffer() const {
    return OutBufCur - OutBufStart;
  }

  //===--------------------------------------------------------------------===//
  // Data Output Interface
  //===--------------------------------------------------------------------===//

  void flush() {
    if (OutBufCur != OutBufStart)
      flush_nonempty();
  }

  raw_ostream &operator<<(char C) {
    if (OutBufCur >= OutBufEnd)
      return write(C);
    *OutBufCur++ = C;
    return *this;
  }

  raw_ostream &operator<<(unsigned char C) {
    if (OutBufCur >= OutBufEnd)
      return write(C);
    *OutBufCur++ = C;
    return *this;
  }

  raw_ostream &operator<<(signed char C) {
    if (OutBufCur >= OutBufEnd)
      return write(C);
    *OutBufCur++ = C;
    return *this;
  }

  raw_ostream &operator<<(const char *Str) {
    // Inline fast path, particulary for constant strings where a
    // sufficiently smart compiler will simplify strlen.

    unsigned Size = strlen(Str);

    // Make sure we can use the fast path.
    if (OutBufCur+Size > OutBufEnd)
      return write(Str, Size);

    memcpy(OutBufCur, Str, Size);
    OutBufCur += Size;
    return *this;
  }

  raw_ostream &operator<<(const std::string& Str) {
    write(Str.data(), Str.length());
    return *this;
  }

  raw_ostream &operator<<(unsigned long N);
  raw_ostream &operator<<(long N);
  raw_ostream &operator<<(unsigned long long N);
  raw_ostream &operator<<(long long N);
  raw_ostream &operator<<(const void *P);
  raw_ostream &operator<<(unsigned int N) {
    this->operator<<(static_cast<unsigned long>(N));
    return *this;
  }

  raw_ostream &operator<<(int N) {
    this->operator<<(static_cast<long>(N));
    return *this;
  }

  raw_ostream &operator<<(double N) {
    this->operator<<(ftostr(N));
    return *this;
  }

  raw_ostream &write(unsigned char C);
  raw_ostream &write(const char *Ptr, unsigned Size);

  // Formatted output, see the format() function in Support/Format.h.
  raw_ostream &operator<<(const format_object_base &Fmt);

  //===--------------------------------------------------------------------===//
  // Subclass Interface
  //===--------------------------------------------------------------------===//

private:
  /// write_impl - The is the piece of the class that is implemented
  /// by subclasses.  This writes the \args Size bytes starting at
  /// \arg Ptr to the underlying stream.
  /// 
  /// \invariant { Size > 0 }
  virtual void write_impl(const char *Ptr, unsigned Size) = 0;

  // An out of line virtual method to provide a home for the class vtable.
  virtual void handle();

  /// current_pos - Return the current position within the stream, not
  /// counting the bytes currently in the buffer.
  virtual uint64_t current_pos() = 0;

  //===--------------------------------------------------------------------===//
  // Private Interface
  //===--------------------------------------------------------------------===//
private:
  /// flush_nonempty - Flush the current buffer, which is known to be
  /// non-empty. This outputs the currently buffered data and resets
  /// the buffer to empty.
  void flush_nonempty();
};

//===----------------------------------------------------------------------===//
// File Output Streams
//===----------------------------------------------------------------------===//

/// raw_fd_ostream - A raw_ostream that writes to a file descriptor.
///
class raw_fd_ostream : public raw_ostream {
  int FD;
  bool ShouldClose;
  uint64_t pos;

  /// write_impl - See raw_ostream::write_impl.
  virtual void write_impl(const char *Ptr, unsigned Size);

  /// current_pos - Return the current position within the stream, not
  /// counting the bytes currently in the buffer.
  virtual uint64_t current_pos() { return pos; }

public:
  /// raw_fd_ostream - Open the specified file for writing. If an
  /// error occurs, information about the error is put into ErrorInfo,
  /// and the stream should be immediately destroyed; the string will
  /// be empty if no error occurred.
  ///
  /// \param Filename - The file to open. If this is "-" then the
  /// stream will use stdout instead.
  /// \param Binary - The file should be opened in binary mode on
  /// platforms that support this distinction.
  raw_fd_ostream(const char *Filename, bool Binary, std::string &ErrorInfo);

  /// raw_fd_ostream ctor - FD is the file descriptor that this writes to.  If
  /// ShouldClose is true, this closes the file when the stream is destroyed.
  raw_fd_ostream(int fd, bool shouldClose, 
                 bool unbuffered=false) : raw_ostream(unbuffered), FD(fd), 
                                          ShouldClose(shouldClose) {}
  
  ~raw_fd_ostream();

  /// close - Manually flush the stream and close the file.
  void close();

  /// tell - Return the current offset with the file.
  uint64_t tell() { return pos + GetNumBytesInBuffer(); }

  /// seek - Flushes the stream and repositions the underlying file descriptor
  ///  positition to the offset specified from the beginning of the file.
  uint64_t seek(uint64_t off);
};

/// raw_stdout_ostream - This is a stream that always prints to stdout.
///
class raw_stdout_ostream : public raw_fd_ostream {
  // An out of line virtual method to provide a home for the class vtable.
  virtual void handle();
public:
  raw_stdout_ostream();
};

/// raw_stderr_ostream - This is a stream that always prints to stderr.
///
class raw_stderr_ostream : public raw_fd_ostream {
  // An out of line virtual method to provide a home for the class vtable.
  virtual void handle();
public:
  raw_stderr_ostream();
};

/// outs() - This returns a reference to a raw_ostream for standard output.
/// Use it like: outs() << "foo" << "bar";
raw_ostream &outs();

/// errs() - This returns a reference to a raw_ostream for standard error.
/// Use it like: errs() << "foo" << "bar";
raw_ostream &errs();


//===----------------------------------------------------------------------===//
// Output Stream Adaptors
//===----------------------------------------------------------------------===//

/// raw_os_ostream - A raw_ostream that writes to an std::ostream.  This is a
/// simple adaptor class.
class raw_os_ostream : public raw_ostream {
  std::ostream &OS;

  /// write_impl - See raw_ostream::write_impl.
  virtual void write_impl(const char *Ptr, unsigned Size);

  /// current_pos - Return the current position within the stream, not
  /// counting the bytes currently in the buffer.
  virtual uint64_t current_pos();

public:
  raw_os_ostream(std::ostream &O) : OS(O) {}
  ~raw_os_ostream();

  /// tell - Return the current offset with the stream.
  uint64_t tell();
};

/// raw_string_ostream - A raw_ostream that writes to an std::string.  This is a
/// simple adaptor class.
class raw_string_ostream : public raw_ostream {
  std::string &OS;

  /// write_impl - See raw_ostream::write_impl.
  virtual void write_impl(const char *Ptr, unsigned Size);

  /// current_pos - Return the current position within the stream, not
  /// counting the bytes currently in the buffer.
  virtual uint64_t current_pos() { return OS.size(); }
public:
  raw_string_ostream(std::string &O) : OS(O) {}
  ~raw_string_ostream();

  /// tell - Return the current offset with the stream.
  uint64_t tell() { return OS.size() + GetNumBytesInBuffer(); }

  /// str - Flushes the stream contents to the target string and returns
  ///  the string's reference.
  std::string& str() {
    flush();
    return OS;
  }
};

/// raw_svector_ostream - A raw_ostream that writes to an SmallVector or
/// SmallString.  This is a simple adaptor class.
class raw_svector_ostream : public raw_ostream {
  SmallVectorImpl<char> &OS;

  /// write_impl - See raw_ostream::write_impl.
  virtual void write_impl(const char *Ptr, unsigned Size);

  /// current_pos - Return the current position within the stream, not
  /// counting the bytes currently in the buffer.
  virtual uint64_t current_pos();
public:
  raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {}
  ~raw_svector_ostream();

  /// tell - Return the current offset with the stream.
  uint64_t tell();
};

} // end llvm namespace

#endif