FormattedStream.h revision 3724b482589af30978f39b50685ef5432863763b 
1//===-- llvm/CodeGen/FormattedStream.h - Formatted streams ------*- 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 contains raw_ostream implementations for streams to do
11// things like pretty-print comments.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_SUPPORT_FORMATTEDSTREAM_H
16#define LLVM_SUPPORT_FORMATTEDSTREAM_H
17
18#include "llvm/Support/raw_ostream.h"
19
20namespace llvm
21{
22  /// formatted_raw_ostream - Formatted raw_fd_ostream to handle
23  /// asm-specific constructs.
24  ///
25  class formatted_raw_ostream : public raw_ostream {
26  public:
27    /// DELETE_STREAM - Tell the destructor to delete the held stream.
28    ///
29    const static bool DELETE_STREAM = true;
30    /// PRESERVE_STREAM - Tell the destructor to not delete the held
31    /// stream.
32    ///
33    const static bool PRESERVE_STREAM = false;
34
35  private:
36    /// TheStream - The real stream we output to. We set it to be
37    /// unbuffered, since we're already doing our own buffering.
38    ///
39    raw_ostream *TheStream;
40    /// DeleteStream - Do we need to delete TheStream in the
41    /// destructor?
42    ///
43    bool DeleteStream;
44
45    /// Column - The current output column of the stream.  The column
46    /// scheme is zero-based.
47    ///
48    unsigned Column;
49
50    virtual void write_impl(const char *Ptr, size_t Size) {
51      ComputeColumn(Ptr, Size);
52      TheStream->write(Ptr, Size);
53    }
54
55    /// current_pos - Return the current position within the stream,
56    /// not counting the bytes currently in the buffer.
57    virtual uint64_t current_pos() {
58      // This has the same effect as calling TheStream.current_pos(),
59      // but that interface is private.
60      return TheStream->tell() - TheStream->GetNumBytesInBuffer();
61    }
62
63    /// ComputeColumn - Examine the current output and figure out
64    /// which column we end up in after output.
65    ///
66    void ComputeColumn(const char *Ptr, size_t Size);
67
68  public:
69    /// formatted_raw_ostream - Open the specified file for
70    /// writing. If an error occurs, information about the error is
71    /// put into ErrorInfo, and the stream should be immediately
72    /// destroyed; the string will be empty if no error occurred.
73    ///
74    /// As a side effect, the given Stream is set to be Unbuffered.
75    /// This is because formatted_raw_ostream does its own buffering,
76    /// so it doesn't want another layer of buffering to be happening
77    /// underneath it.
78    ///
79    formatted_raw_ostream(raw_ostream &Stream, bool Delete = false)
80      : raw_ostream(), TheStream(&Stream), DeleteStream(Delete), Column(0) {
81      // This formatted_raw_ostream inherits from raw_ostream, so it'll do its
82      // own buffering, and it doesn't need or want TheStream to do another
83      // layer of buffering underneath. Resize the buffer to what TheStream
84      // had been using, and tell TheStream not to do its own buffering.
85      TheStream->flush();
86      if (size_t BufferSize = TheStream->GetNumBytesInBuffer())
87        SetBufferSize(BufferSize);
88      TheStream->SetUnbuffered();
89    }
90    explicit formatted_raw_ostream()
91      : raw_ostream(), TheStream(0), DeleteStream(false), Column(0) {}
92
93    ~formatted_raw_ostream() {
94      if (DeleteStream)
95        delete TheStream;
96    }
97
98    void setStream(raw_ostream &Stream, bool Delete = false) {
99      TheStream = &Stream;
100      DeleteStream = Delete;
101
102      // Avoid double-buffering, as above.
103      TheStream->flush();
104      if (size_t BufferSize = TheStream->GetNumBytesInBuffer())
105        SetBufferSize(BufferSize);
106      TheStream->SetUnbuffered();
107    }
108
109    /// PadToColumn - Align the output to some column number.
110    ///
111    /// \param NewCol - The column to move to.
112    /// \param MinPad - The minimum space to give after the most
113    /// recent I/O, even if the current column + minpad > newcol.
114    ///
115    void PadToColumn(unsigned NewCol, unsigned MinPad = 0);
116  };
117
118/// fouts() - This returns a reference to a formatted_raw_ostream for
119/// standard output.  Use it like: fouts() << "foo" << "bar";
120formatted_raw_ostream &fouts();
121
122/// ferrs() - This returns a reference to a formatted_raw_ostream for
123/// standard error.  Use it like: ferrs() << "foo" << "bar";
124formatted_raw_ostream &ferrs();
125
126} // end llvm namespace
127
128
129#endif
130