FormattedStream.h revision 6c304f2314e5fb00488ac6bdfdac180c0ffd3d09
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
31    /// PRESERVE_STREAM - Tell the destructor to not delete the held
32    /// stream.
33    ///
34    const static bool PRESERVE_STREAM = false;
35
36    /// MAX_COLUMN_PAD - This is the maximum column padding we ever
37    /// expect to see.
38    ///
39    const static unsigned MAX_COLUMN_PAD = 100;
40
41  private:
42    /// TheStream - The real stream we output to. We set it to be
43    /// unbuffered, since we're already doing our own buffering.
44    ///
45    raw_ostream *TheStream;
46
47    /// DeleteStream - Do we need to delete TheStream in the
48    /// destructor?
49    ///
50    bool DeleteStream;
51
52    /// ColumnScanned - The current output column of the data that's
53    /// been flushed and the portion of the buffer that's been
54    /// scanned.  The column scheme is zero-based.
55    ///
56    unsigned ColumnScanned;
57
58    /// Scanned - This points to one past the last character in the
59    /// buffer we've scanned.
60    ///
61    iterator Scanned;
62
63    virtual void write_impl(const char *Ptr, size_t Size) {
64      ComputeColumn();
65      TheStream->write(Ptr, Size);
66      Scanned = begin();
67    }
68
69    /// current_pos - Return the current position within the stream,
70    /// not counting the bytes currently in the buffer.
71    virtual uint64_t current_pos() {
72      // This has the same effect as calling TheStream.current_pos(),
73      // but that interface is private.
74      return TheStream->tell() - TheStream->GetNumBytesInBuffer();
75    }
76
77    /// ComputeColumn - Examine the current output and figure out
78    /// which column we end up in after output.
79    ///
80    void ComputeColumn();
81
82  public:
83    /// formatted_raw_ostream - Open the specified file for
84    /// writing. If an error occurs, information about the error is
85    /// put into ErrorInfo, and the stream should be immediately
86    /// destroyed; the string will be empty if no error occurred.
87    ///
88    /// As a side effect, the given Stream is set to be Unbuffered.
89    /// This is because formatted_raw_ostream does its own buffering,
90    /// so it doesn't want another layer of buffering to be happening
91    /// underneath it.
92    ///
93    formatted_raw_ostream(raw_ostream &Stream, bool Delete = false)
94      : raw_ostream(), TheStream(0), DeleteStream(false), ColumnScanned(0) {
95      setStream(Stream, Delete);
96    }
97    explicit formatted_raw_ostream()
98      : raw_ostream(), TheStream(0), DeleteStream(false), ColumnScanned(0) {
99      Scanned = begin();
100    }
101
102    ~formatted_raw_ostream() {
103      flush();
104      releaseStream();
105    }
106
107    void setStream(raw_ostream &Stream, bool Delete = false) {
108      releaseStream();
109
110      TheStream = &Stream;
111      DeleteStream = Delete;
112
113      // This formatted_raw_ostream inherits from raw_ostream, so it'll do its
114      // own buffering, and it doesn't need or want TheStream to do another
115      // layer of buffering underneath. Resize the buffer to what TheStream
116      // had been using, and tell TheStream not to do its own buffering.
117      if (size_t BufferSize = TheStream->GetBufferSize())
118        SetBufferSize(BufferSize);
119      else
120        SetUnbuffered();
121      TheStream->SetUnbuffered();
122
123      Scanned = begin();
124    }
125
126    /// PadToColumn - Align the output to some column number.
127    ///
128    /// \param NewCol - The column to move to.
129    /// \param MinPad - The minimum space to give after the most
130    /// recent I/O, even if the current column + minpad > newcol.
131    ///
132    void PadToColumn(unsigned NewCol, unsigned MinPad = 0);
133
134  private:
135    void releaseStream() {
136      // Delete the stream if needed. Otherwise, transfer the buffer
137      // settings from this raw_ostream back to the underlying stream.
138      if (!TheStream)
139        return;
140      if (DeleteStream)
141        delete TheStream;
142      else if (size_t BufferSize = GetBufferSize())
143        TheStream->SetBufferSize(BufferSize);
144      else
145        TheStream->SetUnbuffered();
146    }
147  };
148
149/// fouts() - This returns a reference to a formatted_raw_ostream for
150/// standard output.  Use it like: fouts() << "foo" << "bar";
151formatted_raw_ostream &fouts();
152
153/// ferrs() - This returns a reference to a formatted_raw_ostream for
154/// standard error.  Use it like: ferrs() << "foo" << "bar";
155formatted_raw_ostream &ferrs();
156
157} // end llvm namespace
158
159
160#endif
161