FormattedStream.h revision 080e3c523e87ec68ca1ea5db4cd49816028dd8bd
1//===-- llvm/Support/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 - A raw_ostream that wraps another one and keeps track
23/// of column position, allowing padding out to specific column boundaries.
24///
25class formatted_raw_ostream : public raw_ostream {
26public:
27  /// DELETE_STREAM - Tell the destructor to delete the held stream.
28  ///
29  static const bool DELETE_STREAM = true;
30
31  /// PRESERVE_STREAM - Tell the destructor to not delete the held
32  /// stream.
33  ///
34  static const bool PRESERVE_STREAM = false;
35
36private:
37  /// TheStream - The real stream we output to. We set it to be
38  /// unbuffered, since we're already doing our own buffering.
39  ///
40  raw_ostream *TheStream;
41
42  /// DeleteStream - Do we need to delete TheStream in the
43  /// destructor?
44  ///
45  bool DeleteStream;
46
47  /// ColumnScanned - The current output column of the data that's
48  /// been flushed and the portion of the buffer that's been
49  /// scanned.  The column scheme is zero-based.
50  ///
51  unsigned ColumnScanned;
52
53  /// Scanned - This points to one past the last character in the
54  /// buffer we've scanned.
55  ///
56  const char *Scanned;
57
58  virtual void write_impl(const char *Ptr, size_t Size) LLVM_OVERRIDE;
59
60  /// current_pos - Return the current position within the stream,
61  /// not counting the bytes currently in the buffer.
62  virtual uint64_t current_pos() const LLVM_OVERRIDE {
63    // Our current position in the stream is all the contents which have been
64    // written to the underlying stream (*not* the current position of the
65    // underlying stream).
66    return TheStream->tell();
67  }
68
69  /// ComputeColumn - Examine the given output buffer and figure out which
70  /// column we end up in after output.
71  ///
72  void ComputeColumn(const char *Ptr, size_t size);
73
74public:
75  /// formatted_raw_ostream - Open the specified file for
76  /// writing. If an error occurs, information about the error is
77  /// put into ErrorInfo, and the stream should be immediately
78  /// destroyed; the string will be empty if no error occurred.
79  ///
80  /// As a side effect, the given Stream is set to be Unbuffered.
81  /// This is because formatted_raw_ostream does its own buffering,
82  /// so it doesn't want another layer of buffering to be happening
83  /// underneath it.
84  ///
85  formatted_raw_ostream(raw_ostream &Stream, bool Delete = false)
86    : raw_ostream(), TheStream(0), DeleteStream(false), ColumnScanned(0) {
87    setStream(Stream, Delete);
88  }
89  explicit formatted_raw_ostream()
90    : raw_ostream(), TheStream(0), DeleteStream(false), ColumnScanned(0) {
91    Scanned = 0;
92  }
93
94  ~formatted_raw_ostream() {
95    flush();
96    releaseStream();
97  }
98
99  void setStream(raw_ostream &Stream, bool Delete = false) {
100    releaseStream();
101
102    TheStream = &Stream;
103    DeleteStream = Delete;
104
105    // This formatted_raw_ostream inherits from raw_ostream, so it'll do its
106    // own buffering, and it doesn't need or want TheStream to do another
107    // layer of buffering underneath. Resize the buffer to what TheStream
108    // had been using, and tell TheStream not to do its own buffering.
109    if (size_t BufferSize = TheStream->GetBufferSize())
110      SetBufferSize(BufferSize);
111    else
112      SetUnbuffered();
113    TheStream->SetUnbuffered();
114
115    Scanned = 0;
116  }
117
118  /// PadToColumn - Align the output to some column number.  If the current
119  /// column is already equal to or more than NewCol, PadToColumn inserts one
120  /// space.
121  ///
122  /// \param NewCol - The column to move to.
123  formatted_raw_ostream &PadToColumn(unsigned NewCol);
124
125private:
126  void releaseStream() {
127    // Delete the stream if needed. Otherwise, transfer the buffer
128    // settings from this raw_ostream back to the underlying stream.
129    if (!TheStream)
130      return;
131    if (DeleteStream)
132      delete TheStream;
133    else if (size_t BufferSize = GetBufferSize())
134      TheStream->SetBufferSize(BufferSize);
135    else
136      TheStream->SetUnbuffered();
137  }
138};
139
140/// fouts() - This returns a reference to a formatted_raw_ostream for
141/// standard output.  Use it like: fouts() << "foo" << "bar";
142formatted_raw_ostream &fouts();
143
144/// ferrs() - This returns a reference to a formatted_raw_ostream for
145/// standard error.  Use it like: ferrs() << "foo" << "bar";
146formatted_raw_ostream &ferrs();
147
148/// fdbgs() - This returns a reference to a formatted_raw_ostream for
149/// debug output.  Use it like: fdbgs() << "foo" << "bar";
150formatted_raw_ostream &fdbgs();
151
152} // end llvm namespace
153
154
155#endif
156