FormattedStream.h revision f28e3c501e033f103405c03a4bbf848cb6e67a2a 
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#include <utility>
20
21namespace llvm {
22
23/// formatted_raw_ostream - A raw_ostream that wraps another one and keeps track
24/// of line and column position, allowing padding out to specific column
25/// boundaries and querying the number of lines written to the stream.
26///
27class formatted_raw_ostream : public raw_ostream {
28public:
29  /// DELETE_STREAM - Tell the destructor to delete the held stream.
30  ///
31  static const bool DELETE_STREAM = true;
32
33  /// PRESERVE_STREAM - Tell the destructor to not delete the held
34  /// stream.
35  ///
36  static const bool PRESERVE_STREAM = false;
37
38private:
39  /// TheStream - The real stream we output to. We set it to be
40  /// unbuffered, since we're already doing our own buffering.
41  ///
42  raw_ostream *TheStream;
43
44  /// DeleteStream - Do we need to delete TheStream in the
45  /// destructor?
46  ///
47  bool DeleteStream;
48
49  /// Position - The current output column and line of the data that's
50  /// been flushed and the portion of the buffer that's been
51  /// scanned.  The line and column scheme is zero-based.
52  ///
53  std::pair<unsigned, unsigned> Position;
54
55  /// Scanned - This points to one past the last character in the
56  /// buffer we've scanned.
57  ///
58  const char *Scanned;
59
60  virtual void write_impl(const char *Ptr, size_t Size) LLVM_OVERRIDE;
61
62  /// current_pos - Return the current position within the stream,
63  /// not counting the bytes currently in the buffer.
64  virtual uint64_t current_pos() const LLVM_OVERRIDE {
65    // Our current position in the stream is all the contents which have been
66    // written to the underlying stream (*not* the current position of the
67    // underlying stream).
68    return TheStream->tell();
69  }
70
71  /// ComputePosition - Examine the given output buffer and figure out the new
72  /// position after output.
73  ///
74  void ComputePosition(const char *Ptr, size_t size);
75
76public:
77  /// formatted_raw_ostream - Open the specified file for
78  /// writing. If an error occurs, information about the error is
79  /// put into ErrorInfo, and the stream should be immediately
80  /// destroyed; the string will be empty if no error occurred.
81  ///
82  /// As a side effect, the given Stream is set to be Unbuffered.
83  /// This is because formatted_raw_ostream does its own buffering,
84  /// so it doesn't want another layer of buffering to be happening
85  /// underneath it.
86  ///
87  formatted_raw_ostream(raw_ostream &Stream, bool Delete = false)
88    : raw_ostream(), TheStream(0), DeleteStream(false), Position(0, 0) {
89    setStream(Stream, Delete);
90  }
91  explicit formatted_raw_ostream()
92    : raw_ostream(), TheStream(0), DeleteStream(false), Position(0, 0) {
93    Scanned = 0;
94  }
95
96  ~formatted_raw_ostream() {
97    flush();
98    releaseStream();
99  }
100
101  void setStream(raw_ostream &Stream, bool Delete = false) {
102    releaseStream();
103
104    TheStream = &Stream;
105    DeleteStream = Delete;
106
107    // This formatted_raw_ostream inherits from raw_ostream, so it'll do its
108    // own buffering, and it doesn't need or want TheStream to do another
109    // layer of buffering underneath. Resize the buffer to what TheStream
110    // had been using, and tell TheStream not to do its own buffering.
111    if (size_t BufferSize = TheStream->GetBufferSize())
112      SetBufferSize(BufferSize);
113    else
114      SetUnbuffered();
115    TheStream->SetUnbuffered();
116
117    Scanned = 0;
118  }
119
120  /// PadToColumn - Align the output to some column number.  If the current
121  /// column is already equal to or more than NewCol, PadToColumn inserts one
122  /// space.
123  ///
124  /// \param NewCol - The column to move to.
125  formatted_raw_ostream &PadToColumn(unsigned NewCol);
126
127  /// getColumn - Return the column number
128  unsigned getColumn() { return Position.first; }
129
130  /// getLine - Return the line number
131  unsigned getLine() { return Position.second; }
132
133private:
134  void releaseStream() {
135    // Delete the stream if needed. Otherwise, transfer the buffer
136    // settings from this raw_ostream back to the underlying stream.
137    if (!TheStream)
138      return;
139    if (DeleteStream)
140      delete TheStream;
141    else if (size_t BufferSize = GetBufferSize())
142      TheStream->SetBufferSize(BufferSize);
143    else
144      TheStream->SetUnbuffered();
145  }
146};
147
148/// fouts() - This returns a reference to a formatted_raw_ostream for
149/// standard output.  Use it like: fouts() << "foo" << "bar";
150formatted_raw_ostream &fouts();
151
152/// ferrs() - This returns a reference to a formatted_raw_ostream for
153/// standard error.  Use it like: ferrs() << "foo" << "bar";
154formatted_raw_ostream &ferrs();
155
156/// fdbgs() - This returns a reference to a formatted_raw_ostream for
157/// debug output.  Use it like: fdbgs() << "foo" << "bar";
158formatted_raw_ostream &fdbgs();
159
160} // end llvm namespace
161
162
163#endif
164