FormattedStream.h revision a96a1824747632ce87ef065b4a13fb777d2b14d6 
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 - 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    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
36  private:
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
74  public:
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
125  private:
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