FormattedStream.h revision cc1c702f628d93f9d84b681059e16652ad09d595 
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    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);
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() {
63      // This has the same effect as calling TheStream.current_pos(),
64      // but that interface is private.
65      return TheStream->tell() - TheStream->GetNumBytesInBuffer();
66    }
67
68    /// ComputeColumn - Examine the given output buffer and figure out which
69    /// column we end up in after output.
70    ///
71    void ComputeColumn(const char *Ptr, size_t size);
72
73  public:
74    /// formatted_raw_ostream - Open the specified file for
75    /// writing. If an error occurs, information about the error is
76    /// put into ErrorInfo, and the stream should be immediately
77    /// destroyed; the string will be empty if no error occurred.
78    ///
79    /// As a side effect, the given Stream is set to be Unbuffered.
80    /// This is because formatted_raw_ostream does its own buffering,
81    /// so it doesn't want another layer of buffering to be happening
82    /// underneath it.
83    ///
84    formatted_raw_ostream(raw_ostream &Stream, bool Delete = false)
85      : raw_ostream(), TheStream(0), DeleteStream(false), ColumnScanned(0) {
86      setStream(Stream, Delete);
87    }
88    explicit formatted_raw_ostream()
89      : raw_ostream(), TheStream(0), DeleteStream(false), ColumnScanned(0) {
90      Scanned = 0;
91    }
92
93    ~formatted_raw_ostream() {
94      flush();
95      releaseStream();
96    }
97
98    void setStream(raw_ostream &Stream, bool Delete = false) {
99      releaseStream();
100
101      TheStream = &Stream;
102      DeleteStream = Delete;
103
104      // This formatted_raw_ostream inherits from raw_ostream, so it'll do its
105      // own buffering, and it doesn't need or want TheStream to do another
106      // layer of buffering underneath. Resize the buffer to what TheStream
107      // had been using, and tell TheStream not to do its own buffering.
108      //
109      // If the underlying stream is unbuffered, just use its preferred buffer
110      // size. We can't treat this as an honest wish for unbuffered output,
111      // because it could very well be a stream we previously forced to be
112      // unbuffered.
113      if (size_t BufferSize = TheStream->GetBufferSize())
114        SetBufferSize(BufferSize);
115      else
116        SetBuffered();
117      TheStream->SetUnbuffered();
118
119      Scanned = 0;
120    }
121
122    /// PadToColumn - Align the output to some column number.  If the current
123    /// column is already equal to or more than NewCol, PadToColumn inserts one
124    /// space.
125    ///
126    /// \param NewCol - The column to move to.
127    void PadToColumn(unsigned NewCol);
128
129  private:
130    void releaseStream() {
131      // Delete the stream if needed. Otherwise, transfer the buffer
132      // settings from this raw_ostream back to the underlying stream.
133      if (!TheStream)
134        return;
135      if (DeleteStream)
136        delete TheStream;
137      else if (size_t BufferSize = GetBufferSize())
138        TheStream->SetBufferSize(BufferSize);
139      else
140        TheStream->SetUnbuffered();
141    }
142  };
143
144/// fouts() - This returns a reference to a formatted_raw_ostream for
145/// standard output.  Use it like: fouts() << "foo" << "bar";
146formatted_raw_ostream &fouts();
147
148/// ferrs() - This returns a reference to a formatted_raw_ostream for
149/// standard error.  Use it like: ferrs() << "foo" << "bar";
150formatted_raw_ostream &ferrs();
151
152} // end llvm namespace
153
154
155#endif
156