1//===-- llvm/Support/FormattedStream.h - Formatted streams ------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains raw_ostream implementations for streams to do
10// things like pretty-print comments.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_SUPPORT_FORMATTEDSTREAM_H
15#define LLVM_SUPPORT_FORMATTEDSTREAM_H
16
17#include "llvm/ADT/SmallString.h"
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. This
26/// assumes that the contents of the stream is valid UTF-8 encoded text. This
27/// doesn't attempt to handle everything Unicode can do (combining characters,
28/// right-to-left markers, etc), but should cover the cases likely to appear in
29/// source code or diagnostic messages.
30class formatted_raw_ostream : public raw_ostream {
31  /// TheStream - The real stream we output to. We set it to be
32  /// unbuffered, since we're already doing our own buffering.
33  ///
34  raw_ostream *TheStream;
35
36  /// Position - The current output column and line of the data that's
37  /// been flushed and the portion of the buffer that's been
38  /// scanned.  The line and column scheme is zero-based.
39  ///
40  std::pair<unsigned, unsigned> Position;
41
42  /// Scanned - This points to one past the last character in the
43  /// buffer we've scanned.
44  ///
45  const char *Scanned;
46
47  /// PartialUTF8Char - Either empty or a prefix of a UTF-8 code unit sequence
48  /// for a Unicode scalar value which should be prepended to the buffer for the
49  /// next call to ComputePosition. This is needed when the buffer is flushed
50  /// when it ends part-way through the UTF-8 encoding of a Unicode scalar
51  /// value, so that we can compute the display width of the character once we
52  /// have the rest of it.
53  SmallString<4> PartialUTF8Char;
54
55  void write_impl(const char *Ptr, size_t Size) override;
56
57  /// current_pos - Return the current position within the stream,
58  /// not counting the bytes currently in the buffer.
59  uint64_t current_pos() const override {
60    // Our current position in the stream is all the contents which have been
61    // written to the underlying stream (*not* the current position of the
62    // underlying stream).
63    return TheStream->tell();
64  }
65
66  /// ComputePosition - Examine the given output buffer and figure out the new
67  /// position after output. This is safe to call multiple times on the same
68  /// buffer, as it records the most recently scanned character and resumes from
69  /// there when the buffer has not been flushed.
70  void ComputePosition(const char *Ptr, size_t size);
71
72  /// UpdatePosition - scan the characters in [Ptr, Ptr+Size), and update the
73  /// line and column numbers. Unlike ComputePosition, this must be called
74  /// exactly once on each region of the buffer.
75  void UpdatePosition(const char *Ptr, size_t Size);
76
77  void setStream(raw_ostream &Stream) {
78    releaseStream();
79
80    TheStream = &Stream;
81
82    // This formatted_raw_ostream inherits from raw_ostream, so it'll do its
83    // own buffering, and it doesn't need or want TheStream to do another
84    // layer of buffering underneath. Resize the buffer to what TheStream
85    // had been using, and tell TheStream not to do its own buffering.
86    if (size_t BufferSize = TheStream->GetBufferSize())
87      SetBufferSize(BufferSize);
88    else
89      SetUnbuffered();
90    TheStream->SetUnbuffered();
91
92    Scanned = nullptr;
93  }
94
95public:
96  /// formatted_raw_ostream - Open the specified file for
97  /// writing. If an error occurs, information about the error is
98  /// put into ErrorInfo, and the stream should be immediately
99  /// destroyed; the string will be empty if no error occurred.
100  ///
101  /// As a side effect, the given Stream is set to be Unbuffered.
102  /// This is because formatted_raw_ostream does its own buffering,
103  /// so it doesn't want another layer of buffering to be happening
104  /// underneath it.
105  ///
106  formatted_raw_ostream(raw_ostream &Stream)
107      : TheStream(nullptr), Position(0, 0) {
108    setStream(Stream);
109  }
110  explicit formatted_raw_ostream() : TheStream(nullptr), Position(0, 0) {
111    Scanned = nullptr;
112  }
113
114  ~formatted_raw_ostream() override {
115    flush();
116    releaseStream();
117  }
118
119  /// PadToColumn - Align the output to some column number.  If the current
120  /// column is already equal to or more than NewCol, PadToColumn inserts one
121  /// space.
122  ///
123  /// \param NewCol - The column to move to.
124  formatted_raw_ostream &PadToColumn(unsigned NewCol);
125
126  unsigned getColumn() {
127    // Calculate current position, taking buffer contents into account.
128    ComputePosition(getBufferStart(), GetNumBytesInBuffer());
129    return Position.first;
130  }
131
132  unsigned getLine() {
133    // Calculate current position, taking buffer contents into account.
134    ComputePosition(getBufferStart(), GetNumBytesInBuffer());
135    return Position.second;
136  }
137
138  raw_ostream &resetColor() override {
139    TheStream->resetColor();
140    return *this;
141  }
142
143  raw_ostream &reverseColor() override {
144    TheStream->reverseColor();
145    return *this;
146  }
147
148  raw_ostream &changeColor(enum Colors Color, bool Bold, bool BG) override {
149    TheStream->changeColor(Color, Bold, BG);
150    return *this;
151  }
152
153  bool is_displayed() const override {
154    return TheStream->is_displayed();
155  }
156
157private:
158  void releaseStream() {
159    // Transfer the buffer settings from this raw_ostream back to the underlying
160    // stream.
161    if (!TheStream)
162      return;
163    if (size_t BufferSize = GetBufferSize())
164      TheStream->SetBufferSize(BufferSize);
165    else
166      TheStream->SetUnbuffered();
167  }
168};
169
170/// fouts() - This returns a reference to a formatted_raw_ostream for
171/// standard output.  Use it like: fouts() << "foo" << "bar";
172formatted_raw_ostream &fouts();
173
174/// ferrs() - This returns a reference to a formatted_raw_ostream for
175/// standard error.  Use it like: ferrs() << "foo" << "bar";
176formatted_raw_ostream &ferrs();
177
178/// fdbgs() - This returns a reference to a formatted_raw_ostream for
179/// debug output.  Use it like: fdbgs() << "foo" << "bar";
180formatted_raw_ostream &fdbgs();
181
182} // end llvm namespace
183
184
185#endif
186