FormattedStream.cpp revision 198090 
1//===-- llvm/Support/FormattedStream.cpp - 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 the implementation of formatted_raw_ostream.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Support/FormattedStream.h"
15
16using namespace llvm;
17
18/// CountColumns - Examine the given char sequence and figure out which
19/// column we end up in after output.
20///
21static unsigned CountColumns(unsigned Column, const char *Ptr, size_t Size) {
22  // Keep track of the current column by scanning the string for
23  // special characters
24
25  for (const char *End = Ptr + Size; Ptr != End; ++Ptr) {
26    ++Column;
27    if (*Ptr == '\n' || *Ptr == '\r')
28      Column = 0;
29    else if (*Ptr == '\t')
30      // Assumes tab stop = 8 characters.
31      Column += (8 - (Column & 0x7)) & 0x7;
32  }
33
34  return Column;
35}
36
37/// ComputeColumn - Examine the current output and figure out which
38/// column we end up in after output.
39void formatted_raw_ostream::ComputeColumn(const char *Ptr, size_t Size) {
40  // If our previous scan pointer is inside the buffer, assume we already
41  // scanned those bytes. This depends on raw_ostream to not change our buffer
42  // in unexpected ways.
43  if (Ptr <= Scanned && Scanned <= Ptr + Size) {
44    // Scan all characters added since our last scan to determine the new
45    // column.
46    ColumnScanned = CountColumns(ColumnScanned, Scanned,
47                                 Size - (Scanned - Ptr));
48  } else
49    ColumnScanned = CountColumns(ColumnScanned, Ptr, Size);
50
51  // Update the scanning pointer.
52  Scanned = Ptr + Size;
53}
54
55/// PadToColumn - Align the output to some column number.
56///
57/// \param NewCol - The column to move to.
58/// \param MinPad - The minimum space to give after the most recent
59/// I/O, even if the current column + minpad > newcol.
60///
61void formatted_raw_ostream::PadToColumn(unsigned NewCol) {
62  // Figure out what's in the buffer and add it to the column count.
63  ComputeColumn(getBufferStart(), GetNumBytesInBuffer());
64
65  // Output spaces until we reach the desired column.
66  indent(std::max(int(NewCol - ColumnScanned), 1));
67}
68
69void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
70  // Figure out what's in the buffer and add it to the column count.
71  ComputeColumn(Ptr, Size);
72
73  // Write the data to the underlying stream (which is unbuffered, so
74  // the data will be immediately written out).
75  TheStream->write(Ptr, Size);
76
77  // Reset the scanning pointer.
78  Scanned = 0;
79}
80
81/// fouts() - This returns a reference to a formatted_raw_ostream for
82/// standard output.  Use it like: fouts() << "foo" << "bar";
83formatted_raw_ostream &llvm::fouts() {
84  static formatted_raw_ostream S(outs());
85  return S;
86}
87
88/// ferrs() - This returns a reference to a formatted_raw_ostream for
89/// standard error.  Use it like: ferrs() << "foo" << "bar";
90formatted_raw_ostream &llvm::ferrs() {
91  static formatted_raw_ostream S(errs());
92  return S;
93}
94