FormattedStream.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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/Debug.h"
15#include "llvm/Support/FormattedStream.h"
16#include <algorithm>
17
18using namespace llvm;
19
20/// UpdatePosition - Examine the given char sequence and figure out which
21/// column we end up in after output, and how many line breaks are contained.
22///
23static void UpdatePosition(std::pair<unsigned, unsigned> &Position, const char *Ptr, size_t Size) {
24  unsigned &Column = Position.first;
25  unsigned &Line = Position.second;
26
27  // Keep track of the current column and line by scanning the string for
28  // special characters
29  for (const char *End = Ptr + Size; Ptr != End; ++Ptr) {
30    ++Column;
31    switch (*Ptr) {
32    case '\n':
33      Line += 1;
34    case '\r':
35      Column = 0;
36      break;
37    case '\t':
38      // Assumes tab stop = 8 characters.
39      Column += (8 - (Column & 0x7)) & 0x7;
40      break;
41    }
42  }
43}
44
45/// ComputePosition - Examine the current output and update line and column
46/// counts.
47void formatted_raw_ostream::ComputePosition(const char *Ptr, size_t Size) {
48  // If our previous scan pointer is inside the buffer, assume we already
49  // scanned those bytes. This depends on raw_ostream to not change our buffer
50  // in unexpected ways.
51  if (Ptr <= Scanned && Scanned <= Ptr + Size)
52    // Scan all characters added since our last scan to determine the new
53    // column.
54    UpdatePosition(Position, Scanned, Size - (Scanned - Ptr));
55  else
56    UpdatePosition(Position, Ptr, Size);
57
58  // Update the scanning pointer.
59  Scanned = Ptr + Size;
60}
61
62/// PadToColumn - Align the output to some column number.
63///
64/// \param NewCol - The column to move to.
65///
66formatted_raw_ostream &formatted_raw_ostream::PadToColumn(unsigned NewCol) {
67  // Figure out what's in the buffer and add it to the column count.
68  ComputePosition(getBufferStart(), GetNumBytesInBuffer());
69
70  // Output spaces until we reach the desired column.
71  indent(std::max(int(NewCol - getColumn()), 1));
72  return *this;
73}
74
75void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
76  // Figure out what's in the buffer and add it to the column count.
77  ComputePosition(Ptr, Size);
78
79  // Write the data to the underlying stream (which is unbuffered, so
80  // the data will be immediately written out).
81  TheStream->write(Ptr, Size);
82
83  // Reset the scanning pointer.
84  Scanned = nullptr;
85}
86
87/// fouts() - This returns a reference to a formatted_raw_ostream for
88/// standard output.  Use it like: fouts() << "foo" << "bar";
89formatted_raw_ostream &llvm::fouts() {
90  static formatted_raw_ostream S(outs());
91  return S;
92}
93
94/// ferrs() - This returns a reference to a formatted_raw_ostream for
95/// standard error.  Use it like: ferrs() << "foo" << "bar";
96formatted_raw_ostream &llvm::ferrs() {
97  static formatted_raw_ostream S(errs());
98  return S;
99}
100
101/// fdbgs() - This returns a reference to a formatted_raw_ostream for
102/// the debug stream.  Use it like: fdbgs() << "foo" << "bar";
103formatted_raw_ostream &llvm::fdbgs() {
104  static formatted_raw_ostream S(dbgs());
105  return S;
106}
107