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 #include "llvm/Support/Debug.h"
16 #include "llvm/Support/raw_ostream.h"
17 #include <algorithm>
18 
19 using namespace llvm;
20 
21 /// UpdatePosition - Examine the given char sequence and figure out which
22 /// column we end up in after output, and how many line breaks are contained.
23 ///
24 static void UpdatePosition(std::pair<unsigned, unsigned> &Position, const char *Ptr, size_t Size) {
25   unsigned &Column = Position.first;
26   unsigned &Line = Position.second;
27 
28   // Keep track of the current column and line by scanning the string for
29   // special characters
30   for (const char *End = Ptr + Size; Ptr != End; ++Ptr) {
31     ++Column;
32     switch (*Ptr) {
33     case '\n':
34       Line += 1;
35       LLVM_FALLTHROUGH;
36     case '\r':
37       Column = 0;
38       break;
39     case '\t':
40       // Assumes tab stop = 8 characters.
41       Column += (8 - (Column & 0x7)) & 0x7;
42       break;
43     }
44   }
45 }
46 
47 /// ComputePosition - Examine the current output and update line and column
48 /// counts.
49 void formatted_raw_ostream::ComputePosition(const char *Ptr, size_t Size) {
50   // If our previous scan pointer is inside the buffer, assume we already
51   // scanned those bytes. This depends on raw_ostream to not change our buffer
52   // in unexpected ways.
53   if (Ptr <= Scanned && Scanned <= Ptr + Size)
54     // Scan all characters added since our last scan to determine the new
55     // column.
56     UpdatePosition(Position, Scanned, Size - (Scanned - Ptr));
57   else
58     UpdatePosition(Position, Ptr, Size);
59 
60   // Update the scanning pointer.
61   Scanned = Ptr + Size;
62 }
63 
64 /// PadToColumn - Align the output to some column number.
65 ///
66 /// \param NewCol - The column to move to.
67 ///
68 formatted_raw_ostream &formatted_raw_ostream::PadToColumn(unsigned NewCol) {
69   // Figure out what's in the buffer and add it to the column count.
70   ComputePosition(getBufferStart(), GetNumBytesInBuffer());
71 
72   // Output spaces until we reach the desired column.
73   indent(std::max(int(NewCol - getColumn()), 1));
74   return *this;
75 }
76 
77 void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
78   // Figure out what's in the buffer and add it to the column count.
79   ComputePosition(Ptr, Size);
80 
81   // Write the data to the underlying stream (which is unbuffered, so
82   // the data will be immediately written out).
83   TheStream->write(Ptr, Size);
84 
85   // Reset the scanning pointer.
86   Scanned = nullptr;
87 }
88 
89 /// fouts() - This returns a reference to a formatted_raw_ostream for
90 /// standard output.  Use it like: fouts() << "foo" << "bar";
91 formatted_raw_ostream &llvm::fouts() {
92   static formatted_raw_ostream S(outs());
93   return S;
94 }
95 
96 /// ferrs() - This returns a reference to a formatted_raw_ostream for
97 /// standard error.  Use it like: ferrs() << "foo" << "bar";
98 formatted_raw_ostream &llvm::ferrs() {
99   static formatted_raw_ostream S(errs());
100   return S;
101 }
102 
103 /// fdbgs() - This returns a reference to a formatted_raw_ostream for
104 /// the debug stream.  Use it like: fdbgs() << "foo" << "bar";
105 formatted_raw_ostream &llvm::fdbgs() {
106   static formatted_raw_ostream S(dbgs());
107   return S;
108 }
109