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 
16 using namespace llvm;
17 
18 /// CountColumns - Examine the given char sequence and figure out which
19 /// column we end up in after output.
20 ///
21 static 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.
39 void 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 ///
61 void 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   unsigned num = NewCol - ColumnScanned;
67   if (NewCol < ColumnScanned || num < 1)
68     num = 1;
69 
70   // Keep a buffer of spaces handy to speed up processing.
71   const char *Spaces = "                                                      "
72     "                                                                         ";
73 
74   assert(num < MAX_COLUMN_PAD && "Unexpectedly large column padding");
75   write(Spaces, num);
76 }
77 
78 void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
79   // Figure out what's in the buffer and add it to the column count.
80   ComputeColumn(Ptr, Size);
81 
82   // Write the data to the underlying stream (which is unbuffered, so
83   // the data will be immediately written out).
84   TheStream->write(Ptr, Size);
85 
86   // Reset the scanning pointer.
87   Scanned = 0;
88 }
89 
90 /// fouts() - This returns a reference to a formatted_raw_ostream for
91 /// standard output.  Use it like: fouts() << "foo" << "bar";
92 formatted_raw_ostream &llvm::fouts() {
93   static formatted_raw_ostream S(outs());
94   return S;
95 }
96 
97 /// ferrs() - This returns a reference to a formatted_raw_ostream for
98 /// standard error.  Use it like: ferrs() << "foo" << "bar";
99 formatted_raw_ostream &llvm::ferrs() {
100   static formatted_raw_ostream S(errs());
101   return S;
102 }
103