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() {
40   // The buffer may have been allocated underneath us.
41   if (Scanned == 0) Scanned = begin();
42   // Scan all characters added since our last scan to determine the new column.
43   ColumnScanned = CountColumns(ColumnScanned, Scanned, end() - Scanned);
44   // We're now current with everything in the buffer.
45   Scanned = end();
46 }
47 
48 /// PadToColumn - Align the output to some column number.
49 ///
50 /// \param NewCol - The column to move to.
51 /// \param MinPad - The minimum space to give after the most recent
52 /// I/O, even if the current column + minpad > newcol.
53 ///
54 void formatted_raw_ostream::PadToColumn(unsigned NewCol, unsigned MinPad) {
55   // Figure out what's in the buffer and add it to the column count.
56   ComputeColumn();
57 
58   // Output spaces until we reach the desired column.
59   unsigned num = NewCol - ColumnScanned;
60   if (NewCol < ColumnScanned || num < MinPad)
61     num = MinPad;
62 
63   // Keep a buffer of spaces handy to speed up processing.
64   const char *Spaces = "                                                      "
65     "                                                                         ";
66 
67   assert(num < MAX_COLUMN_PAD && "Unexpectedly large column padding");
68 
69   write(Spaces, num);
70 }
71 
72 void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
73   // Figure out what's in the buffer and add it to the column count.
74   ComputeColumn();
75 
76   // Write the data to the underlying stream (which is unbuffered, so
77   // the data will be immediately written out).
78   TheStream->write(Ptr, Size);
79 
80   // If this FormattedStream is unbuffered, scan the string that
81   // was just written to determine the new column.
82   if (Ptr == begin()) {
83     // Buffered mode. The buffer is being flushed; reset the scanning
84     // position to the beginning of the buffer.
85     assert(Ptr + Size == end() && "Buffer is not being fully flushed!");
86     Scanned = begin();
87   } else {
88     // Unbuffered mode. Immediately scan the string that was just
89     // written to determine the new column.
90     ColumnScanned = CountColumns(ColumnScanned, Ptr, Size);
91   }
92 }
93 
94 /// fouts() - This returns a reference to a formatted_raw_ostream for
95 /// standard output.  Use it like: fouts() << "foo" << "bar";
96 formatted_raw_ostream &llvm::fouts() {
97   static formatted_raw_ostream S(outs());
98   return S;
99 }
100 
101 /// ferrs() - This returns a reference to a formatted_raw_ostream for
102 /// standard error.  Use it like: ferrs() << "foo" << "bar";
103 formatted_raw_ostream &llvm::ferrs() {
104   static formatted_raw_ostream S(errs());
105   return S;
106 }
107