lib/Support/FormattedStream.cpp

   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
  18 using namespace llvm;
  19
  20 /// CountColumns - Examine the given char sequence and figure out which
  21 /// column we end up in after output.
  22 ///
  23 static unsigned CountColumns(unsigned Column, const char *Ptr, size_t Size) {
  24   // Keep track of the current column by scanning the string for
  25   // special characters
  26
  27   for (const char *End = Ptr + Size; Ptr != End; ++Ptr) {
  28     ++Column;
  29     if (*Ptr == '\n' || *Ptr == '\r')
  30       Column = 0;
  31     else if (*Ptr == '\t')
  32       // Assumes tab stop = 8 characters.
  33       Column += (8 - (Column & 0x7)) & 0x7;
  34   }
  35
  36   return Column;
  37 }
  38
  39 /// ComputeColumn - Examine the current output and figure out which
  40 /// column we end up in after output.
  41 void formatted_raw_ostream::ComputeColumn(const char *Ptr, size_t Size) {
  42   // If our previous scan pointer is inside the buffer, assume we already
  43   // scanned those bytes. This depends on raw_ostream to not change our buffer
  44   // in unexpected ways.
  45   if (Ptr <= Scanned && Scanned <= Ptr + Size) {
  46     // Scan all characters added since our last scan to determine the new
  47     // column.
  48     ColumnScanned = CountColumns(ColumnScanned, Scanned,
  49                                  Size - (Scanned - Ptr));
  50   } else
  51     ColumnScanned = CountColumns(ColumnScanned, Ptr, Size);
  52
  53   // Update the scanning pointer.
  54   Scanned = Ptr + Size;
  55 }
  56
  57 /// PadToColumn - Align the output to some column number.
  58 ///
  59 /// \param NewCol - The column to move to.
  60 ///
  61 formatted_raw_ostream &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   return *this;
  68 }
  69
  70 void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
  71   // Figure out what's in the buffer and add it to the column count.
  72   ComputeColumn(Ptr, Size);
  73
  74   // Write the data to the underlying stream (which is unbuffered, so
  75   // the data will be immediately written out).
  76   TheStream->write(Ptr, Size);
  77
  78   // Reset the scanning pointer.
  79   Scanned = 0;
  80 }
  81
  82 /// fouts() - This returns a reference to a formatted_raw_ostream for
  83 /// standard output.  Use it like: fouts() << "foo" << "bar";
  84 formatted_raw_ostream &llvm::fouts() {
  85   static formatted_raw_ostream S(outs());
  86   return S;
  87 }
  88
  89 /// ferrs() - This returns a reference to a formatted_raw_ostream for
  90 /// standard error.  Use it like: ferrs() << "foo" << "bar";
  91 formatted_raw_ostream &llvm::ferrs() {
  92   static formatted_raw_ostream S(errs());
  93   return S;
  94 }
  95
  96 /// fdbgs() - This returns a reference to a formatted_raw_ostream for
  97 /// the debug stream.  Use it like: fdbgs() << "foo" << "bar";
  98 formatted_raw_ostream &llvm::fdbgs() {
  99   static formatted_raw_ostream S(dbgs());
 100   return S;
 101 }