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/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   indent(std::max(int(NewCol - ColumnScanned), 1));
  67 }
  68
  69 void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
  70   // Figure out what's in the buffer and add it to the column count.
  71   ComputeColumn(Ptr, Size);
  72
  73   // Write the data to the underlying stream (which is unbuffered, so
  74   // the data will be immediately written out).
  75   TheStream->write(Ptr, Size);
  76
  77   // Reset the scanning pointer.
  78   Scanned = 0;
  79 }
  80
  81 /// fouts() - This returns a reference to a formatted_raw_ostream for
  82 /// standard output.  Use it like: fouts() << "foo" << "bar";
  83 formatted_raw_ostream &llvm::fouts() {
  84   static formatted_raw_ostream S(outs());
  85   return S;
  86 }
  87
  88 /// ferrs() - This returns a reference to a formatted_raw_ostream for
  89 /// standard error.  Use it like: ferrs() << "foo" << "bar";
  90 formatted_raw_ostream &llvm::ferrs() {
  91   static formatted_raw_ostream S(errs());
  92   return S;
  93 }