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
  17 using namespace llvm;
  18
  19 /// CountColumns - Examine the given char sequence and figure out which
  20 /// column we end up in after output.
  21 ///
  22 static unsigned CountColumns(unsigned Column, const char *Ptr, size_t Size) {
  23   // Keep track of the current column by scanning the string for
  24   // special characters
  25
  26   for (const char *End = Ptr + Size; Ptr != End; ++Ptr) {
  27     ++Column;
  28     if (*Ptr == '\n' || *Ptr == '\r')
  29       Column = 0;
  30     else if (*Ptr == '\t')
  31       // Assumes tab stop = 8 characters.
  32       Column += (8 - (Column & 0x7)) & 0x7;
  33   }
  34
  35   return Column;
  36 }
  37
  38 /// ComputeColumn - Examine the current output and figure out which
  39 /// column we end up in after output.
  40 void formatted_raw_ostream::ComputeColumn(const char *Ptr, size_t Size) {
  41   // If our previous scan pointer is inside the buffer, assume we already
  42   // scanned those bytes. This depends on raw_ostream to not change our buffer
  43   // in unexpected ways.
  44   if (Ptr <= Scanned && Scanned <= Ptr + Size) {
  45     // Scan all characters added since our last scan to determine the new
  46     // column.
  47     ColumnScanned = CountColumns(ColumnScanned, Scanned,
  48                                  Size - (Scanned - Ptr));
  49   } else
  50     ColumnScanned = CountColumns(ColumnScanned, Ptr, Size);
  51
  52   // Update the scanning pointer.
  53   Scanned = Ptr + Size;
  54 }
  55
  56 /// PadToColumn - Align the output to some column number.
  57 ///
  58 /// \param NewCol - The column to move to.
  59 /// \param MinPad - The minimum space to give after the most recent
  60 /// I/O, even if the current column + minpad > newcol.
  61 ///
  62 void formatted_raw_ostream::PadToColumn(unsigned NewCol) {
  63   // Figure out what's in the buffer and add it to the column count.
  64   ComputeColumn(getBufferStart(), GetNumBytesInBuffer());
  65
  66   // Output spaces until we reach the desired column.
  67   indent(std::max(int(NewCol - ColumnScanned), 1));
  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 }