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 #include "llvm/Support/Debug.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 #include <algorithm>
  18
  19 using namespace llvm;
  20
  21 /// UpdatePosition - Examine the given char sequence and figure out which
  22 /// column we end up in after output, and how many line breaks are contained.
  23 ///
  24 static void UpdatePosition(std::pair<unsigned, unsigned> &Position, const char *Ptr, size_t Size) {
  25   unsigned &Column = Position.first;
  26   unsigned &Line = Position.second;
  27
  28   // Keep track of the current column and line by scanning the string for
  29   // special characters
  30   for (const char *End = Ptr + Size; Ptr != End; ++Ptr) {
  31     ++Column;
  32     switch (*Ptr) {
  33     case '\n':
  34       Line += 1;
  35       LLVM_FALLTHROUGH;
  36     case '\r':
  37       Column = 0;
  38       break;
  39     case '\t':
  40       // Assumes tab stop = 8 characters.
  41       Column += (8 - (Column & 0x7)) & 0x7;
  42       break;
  43     }
  44   }
  45 }
  46
  47 /// ComputePosition - Examine the current output and update line and column
  48 /// counts.
  49 void formatted_raw_ostream::ComputePosition(const char *Ptr, size_t Size) {
  50   // If our previous scan pointer is inside the buffer, assume we already
  51   // scanned those bytes. This depends on raw_ostream to not change our buffer
  52   // in unexpected ways.
  53   if (Ptr <= Scanned && Scanned <= Ptr + Size)
  54     // Scan all characters added since our last scan to determine the new
  55     // column.
  56     UpdatePosition(Position, Scanned, Size - (Scanned - Ptr));
  57   else
  58     UpdatePosition(Position, Ptr, Size);
  59
  60   // Update the scanning pointer.
  61   Scanned = Ptr + Size;
  62 }
  63
  64 /// PadToColumn - Align the output to some column number.
  65 ///
  66 /// \param NewCol - The column to move to.
  67 ///
  68 formatted_raw_ostream &formatted_raw_ostream::PadToColumn(unsigned NewCol) {
  69   // Figure out what's in the buffer and add it to the column count.
  70   ComputePosition(getBufferStart(), GetNumBytesInBuffer());
  71
  72   // Output spaces until we reach the desired column.
  73   indent(std::max(int(NewCol - getColumn()), 1));
  74   return *this;
  75 }
  76
  77 void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
  78   // Figure out what's in the buffer and add it to the column count.
  79   ComputePosition(Ptr, Size);
  80
  81   // Write the data to the underlying stream (which is unbuffered, so
  82   // the data will be immediately written out).
  83   TheStream->write(Ptr, Size);
  84
  85   // Reset the scanning pointer.
  86   Scanned = nullptr;
  87 }
  88
  89 /// fouts() - This returns a reference to a formatted_raw_ostream for
  90 /// standard output.  Use it like: fouts() << "foo" << "bar";
  91 formatted_raw_ostream &llvm::fouts() {
  92   static formatted_raw_ostream S(outs());
  93   return S;
  94 }
  95
  96 /// ferrs() - This returns a reference to a formatted_raw_ostream for
  97 /// standard error.  Use it like: ferrs() << "foo" << "bar";
  98 formatted_raw_ostream &llvm::ferrs() {
  99   static formatted_raw_ostream S(errs());
 100   return S;
 101 }
 102
 103 /// fdbgs() - This returns a reference to a formatted_raw_ostream for
 104 /// the debug stream.  Use it like: fdbgs() << "foo" << "bar";
 105 formatted_raw_ostream &llvm::fdbgs() {
 106   static formatted_raw_ostream S(dbgs());
 107   return S;
 108 }