lib/Support/FormattedStream.cpp

   1 //===-- llvm/Support/FormattedStream.cpp - Formatted streams ----*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains the implementation of formatted_raw_ostream.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/Support/FormattedStream.h"
  14 #include "llvm/Support/Debug.h"
  15 #include "llvm/Support/raw_ostream.h"
  16 #include <algorithm>
  17
  18 using namespace llvm;
  19
  20 /// UpdatePosition - Examine the given char sequence and figure out which
  21 /// column we end up in after output, and how many line breaks are contained.
  22 ///
  23 static void UpdatePosition(std::pair<unsigned, unsigned> &Position, const char *Ptr, size_t Size) {
  24   unsigned &Column = Position.first;
  25   unsigned &Line = Position.second;
  26
  27   // Keep track of the current column and line by scanning the string for
  28   // special characters
  29   for (const char *End = Ptr + Size; Ptr != End; ++Ptr) {
  30     ++Column;
  31     switch (*Ptr) {
  32     case '\n':
  33       Line += 1;
  34       LLVM_FALLTHROUGH;
  35     case '\r':
  36       Column = 0;
  37       break;
  38     case '\t':
  39       // Assumes tab stop = 8 characters.
  40       Column += (8 - (Column & 0x7)) & 0x7;
  41       break;
  42     }
  43   }
  44 }
  45
  46 /// ComputePosition - Examine the current output and update line and column
  47 /// counts.
  48 void formatted_raw_ostream::ComputePosition(const char *Ptr, size_t Size) {
  49   // If our previous scan pointer is inside the buffer, assume we already
  50   // scanned those bytes. This depends on raw_ostream to not change our buffer
  51   // in unexpected ways.
  52   if (Ptr <= Scanned && Scanned <= Ptr + Size)
  53     // Scan all characters added since our last scan to determine the new
  54     // column.
  55     UpdatePosition(Position, Scanned, Size - (Scanned - Ptr));
  56   else
  57     UpdatePosition(Position, Ptr, Size);
  58
  59   // Update the scanning pointer.
  60   Scanned = Ptr + Size;
  61 }
  62
  63 /// PadToColumn - Align the output to some column number.
  64 ///
  65 /// \param NewCol - The column to move to.
  66 ///
  67 formatted_raw_ostream &formatted_raw_ostream::PadToColumn(unsigned NewCol) {
  68   // Figure out what's in the buffer and add it to the column count.
  69   ComputePosition(getBufferStart(), GetNumBytesInBuffer());
  70
  71   // Output spaces until we reach the desired column.
  72   indent(std::max(int(NewCol - getColumn()), 1));
  73   return *this;
  74 }
  75
  76 void formatted_raw_ostream::write_impl(const char *Ptr, size_t Size) {
  77   // Figure out what's in the buffer and add it to the column count.
  78   ComputePosition(Ptr, Size);
  79
  80   // Write the data to the underlying stream (which is unbuffered, so
  81   // the data will be immediately written out).
  82   TheStream->write(Ptr, Size);
  83
  84   // Reset the scanning pointer.
  85   Scanned = nullptr;
  86 }
  87
  88 /// fouts() - This returns a reference to a formatted_raw_ostream for
  89 /// standard output.  Use it like: fouts() << "foo" << "bar";
  90 formatted_raw_ostream &llvm::fouts() {
  91   static formatted_raw_ostream S(outs());
  92   return S;
  93 }
  94
  95 /// ferrs() - This returns a reference to a formatted_raw_ostream for
  96 /// standard error.  Use it like: ferrs() << "foo" << "bar";
  97 formatted_raw_ostream &llvm::ferrs() {
  98   static formatted_raw_ostream S(errs());
  99   return S;
 100 }
 101
 102 /// fdbgs() - This returns a reference to a formatted_raw_ostream for
 103 /// the debug stream.  Use it like: fdbgs() << "foo" << "bar";
 104 formatted_raw_ostream &llvm::fdbgs() {
 105   static formatted_raw_ostream S(dbgs());
 106   return S;
 107 }