include/llvm/Support/FormattedStream.h

   1 //===-- llvm/Support/FormattedStream.h - 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 raw_ostream implementations for streams to do
  10 // things like pretty-print comments.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_SUPPORT_FORMATTEDSTREAM_H
  15 #define LLVM_SUPPORT_FORMATTEDSTREAM_H
  16
  17 #include "llvm/Support/raw_ostream.h"
  18 #include <utility>
  19
  20 namespace llvm {
  21
  22 /// formatted_raw_ostream - A raw_ostream that wraps another one and keeps track
  23 /// of line and column position, allowing padding out to specific column
  24 /// boundaries and querying the number of lines written to the stream.
  25 ///
  26 class formatted_raw_ostream : public raw_ostream {
  27   /// TheStream - The real stream we output to. We set it to be
  28   /// unbuffered, since we're already doing our own buffering.
  29   ///
  30   raw_ostream *TheStream;
  31
  32   /// Position - The current output column and line of the data that's
  33   /// been flushed and the portion of the buffer that's been
  34   /// scanned.  The line and column scheme is zero-based.
  35   ///
  36   std::pair<unsigned, unsigned> Position;
  37
  38   /// Scanned - This points to one past the last character in the
  39   /// buffer we've scanned.
  40   ///
  41   const char *Scanned;
  42
  43   void write_impl(const char *Ptr, size_t Size) override;
  44
  45   /// current_pos - Return the current position within the stream,
  46   /// not counting the bytes currently in the buffer.
  47   uint64_t current_pos() const override {
  48     // Our current position in the stream is all the contents which have been
  49     // written to the underlying stream (*not* the current position of the
  50     // underlying stream).
  51     return TheStream->tell();
  52   }
  53
  54   /// ComputePosition - Examine the given output buffer and figure out the new
  55   /// position after output.
  56   ///
  57   void ComputePosition(const char *Ptr, size_t size);
  58
  59   void setStream(raw_ostream &Stream) {
  60     releaseStream();
  61
  62     TheStream = &Stream;
  63
  64     // This formatted_raw_ostream inherits from raw_ostream, so it'll do its
  65     // own buffering, and it doesn't need or want TheStream to do another
  66     // layer of buffering underneath. Resize the buffer to what TheStream
  67     // had been using, and tell TheStream not to do its own buffering.
  68     if (size_t BufferSize = TheStream->GetBufferSize())
  69       SetBufferSize(BufferSize);
  70     else
  71       SetUnbuffered();
  72     TheStream->SetUnbuffered();
  73
  74     Scanned = nullptr;
  75   }
  76
  77 public:
  78   /// formatted_raw_ostream - Open the specified file for
  79   /// writing. If an error occurs, information about the error is
  80   /// put into ErrorInfo, and the stream should be immediately
  81   /// destroyed; the string will be empty if no error occurred.
  82   ///
  83   /// As a side effect, the given Stream is set to be Unbuffered.
  84   /// This is because formatted_raw_ostream does its own buffering,
  85   /// so it doesn't want another layer of buffering to be happening
  86   /// underneath it.
  87   ///
  88   formatted_raw_ostream(raw_ostream &Stream)
  89       : TheStream(nullptr), Position(0, 0) {
  90     setStream(Stream);
  91   }
  92   explicit formatted_raw_ostream() : TheStream(nullptr), Position(0, 0) {
  93     Scanned = nullptr;
  94   }
  95
  96   ~formatted_raw_ostream() override {
  97     flush();
  98     releaseStream();
  99   }
 100
 101   /// PadToColumn - Align the output to some column number.  If the current
 102   /// column is already equal to or more than NewCol, PadToColumn inserts one
 103   /// space.
 104   ///
 105   /// \param NewCol - The column to move to.
 106   formatted_raw_ostream &PadToColumn(unsigned NewCol);
 107
 108   /// getColumn - Return the column number
 109   unsigned getColumn() { return Position.first; }
 110
 111   /// getLine - Return the line number
 112   unsigned getLine() { return Position.second; }
 113
 114   raw_ostream &resetColor() override {
 115     TheStream->resetColor();
 116     return *this;
 117   }
 118
 119   raw_ostream &reverseColor() override {
 120     TheStream->reverseColor();
 121     return *this;
 122   }
 123
 124   raw_ostream &changeColor(enum Colors Color, bool Bold, bool BG) override {
 125     TheStream->changeColor(Color, Bold, BG);
 126     return *this;
 127   }
 128
 129   bool is_displayed() const override {
 130     return TheStream->is_displayed();
 131   }
 132
 133 private:
 134   void releaseStream() {
 135     // Transfer the buffer settings from this raw_ostream back to the underlying
 136     // stream.
 137     if (!TheStream)
 138       return;
 139     if (size_t BufferSize = GetBufferSize())
 140       TheStream->SetBufferSize(BufferSize);
 141     else
 142       TheStream->SetUnbuffered();
 143   }
 144 };
 145
 146 /// fouts() - This returns a reference to a formatted_raw_ostream for
 147 /// standard output.  Use it like: fouts() << "foo" << "bar";
 148 formatted_raw_ostream &fouts();
 149
 150 /// ferrs() - This returns a reference to a formatted_raw_ostream for
 151 /// standard error.  Use it like: ferrs() << "foo" << "bar";
 152 formatted_raw_ostream &ferrs();
 153
 154 /// fdbgs() - This returns a reference to a formatted_raw_ostream for
 155 /// debug output.  Use it like: fdbgs() << "foo" << "bar";
 156 formatted_raw_ostream &fdbgs();
 157
 158 } // end llvm namespace
 159
 160
 161 #endif