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//===-- llvm/Support/FormattedStream.h - Formatted streams ------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file contains raw_ostream implementations for streams to do
// things like pretty-print comments.
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/raw_ostream.h"
#include <utility>
namespace llvm {
/// formatted_raw_ostream - A raw_ostream that wraps another one and keeps track
/// of line and column position, allowing padding out to specific column
/// boundaries and querying the number of lines written to the stream. This
/// assumes that the contents of the stream is valid UTF-8 encoded text. This
/// doesn't attempt to handle everything Unicode can do (combining characters,
/// right-to-left markers, etc), but should cover the cases likely to appear in
/// source code or diagnostic messages.
class formatted_raw_ostream : public raw_ostream {
/// TheStream - The real stream we output to. We set it to be
/// unbuffered, since we're already doing our own buffering.
raw_ostream *TheStream;
/// Position - The current output column and line of the data that's
/// been flushed and the portion of the buffer that's been
/// scanned. The line and column scheme is zero-based.
std::pair<unsigned, unsigned> Position;
/// Scanned - This points to one past the last character in the
/// buffer we've scanned.
const char *Scanned;
/// PartialUTF8Char - Either empty or a prefix of a UTF-8 code unit sequence
/// for a Unicode scalar value which should be prepended to the buffer for the
/// next call to ComputePosition. This is needed when the buffer is flushed
/// when it ends part-way through the UTF-8 encoding of a Unicode scalar
/// value, so that we can compute the display width of the character once we
/// have the rest of it.
SmallString<4> PartialUTF8Char;
void write_impl(const char *Ptr, size_t Size) override;
/// current_pos - Return the current position within the stream,
/// not counting the bytes currently in the buffer.
uint64_t current_pos() const override {
// Our current position in the stream is all the contents which have been
// written to the underlying stream (*not* the current position of the
// underlying stream).
return TheStream->tell();
/// ComputePosition - Examine the given output buffer and figure out the new
/// position after output. This is safe to call multiple times on the same
/// buffer, as it records the most recently scanned character and resumes from
/// there when the buffer has not been flushed.
void ComputePosition(const char *Ptr, size_t size);
/// UpdatePosition - scan the characters in [Ptr, Ptr+Size), and update the
/// line and column numbers. Unlike ComputePosition, this must be called
/// exactly once on each region of the buffer.
void UpdatePosition(const char *Ptr, size_t Size);
void setStream(raw_ostream &Stream) {
TheStream = &Stream;
// This formatted_raw_ostream inherits from raw_ostream, so it'll do its
// own buffering, and it doesn't need or want TheStream to do another
// layer of buffering underneath. Resize the buffer to what TheStream
// had been using, and tell TheStream not to do its own buffering.
if (size_t BufferSize = TheStream->GetBufferSize())
Scanned = nullptr;
/// formatted_raw_ostream - Open the specified file for
/// writing. If an error occurs, information about the error is
/// put into ErrorInfo, and the stream should be immediately
/// destroyed; the string will be empty if no error occurred.
/// As a side effect, the given Stream is set to be Unbuffered.
/// This is because formatted_raw_ostream does its own buffering,
/// so it doesn't want another layer of buffering to be happening
/// underneath it.
formatted_raw_ostream(raw_ostream &Stream)
: TheStream(nullptr), Position(0, 0) {
explicit formatted_raw_ostream() : TheStream(nullptr), Position(0, 0) {
Scanned = nullptr;
~formatted_raw_ostream() override {
/// PadToColumn - Align the output to some column number. If the current
/// column is already equal to or more than NewCol, PadToColumn inserts one
/// space.
/// \param NewCol - The column to move to.
formatted_raw_ostream &PadToColumn(unsigned NewCol);
unsigned getColumn() {
// Calculate current position, taking buffer contents into account.
ComputePosition(getBufferStart(), GetNumBytesInBuffer());
return Position.first;
unsigned getLine() {
// Calculate current position, taking buffer contents into account.
ComputePosition(getBufferStart(), GetNumBytesInBuffer());
return Position.second;
raw_ostream &resetColor() override {
return *this;
raw_ostream &reverseColor() override {
return *this;
raw_ostream &changeColor(enum Colors Color, bool Bold, bool BG) override {
TheStream->changeColor(Color, Bold, BG);
return *this;
bool is_displayed() const override {
return TheStream->is_displayed();
void releaseStream() {
// Transfer the buffer settings from this raw_ostream back to the underlying
// stream.
if (!TheStream)
if (size_t BufferSize = GetBufferSize())
/// fouts() - This returns a reference to a formatted_raw_ostream for
/// standard output. Use it like: fouts() << "foo" << "bar";
formatted_raw_ostream &fouts();
/// ferrs() - This returns a reference to a formatted_raw_ostream for
/// standard error. Use it like: ferrs() << "foo" << "bar";
formatted_raw_ostream &ferrs();
/// fdbgs() - This returns a reference to a formatted_raw_ostream for
/// debug output. Use it like: fdbgs() << "foo" << "bar";
formatted_raw_ostream &fdbgs();
} // end llvm namespace