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//===- LineIterator.h - Iterator to read a text buffer's lines --*- 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
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/DataTypes.h"
#include <iterator>
namespace llvm {
class MemoryBuffer;
/// A forward iterator which reads text lines from a buffer.
/// This class provides a forward iterator interface for reading one line at
/// a time from a buffer. When default constructed the iterator will be the
/// "end" iterator.
/// The iterator is aware of what line number it is currently processing. It
/// strips blank lines by default, and comment lines given a comment-starting
/// character.
/// Note that this iterator requires the buffer to be nul terminated.
class line_iterator
: public std::iterator<std::forward_iterator_tag, StringRef> {
const MemoryBuffer *Buffer = nullptr;
char CommentMarker = '\0';
bool SkipBlanks = true;
unsigned LineNumber = 1;
StringRef CurrentLine;
/// Default construct an "end" iterator.
line_iterator() = default;
/// Construct a new iterator around some memory buffer.
explicit line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks = true,
char CommentMarker = '\0');
/// Return true if we've reached EOF or are an "end" iterator.
bool is_at_eof() const { return !Buffer; }
/// Return true if we're an "end" iterator or have reached EOF.
bool is_at_end() const { return is_at_eof(); }
/// Return the current line number. May return any number at EOF.
int64_t line_number() const { return LineNumber; }
/// Advance to the next (non-empty, non-comment) line.
line_iterator &operator++() {
return *this;
line_iterator operator++(int) {
line_iterator tmp(*this);
return tmp;
/// Get the current line as a \c StringRef.
StringRef operator*() const { return CurrentLine; }
const StringRef *operator->() const { return &CurrentLine; }
friend bool operator==(const line_iterator &LHS, const line_iterator &RHS) {
return LHS.Buffer == RHS.Buffer &&
LHS.CurrentLine.begin() == RHS.CurrentLine.begin();
friend bool operator!=(const line_iterator &LHS, const line_iterator &RHS) {
return !(LHS == RHS);
/// Advance the iterator to the next line.
void advance();