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//===- LineIterator.h - Iterator to read a text buffer's lines --*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_LINEITERATOR_H
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#define LLVM_SUPPORT_LINEITERATOR_H
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/MemoryBufferRef.h"
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#include <iterator>
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#include <optional>
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namespace llvm {
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class MemoryBuffer;
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/// A forward iterator which reads text lines from a buffer.
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///
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/// This class provides a forward iterator interface for reading one line at
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/// a time from a buffer. When default constructed the iterator will be the
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/// "end" iterator.
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///
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/// The iterator is aware of what line number it is currently processing. It
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/// strips blank lines by default, and comment lines given a comment-starting
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/// character.
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///
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/// Note that this iterator requires the buffer to be nul terminated.
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class line_iterator {
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  std::optional<MemoryBufferRef> Buffer;
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  char CommentMarker = '\0';
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  bool SkipBlanks = true;
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  unsigned LineNumber = 1;
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  StringRef CurrentLine;
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public:
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  using iterator_category = std::forward_iterator_tag;
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  using value_type = StringRef;
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  using difference_type = std::ptrdiff_t;
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  using pointer = value_type *;
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  using reference = value_type &;
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  /// Default construct an "end" iterator.
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  line_iterator() = default;
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  /// Construct a new iterator around an unowned memory buffer.
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  explicit line_iterator(const MemoryBufferRef &Buffer, bool SkipBlanks = true,
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                         char CommentMarker = '\0');
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  /// Construct a new iterator around some memory buffer.
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  explicit line_iterator(const MemoryBuffer &Buffer, bool SkipBlanks = true,
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                         char CommentMarker = '\0');
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  /// Return true if we've reached EOF or are an "end" iterator.
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  bool is_at_eof() const { return !Buffer; }
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  /// Return true if we're an "end" iterator or have reached EOF.
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  bool is_at_end() const { return is_at_eof(); }
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  /// Return the current line number. May return any number at EOF.
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  int64_t line_number() const { return LineNumber; }
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  /// Advance to the next (non-empty, non-comment) line.
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  line_iterator &operator++() {
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    advance();
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    return *this;
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  }
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  line_iterator operator++(int) {
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    line_iterator tmp(*this);
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    advance();
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    return tmp;
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  }
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  /// Get the current line as a \c StringRef.
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  StringRef operator*() const { return CurrentLine; }
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  const StringRef *operator->() const { return &CurrentLine; }
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  friend bool operator==(const line_iterator &LHS, const line_iterator &RHS) {
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    return LHS.Buffer == RHS.Buffer &&
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           LHS.CurrentLine.begin() == RHS.CurrentLine.begin();
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  }
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  friend bool operator!=(const line_iterator &LHS, const line_iterator &RHS) {
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    return !(LHS == RHS);
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  }
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private:
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  /// Advance the iterator to the next line.
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  void advance();
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};
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}
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#endif