--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/llvm/Support/LineIterator.h	Mon Sep 08 22:06:00 2014 +0900
@@ -0,0 +1,85 @@
+//===- LineIterator.h - Iterator to read a text buffer's lines --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_LINEITERATOR_H
+#define LLVM_SUPPORT_LINEITERATOR_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/DataTypes.h"
+#include <iterator>
+
+namespace llvm {
+
+class MemoryBuffer;
+
+/// \brief A forward iterator which reads non-blank 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 also is aware of what line number it is currently processing
+/// and can strip comment lines given the 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;
+  char CommentMarker;
+
+  unsigned LineNumber;
+  StringRef CurrentLine;
+
+public:
+  /// \brief Default construct an "end" iterator.
+  line_iterator() : Buffer(nullptr) {}
+
+  /// \brief Construct a new iterator around some memory buffer.
+  explicit line_iterator(const MemoryBuffer &Buffer, char CommentMarker = '\0');
+
+  /// \brief Return true if we've reached EOF or are an "end" iterator.
+  bool is_at_eof() const { return !Buffer; }
+
+  /// \brief Return true if we're an "end" iterator or have reached EOF.
+  bool is_at_end() const { return is_at_eof(); }
+
+  /// \brief Return the current line number. May return any number at EOF.
+  int64_t line_number() const { return LineNumber; }
+
+  /// \brief Advance to the next (non-empty, non-comment) line.
+  line_iterator &operator++() {
+    advance();
+    return *this;
+  }
+  line_iterator operator++(int) {
+    line_iterator tmp(*this);
+    advance();
+    return tmp;
+  }
+
+  /// \brief 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);
+  }
+
+private:
+  /// \brief Advance the iterator to the next line.
+  void advance();
+};
+}
+
+#endif