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diff --git a/gcc/text-art/ruler.h b/gcc/text-art/ruler.h
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+/* Classes for printing labelled rulers.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   Contributed by David Malcolm <dmalcolm@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef GCC_TEXT_ART_RULER_H
+#define GCC_TEXT_ART_RULER_H
+
+#include "text-art/canvas.h"
+
+namespace text_art {
+
+/* A way to annotate a series of ranges of canvas coordinates
+   with text labels either above or, in this example, below:
+     ├───────┬───────┼───────┬───────┼───────┬───────┤
+             │               │               │
+           label A         label B          label C
+   with logic to ensure that the text labels don't overlap
+   when printed.  */
+
+class x_ruler
+{
+ public:
+  enum class label_dir { ABOVE, BELOW };
+  enum class label_kind
+  {
+    TEXT,
+    TEXT_WITH_BORDER
+  };
+
+  x_ruler (label_dir dir)
+  : m_label_dir (dir),
+    m_size (canvas::size_t (0, 0)),
+    m_has_layout (false)
+  {}
+
+  void add_label (const canvas::range_t &r,
+		  styled_string text,
+		  style::id_t style_id,
+		  label_kind kind = label_kind::TEXT);
+
+  canvas::size_t get_size ()
+  {
+    ensure_layout ();
+    return m_size;
+  }
+
+  void paint_to_canvas (canvas &canvas,
+			canvas::coord_t offset,
+			const theme &theme);
+
+  void debug (const style_manager &sm);
+
+ private:
+  /* A particular label within an x_ruler.
+     Consider e.g.:
+
+     #   x:  01234567890123456789012345678901234567890123456789
+     # y: 0: ├───────┬───────┼───────┬───────┼───────┬───────┤
+     #    1:         │               │               │
+     #    2:       label A         label B          label C
+     #
+
+     Then "label A" is:
+
+     #               m_connector_x == 8
+     #               V
+     #   x:  0123456789012
+     # y: 0:         ┬
+     #    1:         │
+     #    2:       label A
+     #   x:  0123456789012
+     #             ^
+     #             m_text_coord.x == 6
+
+     and m_text_coord is (2, 6).
+     The y cooordinates are stored with respect to label_dir::BELOW;
+     for label_dir::ABOVE we flip them when painting the ruler.  */
+  class label
+  {
+    friend class x_ruler;
+  public:
+    label (const canvas::range_t &range, styled_string text, style::id_t style_id,
+	   label_kind kind);
+
+    bool operator< (const label &other) const;
+
+  private:
+    canvas::range_t m_range;
+    styled_string m_text;
+    style::id_t m_style_id;
+    label_kind m_kind;
+    canvas::rect_t m_text_rect; // includes any border
+    int m_connector_x;
+  };
+
+  void ensure_layout ();
+  void update_layout ();
+  int get_canvas_y (int rel_y) const;
+
+  label_dir m_label_dir;
+  std::vector<label> m_labels;
+  canvas::size_t m_size;
+  bool m_has_layout = false;
+
+};
+
+} // namespace text_art
+
+#endif /* GCC_TEXT_ART_RULER_H */