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#ifndef MOZC_UNIX_IBUS_SURROUNDING_TEXT_UTIL_H_
#define MOZC_UNIX_IBUS_SURROUNDING_TEXT_UTIL_H_

#include <string>

#include "base/port.h"
#include "unix/ibus/ibus_header.h"

namespace mozc {
namespace ibus {

class SurroundingTextUtil {
 public:
  // Calculates |from| - |to| and stores the result into |delta| with
  // checking integer overflow.
  // Returns true when neither |abs(delta)| nor |-delta| does not cause
  // integer overflow, that is, |delta| is in a safe range.
  // Returns false otherwise.
  static bool GetSafeDelta(guint from, guint to, int32 *delta);

  // Returns true if
  // 1. |surrounding_text| contains |selected_text|
  //    from |cursor_pos| to |*anchor_pos|.
  // or,
  // 2. |surrounding_text| contains |selected_text|
  //    from |*anchor_pos| to |cursor_pos|.
  // with calculating |*anchor_pos|,
  // where |cursor_pos| and |*anchor_pos| are counts of Unicode characters.
  // When both 1) and 2) are satisfied, this function calculates
  // |*anchor_pos| for case 1).
  // Otherwise returns false.
  static bool GetAnchorPosFromSelection(
      const string &surrounding_text,
      const string &selected_text,
      guint cursor_pos,
      guint *anchor_pos);

 private:
  DISALLOW_IMPLICIT_CONSTRUCTORS(SurroundingTextUtil);
};

}  // namespace ibus
}  // namespace mozc

#endif  // MOZC_UNIX_IBUS_SURROUNDING_TEXT_UTIL_H_