--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/training/unicharset/validate_grapheme.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,34 @@
+#ifndef TESSERACT_TRAINING_VALIDATE_GRAPHEME_H_
+#define TESSERACT_TRAINING_VALIDATE_GRAPHEME_H_
+
+#include "validator.h"
+
+namespace tesseract {
+
+// Subclass of Validator that validates and segments generic unicode into
+// grapheme clusters, including Latin with diacritics.
+class ValidateGrapheme : public Validator {
+public:
+  ValidateGrapheme(ViramaScript script, bool report_errors) : Validator(script, report_errors) {}
+  ~ValidateGrapheme() override = default;
+
+protected:
+  // Consumes the next Grapheme in codes_[codes_used_++...] and copies it to
+  // parts_ and output_. Returns true if a valid Grapheme was consumed,
+  // otherwise does not increment codes_used_.
+  bool ConsumeGraphemeIfValid() override;
+  // Returns the CharClass corresponding to the given Unicode ch.
+  CharClass UnicodeToCharClass(char32 ch) const override;
+
+private:
+  // Helper returns true if the sequence prev_ch,ch is invalid.
+  bool IsBadlyFormed(char32 prev_ch, char32 ch);
+  // Helper returns true if the sequence prev_ch,ch is an invalid Indic vowel.
+  static bool IsBadlyFormedIndicVowel(char32 prev_ch, char32 ch);
+  // Helper returns true if the sequence prev_ch,ch is invalid Thai.
+  static bool IsBadlyFormedThai(char32 prev_ch, char32 ch);
+};
+
+} // namespace tesseract
+
+#endif // TESSERACT_TRAINING_VALIDATE_GRAPHEME_H_