--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/training/common/intfeaturedist.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,78 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+// Author: rays@google.com (Ray Smith)
+///////////////////////////////////////////////////////////////////////
+// File:        intfeaturedist.h
+// Description: Fast set-difference-based feature distance calculator.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+///////////////////////////////////////////////////////////////////////
+
+#ifndef TESSERACT_CLASSIFY_INTFEATUREDIST_H_
+#define TESSERACT_CLASSIFY_INTFEATUREDIST_H_
+
+#include <vector>
+
+namespace tesseract {
+
+class IntFeatureMap;
+
+// Feature distance calculator designed to provide a fast distance calculation
+// based on set difference between a given feature set and many other feature
+// sets in turn.
+// Representation of a feature set as an array of bools that are sparsely
+// true, and companion arrays that allow fast feature set distance
+// calculations with allowance of offsets in position.
+// Init is expensive, so for greatest efficiency, to re-initialize for a new
+// feature set, use Set(..., false) on the SAME feature set as was used to
+// setup with Set(..., true), to return to its initialized state before
+// reuse with Set(..., true) on a new feature set.
+class IntFeatureDist {
+public:
+  IntFeatureDist();
+  ~IntFeatureDist();
+
+  // Initialize the bool array to the given size of feature space.
+  // The feature_map is just borrowed, and must exist for the entire
+  // lifetime of the IntFeatureDist.
+  void Init(const IntFeatureMap *feature_map);
+
+  // Setup the map for the given indexed_features that have been indexed by
+  // feature_map. After use, use Set(..., false) to reset to the initial state
+  // as this is faster than calling Init for sparse spaces.
+  void Set(const std::vector<int> &indexed_features, int canonical_count, bool value);
+
+  // Compute the distance between the given feature vector and the last
+  // Set feature vector.
+  double FeatureDistance(const std::vector<int> &features) const;
+  double DebugFeatureDistance(const std::vector<int> &features) const;
+
+private:
+  // Clear all data.
+  void Clear();
+
+  // Size of the indexed feature space.
+  int size_;
+  // Total weight of features currently stored in the maps.
+  double total_feature_weight_;
+  // Pointer to IntFeatureMap given at Init to find offset features.
+  const IntFeatureMap *feature_map_;
+  // Array of bools indicating presence of a feature.
+  bool *features_;
+  // Array indicating the presence of a feature offset by one unit.
+  bool *features_delta_one_;
+  // Array indicating the presence of a feature offset by two units.
+  bool *features_delta_two_;
+};
+
+} // namespace tesseract
+
+#endif // TESSERACT_CLASSIFY_INTFEATUREDIST_H_