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diff --git a/extern/draco/dracoenc/src/draco/core/draco_index_type.h b/extern/draco/dracoenc/src/draco/core/draco_index_type.h
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+// Copyright 2016 The Draco Authors.
+//
+// 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.
+//
+// This files provides a basic framework for strongly typed indices that are
+// used within the Draco library. The motivation of using strongly typed indices
+// is to prevent bugs caused by mixing up incompatible indices, such as indexing
+// mesh faces with point indices and vice versa.
+//
+// Usage:
+//      Define strongly typed index using macro:
+//
+//        DEFINE_NEW_DRACO_INDEX_TYPE(value_type, name)
+//
+//      where |value_type| is the data type of the index value (such as int32_t)
+//      and |name| is a unique typename of the new index.
+//
+//      E.g., we can define new index types as:
+//
+//        DEFINE_NEW_DRACO_INDEX_TYPE(int, PointIndex)
+//        DEFINE_NEW_DRACO_INDEX_TYPE(int, FaceIndex)
+//
+//      The new types can then be used in the similar way as the regular weakly
+//      typed indices (such as int32, int64, ...), but they cannot be
+//      accidentally misassigned. E.g.:
+//
+//        PointIndex point_index(10);
+//        FaceIndex face_index;
+//        face_index = point_index;  // Compile error!
+//
+//      One can still cast one type to another explicitly by accessing the index
+//      value directly using the .value() method:
+//
+//        face_index = FaceIndex(point_index.value());  // Compiles OK.
+//
+//      Strongly typed indices support most of the common binary and unary
+//      operators and support for additional operators can be added if
+//      necessary.
+
+#ifndef DRACO_CORE_DRACO_INDEX_TYPE_H_
+#define DRACO_CORE_DRACO_INDEX_TYPE_H_
+
+#include <ostream>
+
+#include "draco/draco_features.h"
+
+namespace draco {
+
+#define DEFINE_NEW_DRACO_INDEX_TYPE(value_type, name) \
+  struct name##_tag_type_ {};                         \
+  typedef IndexType<value_type, name##_tag_type_> name;
+
+template <class ValueTypeT, class TagT>
+class IndexType {
+ public:
+  typedef IndexType<ValueTypeT, TagT> ThisIndexType;
+  typedef ValueTypeT ValueType;
+
+  constexpr IndexType() : value_(ValueTypeT()) {}
+  constexpr explicit IndexType(ValueTypeT value) : value_(value) {}
+
+  constexpr ValueTypeT value() const { return value_; }
+
+  constexpr bool operator==(const IndexType &i) const {
+    return value_ == i.value_;
+  }
+  constexpr bool operator==(const ValueTypeT &val) const {
+    return value_ == val;
+  }
+  constexpr bool operator!=(const IndexType &i) const {
+    return value_ != i.value_;
+  }
+  constexpr bool operator!=(const ValueTypeT &val) const {
+    return value_ != val;
+  }
+  constexpr bool operator<(const IndexType &i) const {
+    return value_ < i.value_;
+  }
+  constexpr bool operator<(const ValueTypeT &val) const { return value_ < val; }
+  constexpr bool operator>(const IndexType &i) const {
+    return value_ > i.value_;
+  }
+  constexpr bool operator>(const ValueTypeT &val) const { return value_ > val; }
+  constexpr bool operator>=(const IndexType &i) const {
+    return value_ >= i.value_;
+  }
+  constexpr bool operator>=(const ValueTypeT &val) const {
+    return value_ >= val;
+  }
+
+  inline ThisIndexType &operator++() {
+    ++value_;
+    return *this;
+  }
+  inline ThisIndexType operator++(int) {
+    const ThisIndexType ret(value_);
+    ++value_;
+    return ret;
+  }
+
+  inline ThisIndexType &operator--() {
+    --value_;
+    return *this;
+  }
+  inline ThisIndexType operator--(int) {
+    const ThisIndexType ret(value_);
+    --value_;
+    return ret;
+  }
+
+  constexpr ThisIndexType operator+(const IndexType &i) const {
+    return ThisIndexType(value_ + i.value_);
+  }
+  constexpr ThisIndexType operator+(const ValueTypeT &val) const {
+    return ThisIndexType(value_ + val);
+  }
+  constexpr ThisIndexType operator-(const IndexType &i) const {
+    return ThisIndexType(value_ - i.value_);
+  }
+  constexpr ThisIndexType operator-(const ValueTypeT &val) const {
+    return ThisIndexType(value_ - val);
+  }
+
+  inline ThisIndexType &operator+=(const IndexType &i) {
+    value_ += i.value_;
+    return *this;
+  }
+  inline ThisIndexType operator+=(const ValueTypeT &val) {
+    value_ += val;
+    return *this;
+  }
+  inline ThisIndexType &operator-=(const IndexType &i) {
+    value_ -= i.value_;
+    return *this;
+  }
+  inline ThisIndexType operator-=(const ValueTypeT &val) {
+    value_ -= val;
+    return *this;
+  }
+  inline ThisIndexType &operator=(const ThisIndexType &i) {
+    value_ = i.value_;
+    return *this;
+  }
+  inline ThisIndexType &operator=(const ValueTypeT &val) {
+    value_ = val;
+    return *this;
+  }
+
+ private:
+  ValueTypeT value_;
+};
+
+// Stream operator << provided for logging purposes.
+template <class ValueTypeT, class TagT>
+std::ostream &operator<<(std::ostream &os, IndexType<ValueTypeT, TagT> index) {
+  return os << index.value();
+}
+
+}  // namespace draco
+
+// Specialize std::hash for the strongly indexed types.
+namespace std {
+
+template <class ValueTypeT, class TagT>
+struct hash<draco::IndexType<ValueTypeT, TagT>> {
+  size_t operator()(const draco::IndexType<ValueTypeT, TagT> &i) const {
+    return static_cast<size_t>(i.value());
+  }
+};
+
+}  // namespace std
+
+#endif  // DRACO_CORE_DRACO_INDEX_TYPE_H_