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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_
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