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// Copyright 2021 The Tint 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.
#ifndef SRC_TINT_UTILS_ENUM_SET_H_
#define SRC_TINT_UTILS_ENUM_SET_H_
#include <cstdint>
#include <functional>
#include <ostream>
#include <type_traits>
#include <utility>
namespace tint::utils {
/// EnumSet is a set of enum values.
/// @note As the EnumSet is backed by a single uint64_t value, it can only hold
/// enum values in the range [0 .. 63].
template <typename ENUM>
struct EnumSet {
public:
/// Enum is the enum type this EnumSet wraps
using Enum = ENUM;
/// Constructor. Initializes the EnumSet with zero.
constexpr EnumSet() = default;
/// Copy constructor.
/// @param s the set to copy
constexpr EnumSet(const EnumSet& s) = default;
/// Constructor. Initializes the EnumSet with the given values.
/// @param values the enumerator values to construct the set with
template <typename... VALUES>
explicit constexpr EnumSet(VALUES... values) : set(Union(values...)) {}
/// Copy assignment operator.
/// @param set the set to assign to this set
/// @return this set so calls can be chained
inline EnumSet& operator=(const EnumSet& set) = default;
/// Copy assignment operator.
/// @param e the enum value
/// @return this set so calls can be chained
inline EnumSet& operator=(Enum e) { return *this = EnumSet{e}; }
/// Adds all the given values to this set
/// @param values the values to add
/// @return this set so calls can be chained
template <typename... VALUES>
inline EnumSet& Add(VALUES... values) {
return Add(EnumSet(std::forward<VALUES>(values)...));
}
/// Removes all the given values from this set
/// @param values the values to remove
/// @return this set so calls can be chained
template <typename... VALUES>
inline EnumSet& Remove(VALUES... values) {
return Remove(EnumSet(std::forward<VALUES>(values)...));
}
/// Adds all of s to this set
/// @param s the enum value
/// @return this set so calls can be chained
inline EnumSet& Add(EnumSet s) { return (*this = *this + s); }
/// Removes all of s from this set
/// @param s the enum value
/// @return this set so calls can be chained
inline EnumSet& Remove(EnumSet s) { return (*this = *this - s); }
/// @param e the enum value
/// @returns a copy of this set with e added
inline EnumSet operator+(Enum e) const {
EnumSet out;
out.set = set | Bit(e);
return out;
}
/// @param e the enum value
/// @returns a copy of this set with e removed
inline EnumSet operator-(Enum e) const {
EnumSet out;
out.set = set & ~Bit(e);
return out;
}
/// @param s the other set
/// @returns the union of this set with s (this ∪ rhs)
inline EnumSet operator+(EnumSet s) const {
EnumSet out;
out.set = set | s.set;
return out;
}
/// @param s the other set
/// @returns the set of entries found in this but not in s (this \ s)
inline EnumSet operator-(EnumSet s) const {
EnumSet out;
out.set = set & ~s.set;
return out;
}
/// @param s the other set
/// @returns the intersection of this set with s (this ∩ rhs)
inline EnumSet operator&(EnumSet s) const {
EnumSet out;
out.set = set & s.set;
return out;
}
/// @param e the enum value
/// @return true if the set contains `e`
inline bool Contains(Enum e) const { return (set & Bit(e)) != 0; }
/// @return true if the set is empty
inline bool Empty() const { return set == 0; }
/// Equality operator
/// @param rhs the other EnumSet to compare this to
/// @return true if this EnumSet is equal to rhs
inline bool operator==(EnumSet rhs) const { return set == rhs.set; }
/// Inequality operator
/// @param rhs the other EnumSet to compare this to
/// @return true if this EnumSet is not equal to rhs
inline bool operator!=(EnumSet rhs) const { return set != rhs.set; }
/// Equality operator
/// @param rhs the enum to compare this to
/// @return true if this EnumSet only contains `rhs`
inline bool operator==(Enum rhs) const { return set == Bit(rhs); }
/// Inequality operator
/// @param rhs the enum to compare this to
/// @return false if this EnumSet only contains `rhs`
inline bool operator!=(Enum rhs) const { return set != Bit(rhs); }
/// @return the underlying value for the EnumSet
inline uint64_t Value() const { return set; }
/// Iterator provides read-only, unidirectional iterator over the enums of an
/// EnumSet.
class Iterator {
static constexpr int8_t kEnd = 63;
Iterator(uint64_t s, int8_t b) : set(s), pos(b) {}
/// Make the constructor accessible to the EnumSet.
friend struct EnumSet;
public:
/// @return the Enum value at this point in the iterator
Enum operator*() const { return static_cast<Enum>(pos); }
/// Increments the iterator
/// @returns this iterator
Iterator& operator++() {
while (pos < kEnd) {
pos++;
if (set & (static_cast<uint64_t>(1) << static_cast<uint64_t>(pos))) {
break;
}
}
return *this;
}
/// Equality operator
/// @param rhs the Iterator to compare this to
/// @return true if the two iterators are equal
bool operator==(const Iterator& rhs) const { return set == rhs.set && pos == rhs.pos; }
/// Inequality operator
/// @param rhs the Iterator to compare this to
/// @return true if the two iterators are different
bool operator!=(const Iterator& rhs) const { return !(*this == rhs); }
private:
const uint64_t set;
int8_t pos;
};
/// @returns an read-only iterator to the beginning of the set
Iterator begin() {
auto it = Iterator{set, -1};
++it; // Move to first set bit
return it;
}
/// @returns an iterator to the beginning of the set
Iterator end() { return Iterator{set, Iterator::kEnd}; }
private:
static constexpr uint64_t Bit(Enum value) {
return static_cast<uint64_t>(1) << static_cast<uint64_t>(value);
}
static constexpr uint64_t Union() { return 0; }
template <typename FIRST, typename... VALUES>
static constexpr uint64_t Union(FIRST first, VALUES... values) {
return Bit(first) | Union(values...);
}
uint64_t set = 0;
};
/// Writes the EnumSet to the std::ostream.
/// @param out the std::ostream to write to
/// @param set the EnumSet to write
/// @returns out so calls can be chained
template <typename ENUM>
inline std::ostream& operator<<(std::ostream& out, EnumSet<ENUM> set) {
out << "{";
bool first = true;
for (auto e : set) {
if (!first) {
out << ", ";
}
first = false;
out << e;
}
return out << "}";
}
} // namespace tint::utils
namespace std {
/// Custom std::hash specialization for tint::utils::EnumSet<T>
template <typename T>
class hash<tint::utils::EnumSet<T>> {
public:
/// @param e the EnumSet to create a hash for
/// @return the hash value
inline std::size_t operator()(const tint::utils::EnumSet<T>& e) const {
return std::hash<uint64_t>()(e.Value());
}
};
} // namespace std
#endif // SRC_TINT_UTILS_ENUM_SET_H_