// Copyright 2020 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef V8_BASE_BITS_ITERATOR_H_ #define V8_BASE_BITS_ITERATOR_H_ #include <type_traits> #include "src/base/bits.h" #include "src/base/iterator.h" namespace v8 { namespace base { namespace bits { template <typename T, bool kMSBFirst = false> class BitsIterator : public iterator<std::forward_iterator_tag, int> { static_assert(std::is_integral<T>::value); public: explicit BitsIterator(T bits) : bits_(bits) {} int operator*() const { return kMSBFirst ? 8 * sizeof(T) - 1 - CountLeadingZeros(bits_) : CountTrailingZeros(bits_); } BitsIterator& operator++() { bits_ &= ~(T{1} << **this); return *this; } bool operator==(BitsIterator other) { return bits_ == other.bits_; } bool operator!=(BitsIterator other) { return bits_ != other.bits_; } private: T bits_; }; // Returns an iterable over the bits in {bits}, from LSB to MSB. template <typename T> auto IterateBits(T bits) { return make_iterator_range(BitsIterator<T>{bits}, BitsIterator<T>{0}); } // Returns an iterable over the bits in {bits}, from MSB to LSB. template <typename T> auto IterateBitsBackwards(T bits) { return make_iterator_range(BitsIterator<T, true>{bits}, BitsIterator<T, true>{0}); } } // namespace bits } // namespace base } // namespace v8 #endif // V8_BASE_BITS_ITERATOR_H_