ART: Refactor bit_utils and stl_util
Move iterator code from bit_utils.h into bit_utils_iterator.h. Move
Identity into stl_util_identity.h. Remove now unnecessary includes,
and fix up transitive users.
Test: m
Change-Id: Id1ce9cda66827c5d00584f39ed310b6b37629906
diff --git a/runtime/base/bit_utils_iterator.h b/runtime/base/bit_utils_iterator.h
new file mode 100644
index 0000000..8514de6
--- /dev/null
+++ b/runtime/base/bit_utils_iterator.h
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * 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 ART_RUNTIME_BASE_BIT_UTILS_ITERATOR_H_
+#define ART_RUNTIME_BASE_BIT_UTILS_ITERATOR_H_
+
+#include <iterator>
+#include <limits>
+#include <type_traits>
+
+#include "base/bit_utils.h"
+#include "base/iteration_range.h"
+#include "base/logging.h"
+#include "base/stl_util.h"
+
+namespace art {
+
+// Using the Curiously Recurring Template Pattern to implement everything shared
+// by LowToHighBitIterator and HighToLowBitIterator, i.e. everything but operator*().
+template <typename T, typename Iter>
+class BitIteratorBase
+ : public std::iterator<std::forward_iterator_tag, uint32_t, ptrdiff_t, void, void> {
+ static_assert(std::is_integral<T>::value, "T must be integral");
+ static_assert(std::is_unsigned<T>::value, "T must be unsigned");
+
+ static_assert(sizeof(T) == sizeof(uint32_t) || sizeof(T) == sizeof(uint64_t), "Unsupported size");
+
+ public:
+ BitIteratorBase() : bits_(0u) { }
+ explicit BitIteratorBase(T bits) : bits_(bits) { }
+
+ Iter& operator++() {
+ DCHECK_NE(bits_, 0u);
+ uint32_t bit = *static_cast<Iter&>(*this);
+ bits_ &= ~(static_cast<T>(1u) << bit);
+ return static_cast<Iter&>(*this);
+ }
+
+ Iter& operator++(int) {
+ Iter tmp(static_cast<Iter&>(*this));
+ ++*this;
+ return tmp;
+ }
+
+ protected:
+ T bits_;
+
+ template <typename U, typename I>
+ friend bool operator==(const BitIteratorBase<U, I>& lhs, const BitIteratorBase<U, I>& rhs);
+};
+
+template <typename T, typename Iter>
+bool operator==(const BitIteratorBase<T, Iter>& lhs, const BitIteratorBase<T, Iter>& rhs) {
+ return lhs.bits_ == rhs.bits_;
+}
+
+template <typename T, typename Iter>
+bool operator!=(const BitIteratorBase<T, Iter>& lhs, const BitIteratorBase<T, Iter>& rhs) {
+ return !(lhs == rhs);
+}
+
+template <typename T>
+class LowToHighBitIterator : public BitIteratorBase<T, LowToHighBitIterator<T>> {
+ public:
+ using BitIteratorBase<T, LowToHighBitIterator<T>>::BitIteratorBase;
+
+ uint32_t operator*() const {
+ DCHECK_NE(this->bits_, 0u);
+ return CTZ(this->bits_);
+ }
+};
+
+template <typename T>
+class HighToLowBitIterator : public BitIteratorBase<T, HighToLowBitIterator<T>> {
+ public:
+ using BitIteratorBase<T, HighToLowBitIterator<T>>::BitIteratorBase;
+
+ uint32_t operator*() const {
+ DCHECK_NE(this->bits_, 0u);
+ static_assert(std::numeric_limits<T>::radix == 2, "Unexpected radix!");
+ return std::numeric_limits<T>::digits - 1u - CLZ(this->bits_);
+ }
+};
+
+template <typename T>
+IterationRange<LowToHighBitIterator<T>> LowToHighBits(T bits) {
+ return IterationRange<LowToHighBitIterator<T>>(
+ LowToHighBitIterator<T>(bits), LowToHighBitIterator<T>());
+}
+
+template <typename T>
+IterationRange<HighToLowBitIterator<T>> HighToLowBits(T bits) {
+ return IterationRange<HighToLowBitIterator<T>>(
+ HighToLowBitIterator<T>(bits), HighToLowBitIterator<T>());
+}
+
+} // namespace art
+
+#endif // ART_RUNTIME_BASE_BIT_UTILS_ITERATOR_H_