blob: 949c9445b3e8b588e626ab660f2b0a8fabbafd29 [file] [log] [blame]
/*
* Copyright (C) 2014 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 __BYTE_BUCKET_ARRAY_H
#define __BYTE_BUCKET_ARRAY_H
#include <cstdint>
#include <cstring>
#include "android-base/logging.h"
namespace android {
/**
* Stores a sparsely populated array. Has a fixed size of 256
* (number of entries that a byte can represent).
*/
template <typename T>
class ByteBucketArray {
public:
ByteBucketArray() : default_() { memset(buckets_, 0, sizeof(buckets_)); }
~ByteBucketArray() {
for (size_t i = 0; i < kNumBuckets; i++) {
if (buckets_[i] != NULL) {
delete[] buckets_[i];
}
}
memset(buckets_, 0, sizeof(buckets_));
}
inline size_t size() const { return kNumBuckets * kBucketSize; }
inline const T& get(size_t index) const { return (*this)[index]; }
const T& operator[](size_t index) const {
if (index >= size()) {
return default_;
}
uint8_t bucket_index = static_cast<uint8_t>(index) >> 4;
T* bucket = buckets_[bucket_index];
if (bucket == NULL) {
return default_;
}
return bucket[0x0f & static_cast<uint8_t>(index)];
}
T& editItemAt(size_t index) {
CHECK(index < size()) << "ByteBucketArray.editItemAt(index=" << index
<< ") with size=" << size();
uint8_t bucket_index = static_cast<uint8_t>(index) >> 4;
T* bucket = buckets_[bucket_index];
if (bucket == NULL) {
bucket = buckets_[bucket_index] = new T[kBucketSize]();
}
return bucket[0x0f & static_cast<uint8_t>(index)];
}
bool set(size_t index, const T& value) {
if (index >= size()) {
return false;
}
editItemAt(index) = value;
return true;
}
private:
enum { kNumBuckets = 16, kBucketSize = 16 };
T* buckets_[kNumBuckets];
T default_;
};
} // namespace android
#endif // __BYTE_BUCKET_ARRAY_H