93 lines
2.8 KiB
C++
93 lines
2.8 KiB
C++
// Copyright 2017 The Abseil 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
|
|
//
|
|
// https://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 ABSL_RANDOM_INTERNAL_EXPLICIT_SEED_SEQ_H_
|
|
#define ABSL_RANDOM_INTERNAL_EXPLICIT_SEED_SEQ_H_
|
|
|
|
#include <algorithm>
|
|
#include <cstddef>
|
|
#include <cstdint>
|
|
#include <initializer_list>
|
|
#include <iterator>
|
|
#include <vector>
|
|
|
|
#include "absl/base/config.h"
|
|
#include "absl/base/internal/endian.h"
|
|
|
|
namespace absl {
|
|
ABSL_NAMESPACE_BEGIN
|
|
namespace random_internal {
|
|
|
|
// This class conforms to the C++ Standard "Seed Sequence" concept
|
|
// [rand.req.seedseq].
|
|
//
|
|
// An "ExplicitSeedSeq" is meant to provide a conformant interface for
|
|
// forwarding pre-computed seed material to the constructor of a class
|
|
// conforming to the "Uniform Random Bit Generator" concept. This class makes no
|
|
// attempt to mutate the state provided by its constructor, and returns it
|
|
// directly via ExplicitSeedSeq::generate().
|
|
//
|
|
// If this class is asked to generate more seed material than was provided to
|
|
// the constructor, then the remaining bytes will be filled with deterministic,
|
|
// nonrandom data.
|
|
class ExplicitSeedSeq {
|
|
public:
|
|
using result_type = uint32_t;
|
|
|
|
ExplicitSeedSeq() : state_() {}
|
|
|
|
// Copy and move both allowed.
|
|
ExplicitSeedSeq(const ExplicitSeedSeq& other) = default;
|
|
ExplicitSeedSeq& operator=(const ExplicitSeedSeq& other) = default;
|
|
ExplicitSeedSeq(ExplicitSeedSeq&& other) = default;
|
|
ExplicitSeedSeq& operator=(ExplicitSeedSeq&& other) = default;
|
|
|
|
template <typename Iterator>
|
|
ExplicitSeedSeq(Iterator begin, Iterator end) {
|
|
for (auto it = begin; it != end; it++) {
|
|
state_.push_back(*it & 0xffffffff);
|
|
}
|
|
}
|
|
|
|
template <typename T>
|
|
ExplicitSeedSeq(std::initializer_list<T> il)
|
|
: ExplicitSeedSeq(il.begin(), il.end()) {}
|
|
|
|
size_t size() const { return state_.size(); }
|
|
|
|
template <typename OutIterator>
|
|
void param(OutIterator out) const {
|
|
std::copy(std::begin(state_), std::end(state_), out);
|
|
}
|
|
|
|
template <typename OutIterator>
|
|
void generate(OutIterator begin, OutIterator end) {
|
|
for (size_t index = 0; begin != end; begin++) {
|
|
*begin = state_.empty() ? 0 : state_[index++];
|
|
if (index >= state_.size()) {
|
|
index = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
protected:
|
|
std::vector<uint32_t> state_;
|
|
};
|
|
|
|
} // namespace random_internal
|
|
ABSL_NAMESPACE_END
|
|
} // namespace absl
|
|
|
|
#endif // ABSL_RANDOM_INTERNAL_EXPLICIT_SEED_SEQ_H_
|