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/*
* Copyright 2017 Google
*
* 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.
*/
#include "Firestore/src/core/util/autoid.h"
#include <random>
#include <string>
#include "Firestore/src/support/secure_random.h"
namespace {
const int kAutoIdLength = 20;
const char kAutoIdAlphabet[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
firestore::SecureRandom shared_random;
} // namespace
namespace firestore {
std::string CreateAutoId() {
std::string auto_id;
auto_id.reserve(kAutoIdLength);
// -2 here because:
// * sizeof(kAutoIdAlphabet) includes the trailing null terminator
// * uniform_int_distribution is inclusive on both sizes
std::uniform_int_distribution<int> letters(0, sizeof(kAutoIdAlphabet) - 2);
for (int i = 0; i < kAutoIdLength; i++) {
int rand_index = letters(shared_random);
auto_id.append(1, kAutoIdAlphabet[rand_index]);
}
return auto_id;
}
} // namespace firestore
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