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// Copyright (C) 2019 Google LLC
//
// 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 ICING_TESTING_RANDOM_STRING_H_
#define ICING_TESTING_RANDOM_STRING_H_
#include <algorithm>
#include <random>
#include <string>
namespace icing {
namespace lib {
inline constexpr std::string_view kAlNumAlphabet =
"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
// Average length of word in English is 4.7 characters.
inline constexpr int kAvgTokenLen = 5;
// Made up value. This results in a fairly reasonable language - the majority of
// generated words are 3-9 characters, ~3% of words are >=20 chars, and the
// longest ones are 27 chars, (roughly consistent with the longest,
// non-contrived English words
// https://en.wikipedia.org/wiki/Longest_word_in_English)
inline constexpr int kTokenStdDev = 7;
template <typename Gen>
std::string RandomString(const std::string_view alphabet, size_t len,
Gen* gen) {
std::uniform_int_distribution<size_t> uniform(0u, alphabet.size() - 1);
std::string result(len, '\0');
std::generate(
std::begin(result), std::end(result),
[&gen, &alphabet, &uniform]() { return alphabet[uniform(*gen)]; });
return result;
}
// Creates a vector containing num_words randomly-generated words for use by
// documents.
template <typename Rand>
std::vector<std::string> CreateLanguages(int num_words, Rand* r) {
std::vector<std::string> language;
std::normal_distribution<> norm_dist(kAvgTokenLen, kTokenStdDev);
while (--num_words >= 0) {
int word_length = 0;
while (word_length < 1) {
word_length = std::round(norm_dist(*r));
}
language.push_back(RandomString(kAlNumAlphabet, word_length, r));
}
return language;
}
// Returns a vector containing num_terms unique terms. Terms are created in
// non-random order starting with "a" to "z" to "aa" to "zz", etc.
std::vector<std::string> GenerateUniqueTerms(int num_terms);
} // namespace lib
} // namespace icing
#endif // ICING_TESTING_RANDOM_STRING_H_
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