73 lines
2.4 KiB
C
73 lines
2.4 KiB
C
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// Copyright 2021 The Tint Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef FUZZERS_TINT_AST_FUZZER_PROBABILITY_CONTEXT_H_
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#define FUZZERS_TINT_AST_FUZZER_PROBABILITY_CONTEXT_H_
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#include <utility>
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#include <vector>
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#include "fuzzers/tint_ast_fuzzer/random_number_generator.h"
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namespace tint {
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namespace fuzzers {
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namespace ast_fuzzer {
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/// This class is intended to be used by the `MutationFinder`s to introduce some
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/// variance to the mutation process.
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class ProbabilityContext {
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public:
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/// Initializes this instance with a random number generator.
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/// @param rng - may not be a `nullptr`. Must remain in scope as long as this
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/// instance exists.
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explicit ProbabilityContext(RandomNumberGenerator* rng);
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/// @copydoc RandomNumberGenerator::RandomBool
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bool RandomBool() { return rng_->RandomBool(); }
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/// @copydoc RandomNumberGenerator::ChoosePercentage
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bool ChoosePercentage(uint32_t percentage) {
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return rng_->ChoosePercentage(percentage);
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}
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/// Returns a random value in the range `[0; arr.size())`.
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/// @tparam T - type of the elements in the vector.
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/// @param arr - may not be empty.
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/// @return the random index in the `arr`.
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template <typename T>
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size_t GetRandomIndex(const std::vector<T>& arr) {
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return static_cast<size_t>(rng_->RandomUint64(arr.size()));
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}
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/// @return the probability of replacing some identifier with some other one.
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uint32_t GetChanceOfReplacingIdentifiers() const {
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return chance_of_replacing_identifiers_;
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}
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private:
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/// @param range - a pair of integers `a` and `b` s.t. `a <= b`.
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/// @return an random number in the range `[a; b]`.
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uint32_t RandomFromRange(std::pair<uint32_t, uint32_t> range);
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RandomNumberGenerator* rng_;
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uint32_t chance_of_replacing_identifiers_;
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};
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} // namespace ast_fuzzer
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} // namespace fuzzers
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} // namespace tint
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#endif // FUZZERS_TINT_AST_FUZZER_PROBABILITY_CONTEXT_H_
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