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authorLexi Winter <lexi@le-fay.org>2025-06-29 19:25:29 +0100
committerLexi Winter <lexi@le-fay.org>2025-06-29 19:25:29 +0100
commitbc524d70253a4ab2fe40c3ca3e5666e267c0a4d1 (patch)
tree1e629e7b46b1d9972a973bc93fd100bcebd395be /src/catch2/generators/catch_generators_adapters.hpp
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+
+// Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.txt or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+#ifndef CATCH_GENERATORS_ADAPTERS_HPP_INCLUDED
+#define CATCH_GENERATORS_ADAPTERS_HPP_INCLUDED
+
+#include <catch2/generators/catch_generators.hpp>
+#include <catch2/internal/catch_meta.hpp>
+#include <catch2/internal/catch_move_and_forward.hpp>
+
+#include <cassert>
+
+namespace Catch {
+namespace Generators {
+
+ template <typename T>
+ class TakeGenerator final : public IGenerator<T> {
+ GeneratorWrapper<T> m_generator;
+ size_t m_returned = 0;
+ size_t m_target;
+ public:
+ TakeGenerator(size_t target, GeneratorWrapper<T>&& generator):
+ m_generator(CATCH_MOVE(generator)),
+ m_target(target)
+ {
+ assert(target != 0 && "Empty generators are not allowed");
+ }
+ T const& get() const override {
+ return m_generator.get();
+ }
+ bool next() override {
+ ++m_returned;
+ if (m_returned >= m_target) {
+ return false;
+ }
+
+ const auto success = m_generator.next();
+ // If the underlying generator does not contain enough values
+ // then we cut short as well
+ if (!success) {
+ m_returned = m_target;
+ }
+ return success;
+ }
+ };
+
+ template <typename T>
+ GeneratorWrapper<T> take(size_t target, GeneratorWrapper<T>&& generator) {
+ return GeneratorWrapper<T>(Catch::Detail::make_unique<TakeGenerator<T>>(target, CATCH_MOVE(generator)));
+ }
+
+
+ template <typename T, typename Predicate>
+ class FilterGenerator final : public IGenerator<T> {
+ GeneratorWrapper<T> m_generator;
+ Predicate m_predicate;
+ public:
+ template <typename P = Predicate>
+ FilterGenerator(P&& pred, GeneratorWrapper<T>&& generator):
+ m_generator(CATCH_MOVE(generator)),
+ m_predicate(CATCH_FORWARD(pred))
+ {
+ if (!m_predicate(m_generator.get())) {
+ // It might happen that there are no values that pass the
+ // filter. In that case we throw an exception.
+ auto has_initial_value = next();
+ if (!has_initial_value) {
+ Detail::throw_generator_exception("No valid value found in filtered generator");
+ }
+ }
+ }
+
+ T const& get() const override {
+ return m_generator.get();
+ }
+
+ bool next() override {
+ bool success = m_generator.next();
+ if (!success) {
+ return false;
+ }
+ while (!m_predicate(m_generator.get()) && (success = m_generator.next()) == true);
+ return success;
+ }
+ };
+
+
+ template <typename T, typename Predicate>
+ GeneratorWrapper<T> filter(Predicate&& pred, GeneratorWrapper<T>&& generator) {
+ return GeneratorWrapper<T>(Catch::Detail::make_unique<FilterGenerator<T, Predicate>>(CATCH_FORWARD(pred), CATCH_MOVE(generator)));
+ }
+
+ template <typename T>
+ class RepeatGenerator final : public IGenerator<T> {
+ static_assert(!std::is_same<T, bool>::value,
+ "RepeatGenerator currently does not support bools"
+ "because of std::vector<bool> specialization");
+ GeneratorWrapper<T> m_generator;
+ mutable std::vector<T> m_returned;
+ size_t m_target_repeats;
+ size_t m_current_repeat = 0;
+ size_t m_repeat_index = 0;
+ public:
+ RepeatGenerator(size_t repeats, GeneratorWrapper<T>&& generator):
+ m_generator(CATCH_MOVE(generator)),
+ m_target_repeats(repeats)
+ {
+ assert(m_target_repeats > 0 && "Repeat generator must repeat at least once");
+ }
+
+ T const& get() const override {
+ if (m_current_repeat == 0) {
+ m_returned.push_back(m_generator.get());
+ return m_returned.back();
+ }
+ return m_returned[m_repeat_index];
+ }
+
+ bool next() override {
+ // There are 2 basic cases:
+ // 1) We are still reading the generator
+ // 2) We are reading our own cache
+
+ // In the first case, we need to poke the underlying generator.
+ // If it happily moves, we are left in that state, otherwise it is time to start reading from our cache
+ if (m_current_repeat == 0) {
+ const auto success = m_generator.next();
+ if (!success) {
+ ++m_current_repeat;
+ }
+ return m_current_repeat < m_target_repeats;
+ }
+
+ // In the second case, we need to move indices forward and check that we haven't run up against the end
+ ++m_repeat_index;
+ if (m_repeat_index == m_returned.size()) {
+ m_repeat_index = 0;
+ ++m_current_repeat;
+ }
+ return m_current_repeat < m_target_repeats;
+ }
+ };
+
+ template <typename T>
+ GeneratorWrapper<T> repeat(size_t repeats, GeneratorWrapper<T>&& generator) {
+ return GeneratorWrapper<T>(Catch::Detail::make_unique<RepeatGenerator<T>>(repeats, CATCH_MOVE(generator)));
+ }
+
+ template <typename T, typename U, typename Func>
+ class MapGenerator final : public IGenerator<T> {
+ // TBD: provide static assert for mapping function, for friendly error message
+ GeneratorWrapper<U> m_generator;
+ Func m_function;
+ // To avoid returning dangling reference, we have to save the values
+ T m_cache;
+ public:
+ template <typename F2 = Func>
+ MapGenerator(F2&& function, GeneratorWrapper<U>&& generator) :
+ m_generator(CATCH_MOVE(generator)),
+ m_function(CATCH_FORWARD(function)),
+ m_cache(m_function(m_generator.get()))
+ {}
+
+ T const& get() const override {
+ return m_cache;
+ }
+ bool next() override {
+ const auto success = m_generator.next();
+ if (success) {
+ m_cache = m_function(m_generator.get());
+ }
+ return success;
+ }
+ };
+
+ template <typename Func, typename U, typename T = FunctionReturnType<Func, U>>
+ GeneratorWrapper<T> map(Func&& function, GeneratorWrapper<U>&& generator) {
+ return GeneratorWrapper<T>(
+ Catch::Detail::make_unique<MapGenerator<T, U, Func>>(CATCH_FORWARD(function), CATCH_MOVE(generator))
+ );
+ }
+
+ template <typename T, typename U, typename Func>
+ GeneratorWrapper<T> map(Func&& function, GeneratorWrapper<U>&& generator) {
+ return GeneratorWrapper<T>(
+ Catch::Detail::make_unique<MapGenerator<T, U, Func>>(CATCH_FORWARD(function), CATCH_MOVE(generator))
+ );
+ }
+
+ template <typename T>
+ class ChunkGenerator final : public IGenerator<std::vector<T>> {
+ std::vector<T> m_chunk;
+ size_t m_chunk_size;
+ GeneratorWrapper<T> m_generator;
+ bool m_used_up = false;
+ public:
+ ChunkGenerator(size_t size, GeneratorWrapper<T> generator) :
+ m_chunk_size(size), m_generator(CATCH_MOVE(generator))
+ {
+ m_chunk.reserve(m_chunk_size);
+ if (m_chunk_size != 0) {
+ m_chunk.push_back(m_generator.get());
+ for (size_t i = 1; i < m_chunk_size; ++i) {
+ if (!m_generator.next()) {
+ Detail::throw_generator_exception("Not enough values to initialize the first chunk");
+ }
+ m_chunk.push_back(m_generator.get());
+ }
+ }
+ }
+ std::vector<T> const& get() const override {
+ return m_chunk;
+ }
+ bool next() override {
+ m_chunk.clear();
+ for (size_t idx = 0; idx < m_chunk_size; ++idx) {
+ if (!m_generator.next()) {
+ return false;
+ }
+ m_chunk.push_back(m_generator.get());
+ }
+ return true;
+ }
+ };
+
+ template <typename T>
+ GeneratorWrapper<std::vector<T>> chunk(size_t size, GeneratorWrapper<T>&& generator) {
+ return GeneratorWrapper<std::vector<T>>(
+ Catch::Detail::make_unique<ChunkGenerator<T>>(size, CATCH_MOVE(generator))
+ );
+ }
+
+} // namespace Generators
+} // namespace Catch
+
+
+#endif // CATCH_GENERATORS_ADAPTERS_HPP_INCLUDED