catch2/interfaces/catch_interfaces_generatortracker.hpp

0001
0002 //              Copyright Catch2 Authors
0003 // Distributed under the Boost Software License, Version 1.0.
0004 //   (See accompanying file LICENSE.txt or copy at
0005 //        https://www.boost.org/LICENSE_1_0.txt)
0006
0007 // SPDX-License-Identifier: BSL-1.0
0008 #ifndef CATCH_INTERFACES_GENERATORTRACKER_HPP_INCLUDED
0009 #define CATCH_INTERFACES_GENERATORTRACKER_HPP_INCLUDED
0010
0011 #include <catch2/internal/catch_unique_ptr.hpp>
0012 #include <catch2/internal/catch_stringref.hpp>
0013
0014 #include <string>
0015
0016 namespace Catch {
0017
0018     namespace Generators {
0019         class GeneratorUntypedBase {
0020             // Caches result from `toStringImpl`, assume that when it is an
0021             // empty string, the cache is invalidated.
0022             mutable std::string m_stringReprCache;
0023
0024             // Counts based on `next` returning true
0025             std::size_t m_currentElementIndex = 0;
0026
0027             /**
0028              * Attempts to move the generator to the next element
0029              *
0030              * Returns true iff the move succeeded (and a valid element
0031              * can be retrieved).
0032              */
0033             virtual bool next() = 0;
0034
0035             //! Customization point for `currentElementAsString`
0036             virtual std::string stringifyImpl() const = 0;
0037
0038         public:
0039             GeneratorUntypedBase() = default;
0040             // Generation of copy ops is deprecated (and Clang will complain)
0041             // if there is a user destructor defined
0042             GeneratorUntypedBase(GeneratorUntypedBase const&) = default;
0043             GeneratorUntypedBase& operator=(GeneratorUntypedBase const&) = default;
0044
0045             virtual ~GeneratorUntypedBase(); // = default;
0046
0047             /**
0048              * Attempts to move the generator to the next element
0049              *
0050              * Serves as a non-virtual interface to `next`, so that the
0051              * top level interface can provide sanity checking and shared
0052              * features.
0053              *
0054              * As with `next`, returns true iff the move succeeded and
0055              * the generator has new valid element to provide.
0056              */
0057             bool countedNext();
0058
0059             std::size_t currentElementIndex() const { return m_currentElementIndex; }
0060
0061             /**
0062              * Returns generator's current element as user-friendly string.
0063              *
0064              * By default returns string equivalent to calling
0065              * `Catch::Detail::stringify` on the current element, but generators
0066              * can customize their implementation as needed.
0067              *
0068              * Not thread-safe due to internal caching.
0069              *
0070              * The returned ref is valid only until the generator instance
0071              * is destructed, or it moves onto the next element, whichever
0072              * comes first.
0073              */
0074             StringRef currentElementAsString() const;
0075         };
0076         using GeneratorBasePtr = Catch::Detail::unique_ptr<GeneratorUntypedBase>;
0077
0078     } // namespace Generators
0079
0080     class IGeneratorTracker {
0081     public:
0082         virtual ~IGeneratorTracker(); // = default;
0083         virtual auto hasGenerator() const -> bool = 0;
0084         virtual auto getGenerator() const -> Generators::GeneratorBasePtr const& = 0;
0085         virtual void setGenerator( Generators::GeneratorBasePtr&& generator ) = 0;
0086     };
0087
0088 } // namespace Catch
0089
0090 #endif // CATCH_INTERFACES_GENERATORTRACKER_HPP_INCLUDED