mirror of https://github.com/OpenTTD/OpenTTD.git
113 lines
2.7 KiB
C++
113 lines
2.7 KiB
C++
/*
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* This file is part of OpenTTD.
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* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
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* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @file library_loader.h Functions/types related to loading libraries dynamically. */
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#ifndef LIBRARY_LOADER_H
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#define LIBRARY_LOADER_H
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class LibraryLoader {
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public:
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/**
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* A function loaded from a library.
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*
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* Will automatically cast to the correct function pointer type on retrieval.
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*/
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class Function {
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public:
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explicit Function(void *p) : p(p) {}
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template <typename T, typename = std::enable_if_t<std::is_function_v<T>>>
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operator T *() const
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{
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return reinterpret_cast<T *>(this->p);
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}
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private:
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void *p;
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};
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/**
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* Load a library with the given filename.
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*/
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explicit LibraryLoader(const std::string &filename)
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{
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this->handle = this->OpenLibrary(filename);
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}
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/**
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* Close the library.
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*/
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~LibraryLoader()
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{
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if (this->handle != nullptr) {
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this->CloseLibrary();
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}
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}
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/**
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* Check whether an error occurred while loading the library or a function.
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*
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* @return Whether an error occurred.
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*/
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bool HasError()
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{
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return this->error.has_value();
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}
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/**
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* Get the last error that occurred while loading the library or a function.
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*
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* @return The error message.
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*/
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std::string GetLastError()
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{
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return this->error.value_or("No error");
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}
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/**
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* Get a function from a loaded library.
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*
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* @param symbol_name The name of the function to get.
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* @return The function. Check HasError() before using.
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*/
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Function GetFunction(const std::string &symbol_name)
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{
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if (this->error.has_value()) return Function(nullptr);
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return Function(this->GetSymbol(symbol_name));
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}
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private:
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/**
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* Open the library with the given filename.
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*
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* Should set error if any error occurred.
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*
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* @param filename The filename of the library to open.
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*/
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void *OpenLibrary(const std::string &filename);
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/**
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* Close the library.
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*/
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void CloseLibrary();
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/**
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* Get a symbol from the library.
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*
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* Should set error if any error occurred.
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*
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* @param symbol_name The name of the symbol to get.
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*/
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void *GetSymbol(const std::string &symbol_name);
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std::optional<std::string> error = {}; ///< The last error that occurred, if set.
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void *handle = nullptr; ///< Handle to the library.
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};
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#endif /* LIBRARY_LOADER_H */
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