fileformatfactory.h

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#pragma once
 
#include <promeki/core/namespace.h>
#include <promeki/core/string.h>
#include <promeki/core/stringlist.h>
#include <promeki/core/list.h>
#include <promeki/core/result.h>
#include <promeki/core/logger.h>
#include <promeki/core/util.h>
 
PROMEKI_NAMESPACE_BEGIN
 
class IODevice;
 
template<typename Product>
class FileFormatFactory {
        public:
                struct Context {
                        int         operation = 0;    
                        String      filename;         
                        String      formatHint;       
                        IODevice   *device = nullptr; 
                };
 
                static int registerFactory(FileFormatFactory *factory) {
                        if(factory == nullptr) return -1;
                        auto &list = factoryList();
                        int ret = list.size();
                        list += factory;
                        promekiInfo("Registered FileFormatFactory %s",
                                factory->name().cstr());
                        return ret;
                }
 
                static const FileFormatFactory *lookup(const Context &ctx) {
                        auto &list = factoryList();
                        for(auto *f : list) {
                                if(f->canDoOperation(ctx)) return f;
                        }
                        return nullptr;
                }
 
                FileFormatFactory() = default;
 
                virtual ~FileFormatFactory() {}
 
                String name() const { return _name; }
 
                const StringList &extensions() const { return _exts; }
 
                bool isExtensionSupported(const String &filename) const {
                        size_t dot = filename.rfind('.');
                        if(dot == String::npos || dot + 1 >= filename.size()) return false;
                        String ext = filename.mid(dot + 1).toLower();
                        for(const auto &item : _exts) {
                                if(ext == item) return true;
                        }
                        return false;
                }
 
                bool isHintSupported(const String &hint) const {
                        String lower = hint.toLower();
                        for(const auto &item : _exts) {
                                if(lower == item) return true;
                        }
                        return false;
                }
 
                virtual bool canDoOperation(const Context &ctx) const {
                        return false;
                }
 
                virtual Result<Product> createForOperation(const Context &ctx) const {
                        return makeError<Product>(Error::NotImplemented);
                }
 
        protected:
                String     _name;  
                StringList _exts;  
 
        private:
                static List<FileFormatFactory *> &factoryList() {
                        static List<FileFormatFactory *> list;
                        return list;
                }
};
 
#define PROMEKI_REGISTER_FILE_FORMAT_FACTORY(product, name) \
        [[maybe_unused]] static int \
        PROMEKI_CONCAT(__promeki_fff_, PROMEKI_UNIQUE_ID) = \
        FileFormatFactory<product>::registerFactory(new name);
 
PROMEKI_NAMESPACE_END