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							82 lines
						
					
					
						
							2.2 KiB
						
					
					
				
			
		
		
		
			
			
			
				
					
				
				
					
				
			
		
		
	
	
							82 lines
						
					
					
						
							2.2 KiB
						
					
					
				
								#include <cstdio>
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								#include <sparsepp/spp.h>
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								using spp::sparse_hash_map;
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								using namespace std;
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								class FileSerializer
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								{
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								public:
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								    // serialize basic types to FILE
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								    // -----------------------------
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								    template <class T>
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								    bool operator()(FILE *fp, const T& value)
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								    {
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								        return fwrite((const void *)&value, sizeof(value), 1, fp) == 1;
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								    }
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								    template <class T>
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								    bool operator()(FILE *fp, T* value)
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								    {
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								        return fread((void *)value, sizeof(*value), 1, fp) == 1;
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								    }
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								    // serialize std::string to FILE
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								    // -----------------------------
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								    bool operator()(FILE *fp, const string& value)
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								    {
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								        const size_t size = value.size();
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								        return (*this)(fp, size) && fwrite(value.c_str(), size, 1, fp) == 1;
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								    }
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								    bool operator()(FILE *fp, string* value)
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								    {
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								        size_t size;
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								        if (!(*this)(fp, &size))
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								            return false;
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								        char* buf = new char[size];
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								        if (fread(buf, size, 1, fp) != 1)
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								        {
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								            delete [] buf;
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								            return false;
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								        }
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								        new (value) string(buf, (size_t)size);
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								        delete[] buf;
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								        return true;
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								    }
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								    // serialize std::pair<const A, B> to FILE - needed for maps
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								    // ---------------------------------------------------------
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								    template <class A, class B>
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								    bool operator()(FILE *fp, const std::pair<const A, B>& value)
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								    {
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								        return (*this)(fp, value.first) && (*this)(fp, value.second);
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								    }
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								    template <class A, class B>
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								    bool operator()(FILE *fp, std::pair<const A, B> *value)
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								    {
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								        return (*this)(fp, (A *)&value->first) && (*this)(fp, &value->second);
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								    }
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								};
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								int main(int, char* [])
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								{
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								    sparse_hash_map<string, int> age{ { "John", 12 }, {"Jane", 13 }, { "Fred", 8 } };
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								    // serialize age hash_map to "ages.dmp" file
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								    FILE *out = fopen("ages.dmp", "wb");
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								    age.serialize(FileSerializer(), out);
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								    fclose(out);
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								    sparse_hash_map<string, int> age_read;
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								    // read from "ages.dmp" file into age_read hash_map
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								    FILE *input = fopen("ages.dmp", "rb");
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								    age_read.unserialize(FileSerializer(), input);
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								    fclose(input);
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								    // print out contents of age_read to verify correct serialization
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								    for (auto& v : age_read)
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								        printf("age_read: %s -> %d\n", v.first.c_str(), v.second);
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								}
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