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