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#include "b64featvector.h"
#include <sstream>
#include <boost/scoped_array.hpp>
#include "b64tools.h"
#include "fdict.h"
using namespace std;
static inline void EncodeFeatureWeight(const string &featname, weight_t weight,
ostream *output) {
output->write(featname.data(), featname.size() + 1);
output->write(reinterpret_cast<char *>(&weight), sizeof(weight_t));
}
string EncodeFeatureVector(const SparseVector<weight_t> &vec) {
string b64;
{
ostringstream base64_strm;
{
ostringstream strm;
for (SparseVector<weight_t>::const_iterator it = vec.begin();
it != vec.end(); ++it)
if (it->second != 0)
EncodeFeatureWeight(FD::Convert(it->first), it->second, &strm);
string data(strm.str());
B64::b64encode(data.data(), data.size(), &base64_strm);
}
b64 = base64_strm.str();
}
return b64;
}
void DecodeFeatureVector(const string &data, SparseVector<weight_t> *vec) {
vec->clear();
if (data.empty()) return;
// Decode data
size_t b64_len = data.size(), len = b64_len / 4 * 3;
boost::scoped_array<char> buf(new char[len]);
bool res =
B64::b64decode(reinterpret_cast<const unsigned char *>(data.data()),
b64_len, buf.get(), len);
assert(res);
// Apply updates
size_t cur = 0;
while (cur < len) {
string feat_name(buf.get() + cur);
if (feat_name.empty()) break; // Encountered trailing \0
int feat_id = FD::Convert(feat_name);
weight_t feat_delta =
*reinterpret_cast<weight_t *>(buf.get() + cur + feat_name.size() + 1);
(*vec)[feat_id] = feat_delta;
cur += feat_name.size() + 1 + sizeof(weight_t);
}
}
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