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#ifndef __BLEUSCORER_H__
#define __BLEUSCORER_H__
#include <algorithm>
#include <cmath>
#include <iostream>
#include <iterator>
#include <set>
#include <sstream>
#include <stdexcept>
#include <string>
#include <vector>
#include <limits.h>
#include "Types.h"
#include "ScoreData.h"
#include "Scorer.h"
#include "ScopedVector.h"
using namespace std;
enum BleuReferenceLengthStrategy { BLEU_AVERAGE, BLEU_SHORTEST, BLEU_CLOSEST };
/**
* Bleu scoring
*/
class BleuScorer: public StatisticsBasedScorer
{
public:
BleuScorer(const string& config = "") : StatisticsBasedScorer("BLEU",config),_refLengthStrategy(BLEU_CLOSEST) {
//configure regularisation
static string KEY_REFLEN = "reflen";
static string REFLEN_AVERAGE = "average";
static string REFLEN_SHORTEST = "shortest";
static string REFLEN_CLOSEST = "closest";
string reflen = getConfig(KEY_REFLEN,REFLEN_CLOSEST);
if (reflen == REFLEN_AVERAGE) {
_refLengthStrategy = BLEU_AVERAGE;
} else if (reflen == REFLEN_SHORTEST) {
_refLengthStrategy = BLEU_SHORTEST;
} else if (reflen == REFLEN_CLOSEST) {
_refLengthStrategy = BLEU_CLOSEST;
} else {
throw runtime_error("Unknown reference length strategy: " + reflen);
}
// cerr << "Using reference length strategy: " << reflen << endl;
}
virtual void setReferenceFiles(const vector<string>& referenceFiles);
virtual void prepareStats(size_t sid, const string& text, ScoreStats& entry);
static const int LENGTH;
size_t NumberOfScores() {
// cerr << "BleuScorer: " << (2 * LENGTH + 1) << endl;
return (2 * LENGTH + 1);
}
//protected:
float calculateScore(const vector<int>& comps);
private:
//no copy
BleuScorer(const BleuScorer&);
~BleuScorer() {}
BleuScorer& operator=(const BleuScorer&);
//Used to construct the ngram map
struct CompareNgrams {
int operator() (const vector<int>& a, const vector<int>& b) {
size_t i;
size_t as = a.size();
size_t bs = b.size();
for (i = 0; i < as && i < bs; ++i) {
if (a[i] < b[i]) {
//cerr << "true" << endl;
return true;
}
if (a[i] > b[i]) {
//cerr << "false" << endl;
return false;
}
}
//entries are equal, shortest wins
return as < bs;;
}
};
typedef map<vector<int>,int,CompareNgrams> counts_t;
typedef map<vector<int>,int,CompareNgrams>::iterator counts_it;
typedef ScopedVector<counts_t> refcounts_t;
/**
* Count the ngrams of each type, up to the given length in the input line.
*/
size_t countNgrams(const string& line, counts_t& counts, unsigned int n);
void dump_counts(counts_t& counts) {
for (counts_it i = counts.begin(); i != counts.end(); ++i) {
cerr << "(";
copy(i->first.begin(), i->first.end(), ostream_iterator<int>(cerr," "));
cerr << ") " << i->second << ", ";
}
cerr << endl;
}
BleuReferenceLengthStrategy _refLengthStrategy;
// data extracted from reference files
refcounts_t _refcounts;
vector<vector<size_t> > _reflengths;
};
#endif // __BLEUSCORER_H__
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