mosesdecoder/mert/Ngram.h
2013-05-29 18:16:15 +01:00

125 lines
2.6 KiB
C++

#ifndef MERT_NGRAM_H_
#define MERT_NGRAM_H_
#include <vector>
#include <string>
#include <boost/unordered_map.hpp>
namespace MosesTuning
{
/** A simple STL-std::map based n-gram counts. Basically, we provide
* typical accessors and mutaors, but we intentionally does not allow
* erasing elements.
*/
class NgramCounts
{
public:
// Used to construct the ngram map
struct NgramComparator {
bool operator()(const std::vector<int>& a, const std::vector<int>& b) const {
std::size_t i;
const std::size_t as = a.size();
const std::size_t bs = b.size();
for (i = 0; i < as && i < bs; ++i) {
if (a[i] < b[i]) {
return true;
}
if (a[i] > b[i]) {
return false;
}
}
// entries are equal, shortest wins
return as < bs;
}
};
typedef std::vector<int> Key;
typedef int Value;
typedef boost::unordered_map<Key, Value>::iterator iterator;
typedef boost::unordered_map<Key, Value>::const_iterator const_iterator;
NgramCounts() : kDefaultCount(1) { }
virtual ~NgramCounts() { }
/**
* If the specified "ngram" is found, we add counts.
* If not, we insert the default count in the container. */
inline void Add(const Key& ngram) {
m_counts[ngram]++;
}
/**
* Return true iff the specified "ngram" is found in the container.
*/
bool Lookup(const Key& ngram, Value* v) const {
const_iterator it = m_counts.find(ngram);
if (it == m_counts.end()) return false;
*v = it->second;
return true;
}
/**
* Clear all elments in the container.
*/
void clear() {
m_counts.clear();
}
/**
* Return true iff the container is empty.
*/
bool empty() const {
return m_counts.empty();
}
/**
* Return the the number of elements in the container.
*/
std::size_t size() const {
return m_counts.size();
}
std::size_t max_size() const {
return m_counts.max_size();
}
// Note: This is mainly used by unit tests.
int get_default_count() const {
return kDefaultCount;
}
iterator find(const Key& ngram) {
return m_counts.find(ngram);
}
const_iterator find(const Key& ngram) const {
return m_counts.find(ngram);
}
Value& operator[](const Key& ngram) {
return m_counts[ngram];
}
iterator begin() {
return m_counts.begin();
}
const_iterator begin() const {
return m_counts.begin();
}
iterator end() {
return m_counts.end();
}
const_iterator end() const {
return m_counts.end();
}
private:
const int kDefaultCount;
boost::unordered_map<Key, Value> m_counts;
};
}
#endif // MERT_NGRAM_H_