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#ifndef _MERT_GEOMETRY_H_
#define _MERT_GEOMETRY_H_
#include <vector>
#include <iostream>
#include <boost/shared_ptr.hpp>
#include "hg.h"
#include "sparse_vector.h"
static const double kMinusInfinity = -std::numeric_limits<double>::infinity();
static const double kPlusInfinity = std::numeric_limits<double>::infinity();
struct MERTPoint {
MERTPoint() : x(), m(), b(), edge() {}
MERTPoint(double _m, double _b) :
x(kMinusInfinity), m(_m), b(_b), edge() {}
MERTPoint(double _x, double _m, double _b, const boost::shared_ptr<MERTPoint>& p1_, const boost::shared_ptr<MERTPoint>& p2_) :
x(_x), m(_m), b(_b), p1(p1_), p2(p2_), edge() {}
MERTPoint(double _m, double _b, const Hypergraph::Edge& edge) :
x(kMinusInfinity), m(_m), b(_b), edge(&edge) {}
double x; // x intersection with previous segment in env, or -inf if none
double m; // this line's slope
double b; // intercept with y-axis
// we keep a pointer to the "parents" of this segment so we can reconstruct
// the Viterbi translation corresponding to this segment
boost::shared_ptr<MERTPoint> p1;
boost::shared_ptr<MERTPoint> p2;
// only MERTPoints created from an edge using the ConvexHullWeightFunction
// have rules
// TRulePtr rule;
const Hypergraph::Edge* edge;
// recursively recover the Viterbi translation that will result from setting
// the weights to origin + axis * x, where x is any value from this->x up
// until the next largest x in the containing ConvexHull
void ConstructTranslation(std::vector<WordID>* trans) const;
void CollectEdgesUsed(std::vector<bool>* edges_used) const;
};
// this is the semiring value type,
// it defines constructors for 0, 1, and the operations + and *
struct ConvexHull {
// create semiring zero
ConvexHull() : is_sorted(true) {} // zero
// for debugging:
ConvexHull(const std::vector<boost::shared_ptr<MERTPoint> >& s) : points(s) { Sort(); }
// create semiring 1 or 0
explicit ConvexHull(int i);
ConvexHull(int n, MERTPoint* point) : is_sorted(true), points(n, boost::shared_ptr<MERTPoint>(point)) {}
const ConvexHull& operator+=(const ConvexHull& other);
const ConvexHull& operator*=(const ConvexHull& other);
bool IsMultiplicativeIdentity() const {
return size() == 1 && (points[0]->b == 0.0 && points[0]->m == 0.0) && (!points[0]->edge) && (!points[0]->p1) && (!points[0]->p2); }
const std::vector<boost::shared_ptr<MERTPoint> >& GetSortedSegs() const {
if (!is_sorted) Sort();
return points;
}
size_t size() const { return points.size(); }
private:
bool IsEdgeEnvelope() const {
return points.size() == 1 && points[0]->edge; }
void Sort() const;
mutable bool is_sorted;
mutable std::vector<boost::shared_ptr<MERTPoint> > points;
};
std::ostream& operator<<(std::ostream& os, const ConvexHull& env);
struct ConvexHullWeightFunction {
ConvexHullWeightFunction(const SparseVector<double>& ori,
const SparseVector<double>& dir) : origin(ori), direction(dir) {}
const ConvexHull operator()(const Hypergraph::Edge& e) const;
const SparseVector<double> origin;
const SparseVector<double> direction;
};
#endif
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