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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <string>
#include <limits>
#include "metrics.h"
namespace search::features::fieldmatch {
/**
* <p>Information on segment start points stored temporarily during string match metric calculation.</p>
*
* <p>Given that we want to start a segment at i, this holdes the best known metrics up to i and the end of the previous
* segment. In addition it holds information on how far we have tried to look for alternative segments from this
* starting point (skipI and previousJ).</p>
*
* @author <a href="mailto:bratseth@yahoo-inc.com">Jon Bratseth</a>
* @author Simon Thoresen Hult
* @version $Id$
*/
class SegmentStart {
public:
/**
* Convenience typedefs.
*/
using UP = std::unique_ptr<SegmentStart>;
using SP = std::shared_ptr<SegmentStart>;
public:
/**
* Creates a segment start point for any i position where the j is not known.
*
* @param owner The computar that pwns th1s.
* @param metrics The best known metric.
* @param previousJ The previous j.
* @param i The start position.
* @param j The end position.
*/
SegmentStart(Computer *owner, const Metrics & metrics,
uint32_t previousJ = 0, uint32_t i = 0,
uint32_t j = std::numeric_limits<uint32_t>::max());
/**
* Resets this object.
*
* @param metrics The best known metric.
* @param previousJ The previous j.
* @param i The start position.
* @param j The end position.
*/
void reset(const Metrics & metrics, uint32_t previousJ = 0, uint32_t i = 0,
uint32_t j = std::numeric_limits<uint32_t>::max());
/**
* Returns the current best metrics for this starting point
*
* @return The metrics.
*/
const Metrics & getMetrics() const {
return _metrics;
}
/**
* Stores that we have explored to a certain j from the current previousJ.
*
* @param j The new position we have explored to.
* @return This, to allow chaining.
*/
SegmentStart &exploredTo(uint32_t j);
/**
* Offers an alternative history leading up to this point, which is accepted and stored if it is better than the
* current history
*
* @param previousJ The previous j offered.
* @param metrics The offered metrics.
* @return Whether or not the new history was accepted.
*/
bool offerHistory(int previousJ, const Metrics & metrics);
/**
* Returns whether there are still unexplored j's for this i.
*
* @return Whether or not there are unexplored j's.
*/
bool isOpen() const {
return _open;
}
/**
* Sets whether there are still unexplored j's for this i.
*
* @param open Whehter or not there are unexplored j's.
* @return This, to allow chaining.
*/
SegmentStart &setOpen(bool open) {
_open = open;
return *this;
}
/**
* Returns the i for which this is the possible segment starting points.
*
* @return The i value.
*/
uint32_t getI() const {
return _i;
}
/**
* Returns the j ending the previous segmentation producing those best metrics.
*
* @return The previous j value.
*/
uint32_t getPreviousJ() const {
return _previousJ;
}
/**
* Returns the semantic distance from the previous j which is explored so far, exclusive
* (meaning, if the value is 0, 0 is <i>not</i> explored yet)
*
* @return The distance explored.
*/
uint32_t getSemanticDistanceExplored() const {
return _semanticDistanceExplored;
}
/**
* Sets the semantic distance from the previous j which is explored so far, exclusive.
*
* @param distance The distance explored.
* @return This, to allow chaining.
*/
SegmentStart &setSemanticDistanceExplored(uint32_t distance) {
_semanticDistanceExplored = distance;
return *this;
}
/**
* Returns the position startI we should start at from this start point i. startI==i except when there are i's from
* this starting point which are not found anywhere in the field. In that case, startI==i+the number of terms
* following i which are known not to be present.
*
* @return The start i value.
*/
uint32_t getStartI() const {
return _i + _skipI;
}
/**
* Increments the startI by one because we have discovered that the term at the current startI is not present in the
* field.
*
* @return This, to allow chaining.
*/
SegmentStart &incrementStartI() {
_skipI++;
return *this;
}
/**
* Returns a string representation of this.
*
* @return A string representation.
*/
vespalib::string toString();
private:
Computer *_owner;
Metrics _metrics; // The best known metrics up to this starting point.
uint32_t _i; // The i for which this is the possible segment starting points.
uint32_t _skipI;
uint32_t _previousJ; // The j ending the previous segmentation producing those best metrics.
uint32_t _semanticDistanceExplored; // The semantic distance from the current previousJ which is already explored.
bool _open; // There are possibly more j's to try at this starting point.
};
}
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