Class: Ferret::Search::ReqExclScorer

Inherits:
Scorer
  • Object
show all
Defined in:
lib/ferret/search/req_excl_scorer.rb

Overview

A Scorer for queries with a required subscorer and an excluding (prohibited) subscorer.

This Scorer implements Scorer#skip_to(int), and it uses the skip_to() on the given scorers.

Constant Summary

Constants inherited from Scorer

Scorer::MAX_DOCS

Instance Attribute Summary

Attributes inherited from Scorer

#similarity

Instance Method Summary collapse

Methods inherited from Scorer

#each_hit, #each_hit_up_to

Constructor Details

#initialize(req_scorer, excl_scorer) ⇒ ReqExclScorer

Construct a ReqExclScorer.

req_scorer

The scorer that must match, except where

excl_scorer

indicates exclusion.



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# File 'lib/ferret/search/req_excl_scorer.rb', line 11

def initialize(req_scorer, excl_scorer) 
  super(nil) # No similarity used.
  @req_scorer = req_scorer
  @excl_scorer = excl_scorer

  @first_time = true
end

Instance Method Details

#doc ⇒ Object

only call when you know that a doc exists



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# File 'lib/ferret/search/req_excl_scorer.rb', line 74

def doc() 
  return @req_scorer.doc
end

#explain(doc) ⇒ Object 



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# File 'lib/ferret/search/req_excl_scorer.rb', line 114

def explain(doc)
  e = Explanation.new()
  if @excl_scorer.skip_to(doc) and @excl_scorer.doc == doc
    e.description = "excluded"
  else 
    e.description = "not excluded"
    e.details << @req_scorer.explain(doc)
  end
  return e
end

#next? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ferret/search/req_excl_scorer.rb', line 20

def next?
  if @first_time
    if not @excl_scorer.next?
      @excl_scorer = nil # exhausted at start
    end
    @first_time = false
  end
  if @req_scorer == nil 
    return false
  end
  if not @req_scorer.next?
    @req_scorer = nil; # exhausted, nothing left
    return false
  end
  if @excl_scorer == nil
    return true # @req_scorer.next? already returned true
  end
  return to_non_excluded()
end

#score ⇒ Object

Returns the score of the current document matching the query.

Initially invalid, until #next? is called the first time.

returns

The score of the required scorer.



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# File 'lib/ferret/search/req_excl_scorer.rb', line 83

def score()
  return @req_scorer.score()
end

#skip_to(target) ⇒ Object

Skips to the first match beyond the current whose document number is greater than or equal to a given target.

When this method is used the #explain(int) method should not be used.

target

The target document number.

returns

true iff there is such a match.



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# File 'lib/ferret/search/req_excl_scorer.rb', line 94

def skip_to(target)
  if (@first_time) 
    @first_time = false
    if (! @excl_scorer.skip_to(target)) 
      @excl_scorer = nil; # exhausted
    end
  end
  if (@req_scorer == nil) 
    return false
  end
  if (@excl_scorer == nil) 
    return @req_scorer.skip_to(target)
  end
  if (! @req_scorer.skip_to(target)) 
    @req_scorer = nil
    return false
  end
  return to_non_excluded()
end

#to_non_excluded ⇒ Object

Advance to non excluded doc. On entry:

  • @req_scorer != nil

  • @excl_scorer != nil

  • @req_scorer was advanced once via next? or skip_to() and @req_scorer.doc() may still be excluded.

Advances @req_scorer a non excluded required doc, if any.

returns

true iff there is a non excluded required doc.



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# File 'lib/ferret/search/req_excl_scorer.rb', line 51

def to_non_excluded()
  excl_doc = @excl_scorer.doc
  begin 
    req_doc = @req_scorer.doc # may be excluded
    if (req_doc < excl_doc) 
      return true # @req_scorer advanced to before @excl_scorer, ie. not excluded
    elsif (req_doc > excl_doc) 
      unless @excl_scorer.skip_to(req_doc) 
        @excl_scorer = nil # exhausted, no more exclusions
        return true
      end
      excl_doc = @excl_scorer.doc
      if excl_doc > req_doc 
        return true; # not excluded
      end
    end
  end while @req_scorer.next?
  @req_scorer = nil; # exhausted, nothing left
  return false
end