Class: Ferret::Search::QueryFilter

Inherits:
Filter
  • Object
show all
Defined in:
lib/ferret/search/query_filter.rb

Overview

Constrains search results to only match those which also match a provided query. Results are cached, so that searches after the first on the same index using this filter are much faster.

This could be used, for example, with a RangeQuery on a suitably formatted date field to implement date filtering. One could re-use a single QueryFilter that matches, e.g., only documents modified within the last week. The QueryFilter and RangeQuery would only need to be reconstructed once per day.

Instance Method Summary collapse

Constructor Details

#initialize(query) ⇒ QueryFilter

Constructs a filter which only matches documents matching query.



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# File 'lib/ferret/search/query_filter.rb', line 16

def initialize(query) 
  @query = query
  @cache = nil 
end

Instance Method Details

#bits(reader) ⇒ Object 



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# File 'lib/ferret/search/query_filter.rb', line 21

def bits(reader)

  if (@cache == nil) 
    @cache = Ferret::Utils::WeakKeyHash.new
  end

  @cache.synchronize() do # check cache
    bits = @cache[reader]
    if bits
      return bits
    end
  end

  bits = Ferret::Utils::BitVector.new()

  IndexSearcher.new(reader).search_each(@query) do |doc, score|
    bits.set(doc)  # set bit for hit
  end

  @cache.synchronize() do # update cache
    @cache[reader] = bits
  end

  return bits
end

#to_s ⇒ Object 



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# File 'lib/ferret/search/query_filter.rb', line 47

def to_s() 
  return "QueryFilter(#{@query})"
end