Class: Factbase::Query

Inherits:
Object
  • Object
show all
Defined in:
lib/factbase/query.rb

Overview

Query.

This is an internal class, it is not supposed to be instantiated directly. It is created by the query() method of the Factbase class.

It is NOT thread-safe!

Author

Yegor Bugayenko ([email protected])

Copyright

Copyright © 2024-2025 Yegor Bugayenko

License

MIT

Instance Method Summary collapse

Constructor Details

#initialize(maps, term, fb) ⇒ Query

Constructor.

Parameters:

  • maps (Array<Fact>) —

    Array of facts to start with

  • term (String|Factbase::Term) —

    The query term



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# File 'lib/factbase/query.rb', line 26

def initialize(maps, term, fb)
  @maps = maps
  @term = term.is_a?(String) ? Factbase::Syntax.new(term).to_term : term
  @fb = fb
end

Instance Method Details

#delete!(fb = @fb) ⇒ Integer

Delete all facts that match the query.

Parameters:

  • fb (Factbase) (defaults to: @fb) —

    The factbase to delete from

Returns:

  • (Integer) —

    Total number of facts deleted



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# File 'lib/factbase/query.rb', line 81

def delete!(fb = @fb)
  deleted = 0
  @maps.delete_if do |m|
    f = Factbase::Fact.new(m)
    if @term.evaluate(f, @maps, fb)
      deleted += 1
      true
    else
      false
    end
  end
  deleted
end

#each(fb = @fb, params = {}) {|Fact| ... } ⇒ Integer

Iterate facts one by one.

Parameters:

  • fb (Factbase) (defaults to: @fb) —

    The factbase

  • params (Hash) (defaults to: {}) —

    Optional params accessible in the query via the “$” symbol

Yields:

  • (Fact) —

    Facts one-by-one

Returns:

  • (Integer) —

    Total number of facts yielded (if block given), otherwise enumerator



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# File 'lib/factbase/query.rb', line 43

def each(fb = @fb, params = {})
  return to_enum(__method__, fb, params) unless block_given?
  yielded = 0
  params = params.transform_keys(&:to_s) if params.is_a?(Hash)
  maybe = @term.predict(@maps, Factbase::Tee.new({}, params))
  maybe ||= @maps unless maybe.equal?(@maps)
  maybe.each do |m|
    extras = {}
    f = Factbase::Fact.new(m)
    f = Factbase::Tee.new(f, params)
    a = Factbase::Accum.new(f, extras, false)
    r = @term.evaluate(a, @maps, fb)
    unless r.is_a?(TrueClass) || r.is_a?(FalseClass)
      raise "Unexpected evaluation result of type #{r.class}, must be Boolean at #{@term.inspect}"
    end
    next unless r
    yield Factbase::Accum.new(f, extras, true)
    yielded += 1
  end
  yielded
end

#one(fb = @fb, params = {}) ⇒ String|Integer|Float|Time|Array|NilClass

Read a single value.

Parameters:

  • fb (Factbase) (defaults to: @fb) —

    The factbase

  • params (Hash) (defaults to: {}) —

    Optional params accessible in the query via the “$” symbol

Returns:

  • (String|Integer|Float|Time|Array|NilClass) —

    The value evaluated



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# File 'lib/factbase/query.rb', line 69

def one(fb = @fb, params = {})
  params = params.transform_keys(&:to_s) if params.is_a?(Hash)
  r = @term.evaluate(Factbase::Tee.new(Factbase::Fact.new({}), params), @maps, fb)
  unless %w[String Integer Float Time Array NilClass].include?(r.class.to_s)
    raise "Incorrect type #{r.class} returned by #{@term.inspect}"
  end
  r
end

#to_s ⇒ String

Print it as a string.

Returns:

  • (String) —

    The query as a string



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# File 'lib/factbase/query.rb', line 34

def to_s
  @term.to_s
end