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(fb, maps, mutex, query) ⇒ Query

Constructor.

Parameters:

  • fb (Factbase) —

    Factbase

  • maps (Array<Fact>) —

    Array of facts to start with

  • mutex (Mutex) —

    Mutex to sync all modifications to the maps

  • query (String) —

    The query as a string



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# File 'lib/factbase/query.rb', line 45

def initialize(fb, maps, mutex, query)
  @fb = fb
  @maps = maps
  @mutex = mutex
  @query = query
end

Instance Method Details

#delete! ⇒ Integer

Delete all facts that match the query.

Returns:

  • (Integer) —

    Total number of facts deleted



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# File 'lib/factbase/query.rb', line 98

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

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

Iterate facts one by one.

Parameters:

  • 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



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# File 'lib/factbase/query.rb', line 62

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

#one(params = {}) ⇒ Object

Read a single value.

Parameters:

  • params (Hash) (defaults to: {}) —

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

Returns:

  • The value evaluated



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# File 'lib/factbase/query.rb', line 86

def one(params = {})
  term = Factbase::Syntax.new(@fb, @query).to_term
  params = params.transform_keys(&:to_s) if params.is_a?(Hash)
  r = term.evaluate(Factbase::Tee.new(nil, params), @maps)
  unless %w[String Integer Float Time Array NilClass].include?(r.class.to_s)
    raise "Incorrect type #{r.class} returned by #{@query}"
  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 54

def to_s
  @query.to_s
end