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Versions: 11
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Contents
# frozen_string_literal: true
module Prefab
class WeightedValueResolver
MAX_32_FLOAT = 4_294_967_294.0
def initialize(weights, config_key, lookup_key)
@weights = weights
@config_key = config_key
@lookup_key = lookup_key
end
def resolve
percent = @lookup_key ? user_percent : rand
index = variant_index(percent)
@weights[index]
end
def user_percent
to_hash = "#{@config_key}#{@lookup_key}"
int_value = Murmur3.murmur3_32(to_hash)
int_value / MAX_32_FLOAT
end
def variant_index(percent_through_distribution)
distribution_space = @weights.inject(0) { |sum, v| sum + v.weight }
bucket = distribution_space * percent_through_distribution
sum = 0
@weights.each_with_index do |variant_weight, index|
return index if bucket < sum + variant_weight.weight
sum += variant_weight.weight
end
# In the event that all weights are zero, return the last variant
@weights.size - 1
end
end
end
Version data entries
11 entries across 11 versions & 1 rubygems