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enquirable.rb
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enquirable.rb
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# frozen_string_literal: true
<<~DOC
# basic concept of an enumerable that supports queries on elements.
e.g.
enq = Enquireable['test', 'Something', 'Third Thing']
enq.test? => true
enq.somthing? => true
enq.third_thing? => true
enq.not_here? => false
I need an inheritance tree:
Object
Array/Set/OtherEnumerable (passed in)
TrueDelagtor -> delagator that converts back to caller
EnquirableMeta?
Enquirable?
Specifics
TrueDelagator - if delegating to Set from Enquriable
converts all Set objects back into Enquirables before returning them.
DOC
require 'pry'
# An object that supports boolean flag queries for each element.
# e.g.
# enq = Enquirable.new(['feature', 'Other Feature'])
# enq.feature? == true
# enq.other_feature == true
# enq.non_pressent_feature == false
class Enquirable
def initialize(enumerable)
@enum = enumerable
@mapping = build_mapping enumerable
end
def build_mapping(enum)
mapping = {}
enum.each do |element|
sym = (element.gsub(' ', '_').downcase + '?').to_sym
mapping_error(mapping, sym, element) if mapping.include? sym
mapping[sym] = element
end
mapping.keys.to_set
end
def mapping_error(mapping, key, original)
cause = mapping[key].inspect
original = original.inspect
key = key.inspect
msg = "duplicate key #{key} produced by values: #{original} #{cause}"
raise ArgumentError, msg
end
def respond_to_missing?(symbol, *)
@enum.respond_to?(symbol) || super
end
def method_missing(symbol, *args, &block)
return send_with_recast(symbol, *args, &block) if @enum.respond_to? symbol
return true if @mapping.include? symbol
return false if symbol[-1] == '?'
super
end
def send_with_recast(symbol, *args, &block)
result = @enum.send(symbol, *args, &block)
return Enquirable.new(result) if result.is_a? @enum.class
result
end
end