Ever find yourself transmitting vast numbers of "flags" as variables in a JSON
payload? Or, even worse, doing boolean calculations over and over on the client
side? If so, bitv is here for you: use server-side precalculation to
determine various flags for a set of entities, communicate them as simple
arrays of integers in your JSON payload, and use bitwise operators in
JavaScript to perform filtering quickly on the client side.
> bv = BitVector.new([:a, :b, :c, :d, :e, :f])
=> #<BitVector:0x00000001873100 @possibilities=[:a, :b, :c, :d, :e, :f]>
> bv.targets = {argyle: [:a, :c], polka_dot: [:b, :c, :d], stripes: [:d, :e], solid: [:b, :e, :f]}
=> {:argyle=>[:a, :c], :polka_dot=>[:b, :c, :d], :stripes=>[:d, :e], :solid=>[:b, :e, :f]}
> puts bv.json
{"vectorLength":1,"possibilities":{"a":[0,1],"b":[0,2],"c":[0,4],"d":[0,8],"e":[0,16],"f":[0,32]},"targets":{"argyle":[5],"polka_dot":[14],"stripes":[24],"solid":[50]}}
> bv.targets_matching :b
=> [:polka_dot, :solid]
> bv.targets_matching :b, :a
=> []
> bv.targets_matching :b, :c
=> [:polka_dot]