51 lines
1.1 KiB
CoffeeScript
51 lines
1.1 KiB
CoffeeScript
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{car, cdr, cons, pairp, nilp, nil, list, listToString} = require './lists'
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reduce = (lst, iteratee, memo, context) ->
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count = 0
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ptr = lst
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while not nilp ptr
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[item, ptr] = [(car ptr), (cdr ptr)]
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memo = iteratee.call(context, memo, item, count, lst)
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count++
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iteratee.call(context, memo, nil, count, lst)
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map = (lst, iteratee, context) ->
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return nil if nilp lst
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root = cons("")
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reducer = (memo, item, count) ->
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next = cons(iteratee.call(context, item, count, lst))
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memo[1] = next
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next
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reduce(lst, reducer, root, context)
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(cdr root)
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rmap = (lst, iteratee, context) ->
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reducer = (memo, item, count) ->
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cons(iteratee.call(context, item, count, lst), memo)
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reduce(lst, reducer, nil, context)
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filter = (lst, iteratee, context) ->
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return nil if nilp lst
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root = cons("")
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reducer = (memo, item, count) ->
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if iteratee.call(context, item, count, lst)
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next = cons(item)
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memo[1] = next
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next
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else
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memo
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reduce(lst, reducer, root, context)
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(cdr root)
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module.exports =
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reduce: reduce
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map: map
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rmap: rmap
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filter: filter
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