mirror of https://github.com/janet-lang/janet
108 lines
2.3 KiB
Plaintext
108 lines
2.3 KiB
Plaintext
###
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###
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### Iterators
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###
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###
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(def iter (do
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(defn array-iter [x]
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(def len (length x))
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(var i 0)
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{:more (fn [] (< i len))
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:next (fn []
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(def ret (get x i))
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(:= i (+ i 1))
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ret)})
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(def iters {
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:array array-iter
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:tuple array-iter
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:struct identity})
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(fn [x]
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(def makei (get iters (type x)))
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(if makei (makei x) (error "expected sequence")))))
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(defn range2 [bottom top]
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(var i bottom)
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{
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:more (fn [] (< i top))
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:next (fn []
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(def ret i)
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(:= i (+ i 1))
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ret)
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})
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(defn range [top] (range2 0 top))
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(defn doiter [itr]
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(def {:more more :next next} (iter itr))
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(while (more) (next)))
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(defn foreach [itr f]
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(def {:more more :next next} (iter itr))
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(while (more) (f (next))))
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(defn iter2array [itr]
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(def {:more more :next next} (iter itr))
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(def a @[])
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(while (more) (array.push a (next)))
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a)
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(defn map [f itr]
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(def {:more more :next next} (iter itr))
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{:more more :next (fn [] (f (next)))})
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(defn reduce [f start itr]
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(def itr (iter itr))
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(def {:more more :next next} itr)
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(if (more)
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(reduce f (f start (next)) itr)
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start))
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(defn filter [pred itr]
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(def itr (iter itr))
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(def {:more more :next next} itr)
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(var alive true)
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(var temp nil)
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(var isnew true)
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(defn nextgood []
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(if alive
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(if (more)
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(do
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(def n (next))
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(if (pred n) n (nextgood)))
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(:= alive false))))
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(defn nnext [] (def ret temp) (:= temp (nextgood)) ret)
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(defn nmore [] (when isnew (:= isnew false) (nnext)) alive)
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{:more nmore :next nnext})
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(defn pairs [x]
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(var lastkey (next x nil))
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{
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:more (fn [] lastkey)
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:next (fn []
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(def ret (tuple lastkey (get x lastkey)))
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(:= lastkey (next x lastkey))
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ret)
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})
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(defn keys [x]
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(var lastkey (next x nil))
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{
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:more (fn [] lastkey)
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:next (fn []
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(def ret lastkey)
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(:= lastkey (next x lastkey))
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ret)
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})
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(defn values [x]
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(var lastkey (next x nil))
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{
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:more (fn [] lastkey)
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:next (fn []
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(def ret (get x lastkey))
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(:= lastkey (next x lastkey))
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ret)
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})
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