42 lines
931 B
Clojure
42 lines
931 B
Clojure
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(ns rss-thread-watch.utils
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"Util functions"
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(:gen-class))
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;; ===== Generic functions ====
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(defn indices
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;; https://stackoverflow.com/questions/8641305/find-index-of-an-element-matching-a-predicate-in-clojure
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"Returns indexes of elements passing predicate"
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[pred coll]
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(keep-indexed #(when (pred %2) %1) coll))
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;; ===== Macros =====
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(defmacro nil?-else
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"Return x unless it's nil, the return y"
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[x y]
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`(let [result# ~x]
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(if (nil? result#)
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~y
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result#)))
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(defmacro when-else
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"Evaluates tst, if it's true returns it's result.
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If it's not, return else"
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[tst else]
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`(let [res# ~tst]
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(if res#
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res#
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~else)))
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(defmacro ret=
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"compares two values using [=]. If the result is true
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returns the value, else the result of [=].
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Usefull with if-else"
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[x y]
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`(let [x# ~x
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y# ~y
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result# ~(= x y)]
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(if result#
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~x
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result#)))
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