Add support for Scheme and Racket language.

sources_non_forked/slimv/swank-clojure/swank/util.clj

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+(ns swank.util
+  (:import (java.io StringReader)
+           (clojure.lang LineNumberingPushbackReader)))
+
+(defmacro one-of?
+  "Short circuiting value comparison."
+  ([val & possible]
+     (let [v (gensym)]
+       `(let [~v ~val]
+          (or ~@(map (fn [p] `(= ~v ~p)) possible))))))
+
+(defn find-first
+  "Returns the first entry in a coll matches a given predicate."
+  ([coll] (find-first identity coll))
+  ([pred coll]
+     (first (filter pred coll))))
+
+(defn position
+  "Finds the first position of an item that matches a given predicate
+   within col. Returns nil if not found. Optionally provide a start
+   offset to search from."
+  ([pred coll] (position pred coll 0))
+  ([pred coll start]
+     (loop [coll (drop start coll), i start]
+       (when (seq coll)
+         (if (pred (first coll))
+           i
+           (recur (rest coll) (inc i))))))
+  {:tag Integer})
+
+(when-not (ns-resolve 'clojure.core 'group-by)
+  ;; TODO: not sure why eval is necessary here; breaks without it.
+  (eval '(defn group-by
+           "Categorizes elements within a coll into a map based on a function."
+           ([f coll]
+              (reduce
+               (fn [ret x]
+                 (let [k (f x)]
+                   (assoc ret k (conj (get ret k []) x))))
+               {})))))
+
+(when-not (ns-resolve 'clojure.core 'flatten)
+  (eval '(defn flatten [x]
+           (filter (complement sequential?)
+                   (rest (tree-seq sequential? seq x))))))
+
+(defmacro returning [[var ret] & body]
+  `(let [~var ~ret]
+     ~@body
+     ~var))
+
+
+(defn deep-replace [smap coll]
+  (map #(if (or (seq? %) (vector? %))
+          (deep-replace smap %)
+          %)
+       (replace smap coll)))
+
+(defmacro keep-bindings [bindings f]
+  (let [bind-vars (take (count bindings) (repeatedly gensym))]
+    `(let [~@(interleave bind-vars bindings)]
+       (fn [& args#]
+         (binding [~@(interleave bindings bind-vars)]
+           (apply ~f args#))))))
+
+(defmacro continuously [& body]
+  `(loop [] ~@body (recur)))
+
+(defmacro failing-gracefully [& body]
+  `(try
+    ~@body
+    (catch Throwable _# nil)))