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Diffstat (limited to 'src/clojure/contrib/seq_utils.clj')
| -rw-r--r-- | src/clojure/contrib/seq_utils.clj | 223 |
1 files changed, 0 insertions, 223 deletions
diff --git a/src/clojure/contrib/seq_utils.clj b/src/clojure/contrib/seq_utils.clj deleted file mode 100644 index ad913f70..00000000 --- a/src/clojure/contrib/seq_utils.clj +++ /dev/null @@ -1,223 +0,0 @@ -;;; seq_utils.clj -- Sequence utilities for Clojure - -;; by Stuart Sierra, http://stuartsierra.com/ -;; last updated March 2, 2009 - -;; Copyright (c) Stuart Sierra, 2008. All rights reserved. The use -;; and distribution terms for this software are covered by the Eclipse -;; Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) -;; which can be found in the file epl-v10.html at the root of this -;; distribution. By using this software in any fashion, you are -;; agreeing to be bound by the terms of this license. You must not -;; remove this notice, or any other, from this software. - - -;; Change Log -;; -;; January 10, 2009 (Stuart Sierra): -;; -;; * BREAKING CHANGE: "includes?" now takes collection as first -;; argument. This is more consistent with Clojure collection -;; functions; see discussion at http://groups.google.com/group/clojure/browse_thread/thread/8b2c8dc96b39ddd7/a8866d34b601ff43 - - -(ns - #^{:author "Stuart Sierra (and others)", - :doc "Sequence utilities for Clojure"} - clojure.contrib.seq-utils - (:import (java.util.concurrent LinkedBlockingQueue TimeUnit) - (java.lang.ref WeakReference))) - - -;; 'flatten' written by Rich Hickey, -;; see http://groups.google.com/group/clojure/msg/385098fabfcaad9b -(defn flatten - "Takes any nested combination of sequential things (lists, vectors, - etc.) and returns their contents as a single, flat sequence. - (flatten nil) returns nil." - [x] - (filter (complement sequential?) - (rest (tree-seq sequential? seq x)))) - -(defn separate - "Returns a vector: - [ (filter f s), (filter (complement f) s) ]" - [f s] - [(filter f s) (filter (complement f) s)]) - -(defn includes? - "Returns true if coll contains something equal (with =) to x, - in linear time." - [coll x] - (if (some (fn [y] (= y x)) coll) - true false)) - -(defn indexed - "Returns a lazy sequence of [index, item] pairs, where items come - from 's' and indexes count up from zero. - - (indexed '(a b c d)) => ([0 a] [1 b] [2 c] [3 d])" - [s] - (map vector (iterate inc 0) s)) - -;; group-by written by Rich Hickey; -;; see http://paste.lisp.org/display/64190 -(defn group-by - "Returns a sorted map of the elements of coll keyed by the result of - f on each element. The value at each key will be a vector of the - corresponding elements, in the order they appeared in coll." - [f coll] - (reduce - (fn [ret x] - (let [k (f x)] - (assoc ret k (conj (get ret k []) x)))) - (sorted-map) coll)) - -;; partition-by originally written by Rich Hickey; -;; modified by Stuart Sierra -(defn partition-by - "Applies f to each value in coll, splitting it each time f returns - a new value. Returns a lazy seq of lazy seqs." - [f coll] - (when-let [s (seq coll)] - (let [fst (first s) - fv (f fst) - run (cons fst (take-while #(= fv (f %)) (rest s)))] - (lazy-seq - (cons run (partition-by f (drop (count run) s))))))) - -(defn frequencies - "Returns a map from distinct items in coll to the number of times - they appear." - [coll] - (reduce (fn [counts x] - (assoc counts x (inc (get counts x 0)))) - {} coll)) - -;; recursive sequence helpers by Christophe Grand -;; see http://clj-me.blogspot.com/2009/01/recursive-seqs.html -(defmacro rec-seq - "Similar to lazy-seq but binds the resulting seq to the supplied - binding-name, allowing for recursive expressions." - [binding-name & body] - `(let [s# (atom nil)] - (reset! s# (lazy-seq (let [~binding-name @s#] ~@body))))) - -(defmacro rec-cat - "Similar to lazy-cat but binds the resulting sequence to the supplied - binding-name, allowing for recursive expressions." - [binding-name & exprs] - `(rec-seq ~binding-name (lazy-cat ~@exprs))) - - -;; reductions by Chris Houser -;; see http://groups.google.com/group/clojure/browse_thread/thread/3edf6e82617e18e0/58d9e319ad92aa5f?#58d9e319ad92aa5f -(defn reductions - "Returns a lazy seq of the intermediate values of the reduction (as - per reduce) of coll by f, starting with init." - ([f coll] - (if (seq coll) - (rec-seq self (cons (first coll) (map f self (rest coll)))) - (cons (f) nil))) - ([f init coll] - (rec-seq self (cons init (map f self coll))))) - -(defn rotations - "Returns a lazy seq of all rotations of a seq" - [x] - (if (seq x) - (map - (fn [n _] - (lazy-cat (drop n x) (take n x))) - (iterate inc 0) x) - (list nil))) - -(defn partition-all - "Returns a lazy sequence of lists like clojure.core/partition, but may - include lists with fewer than n items at the end." - ([n coll] - (partition-all n n coll)) - ([n step coll] - (lazy-seq - (when-let [s (seq coll)] - (cons (take n s) (partition-all n step (drop step s))))))) - -(defn shuffle - "Return a random permutation of coll" - [coll] - (let [l (java.util.ArrayList. coll)] - (java.util.Collections/shuffle l) - (seq l))) - -(defn rand-elt - "Return a random element of this seq" - [s] - (nth s (rand-int (count s)))) - - -;; seq-on written by Konrad Hinsen -(defmulti seq-on - "Returns a seq on the object s. Works like the built-in seq but as - a multimethod that can have implementations for new classes and types." - {:arglists '([s])} - type) - -(defmethod seq-on :default - [s] - (seq s)) - - -(defn find-first - "Returns the first item of coll for which (pred item) returns logical true. - Consumes sequences up to the first match, will consume the entire sequence - and return nil if no match is found." - [pred coll] - (first (filter pred coll))) - -; based on work related to Rich Hickey's seque. -; blame Chouser for anything broken or ugly. -(defn fill-queue - "filler-func will be called in another thread with a single arg - 'fill'. filler-func may call fill repeatedly with one arg each - time which will be pushed onto a queue, blocking if needed until - this is possible. fill-queue will return a lazy seq of the values - filler-func has pushed onto the queue, blocking if needed until each - next element becomes available. filler-func's return value is ignored." - ([filler-func & optseq] - (let [opts (apply array-map optseq) - apoll (:alive-poll opts 1) - q (LinkedBlockingQueue. (:queue-size opts 1)) - NIL (Object.) ;nil sentinel since LBQ doesn't support nils - weak-target (Object.) - alive? (WeakReference. weak-target) - fill (fn fill [x] - (if (.get alive?) - (if (.offer q (if (nil? x) NIL x) apoll TimeUnit/SECONDS) - x - (recur x)) - (throw (Exception. "abandoned")))) - f (future - (try - (filler-func fill) - (finally - (.put q q))) ;q itself is eos sentinel - nil)] ; set future's value to nil - ((fn drain [] - weak-target ; force closing over this object - (lazy-seq - (let [x (.take q)] - (if (identical? x q) - @f ;will be nil, touch just to propagate errors - (cons (if (identical? x NIL) nil x) - (drain)))))))))) - -(defn positions - "Returns a lazy sequence containing the positions at which pred - is true for items in coll." - [pred coll] - (for [[idx elt] (indexed coll) :when (pred elt)] idx)) - - - - - |