core.clj

;   Copyright (c) Laurent Petit and others, March 2009. 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.

;; functions/macros variants of the ones that can be found in clojure.core

;; note to other contrib members: feel free to add to this lib

(ns
  ^{:author "Laurent Petit (and others)"
     :doc "Functions/macros variants of the ones that can be found in clojure.core 
 (note to other contrib members: feel free to add to this lib)"}
  clojure.contrib.core
  (:use clojure.contrib.def))

(defmacro- defnilsafe [docstring non-safe-name nil-safe-name]
  `(defmacro ~nil-safe-name ~docstring
     {:arglists '([~'x ~'form] [~'x ~'form ~'& ~'forms])}
	   ([x# form#]
	     `(let [~'i# ~x#] (when-not (nil? ~'i#) (~'~non-safe-name ~'i# ~form#))))
  	 ([x# form# & more#]
	     `(~'~nil-safe-name (~'~nil-safe-name ~x# ~form#) ~@more#))))
       
(defnilsafe 
  "Same as clojure.core/-> but returns nil as soon as the threaded value is nil itself (thus short-circuiting any pending computation).
   Examples :
   (-?> \"foo\" .toUpperCase (.substring 1)) returns \"OO\"
   (-?> nil .toUpperCase (.substring 1)) returns nil
   "
   -> -?>)
    
(defnilsafe 
  "Same as clojure.core/.. but returns nil as soon as the threaded value is nil itself (thus short-circuiting any pending computation).
   Examples :
   (.?. \"foo\" .toUpperCase (.substring 1)) returns \"OO\"
   (.?. nil .toUpperCase (.substring 1)) returns nil
   "
   .. .?.)

(defnilsafe
  "Same as clojure.core/->> but returns nil as soon as the threaded value is nil itself (thus short-circuiting any pending computation).
   Examples :
   (-?>> (range 5) (map inc)) returns (1 2 3 4 5)
   (-?>> [] seq (map inc)) returns nil
   "
  ->> -?>>)

;; ----------------------------------------------------------------------
;; scgilardi at gmail

(defn dissoc-in
  "Dissociates an entry from a nested associative structure returning a new
  nested structure. keys is a sequence of keys. Any empty maps that result
  will not be present in the new structure."
  [m [k & ks :as keys]]
  (if ks
    (if-let [nextmap (get m k)]
      (let [newmap (dissoc-in nextmap ks)]
        (if (seq newmap)
          (assoc m k newmap)
          (dissoc m k)))
      m)
    (dissoc m k)))

(defn new-by-name
  "Constructs a Java object whose class is specified by a String."
  [class-name & args]
  (clojure.lang.Reflector/invokeConstructor
   (clojure.lang.RT/classForName class-name)
   (into-array Object args)))

(defn seqable?
  "Returns true if (seq x) will succeed, false otherwise."
  [x]
  (or (seq? x)
      (instance? clojure.lang.Seqable x)
      (nil? x)
      (instance? Iterable x)
      (-> x .getClass .isArray)
      (string? x)
      (instance? java.util.Map x)))

;; ----------------------------------------------------------------------