get-in support for default #256

Signed-off-by: Stuart Halloway <stu@thinkrelevance.com>

2 files changed, 39 insertions, 4 deletions

diff --git a/src/clj/clojure/core.clj b/src/clj/clojure/core.clj
index 11800ead..ca615435 100644
--- a/src/clj/clojure/core.clj
+++ b/src/clj/clojure/core.clj
@@ -4907,10 +4907,15 @@
 ;;;;;;;;;;;;; nested associative ops ;;;;;;;;;;;
 
 (defn get-in
-  "returns the value in a nested associative structure, where ks is a sequence of keys"
-  {:added "1.0"}
-  [m ks]
-  (reduce get m ks))
+  "Returns the value in a nested associative structure,
+  where ks is a sequence of ke(ys. Returns nil if the key is not present,
+  or the not-found value if supplied."
+  ([m ks]
+   (reduce get m ks))
+  ([m ks not-found]
+   (if (seq ks)
+     (get (reduce get m (butlast ks)) (last ks) not-found)
+     m)))
 
 (defn assoc-in
   "Associates a value in a nested associative structure, where ks is a
diff --git a/test/clojure/test_clojure/data_structures.clj b/test/clojure/test_clojure/data_structures.clj
index ee4fd41a..0ea8deca 100644
--- a/test/clojure/test_clojure/data_structures.clj
+++ b/test/clojure/test_clojure/data_structures.clj
@@ -517,6 +517,35 @@
       {} {:a 1 :b 2}
       #{} #{1 2} ))
 
+(deftest test-get
+  (let [m {:a 1, :b 2, :c {:d 3, :e 4}, :f nil, :g false, nil {:h 5}}]
+    (is (thrown? IllegalArgumentException (get-in {:a 1} 5)))
+    (are [x y] (= x y)
+         (get m :a) 1
+         (get m :e) nil
+         (get m :e 0) 0
+         (get m :b 0) 2
+         (get m :f 0) nil
+
+         (get-in m [:c :e]) 4
+         (get-in m '(:c :e)) 4
+         (get-in m [:c :x]) nil
+         (get-in m [:f]) nil
+         (get-in m [:g]) false
+         (get-in m [:h]) nil
+         (get-in m []) m
+         (get-in m nil) m
+
+         (get-in m [:c :e] 0) 4
+         (get-in m '(:c :e) 0) 4
+         (get-in m [:c :x] 0) 0
+         (get-in m [:b] 0) 2
+         (get-in m [:f] 0) nil
+         (get-in m [:g] 0) false
+         (get-in m [:h] 0) 0
+         (get-in m [:x :y] {:y 1}) {:y 1}
+         (get-in m [] 0) m
+         (get-in m nil 0) m)))
 
 ;; *** Sets ***
 
@@ -798,3 +827,4 @@
       (range 1 6) (-> EMPTY
                     (into (range 7))
                     pop))))
+