Merge pull request #73 from thomasathorne/biview

Add `parser` path.

src/clj/com/rpl/specter.cljx

@@ -270,6 +270,13 @@
     (next-fn (afn structure))
     ))
 
+(defpath parser [parse-fn unparse-fn]
+  (select* [this structure next-fn]
+    (next-fn (parse-fn structure)))
+  (transform* [this structure next-fn]
+    (unparse-fn (next-fn (parse-fn structure)))
+    ))
+
 (defn selected?
   "Filters the current value based on whether a selector finds anything.
   e.g. (selected? :vals ALL even?) keeps the current element only if an

test/com/rpl/specter/core_test.cljx

@@ -242,6 +242,18 @@
        (s/transform (s/view afn) identity i)
        )))
 
+(defspec parser-test
+  (for-all+
+    [i gen/int
+     afn (gen/elements [inc dec #(* % 2)])
+     bfn (gen/elements [inc dec #(* % 2)])
+     cfn (gen/elements [inc dec #(* % 2)])]
+    (and (= (first (s/select (s/parser afn bfn) i))
+            (afn i))
+         (= (s/transform (s/parser afn bfn) cfn i)
+            (-> i afn cfn bfn))
+         )))
+
 (deftest selected?-test
   (is (= [[1 3 5] [2 :a] [7 11 4 2 :a] [10 1 :a] []]
          (s/setval [s/ALL (s/selected? s/ALL even?) s/END]