Merge pull request #759 from adzerk/make-fromFullPaths-tail-recursive

Make fromFullPaths tail recursive

circe/src/main/scala/com/kevel/apso/circe/Implicits.scala

@@ -1,5 +1,6 @@
 package com.kevel.apso.circe
 
+import scala.annotation.tailrec
 import scala.util.Try
 
 import io.circe._
@@ -121,11 +122,17 @@ object Implicits {
       }
     }
 
-    paths match {
-      case Nil => Json.obj()
-      case (path, value) :: rem =>
-        createJson(path.split(separatorRegex).toList, value).deepMerge(fromFullPaths(rem, separatorRegex))
+    @tailrec
+    def fromFullPathsRec(paths: Seq[(String, Json)], acc: Json): Json = {
+      paths match {
+        case Nil => acc
+        case (path, value) :: rem =>
+          val newAcc = acc.deepMerge(createJson(path.split(separatorRegex).toList, value))
+          fromFullPathsRec(rem, newAcc)
+      }
     }
+
+    fromFullPathsRec(paths, Json.obj())
   }
 
   final implicit class ApsoJsonEncoder[A](val encoder: Encoder[A]) extends AnyVal {

circe/src/test/scala/com/kevel/apso/circe/ImplicitsSpec.scala

@@ -26,6 +26,19 @@ class ImplicitsSpec extends Specification {
 
         res mustEqual expectedJson
       }
+
+      "not throw a StackOverflowError for large lists of paths" in {
+        val paths = (1 to 10000).map(i => (s"a.v$i", i.asJson)).toList
+        fromFullPaths(paths, ".") must not(throwAn[StackOverflowError])
+      }
+
+      "giving precedence to the last path value if duplicate paths exist" in {
+        val json1 = fromFullPaths(List("a" -> 1.asJson, "a" -> 2.asJson, "a" -> 3.asJson))
+        json1 mustEqual json"""{"a": 3}"""
+
+        val json2 = fromFullPaths(List("a.b.c" -> 1.asJson, "a.b" -> 2.asJson, "a" -> 3.asJson))
+        json2 mustEqual json"""{"a": 3}"""
+      }
     }
 
     "provide a method to get the key set of a JSON Object" in {