JsonCursor composition (#1110)

zio · May 13, 2024 · 3d682cf · 3d682cf
1 parent 7f5ed7e
commit 3d682cf
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Showing 2 changed files with 33 additions and 7 deletions.
diff --git a/zio-json/shared/src/main/scala/zio/json/ast/JsonCursor.scala b/zio-json/shared/src/main/scala/zio/json/ast/JsonCursor.scala
@@ -19,18 +19,20 @@ sealed trait JsonCursor[-From, +To <: Json] { self =>
   final def >>>[Next <: Json](that: JsonCursor[To, Next]): JsonCursor[From, Next] =
     (that.asInstanceOf[JsonCursor[_ <: Json, _ <: Json]] match {
       case JsonCursor.Identity =>
-        that
+        self
 
-      case JsonCursor.DownField(oldParent @ _, name) =>
-        JsonCursor.DownField(self.asInstanceOf[JsonCursor[Json, Json.Obj]], name)
+      case JsonCursor.DownField(oldParent: JsonCursor[To, Json.Obj], name) =>
+        JsonCursor.DownField(self >>> oldParent, name)
 
-      case JsonCursor.DownElement(oldParent @ _, index) =>
-        JsonCursor.DownElement(self.asInstanceOf[JsonCursor[Json, Json.Arr]], index)
+      case JsonCursor.DownElement(oldParent: JsonCursor[To, Json.Arr], index) =>
+        JsonCursor.DownElement(self >>> oldParent, index)
 
-      case JsonCursor.FilterType(oldParent @ _, tpe) =>
-        JsonCursor.FilterType(self.asInstanceOf[JsonCursor[Json, Json]], tpe)
+      case JsonCursor.FilterType(oldParent: JsonCursor[To, _], tpe) =>
+        JsonCursor.FilterType(self >>> oldParent, tpe)
     }).asInstanceOf[JsonCursor[From, Next]]
 
+  final def andThen[Next <: Json](that: JsonCursor[To, Next]): JsonCursor[From, Next] = self >>> that
+
   final def isArray: JsonCursor[Json, Json.Arr] = filterType(JsonType.Arr)
 
   final def isBool: JsonCursor[Json, Json.Bool] = filterType(JsonType.Bool)

diff --git a/zio-json/shared/src/test/scala/zio/json/ast/JsonSpec.scala b/zio-json/shared/src/test/scala/zio/json/ast/JsonSpec.scala
@@ -1,5 +1,6 @@
 package zio.json.ast
 
+import zio.json._
 import zio.test.Assertion._
 import zio.test._
 
@@ -243,6 +244,29 @@ object JsonSpec extends ZIOSpecDefault {
           assert(tweet.get(combined))(
             isRight(equalTo(Json.Str("twitter")))
           )
+        },
+        test(">>>, array, filterType (second operand of >>> is complex)") {
+          val downEntities = JsonCursor.field("entities")
+          val downHashtag =
+            JsonCursor.isObject >>> JsonCursor.field("hashtags") >>> JsonCursor.isArray >>> JsonCursor.element(0)
+
+          val combined = downEntities >>> downHashtag
+
+          assert(tweet.get(combined))(
+            isRight(equalTo(Json.Str("twitter")))
+          )
+        },
+        test(">>>, combination of some methods of JsonCursor (second operand of >>> is complex)") {
+          val posts: Json = """{"posts": [{"id": 0, "title": "foo"}]}""".fromJson[Json].toOption.get
+
+          val downPosts = JsonCursor.field("posts")
+          val downTitle = JsonCursor.isArray >>> JsonCursor.element(0) >>> JsonCursor.isObject >>>
+            JsonCursor.field("title") >>> JsonCursor.isString
+          val combined = downPosts >>> downTitle
+
+          assert(posts.get(combined))(
+            isRight(equalTo(Json.Str("foo")))
+          )
         }
       ),
       suite("intersect")(