feat(builtin): add partition function

Author: lzgabel

src/main/scala/org/camunda/feel/impl/builtin/ListBuiltinFunctions.scala

@@ -69,7 +69,8 @@ class ListBuiltinFunctions(private val valueMapper: ValueMapper) {
       joinWithDelimiterFunction,
       joinWithDelimiterAndPrefixAndSuffixFunction
     ),
-    "is empty"         -> List(emptyFunction)
+    "is empty"         -> List(emptyFunction),
+    "partition"        -> List(partitionFunction)
   )
 
   private def listContainsFunction =
@@ -518,4 +519,16 @@ class ListBuiltinFunctions(private val valueMapper: ValueMapper) {
       }
     )
 
+  private def partitionFunction =
+    builtinFunction(
+      params = List("list", "size"),
+      invoke = { case List(ValList(list), ValNumber(size)) =>
+        if (size.intValue > 0) {
+          ValList(list.grouped(size.intValue).map(l => ValList(l)).toList)
+        } else {
+          ValNull
+        }
+      }
+    )
+
 }

src/test/scala/org/camunda/feel/impl/builtin/BuiltinListFunctionsTest.scala

@@ -570,4 +570,17 @@ class BuiltinListFunctionsTest
     evaluateExpression(" is empty([1,2,3]) ") should returnResult(false)
     evaluateExpression(" is empty(list: [1]) ") should returnResult(false)
   }
+
+  "A partition() function" should "return list partitioned by _" in {
+    evaluateExpression(" partition([1,2,3,4,5], 2) ") should returnResult(
+      List(List(1, 2), List(3, 4), List(5))
+    )
+    evaluateExpression(" partition([], 2) ") should returnResult(List())
+    evaluateExpression(" partition([1], 2) ") should returnResult(List(List(1)))
+  }
+
+  it should "return null if the size is invalid" in {
+    evaluateExpression(" partition([1,2], 0) ") should returnNull()
+    evaluateExpression(" partition([1,2], -1) ") should returnNull()
+  }
 }