adding debug mode check for nulls in FrameColumnImpl and simplifying KType.toColumnKind()

Author: Jolanrensen

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/columns/FrameColumnImpl.kt

@@ -1,12 +1,14 @@
 package org.jetbrains.kotlinx.dataframe.impl.columns
 
 import org.jetbrains.kotlinx.dataframe.AnyRow
+import org.jetbrains.kotlinx.dataframe.BuildConfig
 import org.jetbrains.kotlinx.dataframe.DataColumn
 import org.jetbrains.kotlinx.dataframe.DataFrame
 import org.jetbrains.kotlinx.dataframe.api.schema
 import org.jetbrains.kotlinx.dataframe.columns.ColumnGroup
 import org.jetbrains.kotlinx.dataframe.columns.ColumnResolutionContext
 import org.jetbrains.kotlinx.dataframe.columns.FrameColumn
+import org.jetbrains.kotlinx.dataframe.impl.anyNull
 import org.jetbrains.kotlinx.dataframe.impl.createStarProjectedType
 import org.jetbrains.kotlinx.dataframe.impl.schema.intersectSchemas
 import org.jetbrains.kotlinx.dataframe.nrow
@@ -26,6 +28,14 @@ internal open class FrameColumnImpl<T> constructor(
     ),
     FrameColumn<T> {
 
+    init {
+        // Checks for nulls in the `values` list.
+        // This only runs with `kotlin.dataframe.debug=true` in gradle.properties.
+        if (BuildConfig.DEBUG) {
+            require(!values.anyNull()) { "FrameColumn cannot null values." }
+        }
+    }
+
     override fun rename(newName: String) = FrameColumnImpl(newName, values, schema, distinct)
 
     override fun defaultValue() = null

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/columns/Utils.kt

@@ -2,10 +2,11 @@ package org.jetbrains.kotlinx.dataframe.impl.columns
 
 import org.jetbrains.kotlinx.dataframe.AnyBaseCol
 import org.jetbrains.kotlinx.dataframe.AnyCol
+import org.jetbrains.kotlinx.dataframe.AnyFrame
+import org.jetbrains.kotlinx.dataframe.AnyRow
 import org.jetbrains.kotlinx.dataframe.ColumnsContainer
 import org.jetbrains.kotlinx.dataframe.DataColumn
 import org.jetbrains.kotlinx.dataframe.DataFrame
-import org.jetbrains.kotlinx.dataframe.DataRow
 import org.jetbrains.kotlinx.dataframe.api.asColumnGroup
 import org.jetbrains.kotlinx.dataframe.api.cast
 import org.jetbrains.kotlinx.dataframe.api.name
@@ -43,7 +44,6 @@ import org.jetbrains.kotlinx.dataframe.nrow
 import org.jetbrains.kotlinx.dataframe.type
 import kotlin.reflect.KType
 import kotlin.reflect.full.isSubtypeOf
-import kotlin.reflect.jvm.jvmErasure
 import kotlin.reflect.typeOf
 
 internal fun <T> BaseColumn<T>.checkEquals(other: Any?): Boolean {
@@ -471,13 +471,17 @@ internal fun List<ColumnWithPath<*>>.allColumnsExceptKeepingStructure(
     return subtrees.map { it.data!!.addPath(it.pathFromRoot()) }
 }
 
+/**
+ * Retrieves the correct [ColumnKind] based on the [type][KType] of the values in the column.
+ *
+ * NOTE: nullable DataFrames cannot become a [FrameColumns][FrameColumn],
+ * so they become [ValueColumns][ValueColumn] instead.
+ */
 internal fun KType.toColumnKind(): ColumnKind =
-    jvmErasure.let {
-        when (it) {
-            DataFrame::class -> ColumnKind.Frame
-            DataRow::class -> ColumnKind.Group
-            else -> ColumnKind.Value
-        }
+    when {
+        this.isSubtypeOf(typeOf<AnyFrame>()) -> ColumnKind.Frame
+        this.isSubtypeOf(typeOf<AnyRow?>()) -> ColumnKind.Group
+        else -> ColumnKind.Value
     }
 
 internal fun <C> ColumnsResolver<C>.resolve(

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/columns/DataColumns.kt

@@ -1,6 +1,10 @@
 package org.jetbrains.kotlinx.dataframe.columns
 
+import io.kotest.assertions.throwables.shouldThrow
 import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.AnyFrame
+import org.jetbrains.kotlinx.dataframe.DataColumn
+import org.jetbrains.kotlinx.dataframe.api.dataFrameOf
 import org.jetbrains.kotlinx.dataframe.api.toColumn
 import org.jetbrains.kotlinx.dataframe.api.toDataFrame
 import org.junit.Test
@@ -28,4 +32,22 @@ class DataColumns {
         val col = listOf(URI.create("http://example.com"), null).toColumn("a")
         col.type().toString() shouldBe "java.net.URI?"
     }
+
+    @Test
+    fun `allow no nulls in frame columns`() {
+        // enable kotlin.dataframe.debug=true for this
+        shouldThrow<IllegalArgumentException> {
+            DataColumn.createFrameColumn(
+                name = "",
+                groups = listOf(dataFrameOf("a")(1), null) as List<AnyFrame>,
+            )
+        }
+
+        shouldThrow<IllegalArgumentException> {
+            DataColumn.create(
+                "",
+                listOf(dataFrameOf("a")(1), null),
+            )
+        }
+    }
 }