Nullable that does not have nulls. Not nullable that has(!) nulls

Author: Kopilov

core/generated-sources/src/main/kotlin/org/jetbrains/kotlinx/dataframe/DataColumn.kt

@@ -97,7 +97,7 @@ public interface DataColumn<out T> : BaseColumn<T> {
         public fun empty(name: String = ""): AnyCol = createValueColumn(name, emptyList<Unit>(), typeOf<Unit>())
     }
 
-    public fun hasNulls(): Boolean = type().isMarkedNullable
+    public fun hasNulls(): Boolean = values().any { it == null }
 
     override fun distinct(): DataColumn<T>
 

core/generated-sources/src/test/kotlin/org/jetbrains/kotlinx/dataframe/api/contains.kt

@@ -1,7 +1,11 @@
 package org.jetbrains.kotlinx.dataframe.api
 
 import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.DataColumn
+import org.jetbrains.kotlinx.dataframe.hasNulls
 import org.junit.Test
+import kotlin.reflect.full.withNullability
+import kotlin.reflect.typeOf
 
 class ContainsTests {
 
@@ -61,4 +65,12 @@ class ContainsTests {
         row.containsKey(b) shouldBe false
         row.containsKey(A::b) shouldBe false
     }
+
+    @Test
+    fun `nullable vs has nulls`() {
+        val nullable = DataColumn.create("nullable", listOf("a" as String?, "b" as String?, "c" as String?))
+        nullable.hasNulls shouldBe false
+        val notNullable = DataColumn.create("notNullable", listOf("a" as String?, "b" as String?, "c" as String?, null as String?), typeOf<String>().withNullability(false))
+        notNullable.hasNulls shouldBe true
+    }
 }

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/DataColumn.kt

@@ -97,7 +97,7 @@ public interface DataColumn<out T> : BaseColumn<T> {
         public fun empty(name: String = ""): AnyCol = createValueColumn(name, emptyList<Unit>(), typeOf<Unit>())
     }
 
-    public fun hasNulls(): Boolean = type().isMarkedNullable
+    public fun hasNulls(): Boolean = values().any { it == null }
 
     override fun distinct(): DataColumn<T>
 

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/api/contains.kt

@@ -1,7 +1,11 @@
 package org.jetbrains.kotlinx.dataframe.api
 
 import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.DataColumn
+import org.jetbrains.kotlinx.dataframe.hasNulls
 import org.junit.Test
+import kotlin.reflect.full.withNullability
+import kotlin.reflect.typeOf
 
 class ContainsTests {
 
@@ -61,4 +65,12 @@ class ContainsTests {
         row.containsKey(b) shouldBe false
         row.containsKey(A::b) shouldBe false
     }
+
+    @Test
+    fun `nullable vs has nulls`() {
+        val nullable = DataColumn.create("nullable", listOf("a" as String?, "b" as String?, "c" as String?))
+        nullable.hasNulls shouldBe false
+        val notNullable = DataColumn.create("notNullable", listOf("a" as String?, "b" as String?, "c" as String?, null as String?), typeOf<String>().withNullability(false))
+        notNullable.hasNulls shouldBe true
+    }
 }