added reflective isArray functions (with tests), so we can treat arra…

…ys as values in toDataFrame { properties() }

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

@@ -1,3 +1,5 @@
+@file:OptIn(ExperimentalUnsignedTypes::class)
+
 package org.jetbrains.kotlinx.dataframe.impl
 
 import org.jetbrains.kotlinx.dataframe.AnyFrame
@@ -467,3 +469,104 @@ internal fun nothingType(nullable: Boolean): KType =
     } else {
         typeOf<List<Nothing>>()
     }.arguments.first().type!!
+
+@OptIn(ExperimentalUnsignedTypes::class)
+private val primitiveArrayClasses = setOf(
+    BooleanArray::class,
+    ByteArray::class,
+    ShortArray::class,
+    IntArray::class,
+    LongArray::class,
+    FloatArray::class,
+    DoubleArray::class,
+    CharArray::class,
+
+    UByteArray::class,
+    UShortArray::class,
+    UIntArray::class,
+    ULongArray::class,
+)
+
+/**
+ * Returns `true` if this class is a primitive array class like `XArray`.
+ *
+ * Use [KClass.isArray] to also check for `Array<>`.
+ */
+internal val KClass<*>.isPrimitiveArray: Boolean
+    get() = this in primitiveArrayClasses
+
+/**
+ * Returns `true` if this class is an array, either a primitive array like `XArray` or `Array<>`.
+ *
+ * Use [KClass.isPrimitiveArray] to only check for primitive arrays.
+ */
+internal val KClass<*>.isArray: Boolean
+    get() = this in primitiveArrayClasses ||
+        this.qualifiedName == Array::class.qualifiedName // instance check fails
+
+/**
+ * Returns `true` if this type is of a primitive array like `XArray`.
+ *
+ * Use [KType.isArray] to also check for `Array<>`.
+ */
+internal val KType.isPrimitiveArray: Boolean
+    get() =
+        if (arguments.isNotEmpty()) {
+            // Catching https://github.com/Kotlin/dataframe/issues/678
+            // as typeOf<Array<Int>>().classifier == IntArray::class
+            false
+        } else {
+            (classifier as? KClass<*>)?.isPrimitiveArray == true
+        }
+
+
+/**
+ * Returns `true` if this type is of an array, either a primitive array like `XArray` or `Array<>`.
+ *
+ * Use [KType.isPrimitiveArray] to only check for primitive arrays.
+ */
+internal val KType.isArray: Boolean
+    get() = (classifier as? KClass<*>)?.isArray == true
+
+/**
+ * Returns `true` if this object is a primitive array like `XArray`.
+ *
+ * Use [Any.isArray] to also check for the `Array<>` object.
+ */
+internal val Any.isPrimitiveArray: Boolean
+    get() = this::class.isPrimitiveArray
+
+/**
+ * Returns `true` if this object is an array, either a primitive array like `XArray` or `Array<>`.
+ *
+ * Use [Any.isPrimitiveArray] to only check for primitive arrays.
+ */
+internal val Any.isArray: Boolean
+    get() = this::class.isArray
+
+/**
+ * Returns this array object as a list of values.
+ *
+ * @throws IllegalArgumentException if this object is not an array
+ */
+internal fun Any.asArrayToList(): List<*> {
+    require(this.isArray) { "Not an array" }
+    return when (this) {
+        is BooleanArray -> toList()
+        is ByteArray -> toList()
+        is ShortArray -> toList()
+        is IntArray -> toList()
+        is LongArray -> toList()
+        is FloatArray -> toList()
+        is DoubleArray -> toList()
+        is CharArray -> toList()
+
+        is UByteArray -> toList()
+        is UShortArray -> toList()
+        is UIntArray -> toList()
+        is ULongArray -> toList()
+
+        is Array<*> -> toList()
+        else -> error("Not an array")
+    }
+}

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/api/toDataFrame.kt

@@ -18,6 +18,7 @@ import org.jetbrains.kotlinx.dataframe.impl.asList
 import org.jetbrains.kotlinx.dataframe.impl.columnName
 import org.jetbrains.kotlinx.dataframe.impl.emptyPath
 import org.jetbrains.kotlinx.dataframe.impl.getListType
+import org.jetbrains.kotlinx.dataframe.impl.isArray
 import org.jetbrains.kotlinx.dataframe.impl.isGetterLike
 import org.jetbrains.kotlinx.dataframe.impl.projectUpTo
 import org.jetbrains.kotlinx.dataframe.impl.schema.sortWithConstructors
@@ -51,7 +52,8 @@ internal val KClass<*>.isValueType: Boolean
         this in valueTypes ||
             this.isSubclassOf(Number::class) ||
             this.isSubclassOf(Enum::class) ||
-            this.isSubclassOf(Temporal::class)
+            this.isSubclassOf(Temporal::class) ||
+            this.isArray
 
 internal class CreateDataFrameDslImpl<T>(
     override val source: Iterable<T>,

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

@@ -1,9 +1,9 @@
 package org.jetbrains.kotlinx.dataframe.api
 
 import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.DataColumn
 import org.jetbrains.kotlinx.dataframe.DataFrame
 import org.jetbrains.kotlinx.dataframe.DataRow
-import org.jetbrains.kotlinx.dataframe.alsoDebug
 import org.jetbrains.kotlinx.dataframe.annotations.DataSchema
 import org.jetbrains.kotlinx.dataframe.columns.ColumnKind
 import org.jetbrains.kotlinx.dataframe.kind
@@ -392,4 +392,19 @@ class CreateDataFrameTests {
             properties(JavaPojo::getB)
         } shouldBe dataFrameOf("b")("bb")
     }
+
+    data class Arrays(val a: IntArray, val b: Array<Int>, val c: Array<Int?>)
+
+    @Test
+    fun `arrays in to DF`() {
+        val df = listOf(
+            Arrays(intArrayOf(1, 2), arrayOf(3, 4), arrayOf(5, null))
+        ).toDataFrame(maxDepth = Int.MAX_VALUE)
+
+        df.schema() shouldBe dataFrameOf(
+            DataColumn.createValueColumn("a", listOf(intArrayOf(1, 2)), typeOf<IntArray>()),
+            DataColumn.createValueColumn("b", listOf(arrayOf(3, 4)), typeOf<Array<Int>>()),
+            DataColumn.createValueColumn("c", listOf(arrayOf(5, null)), typeOf<Array<Int?>>()),
+        ).schema()
+    }
 }

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/types/UtilTests.kt

@@ -1,12 +1,15 @@
 package org.jetbrains.kotlinx.dataframe.types
 
 import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.impl.asArrayToList
 import org.jetbrains.kotlinx.dataframe.impl.commonParent
 import org.jetbrains.kotlinx.dataframe.impl.commonParents
 import org.jetbrains.kotlinx.dataframe.impl.commonType
 import org.jetbrains.kotlinx.dataframe.impl.commonTypeListifyValues
 import org.jetbrains.kotlinx.dataframe.impl.createType
 import org.jetbrains.kotlinx.dataframe.impl.guessValueType
+import org.jetbrains.kotlinx.dataframe.impl.isArray
+import org.jetbrains.kotlinx.dataframe.impl.isPrimitiveArray
 import org.jetbrains.kotlinx.dataframe.impl.nothingType
 import org.jetbrains.kotlinx.dataframe.impl.replaceGenericTypeParametersWithUpperbound
 import org.junit.Test
@@ -17,6 +20,55 @@ import kotlin.reflect.typeOf
 
 class UtilTests {
 
+    @OptIn(ExperimentalUnsignedTypes::class)
+    @Test
+    fun `isArray tests`() {
+        // KClass isArray
+        BooleanArray::class.isArray shouldBe true
+        UIntArray::class.isArray shouldBe true
+        Array::class.isArray shouldBe true
+
+        // KClass isPrimitiveArray
+        BooleanArray::class.isPrimitiveArray shouldBe true
+        UIntArray::class.isPrimitiveArray shouldBe true
+        Array::class.isPrimitiveArray shouldBe false
+
+        // KType isArray
+        typeOf<BooleanArray>().isArray shouldBe true
+        typeOf<UIntArray>().isArray shouldBe true
+        typeOf<Array<Int>>().isArray shouldBe true
+        typeOf<Array<Int?>>().isArray shouldBe true
+        typeOf<Array<*>>().isArray shouldBe true
+
+        // KType isPrimitiveArray
+        typeOf<BooleanArray>().isPrimitiveArray shouldBe true
+        typeOf<UIntArray>().isPrimitiveArray shouldBe true
+        typeOf<Array<Int>>().isPrimitiveArray shouldBe false
+        typeOf<Array<Int?>>().isPrimitiveArray shouldBe false
+        typeOf<Array<*>>().isPrimitiveArray shouldBe false
+
+        // Any isArray
+        booleanArrayOf().isArray shouldBe true
+        uintArrayOf().isArray shouldBe true
+        arrayOf(1).isArray shouldBe true
+        arrayOf(1, null).isArray shouldBe true
+        arrayOfNulls<Any?>(1).isArray shouldBe true
+
+        // Any isPrimitiveArray
+        booleanArrayOf().isPrimitiveArray shouldBe true
+        uintArrayOf().isPrimitiveArray shouldBe true
+        arrayOf(1).isPrimitiveArray shouldBe false
+        arrayOf(1, null).isPrimitiveArray shouldBe false
+        arrayOfNulls<Any?>(1).isPrimitiveArray shouldBe false
+
+        // Any asArrayToList
+        booleanArrayOf(true, false).asArrayToList() shouldBe listOf(true, false)
+        uintArrayOf(1u, 2u).asArrayToList() shouldBe listOf(1u, 2u)
+        arrayOf(1, 2).asArrayToList() shouldBe listOf(1, 2)
+        arrayOf(1, null).asArrayToList() shouldBe listOf(1, null)
+        arrayOfNulls<Any?>(1).asArrayToList() shouldBe listOf(null)
+    }
+
     @Test
     fun commonParentsTests() {
         commonParents(Int::class, Int::class) shouldBe listOf(Int::class)