POJO toDataFrame support (and array improvements)

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

@@ -13,6 +13,7 @@ import org.jetbrains.kotlinx.dataframe.impl.asList
 import org.jetbrains.kotlinx.dataframe.impl.columnName
 import org.jetbrains.kotlinx.dataframe.impl.columns.guessColumnType
 import org.jetbrains.kotlinx.dataframe.index
+import kotlin.reflect.KCallable
 import kotlin.reflect.KClass
 import kotlin.reflect.KProperty
 
@@ -115,24 +116,26 @@ public fun Iterable<Pair<String, Iterable<Any?>>>.toDataFrameFromPairs(): AnyFra
 public interface TraversePropertiesDsl {
 
     /**
-     * Skip given [classes] during recursive (dfs) traversal
+     * Skip given [classes] during recursive (dfs) traversal.
      */
     public fun exclude(vararg classes: KClass<*>)
 
     /**
-     * Skip given [properties] during recursive (dfs) traversal
+     * Skip given [properties] during recursive (dfs) traversal.
+     * These can also be getter-like functions (like `getX()` or `isX()`).
      */
-    public fun exclude(vararg properties: KProperty<*>)
+    public fun exclude(vararg properties: KCallable<*>)
 
     /**
-     * Store given [classes] in ValueColumns without transformation into ColumnGroups or FrameColumns
+     * Store given [classes] in ValueColumns without transformation into ColumnGroups or FrameColumns.
      */
     public fun preserve(vararg classes: KClass<*>)
 
     /**
-     * Store given [properties] in ValueColumns without transformation into ColumnGroups or FrameColumns
+     * Store given [properties] in ValueColumns without transformation into ColumnGroups or FrameColumns.
+     * These can also be getter-like functions (like `getX()` or `isX()`).
      */
-    public fun preserve(vararg properties: KProperty<*>)
+    public fun preserve(vararg properties: KCallable<*>)
 }
 
 public inline fun <reified T> TraversePropertiesDsl.preserve(): Unit = preserve(T::class)
@@ -148,7 +151,7 @@ public abstract class CreateDataFrameDsl<T> : TraversePropertiesDsl {
     public infix fun AnyBaseCol.into(path: ColumnPath): Unit = add(this, path)
 
     public abstract fun properties(
-        vararg roots: KProperty<*>,
+        vararg roots: KCallable<*>,
         maxDepth: Int = 0,
         body: (TraversePropertiesDsl.() -> Unit)? = null,
     )

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

@@ -4,7 +4,7 @@ import org.jetbrains.kotlinx.dataframe.DataFrame
 import org.jetbrains.kotlinx.dataframe.DataRow
 import org.jetbrains.kotlinx.dataframe.annotations.ColumnName
 import org.jetbrains.kotlinx.dataframe.annotations.DataSchema
-import org.jetbrains.kotlinx.dataframe.impl.schema.getPropertiesOrder
+import org.jetbrains.kotlinx.dataframe.impl.schema.getPropertyOrderFromPrimaryConstructor
 import org.jetbrains.kotlinx.dataframe.schema.ColumnSchema
 import kotlin.reflect.KClass
 import kotlin.reflect.KType
@@ -53,7 +53,7 @@ internal object MarkersExtractor {
         }
 
     private fun getFields(markerClass: KClass<*>, nullableProperties: Boolean): List<GeneratedField> {
-        val order = getPropertiesOrder(markerClass)
+        val order = getPropertyOrderFromPrimaryConstructor(markerClass) ?: emptyMap()
         return markerClass.memberProperties.sortedBy { order[it.name] ?: Int.MAX_VALUE }.mapIndexed { _, it ->
             val fieldName = ValidFieldName.of(it.name)
             val columnName = it.findAnnotation<ColumnName>()?.name ?: fieldName.unquoted

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

@@ -14,7 +14,9 @@ import org.jetbrains.kotlinx.dataframe.impl.columns.toColumnSet
 import org.jetbrains.kotlinx.dataframe.nrow
 import java.math.BigDecimal
 import java.math.BigInteger
+import kotlin.reflect.KCallable
 import kotlin.reflect.KClass
+import kotlin.reflect.KFunction
 import kotlin.reflect.KProperty
 import kotlin.reflect.KType
 import kotlin.reflect.KTypeProjection
@@ -23,6 +25,7 @@ import kotlin.reflect.full.createType
 import kotlin.reflect.full.findAnnotation
 import kotlin.reflect.full.isSubtypeOf
 import kotlin.reflect.full.starProjectedType
+import kotlin.reflect.full.valueParameters
 import kotlin.reflect.full.withNullability
 import kotlin.reflect.jvm.jvmErasure
 import kotlin.reflect.typeOf
@@ -337,5 +340,32 @@ internal fun List<String>.joinToCamelCaseString(): String {
         .replaceFirstChar { it.lowercaseChar() }
 }
 
+internal fun KFunction<*>.isGetterLike(): Boolean =
+    (name.startsWith("get") || name.startsWith("is")) && valueParameters.isEmpty()
+
+internal fun KCallable<*>.isGetterLike(): Boolean =
+    when (this) {
+        is KProperty<*> -> true
+        is KFunction<*> -> isGetterLike()
+        else -> false
+    }
+
 @PublishedApi
-internal val <T> KProperty<T>.columnName: String get() = findAnnotation<ColumnName>()?.name ?: name
+internal val KProperty<*>.columnName: String
+    get() = findAnnotation<ColumnName>()?.name ?: name
+
+@PublishedApi
+internal val KCallable<*>.columnName: String
+    get() = findAnnotation<ColumnName>()?.name
+        ?: when (this) {
+            // for defining the column names based on a getter-function, we use the function name minus the get/is prefix
+            is KFunction<*> ->
+                name
+                    .removePrefix("get")
+                    .removePrefix("is")
+                    .replaceFirstChar { it.lowercase() }
+
+            is KProperty<*> -> this.columnName
+
+            else -> name
+        }