Sort df.compileTimeSchema() columns according to df.schema() so they're easier to compare

core/api/core.api

@@ -10130,6 +10130,10 @@ public final class org/jetbrains/kotlinx/dataframe/impl/api/MapKt {
 	public static final fun mapNotNullValues (Lorg/jetbrains/kotlinx/dataframe/DataColumn;Lkotlin/jvm/functions/Function1;)Lorg/jetbrains/kotlinx/dataframe/DataColumn;
 }
 
+public final class org/jetbrains/kotlinx/dataframe/impl/api/SchemaKt {
+	public static final fun compileTimeSchemaImpl (Lorg/jetbrains/kotlinx/dataframe/schema/DataFrameSchema;Lkotlin/reflect/KClass;)Lorg/jetbrains/kotlinx/dataframe/schema/DataFrameSchema;
+}
+
 public final class org/jetbrains/kotlinx/dataframe/impl/api/ToDataFrameKt {
 	public static final fun convertToDataFrame (Ljava/lang/Iterable;Lkotlin/reflect/KClass;Ljava/util/List;Ljava/util/Set;Ljava/util/Set;Ljava/util/Set;I)Lorg/jetbrains/kotlinx/dataframe/DataFrame;
 	public static final fun createDataFrameImpl (Ljava/lang/Iterable;Lkotlin/reflect/KClass;Lkotlin/jvm/functions/Function1;)Lorg/jetbrains/kotlinx/dataframe/DataFrame;

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

@@ -3,9 +3,9 @@ package org.jetbrains.kotlinx.dataframe.api
 import org.jetbrains.kotlinx.dataframe.AnyFrame
 import org.jetbrains.kotlinx.dataframe.AnyRow
 import org.jetbrains.kotlinx.dataframe.DataFrame
+import org.jetbrains.kotlinx.dataframe.impl.api.compileTimeSchemaImpl
 import org.jetbrains.kotlinx.dataframe.impl.owner
 import org.jetbrains.kotlinx.dataframe.impl.schema.extractSchema
-import org.jetbrains.kotlinx.dataframe.impl.schema.getSchema
 import org.jetbrains.kotlinx.dataframe.schema.DataFrameSchema
 
 // region DataRow
@@ -26,5 +26,5 @@ public fun GroupBy<*, *>.schema(): DataFrameSchema = toDataFrame().schema()
 
 // endregion
 
-@Suppress("UnusedReceiverParameter")
-public inline fun <reified T> DataFrame<T>.compileTimeSchema(): DataFrameSchema = getSchema(T::class)
+public inline fun <reified T> DataFrame<T>.compileTimeSchema(): DataFrameSchema =
+    compileTimeSchemaImpl(schema(), T::class)

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

@@ -0,0 +1,55 @@
+package org.jetbrains.kotlinx.dataframe.impl.api
+
+import org.jetbrains.kotlinx.dataframe.columns.ColumnPath
+import org.jetbrains.kotlinx.dataframe.impl.schema.DataFrameSchemaImpl
+import org.jetbrains.kotlinx.dataframe.impl.schema.getSchema
+import org.jetbrains.kotlinx.dataframe.schema.ColumnSchema
+import org.jetbrains.kotlinx.dataframe.schema.DataFrameSchema
+import kotlin.reflect.KClass
+
+@PublishedApi
+internal fun compileTimeSchemaImpl(runtimeSchema: DataFrameSchema, klass: KClass<*>): DataFrameSchema {
+    val compileSchema = getSchema(klass)
+    val root = ColumnPath(emptyList())
+    val order = buildMap {
+        putColumnsOrder(runtimeSchema, path = root)
+    }
+    return compileSchema.sortedBy(order, path = root)
+}
+
+internal fun MutableMap<ColumnPath, Int>.putColumnsOrder(schema: DataFrameSchema, path: ColumnPath) {
+    schema.columns.entries.forEachIndexed { i, (name, column) ->
+        val columnPath = path + name
+        this[columnPath] = i
+        when (column) {
+            is ColumnSchema.Frame -> {
+                putColumnsOrder(column.schema, columnPath)
+            }
+
+            is ColumnSchema.Group -> {
+                putColumnsOrder(column.schema, columnPath)
+            }
+        }
+    }
+}
+
+internal fun DataFrameSchema.sortedBy(order: Map<ColumnPath, Int>, path: ColumnPath): DataFrameSchema {
+    val sorted = columns.map { (name, column) ->
+        name to when (column) {
+            is ColumnSchema.Frame -> ColumnSchema.Frame(
+                column.schema.sortedBy(order, path + name),
+                column.nullable,
+                column.contentType,
+            )
+
+            is ColumnSchema.Group -> ColumnSchema.Group(column.schema.sortedBy(order, path + name), column.contentType)
+
+            is ColumnSchema.Value -> column
+
+            else -> TODO("unexpected ColumnSchema class ${column::class}")
+        }
+    }.sortedBy { (name, _) ->
+        order[path + name]
+    }.toMap()
+    return DataFrameSchemaImpl(sorted)
+}

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

@@ -0,0 +1,26 @@
+package org.jetbrains.kotlinx.dataframe.api
+
+import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.DataRow
+import org.junit.Test
+
+class SchemaTests {
+    @Test
+    fun `columns order test`() {
+        val row = dataFrameOf("c", "b")(4, 5).first()
+        val df = dataFrameOf("abc", "a", "a123", "nested")(1, 2, 3, row).cast<Schema>()
+        df.schema().toString() shouldBe df.compileTimeSchema().toString()
+    }
+}
+
+private interface Schema {
+    val a: Int
+    val abc: Int
+    val a123: Int
+    val nested: DataRow<Nested>
+}
+
+private interface Nested {
+    val b: Int
+    val c: Int
+}