Add support for interpreted distinct operation (#1137)

Introduced the `distinct` operation with added annotations for refinement and interpretability. Updated tests to cover the new functionality and adjusted related plugins to integrate `distinct` logic alongside `select`.

Author: zaleslaw

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

@@ -4,6 +4,8 @@ import org.jetbrains.kotlinx.dataframe.AnyColumnReference
 import org.jetbrains.kotlinx.dataframe.ColumnsSelector
 import org.jetbrains.kotlinx.dataframe.DataFrame
 import org.jetbrains.kotlinx.dataframe.annotations.AccessApiOverload
+import org.jetbrains.kotlinx.dataframe.annotations.Interpretable
+import org.jetbrains.kotlinx.dataframe.annotations.Refine
 import org.jetbrains.kotlinx.dataframe.api.Select.SelectSelectingOptions
 import org.jetbrains.kotlinx.dataframe.columns.ColumnSet
 import org.jetbrains.kotlinx.dataframe.columns.SingleColumn
@@ -51,6 +53,8 @@ public fun <T> DataFrame<T>.distinct(): DataFrame<T> = distinctBy { all() }
  * {@include [DistinctDocs]}
  * {@set PHRASE_ENDING the specified columns}.
  */
+@Refine
+@Interpretable("Distinct0")
 public fun <T, C> DataFrame<T>.distinct(columns: ColumnsSelector<T, C>): DataFrame<T> = select(columns).distinct()
 
 /**

plugins/kotlin-dataframe/src/org/jetbrains/kotlinx/dataframe/plugin/impl/api/select.kt

@@ -24,6 +24,9 @@ import org.jetbrains.kotlinx.dataframe.plugin.impl.ignore
 import org.jetbrains.kotlinx.dataframe.plugin.impl.type
 import org.jetbrains.kotlinx.dataframe.plugin.utils.Names
 
+/**
+ * NOTE: Serves both, select and distinct operations.
+ */
 internal class Select0 : AbstractInterpreter<PluginDataFrameSchema>() {
     val Arguments.receiver: PluginDataFrameSchema by dataFrame()
     val Arguments.columns: ColumnsResolver by arg()

plugins/kotlin-dataframe/src/org/jetbrains/kotlinx/dataframe/plugin/loadInterpreter.kt

@@ -312,6 +312,7 @@ internal inline fun <reified T> String.load(): T {
         "Rename" -> Rename()
         "RenameMapping" -> RenameMapping()
         "Select0" -> Select0()
+        "Distinct0" -> Select0()
         "Expr0" -> Expr0()
         "And0" -> And0()
         "Remove0" -> Remove0()

plugins/kotlin-dataframe/testData/box/distinct.kt

@@ -0,0 +1,25 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.annotations.*
+import org.jetbrains.kotlinx.dataframe.api.*
+import org.jetbrains.kotlinx.dataframe.io.*
+
+fun box(): String {
+    val personsDf = dataFrameOf("name", "age", "city", "weight", "height", "yearsToRetirement")(
+        "Alice", 15, "London", 99.5, "1.85", 50,
+        "Bob", 20, "Paris", 140.0, "1.35", 45,
+        "Charlie", 100, "Dubai", 75.0, "1.95", 0,
+        "Rose", 1, "Moscow", 45.33, "0.79", 64,
+        "Dylan", 35, "London", 23.4, "1.83", 30,
+        "Eve", 40, "Paris", 56.72, "1.85", 25,
+        "Frank", 55, "Dubai", 78.9, "1.35", 10,
+        "Grace", 29, "Moscow", 67.8, "1.65", 36,
+        "Hank", 60, "Paris", 80.22, "1.75", 5,
+        "Isla", 22, "London", 75.1, "1.85", 43,
+    )
+
+    val res = personsDf.distinct { name and age }
+    res.name
+    res.age
+    res.compareSchemas()
+    return "OK"
+}

plugins/kotlin-dataframe/tests-gen/org/jetbrains/kotlin/fir/dataframe/DataFrameBlackBoxCodegenTestGenerated.java

@@ -154,6 +154,12 @@ public void testDiff() {
     runTest("testData/box/diff.kt");
   }
 
+  @Test
+  @TestMetadata("distinct.kt")
+  public void testDistinct() {
+        runTest("testData/box/distinct.kt");
+    }
+
   @Test
   @TestMetadata("dropNA.kt")
   public void testDropNA() {