Add an additional example for ExprFunction

examples/src/kotlin/org/partiql/examples/MergeKeyValues.kt

@@ -0,0 +1,89 @@
+package org.partiql.examples
+
+import org.partiql.lang.eval.BindingCase
+import org.partiql.lang.eval.BindingName
+import org.partiql.lang.eval.EvaluationSession
+import org.partiql.lang.eval.ExprFunction
+import org.partiql.lang.eval.ExprValue
+import org.partiql.lang.eval.ExprValueFactory
+import org.partiql.lang.eval.ExprValueType
+import org.partiql.lang.eval.StructOrdering
+import org.partiql.lang.eval.namedValue
+import org.partiql.lang.eval.stringValue
+import org.partiql.lang.types.FunctionSignature
+import org.partiql.lang.types.StaticType
+import java.lang.Exception
+import kotlin.collections.HashMap
+
+abstract class MergeKeysBaseExprFunction(
+    val valueFactory: ExprValueFactory,
+) : ExprFunction
+
+/**
+ * For the Given [ExprValue] representing collection of structs, merges key/values based on the given inputs in flatten list
+ * for values.
+ *
+ * E.g.
+ * Given:
+ *  [
+ *      {'Name':'certificate','Values':['abc', 'cde']},
+ *      {'Name':'certificate','Values':['ghj', 'klu']},
+ *      {'Name':'test','Values':['ghj', 'klu']}
+ *  ]
+ *  'Name' as mergeKey
+ *  'Values' as valueKey
+ *
+ *  Expected:
+ *  [
+ *      {'test': ['ghj', 'klu']},
+ *      {'certificate': ['abc', 'cde', 'ghj', 'klu']}
+ *  ]
+ */
+class MergeKeyValues(valueFactory: ExprValueFactory) :
+    MergeKeysBaseExprFunction(valueFactory) {
+    override val signature = FunctionSignature(
+        name = "merge_key_values",
+        requiredParameters = listOf(
+            StaticType.unionOf(StaticType.BAG, StaticType.LIST, StaticType.SEXP),
+            StaticType.STRING,
+            StaticType.STRING
+        ),
+        returnType = StaticType.LIST
+    )
+
+    override fun callWithRequired(session: EvaluationSession, required: List<ExprValue>): ExprValue {
+        val mergeKey = required[1].stringValue()
+        val valueKey = required[2].stringValue()
+        val result = HashMap<String, MutableList<ExprValue>>()
+
+        required[0].forEach {
+            if (it.type != ExprValueType.STRUCT) {
+                throw Exception("All elements on input collection must be of type struct. Erroneous value: $it")
+            }
+
+            val binding = it.bindings[BindingName(mergeKey, BindingCase.INSENSITIVE)]
+            val bindingValue = binding!!.stringValue()
+            val valueElem = it.bindings[BindingName(valueKey, BindingCase.INSENSITIVE)]
+
+            if (valueElem != null) {
+                if (result[bindingValue] == null) {
+                    result[bindingValue] = mutableListOf(valueElem)
+                } else {
+                    result[bindingValue]!!.add(valueElem)
+                }
+            }
+        }
+
+        val keys = result.keys.map { valueFactory.newString(it) }
+        val values = result.values.map { valueFactory.newList(it).flatten() }
+
+        val listOfStructs = keys.zip(values)
+            .map {
+                valueFactory.newStruct(
+                    listOf(valueFactory.newList(it.second).namedValue(it.first)).asSequence(),
+                    StructOrdering.UNORDERED
+                )
+            }
+        return valueFactory.newList(listOfStructs)
+    }
+}

examples/test/org/partiql/examples/MergeKeyValuesTests.kt

@@ -0,0 +1,125 @@
+/*
+ * Copyright 2022 Amazon.com, Inc. or its affiliates.  All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at:
+ *
+ *      http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
+ * language governing permissions and limitations under the License.
+ */
+package org.partiql.examples
+
+import com.amazon.ion.system.IonSystemBuilder
+import junit.framework.TestCase.assertEquals
+import junit.framework.TestCase.assertNotNull
+import org.junit.Assert.assertThrows
+import org.junit.Test
+import org.partiql.lang.eval.EvaluationSession
+import org.partiql.lang.eval.ExprValueFactory
+import org.partiql.lang.eval.StructOrdering
+import org.partiql.lang.eval.namedValue
+
+class MergeKeyValuesTests {
+    private val ion = IonSystemBuilder.standard().build()
+    private val factory = ExprValueFactory.standard(ion)
+    private val session = EvaluationSession.standard()
+
+    @Test
+    fun testFunction() {
+        val fn = MergeKeyValues(factory)
+
+        val ionValue1 = ion.newList(ion.newString("abc"), ion.newString("cde"))
+        val ionValue2 = ion.newList(ion.newString("ghj"), ion.newString("klu"))
+        val ionValue3 = ion.newList(ion.newString("ghj"), ion.newString("klu"))
+
+        val list1 = listOf(
+            factory.newString("certificate").namedValue(factory.newSymbol("Name")),
+            factory.newFromIonValue(ionValue1).namedValue(factory.newSymbol("Values")),
+        )
+        val list2 = listOf(
+            factory.newString("certificate").namedValue(factory.newSymbol("Name")),
+            factory.newFromIonValue(ionValue2).namedValue(factory.newSymbol("Values")),
+        )
+        val list3 = listOf(
+            factory.newString("test").namedValue(factory.newSymbol("Name")),
+            factory.newFromIonValue(ionValue3).namedValue(factory.newSymbol("Values")),
+        )
+        val res1 = fn.callWithRequired(
+            session,
+            listOf(
+                factory.newBag(
+                    listOf(
+                        factory.newStruct(list1.asSequence(), StructOrdering.UNORDERED),
+                        factory.newStruct(list2.asSequence(), StructOrdering.UNORDERED),
+                        factory.newStruct(list3.asSequence(), StructOrdering.UNORDERED)
+                    )
+                ),
+                factory.newString("Name"),
+                factory.newString("Values")
+            )
+        )
+
+        val res2 = fn.callWithRequired(
+            session,
+            listOf(
+                factory.newSexp(
+                    listOf(
+                        factory.newStruct(list1.asSequence(), StructOrdering.UNORDERED),
+                        factory.newStruct(list2.asSequence(), StructOrdering.UNORDERED),
+                        factory.newStruct(list3.asSequence(), StructOrdering.UNORDERED)
+                    )
+                ),
+                factory.newString("Name"),
+                factory.newString("Values")
+            )
+        )
+
+        val res3 = fn.callWithRequired(
+            session,
+            listOf(
+                factory.newList(
+                    listOf(
+                        factory.newStruct(list1.asSequence(), StructOrdering.UNORDERED),
+                        factory.newStruct(list2.asSequence(), StructOrdering.UNORDERED),
+                        factory.newStruct(list3.asSequence(), StructOrdering.UNORDERED)
+                    )
+                ),
+                factory.newString("Name"),
+                factory.newString("Values")
+            )
+        )
+
+        setOf(res1, res2, res3).forEach {
+            assertNotNull(it)
+            assertEquals(
+                "[{'test': ['ghj', 'klu']}, {'certificate': ['abc', 'cde', 'ghj', 'klu']}]",
+                it.toString()
+            )
+        }
+
+        val ex = assertThrows(Exception::class.java) {
+            fn.callWithRequired(
+                session,
+                listOf(
+                    factory.newList(
+                        listOf(
+                            factory.newInt(10),
+                            factory.newStruct(list2.asSequence(), StructOrdering.UNORDERED),
+                        )
+                    ),
+                    factory.newString("Name"),
+                    factory.newString("Values")
+                )
+            )
+        }
+
+        assertEquals(
+            "All elements on input collection must be of type struct. Erroneous value: 10",
+            ex.message
+        )
+    }
+}