define transformations

.gitignore

@@ -37,3 +37,4 @@ generated-test-src
 /*.json
 /*.xmi
 **/bin/
+.netlify

core/src/main/kotlin/com/strumenta/kolasu/transformation/Transformation.kt

@@ -235,9 +235,9 @@ open class ASTTransformer(
      * Performs the transformation of a node and, recursively, its descendants.
      */
     @JvmOverloads
-    open fun transform(source: Any?, parent: Node? = null): Node? {
+    open fun transform(source: Any?, parent: Node? = null): List<Node> {
         if (source == null) {
-            return null
+            return emptyList()
         }
         if (source is Collection<*>) {
             throw Error("Mapping error: received collection when value was expected")
@@ -247,7 +247,7 @@ open class ASTTransformer(
         if (factory != null) {
             node = makeNode(factory, source, allowGenericNode = allowGenericNode)
             if (node == null) {
-                return null
+                return emptyList()
             }
             if (!factory.skipChildren && !factory.childrenSetAtConstruction) {
                 setChildren(factory, source, node)
@@ -269,7 +269,7 @@ open class ASTTransformer(
                 throw IllegalStateException("Unable to translate node $source (class ${source.javaClass})")
             }
         }
-        return node
+        return listOf(node)
     }
 
     private fun setChildren(

core/src/test/kotlin/com/strumenta/kolasu/transformation/ASTTransformerTest.kt

@@ -70,7 +70,7 @@ class ASTTransformerTest {
                 DisplayIntStatement(value = 456)
             )
         )
-        val transformedCU = transformer.transform(cu)!!
+        val transformedCU = transformer.transform(cu)!!.first()
         assertASTsAreEqual(cu, transformedCU, considerPosition = true)
         assertTrue { transformedCU.hasValidParents() }
         assertEquals(transformedCU.origin, cu)
@@ -280,4 +280,37 @@ class ASTTransformerTest {
         assertEquals(transformedCU.origin, cu)
         assertIs<GenericNode>(transformedCU.statements[0].origin)
     }
+
+    @Test
+    fun testTransforingOneNodeToMany() {
+        val transformer = ASTTransformer()
+        transformer.registerNodeFactory(BarRoot::class, BazRoot::class)
+            .withChild(BarRoot::stmts, BazRoot::stmts)
+        transformer.registerNodeFactory(BarStmt::class) { s ->
+            listOf(BazStmt("${s.desc}-1"), BazStmt("${s.desc}-2"))
+        }
+
+        val original = BarRoot(
+            stmts = mutableListOf(
+                BarStmt("a"),
+                BarStmt("b")
+            )
+        )
+        val transformed = transformer.transform(original) as BazRoot
+        assertTrue { transformed.hasValidParents() }
+        assertEquals(transformed.origin, original)
+        assertASTsAreEqual(BazRoot(mutableListOf(
+            BazStmt("a-1"),
+            BazStmt("a-2"),
+            BazStmt("b-1"),
+            BazStmt("b-2")
+        )))
+    }
 }
+
+data class BazRoot(var stmts: MutableList<BazStmt> = mutableListOf()) : Node()
+
+data class BazStmt(val desc: String) : Node()
+
+data class BarRoot(var stmts: MutableList<BarStmt> = mutableListOf()) : Node()
+data class BarStmt(val desc: String) : Node()

gradle.properties

@@ -1,5 +1,5 @@
 version=1.5.16-SNAPSHOT
-kotlin_version=1.8.10
+kotlin_version=1.8.21
 dokka_version=1.8.10
 antlr_version=4.9.3
 clikt_version=3.5.0