Revisited AST transformers for Kolasu 1.7

core/src/main/kotlin/com/strumenta/starlasu/mapping/ParseTreeToASTTransformer.kt

@@ -3,12 +3,13 @@ package com.strumenta.starlasu.mapping
 import com.strumenta.starlasu.model.ASTNode
 import com.strumenta.starlasu.model.Node
 import com.strumenta.starlasu.model.Origin
-import com.strumenta.starlasu.model.Source
 import com.strumenta.starlasu.parsing.ParseTreeOrigin
 import com.strumenta.starlasu.parsing.withParseTreeNode
 import com.strumenta.starlasu.transformation.ASTTransformer
-import com.strumenta.starlasu.transformation.NodeFactory
-import com.strumenta.starlasu.validation.Issue
+import com.strumenta.starlasu.transformation.FailingASTTransformation
+import com.strumenta.starlasu.transformation.FaultTolerance
+import com.strumenta.starlasu.transformation.TransformationContext
+import com.strumenta.starlasu.transformation.TransformationRule
 import org.antlr.v4.runtime.ParserRuleContext
 import org.antlr.v4.runtime.tree.ParseTree
 import kotlin.reflect.KClass
@@ -20,29 +21,41 @@ import kotlin.reflect.KClass
 open class ParseTreeToASTTransformer
     @JvmOverloads
     constructor(
-        issues: MutableList<Issue> = mutableListOf(),
-        allowGenericNode: Boolean = true,
-        val source: Source? = null,
-        throwOnUnmappedNode: Boolean = true,
-    ) : ASTTransformer(issues, allowGenericNode, throwOnUnmappedNode) {
+        faultTolerance: FaultTolerance = FaultTolerance.THROW_ONLY_ON_UNMAPPED,
+    ) : ASTTransformer(faultTolerance) {
         /**
          * Performs the transformation of a node and, recursively, its descendants. In addition to the overridden method,
          * it also assigns the parseTreeNode to the AST node so that it can keep track of its position.
          * However, a node factory can override the parseTreeNode of the nodes it creates (but not the parent).
          */
         override fun transformIntoNodes(
             source: Any?,
-            parent: ASTNode?,
+            context: TransformationContext,
             expectedType: KClass<out ASTNode>,
         ): List<ASTNode> {
-            val transformed = super.transformIntoNodes(source, parent, expectedType)
+            if (source is ParserRuleContext && source.exception != null) {
+                if (faultTolerance == FaultTolerance.STRICT) {
+                    throw RuntimeException("Failed to transform $source into $expectedType", source.exception)
+                }
+                val origin =
+                    FailingASTTransformation(
+                        asOrigin(source, context),
+                        "Failed to transform $source into $expectedType because of an error (${source.exception.message})",
+                    )
+                val nodes = defaultNodes(source, context, expectedType)
+                nodes.forEach { node ->
+                    node.origin = origin
+                }
+                return nodes
+            }
+            val transformed = super.transformIntoNodes(source, context, expectedType)
             return transformed
                 .map { node ->
                     if (source is ParserRuleContext) {
                         if (node.origin == null) {
-                            node.withParseTreeNode(source, this.source)
+                            node.withParseTreeNode(source, context.source)
                         } else if (node.position != null && node.source == null) {
-                            node.position!!.source = this.source
+                            node.position!!.source = context.source
                         }
                     }
                     return listOf(node)
@@ -57,7 +70,15 @@ open class ParseTreeToASTTransformer
             return if (origin is ParseTreeOrigin) origin.parseTree else source
         }
 
-        override fun asOrigin(source: Any): Origin? = if (source is ParseTree) ParseTreeOrigin(source) else null
+        override fun asOrigin(
+            source: Any,
+            context: TransformationContext,
+        ): Origin? =
+            if (source is ParseTree) {
+                ParseTreeOrigin(source, context.source)
+            } else {
+                null
+            }
 
         override fun asString(source: Any): String? =
             if (source is ParseTree) {
@@ -71,19 +92,19 @@ open class ParseTreeToASTTransformer
          * wrapper. When there is only a ParserRuleContext child we can transform
          * that child and return that result.
          */
-        fun <P : ParserRuleContext> registerNodeFactoryUnwrappingChild(kclass: KClass<P>): NodeFactory<P, Node> =
-            registerNodeFactory(kclass) { source, transformer, _ ->
+        fun <P : ParserRuleContext> registerRuleUnwrappingChild(kclass: KClass<P>): TransformationRule<P, Node> =
+            registerRule(kclass) { source, context, _ ->
                 val nodeChildren = source.children.filterIsInstance<ParserRuleContext>()
                 require(nodeChildren.size == 1) {
                     "Node $source (${source.javaClass}) has ${nodeChildren.size} " +
                         "node children: $nodeChildren"
                 }
-                transformer.transform(nodeChildren[0]) as Node
+                transform(nodeChildren[0], context) as Node
             }
 
         /**
          * Alternative to registerNodeFactoryUnwrappingChild(KClass) which is slightly more concise.
          */
-        inline fun <reified P : ParserRuleContext> registerNodeFactoryUnwrappingChild(): NodeFactory<P, Node> =
-            registerNodeFactoryUnwrappingChild(P::class)
+        inline fun <reified P : ParserRuleContext> registerRuleUnwrappingChild(): TransformationRule<P, Node> =
+            registerRuleUnwrappingChild(P::class)
     }

core/src/main/kotlin/com/strumenta/starlasu/mapping/Support.kt

@@ -3,6 +3,7 @@ package com.strumenta.starlasu.mapping
 import com.strumenta.starlasu.model.ASTNode
 import com.strumenta.starlasu.parsing.getOriginalText
 import com.strumenta.starlasu.transformation.ASTTransformer
+import com.strumenta.starlasu.transformation.TransformationContext
 import org.antlr.v4.runtime.ParserRuleContext
 
 /**
@@ -13,8 +14,11 @@ import org.antlr.v4.runtime.ParserRuleContext
  * JPostIncrementExpr(translateCasted<JExpression>(expression().first()))
  * ```
  */
-inline fun <reified T : ASTNode> ASTTransformer.translateCasted(original: Any): T {
-    val result = transform(original, expectedType = T::class)
+inline fun <reified T : ASTNode> ASTTransformer.translateCasted(
+    original: Any,
+    context: TransformationContext,
+): T {
+    val result = transform(original, context, expectedType = T::class)
     if (result is Nothing) {
         throw IllegalStateException("Transformation produced Nothing")
     }
@@ -30,8 +34,11 @@ inline fun <reified T : ASTNode> ASTTransformer.translateCasted(original: Any):
  * JExtendsType(translateCasted(pt.typeType()), translateList(pt.annotation()))
  * ```
  */
-inline fun <reified T : ASTNode> ASTTransformer.translateList(original: Collection<out Any>?): MutableList<T> =
-    original?.map { transformIntoNodes(it, expectedType = T::class) as List<T> }?.flatten()?.toMutableList()
+inline fun <reified T : ASTNode> ASTTransformer.translateList(
+    original: Collection<out Any>?,
+    context: TransformationContext,
+): MutableList<T> =
+    original?.map { transformIntoNodes(it, context, expectedType = T::class) as List<T> }?.flatten()?.toMutableList()
         ?: mutableListOf()
 
 /**
@@ -47,9 +54,12 @@ inline fun <reified T : ASTNode> ASTTransformer.translateList(original: Collecti
  *  )
  *  ```
  */
-inline fun <reified T : ASTNode> ASTTransformer.translateOptional(original: Any?): T? {
+inline fun <reified T : ASTNode> ASTTransformer.translateOptional(
+    original: Any?,
+    context: TransformationContext,
+): T? {
     return original?.let {
-        val transformed = transform(it, expectedType = T::class)
+        val transformed = transform(it, context, expectedType = T::class)
         if (transformed == null) {
             return null
         } else {
@@ -69,7 +79,10 @@ inline fun <reified T : ASTNode> ASTTransformer.translateOptional(original: Any?
  * }
  * ```
  */
-fun <T> ParseTreeToASTTransformer.translateOnlyChild(parent: ParserRuleContext): T = translateCasted(parent.onlyChild)
+fun <T> ParseTreeToASTTransformer.translateOnlyChild(
+    parent: ParserRuleContext,
+    context: TransformationContext,
+): T = translateCasted(parent.onlyChild, context)
 
 /**
  * It returns the only child (of type ParseRuleContext). If there is no children or more than

core/src/main/kotlin/com/strumenta/starlasu/parsing/KolasuParser.kt

@@ -6,6 +6,8 @@ import com.strumenta.starlasu.model.PropertyDescription
 import com.strumenta.starlasu.model.Source
 import com.strumenta.starlasu.model.assignParents
 import com.strumenta.starlasu.model.processProperties
+import com.strumenta.starlasu.transformation.ASTTransformer
+import com.strumenta.starlasu.transformation.TransformationContext
 import com.strumenta.starlasu.traversing.walk
 import com.strumenta.starlasu.validation.Issue
 import com.strumenta.starlasu.validation.IssueType
@@ -164,14 +166,26 @@ abstract class KolasuParser<R : Node, P : Parser, C : ParserRuleContext, T : Kol
     }
 
     /**
-     * Transforms a parse tree into an AST (second parsing stage).
+     * Transforms a parse tree into an AST (second parsing stage). By default, it uses the AST transformer obtained by
+     * calling [setupASTTransformer]. However, if you want to use a different transformation strategy, you can override
+     * this method. In that case, remember to ensure that the resulting AST has parent nodes properly set, or call
+     * [assignParents] on it.
      */
-    protected abstract fun parseTreeToAst(
+    protected open fun parseTreeToAst(
         parseTreeRoot: C,
         considerPosition: Boolean = true,
         issues: MutableList<Issue>,
         source: Source? = null,
-    ): R?
+    ): R? {
+        val transformer = setupASTTransformer()
+        if (transformer == null) {
+            throw IllegalStateException("No AST transformer available, and parseTreeToAst not overridden.")
+        } else {
+            return transformer.transform(parseTreeRoot, TransformationContext(issues = issues)) as R?
+        }
+    }
+
+    protected open fun setupASTTransformer(): ASTTransformer? = null
 
     protected open fun attachListeners(
         parser: P,
@@ -312,7 +326,6 @@ abstract class KolasuParser<R : Node, P : Parser, C : ParserRuleContext, T : Kol
         val firstStage = parseFirstStage(inputStream, measureLexingTime)
         val myIssues = firstStage.issues.toMutableList()
         var ast = parseTreeToAst(firstStage.root!!, considerPosition, myIssues, source)
-        assignParents(ast)
         ast = if (ast == null) null else postProcessAst(ast, myIssues)
         if (ast != null && !considerPosition) {
             // Remove parseTreeNodes because they cause the position to be computed

core/src/main/kotlin/com/strumenta/starlasu/transformation/DummyNodes.kt

@@ -1,6 +1,7 @@
 package com.strumenta.starlasu.transformation
 
 import com.strumenta.starlasu.model.ASTNode
+import com.strumenta.starlasu.model.GenericErrorNode
 import com.strumenta.starlasu.model.Node
 import com.strumenta.starlasu.model.PossiblyNamed
 import com.strumenta.starlasu.model.ReferenceByName
@@ -15,7 +16,7 @@ import kotlin.reflect.full.primaryConstructor
 import kotlin.reflect.jvm.javaType
 
 /**
- * This logic instantiate a node of the given class with dummy values.
+ * This logic instantiates a node of the given class with dummy values.
  * This is useful because it permits to add an element that "fit" and make the typesystem happy.
  * Typically, the only goal of the element would be to hold some annotation that indicates that the element
  * is representing an error or a missing transformation or something of that sort.
@@ -87,12 +88,20 @@ private fun <T : Any> KClass<T>.toInstantiableType(levelOfDummyTree: Int = 0): K
             }
         }
 
+        this == ASTNode::class -> {
+            // This happens when the target type is not known, e.g.
+            // registerTransform(X::class) { TODO("X not yet mapped") }
+            GenericErrorNode::class as KClass<out T>
+        }
+
         this.isAbstract -> {
-            throw IllegalStateException("We cannot instantiate an abstract class (but we can handle sealed classes)")
+            throw IllegalStateException(
+                "We cannot instantiate the abstract class ${this.qualifiedName} (but we can handle sealed classes)",
+            )
         }
 
         this.java.isInterface -> {
-            throw IllegalStateException("We cannot instantiate an interface")
+            throw IllegalStateException("We cannot instantiate the interface ${this.qualifiedName}")
         }
 
         else -> {

core/src/main/kotlin/com/strumenta/starlasu/transformation/IdentityTransformation.kt

@@ -12,12 +12,12 @@ import kotlin.reflect.jvm.javaType
 
 val IDENTTITY_TRANSFORMATION: (
     source: Any?,
-    parent: ASTNode?,
+    context: TransformationContext,
     expectedType: KClass<out ASTNode>,
     astTransformer: ASTTransformer,
 ) -> List<ASTNode> = {
     source: Any?,
-    parent: ASTNode?,
+    context: TransformationContext,
     expectedType: KClass<out ASTNode>,
     astTransformer: ASTTransformer,
     ->
@@ -47,21 +47,22 @@ val IDENTTITY_TRANSFORMATION: (
                 // mt is ParameterizedType && mt.rawType == List::class.java -> mutableListOf<Any>()
                 when {
                     (parameter.type.classifier as KClass<*>).isSubclassOf(ASTNode::class) -> {
-                        params[parameter] = astTransformer.transform(originalValue)
+                        params[parameter] = astTransformer.transform(originalValue, context)
                     }
 
                     mt is ParameterizedType &&
                         mt.rawType == List::class.java &&
                         (mt.actualTypeArguments.first() as? Class<*>)?.kotlin?.isSubclassOf(ASTNode::class) == true -> {
-                        params[parameter] = astTransformer.translateList<ASTNode>(originalValue as List<ASTNode>)
+                        params[parameter] =
+                            astTransformer.translateList<ASTNode>(originalValue as List<ASTNode>, context)
                     }
 
                     else -> params[parameter] = originalValue
                 }
             }
 
             val newInstance = primaryConstructor.callBy(params) as ASTNode
-            newInstance.parent = parent
+            newInstance.parent = context.parent
             newInstance.origin = source
             listOf(newInstance)
         }