M2M: Handle intermediate objects created during transform

.gitignore

@@ -25,3 +25,4 @@
 **/legend-engine-language-pure-grammar/src/main/antlr4/org/finos/legend/engine/language/pure/grammar/from/antlr4/core/gen/
 /welcome.pure
 /legend-engine-core/legend-engine-core-shared/legend-engine-shared-core/src/main/resources/legendExecutionVersion.json
+strip-ai-coauthors.sh

docs/engineering/README.md

@@ -106,6 +106,7 @@ all backends. See [Testing Strategy — PCT](testing/testing-strategy.md#5-pct-p
 | [Router & Pure-to-SQL](architecture/router-and-pure-to-sql.md) | Routing strategies, clustering, SQL generation pipeline, dialect extension |
 | [ModelJoin](architecture/model-join.md) | Store-agnostic model-level associations: parser, compiler, router, and Relational SQL translation |
 | [Pre-Evaluation (preeval)](architecture/preeval.md) | AST simplification pass that runs before the router: constant folding, let inlining, short-circuiting |
+| [Source Tree Calculation](architecture/source-tree-calculation.md) | calculateSourceTree pipeline and the new-instance operator pattern: intermediate-class handling, edge cases, design alternatives |
 
 ### Guides
 

legend-engine-core/legend-engine-core-pure/legend-engine-pure-code-compiled-core/src/main/resources/core/pure/corefunctions/metaExtension.pure

@@ -122,6 +122,31 @@ function {doc.doc = 'Get all properties on the provided type / class'}
      ->concatenate($class.qualifiedPropertiesFromAssociations)
 }
 
+function {doc.doc = 'Get all properties on the provided class and (transitively) on every class-typed property in its hierarchy. Cycle-safe.'}
+   meta::pure::functions::meta::allNestedProperties(class:Class<Any>[1]) : AbstractProperty<Any>[*]
+{
+   meta::pure::functions::meta::allNestedProperties($class, ^Map<String, Class<Any>>())
+}
+
+function <<access.private>>
+   meta::pure::functions::meta::allNestedProperties(class:Class<Any>[1], visited:Map<String, Class<Any>>[1]) : AbstractProperty<Any>[*]
+{
+   let key = $class->elementToPath();
+   if($visited->get($key)->isNotEmpty(),
+      | [],
+      | let visitedNext = $visited->put($key, $class);
+        let properties = $class->allProperties();
+        let nestedClassTypes = $class->meta::pure::functions::meta::hierarchicalProperties()
+                                     ->map(p | $p.genericType.rawType->toOne())
+                                     ->filter(t | $t->instanceOf(Class))
+                                     ->cast(@Class<Any>)
+                                     ->removeDuplicates();
+        $properties->concatenate(
+           $nestedClassTypes->map(cl | $cl->meta::pure::functions::meta::allNestedProperties($visitedNext))
+        )->removeDuplicates();
+   );
+}
+
 function {doc.doc = 'Get all nested types present in the property tree of this class or its hierarchy.'}
    meta::pure::functions::meta::allNestedPropertyTypes(class : Class<Any>[1]) : Type[*]
 {