Rust: Add codegen for generating a toStringImpl that delegates to getAPrimaryQlClass

misc/codegen/generators/qlgen.py

@@ -237,6 +237,9 @@ def get_ql_class(self, cls: schema.Class) -> ql.Class:
                 hideable="ql_hideable" in cls.pragmas,
                 internal="ql_internal" in cls.pragmas,
                 cfg=cls.cfg,
+                to_string_impl_from_primary_class=bool(
+                    cls.pragmas.get("ql_to_string_impl_from_primary_class")
+                ),
             )
         return self._class_cache[cache_key]
 

misc/codegen/lib/ql.py

@@ -117,6 +117,7 @@ class Class:
     doc: List[str] = field(default_factory=list)
     hideable: bool = False
     cfg: bool = False
+    to_string_impl_from_primary_class: bool = False
 
     def __post_init__(self):
         def get_bases(bases):

misc/codegen/lib/schemadefs.py

@@ -263,6 +263,12 @@ def __getitem__(self, item):
 
 ql.add(_Parametrized(_ClassPragma("default_doc_name"), factory=lambda doc: doc))
 ql.add(_ClassPragma("hideable", inherited=True))
+ql.add(
+    _Parametrized(
+        _ClassPragma("to_string_impl_from_primary_class", inherited=True),
+        factory=lambda enabled: enabled,
+    )
+)
 ql.add(_Pragma("internal"))
 ql.add(_Parametrized(_Pragma("name"), factory=lambda name: name))
 ql.add(_Parametrized(_PropertyPragma("db_table_name"), factory=lambda name: name))

misc/codegen/templates/ql_class.mustache

@@ -77,6 +77,10 @@ module Generated {
     {{/root}}
     {{#final}}
     override string getAPrimaryQlClass() { result = "{{name}}" }
+    {{#to_string_impl_from_primary_class}}
+
+    override string toStringImpl() { result = this.getAPrimaryQlClass() }
+    {{/to_string_impl_from_primary_class}}
     {{/final}}
     {{#properties}}
 

misc/codegen/test/test_qlgen.py

@@ -196,6 +196,47 @@ def test_one_empty_class(generate_classes):
     }
 
 
+def test_to_string_impl_from_primary_class(generate_classes):
+    assert generate_classes(
+        [
+            schema.Class(
+                "A",
+                derived={"B"},
+                pragmas={"ql_to_string_impl_from_primary_class": True},
+            ),
+            schema.Class(
+                "B",
+                bases=["A"],
+                pragmas={"ql_to_string_impl_from_primary_class": True},
+            ),
+        ]
+    ) == {
+        "A.qll": (
+            a_ql_class_public(name="A"),
+            a_ql_stub(name="A"),
+            a_ql_class(
+                name="A",
+                imports=[stub_import_prefix + "A"],
+                to_string_impl_from_primary_class=True,
+            ),
+        ),
+        "B.qll": (
+            a_ql_class_public(name="B", imports=[stub_import_prefix + "A"]),
+            a_ql_stub(name="B"),
+            a_ql_class(
+                name="B",
+                final=True,
+                bases=["A"],
+                bases_impl=["AImpl::A"],
+                imports=[
+                    stub_import_prefix_internal + "AImpl::Impl as AImpl",
+                ],
+                to_string_impl_from_primary_class=True,
+            ),
+        ),
+    }
+
+
 def test_one_empty_internal_class(generate_classes):
     assert generate_classes([schema.Class("A", pragmas=["ql_internal"])]) == {
         "A.qll": (

misc/codegen/test/test_schemaloader.py

@@ -382,6 +382,29 @@ class A:
     }
 
 
+def test_inherited_to_string_impl_from_primary_class_pragma():
+    @load
+    class data:
+        @defs.ql.to_string_impl_from_primary_class(True)
+        class A:
+            pass
+
+        class B(A):
+            pass
+
+        @defs.ql.to_string_impl_from_primary_class(False)
+        class C(B):
+            pass
+
+        class D(C):
+            pass
+
+    assert data.classes["A"].pragmas["ql_to_string_impl_from_primary_class"] is True
+    assert data.classes["B"].pragmas["ql_to_string_impl_from_primary_class"] is True
+    assert data.classes["C"].pragmas["ql_to_string_impl_from_primary_class"] is False
+    assert data.classes["D"].pragmas["ql_to_string_impl_from_primary_class"] is False
+
+
 def test_synth_from_class():
     @load
     class data: