Tweak the way scopes work

Should make it clearer what a "variable" is and allow more flexibility
in what a variable can be (previously it could only be an object, but
now it can be e.g. a reference to the template or a special shortcut)

blueprintcompiler/language/common.py

@@ -35,11 +35,29 @@ OBJECT_CONTENT_HOOKS = AnyOf()
 VALUE_HOOKS = AnyOf()
 
 
-class Scope:
-    def get_variables(self) -> T.Iterator[str]:
-        yield from self.get_objects().keys()
+class ScopeVariable:
+    def __init__(self, name: str, gir_class: gir.GirType, xml_func):
+        self._name = name
+        self._gir_class = gir_class
+        self._xml_func = xml_func
 
-    def get_objects(self) -> T.Dict[str, T.Any]:
+    @property
+    def name(self) -> str:
+        return self._name
+
+    @property
+    def gir_class(self) -> gir.GirType:
+        return self._gir_class
+
+    def emit_xml(self, xml: XmlEmitter):
+        if f := self._xml_func:
+            f(xml)
+        else:
+            raise NotImplementedError()
+
+class Scope:
+    @property
+    def variables(self) -> T.Dict[str, ScopeVariable]:
         raise NotImplementedError()
 
     @property
@@ -53,4 +71,3 @@ class Scope:
     @property
     def this_type_glib_name(self) -> T.Optional[str]:
         return None
-

blueprintcompiler/language/expression.py

@@ -49,9 +49,7 @@ class IdentExpr(AstNode):
         if self.is_this:
             raise CompilerBugError()
 
-        xml.start_tag("constant")
-        xml.put_text(self.tokens["ident"])
-        xml.end_tag()
+        self.parent_by_type(Scope).variables[self.tokens["ident"]].emit_xml(xml)
 
 
 class LookupOp(InfixExpr):

blueprintcompiler/language/lambdas.py

@@ -38,9 +38,10 @@ class Lambda(Value, Scope):
         for child in self.children:
             child.emit_xml(xml)
 
-    def get_objects(self):
+    @property
+    def variables(self) -> T.Dict[str, ScopeVariable]:
         return {
-            **self.parent.parent_by_type(Scope).get_objects(),
+            **self.parent.parent_by_type(Scope).variables,
             self.tokens["argument"]: None,
         }
 

blueprintcompiler/language/ui.py

@@ -62,8 +62,17 @@ class UI(AstNode, Scope):
     def objects_by_id(self):
         return { obj.tokens["id"]: obj for obj in self.iterate_children_recursive() if obj.tokens["id"] is not None }
 
-    def get_objects(self):
-        return self.objects_by_id
+    @property
+    def variables(self):
+        def emit_xml(xml: XmlEmitter, obj_id: str):
+            xml.start_tag("constant")
+            xml.put_text(obj_id)
+            xml.end_tag()
+
+        return {
+            id: ScopeVariable(id, obj.gir_class, lambda xml: emit_xml(xml, id))
+            for id, obj in self.objects_by_id.items()
+        }
 
     @validate()
     def gir_errors(self):