Add: optimise switch returning constants

nml/expression/spritegroup_ref.py

@@ -15,6 +15,7 @@
 
 from nml import generic
 from nml.actions import action2
+from nml.ast import switch
 from .base_expression import Type, Expression
 
 class SpriteGroupRef(Expression):
@@ -72,6 +73,16 @@ def get_action2_id(self, feature):
         return spritegroup.get_action2(feature).id
 
     def reduce(self, id_dicts = [], unknown_id_fatal = True):
+        if self.name.value != 'CB_FAILED':
+            spritegroup = action2.resolve_spritegroup(self.name)
+            if isinstance(spritegroup, switch.Switch) and spritegroup.body.default is not None and spritegroup.expr.is_read_only():
+                value = spritegroup.body.default.value
+                for r in spritegroup.body.ranges:
+                    if value != r.result.value:
+                        return self
+                    value = r.result.value
+                generic.print_warning("Block '{}' returns a constant, optimising.".format(spritegroup.name.value), self.pos)
+                return value
         return self
 
     def type(self):