feat: add support for local expressions in ADExpressionContext and update smart condition handling

adexpressioncontext.py

@@ -1,5 +1,5 @@
 import pyparsing as pp
-from expressionparser import BaseExpressionContext
+from expressionparser import BaseExpressionContext, ExpressionParser
 
 class ADExpressionContext(BaseExpressionContext):
     def __init__(self,appdaemon_api, sensor_existence_validation = True):
@@ -13,6 +13,7 @@ class ADExpressionContext(BaseExpressionContext):
         self.sensors_default_value = dict()
         self.sensor_states = dict()
         self.sensor_existence_validation = sensor_existence_validation
+        self.local_expressions = {}
 
         self.declare_default_constants()
 
@@ -131,7 +132,22 @@ class ADExpressionContext(BaseExpressionContext):
     def get_entities_to_listen(self):
         return self.entities_to_listen
 
-    def get_constant_value(self,name): return self.variables[name]
+    def get_constant_value(self, name):
+        if name in self.local_expressions:
+            return self.local_expressions[name].eval()
+        return self.variables[name]
+
+    def declare_local_expression(self, name: str, expression_string: str):
+        assert name not in self.variables, f"'{name}' is already declared"
+        assert name.replace('_', '').isalnum() and name.isascii(), f"Invalid local expression name: {name}"
+        # Register as a constant placeholder so the variable parser recognises it
+        self.variables[name] = None
+        self.constants.append(name)
+        self.parser = None  # reset variable parser cache
+        # Parse the expression; set_context registers its sensor dependencies
+        # Store only the parsed tree so evaluation skips the top-level reset()
+        full_parser = ExpressionParser(expression_string, self)
+        self.local_expressions[name] = full_parser.parsed_data
 
     def declare_constant(self,name : str,value):
         def is_a_sensor(string):