Add consumer formula generator excluding phantom loads

Meters with successors can still have loads not represented in the
component graph.  These are called phantom loads.

Tracking phantom loads requires larger formulas and expects all meters
to be available.

This commit implements the consumer formula generator as it is
implemented in the SDK - exclude producer and battery powers from the
grid power, or when there is no grid meter, add all the non battery
and producer meters.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

src/config.rs

@@ -24,6 +24,17 @@ pub struct ComponentGraphConfig {
     /// is `true`, the formulas will not include fallback components.
     pub disable_fallback_components: bool,
 
+    /// Meters with successors can still have loads not represented in the
+    /// component graph.  These are called phantom loads.
+    ///
+    /// When this is `true`, phantom loads are included in formulas by excluding
+    /// the measurements of successor meters from the measurements of their
+    /// predecessor meters.
+    ///
+    /// When `false`, consumer formula is generated by excluding production
+    /// and battery components from the grid measurements.
+    pub include_phantom_loads_in_consumer_formula: bool,
+
     /// Whether to prefer PV inverters when generating PV formulas.  When this
     /// is `true`, PV inverters will be the primary source and PV meters will be
     /// the fallback.  When `false`, PV meters will be the primary source.

src/graph/formulas/formula.rs

@@ -43,7 +43,7 @@ where
 // evaluator.
 #[derive(Debug, Clone, PartialEq)]
 pub struct AggregationFormula {
-    expr: Expr,
+    pub(crate) expr: Expr,
 }
 
 impl From<Expr> for AggregationFormula {