Add g mg conversion

fhirpathpy/engine/invocations/misc.py

@@ -254,4 +254,4 @@ def singleton(coll, type):
         if (val is not None):
             return val
         raise Exception("Expected {type}, but got: {coll}".format(type=type.lower(), coll=coll))
-    raise Exception("Not supported type {}".format(type))
+    raise Exception("Not supported type {}".format(type))

fhirpathpy/engine/nodes.py

@@ -149,6 +149,7 @@ class FP_Quantity(FP_Type):
     _year_month_conversion_factor = {"'a'": 12, "'mo'": 1}
     _m_cm_mm_conversion_factor = {"'m'": 1.0, "'cm'": 0.01, "'mm'": 0.001}
     _lbs_kg_conversion_factor = {"'kg'": 1.0, "lbs": 0.453592}
+    _g_mg_conversion_factor = {"'g'": 1.0, "'mg'": 0.001}
 
     datetime_multipliers = {
         **{key: Decimal("604800") for key in ["'wk'", "week", "weeks"]},
@@ -194,6 +195,11 @@ def __eq__(self, other):
                 other_value_in_seconds = other.value * self.datetime_multipliers[other.unit]
                 return self_value_in_seconds == other_value_in_seconds
             else:
+                if self.unit != other.unit:
+                    converted = FP_Quantity.conv_unit_to(self.unit, self.value, other.unit)
+                    if converted is not None:
+                        return other.value == converted.value and other.unit == converted.unit
+
                 return self.value == other.value and self.unit == other.unit
         else:
             return super().__eq__(other)
@@ -242,6 +248,13 @@ def conv_unit_to(fromUnit, value, toUnit):
             rounded_value = converted_value.quantize(Decimal("1."), rounding=ROUND_UP)
             return FP_Quantity(rounded_value, toUnit)
 
+        from_g_mg_magnitude = FP_Quantity._g_mg_conversion_factor.get(fromUnit)
+        to_g_mg_magnitude = FP_Quantity._g_mg_conversion_factor.get(toUnit)
+        if from_g_mg_magnitude and to_g_mg_magnitude:
+            converted_value = (Decimal(from_g_mg_magnitude) * value) / Decimal(to_g_mg_magnitude)
+            rounded_value = converted_value.quantize(Decimal("1."), rounding=ROUND_UP)
+            return FP_Quantity(rounded_value, toUnit)
+
         return None
 
     def _compare_years_and_months(self, other, year_units=["year", "years"]):