Use subparser instead of multiple quantities

electronicparsers/quantumespresso/parser.py

@@ -2037,13 +2037,14 @@ def str_to_sticks(val_in):
             ),
             Quantity(
                 'number_of_electrons',
-                rf'number of electrons\s*=\s*({re_float})',
-                dtype=float,
-            ),
-            Quantity(
-                'number_of_spin_electrons',
-                rf'number of electrons\s*=[\s\S]*up:\s*({re_float})\s*,\s*down:\s*({re_float})',
-                dtype=float,
+                rf'(number of electrons\s*=[^\n]*)',
+                sub_parser=TextParser(
+                    quantities=[
+                        Quantity('total', rf'number of electrons\s*=\s*({re_float})', dtype=float),
+                        Quantity('up', rf'up:\s*({re_float})', dtype=float),
+                        Quantity('down', rf'down:\s*({re_float})', dtype=float),
+                    ],
+                ),
             ),
             Quantity(
                 'x_qe_number_of_states',
@@ -2795,6 +2796,16 @@ def __init__(self):
         }
         self._re_label = re.compile(r'([A-Z][a-z]?)')
 
+    def get_n_electrons_safe(self) -> float:
+        n_electrons = self.out_parser.get('run', [])
+        if n_electrons:
+            n_electrons = n_electrons[0].get_header('number_of_electrons', {})
+            if total_n_electrons := n_electrons.get('total'):
+                return total_n_electrons
+            elif (up := n_electrons.get('up')) and (down := n_electrons.get('down')):
+                self.logger.warning('Number of electrons not found. Using spin up + down.')
+                return up + down
+
     def parse_scc(self, run, calculation):
         sec_run = self.archive.run[-1]
         initial_time = (
@@ -2914,8 +2925,7 @@ def parse_scc(self, run, calculation):
             if np.array(fermi_energy).dtype == float:
                 sec_energy.fermi = fermi_energy * ureg.eV
 
-        n_electrons = run.get_header('number_of_electrons', [])
-        if homo is None and fermi_energy is None and len(n_electrons) == 0:
+        if homo is None and fermi_energy is None and len(self.get_n_electrons_safe()) == 0:
             self.logger.error('Reference energy is not defined')
 
         for key in ['magnetization_total', 'magnetization_absolute']:
@@ -3494,15 +3504,7 @@ def parse_method(self, run):
                 if atom_sp[i] is not None:
                     setattr(sec_method_atom_kind, atom_species_names[i], atom_sp[i])
 
-        if (n_electrons := run.get_header('number_of_electrons')) is not None:
-            sec_method.electronic.n_electrons = n_electrons
-        elif (
-            len(
-                n_spin_electrons := list(run.get_header('number_of_spin_electrons', []))
-            )
-            == 2
-        ):
-            sec_method.electronic.n_electrons = sum(n_spin_electrons)
+        sec_method.electronic.n_electrons = self.get_n_electrons_safe()
 
     def init_parser(self):
         self.out_parser.mainfile = self.filepath