HLT1 filtering in Hlt2Line

Adds field for HLT1 filtering for HLT2 lines

\cc @sstahl @nskidmor

Hlt/Moore/python/Moore/lines.py

@@ -19,7 +19,8 @@ except ImportError:
     cache = lambda func: cached(cache={})(func)
 
 from Configurables import LumiCounterMerger
-from PyConf.Algorithms import DeterministicPrescaler
+from PyConf.Algorithms import (DeterministicPrescaler, LoKi__HDRFilter as
+                               HltDecReportsFilter, HltDecReportsDecoder)
 from PyConf.application import make_odin
 from PyConf.components import Algorithm
 from PyConf.control_flow import CompositeNode, NodeLogic
@@ -30,6 +31,8 @@ from Moore.selreports import (
 )
 from RecoConf.reconstruction_objects import make_pvs
 
+from PyConf.application import default_raw_event
+
 from .persistence.particle_moving import (
     CopyParticles,
     dvalgorithm_locations,
@@ -259,16 +262,31 @@ class Hlt2Line(DecisionLine):
             `node` attribute) will ensure that the reconstruction algorithms
             that produce the reconstruction objects will run when the line
             fires
+        hlt1_filter_code (string): If not empty, the string is used to define a
+             HLT1 filter that is prepended to the control flow defined by `algs`.
+             LoKi__HDRFilter-code is used.
     """
 
     _NAME_PREFIX = "Hlt2"
 
-    def __init__(self,
-                 name,
-                 algs,
-                 prescale=1.,
-                 extra_outputs=None,
-                 persistreco=False):
+    def __init__(
+            self,
+            name,
+            algs,
+            prescale=1.,
+            extra_outputs=None,
+            persistreco=False,
+            hlt1_filter_code="",
+    ):
+        if hlt1_filter_code:
+            hlt1_dec_reports = HltDecReportsDecoder(
+                RawEventLocations=default_raw_event(
+                    bank_types=["HltDecReports"]),
+                SourceID=1)
+            hlt1_filter = HltDecReportsFilter(
+                Location=hlt1_dec_reports.OutputHltDecReportsLocation,
+                Code=hlt1_filter_code)
+            algs = [hlt1_filter] + algs
         super(Hlt2Line, self).__init__(name, algs, prescale)
         if not self.name.startswith(self._NAME_PREFIX):
             raise ValueError("name {!r} does not start with {!r}".format(