--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/service/mqtt_to_rdf/candidate_binding.py	Mon Sep 06 15:38:48 2021 -0700
@@ -0,0 +1,40 @@
+from dataclasses import dataclass
+from typing import Dict, Iterator
+
+from prometheus_client import Summary
+from rdflib import BNode, Graph
+from rdflib.term import Node, Variable
+
+from inference_types import BindableTerm, BindingUnknown, Triple
+
+
+@dataclass
+class CandidateBinding:
+    binding: Dict[BindableTerm, Node]
+
+    def __repr__(self):
+        b = " ".join("%s=%s" % (k, v) for k, v in sorted(self.binding.items()))
+        return f'CandidateBinding({b})'
+
+    def apply(self, g: Graph) -> Iterator[Triple]:
+        for stmt in g:
+            try:
+                bound = (self._applyTerm(stmt[0]), self._applyTerm(stmt[1]), self._applyTerm(stmt[2]))
+            except BindingUnknown:
+                continue
+            yield bound
+
+    def _applyTerm(self, term: Node):
+        if isinstance(term, (Variable, BNode)):
+            if term in self.binding:
+                return self.binding[term]
+            else:
+                raise BindingUnknown()
+        return term
+
+    def addNewBindings(self, newBindings: 'CandidateBinding'):
+        for k, v in newBindings.binding.items():
+            if k in self.binding and self.binding[k] != v:
+                raise ValueError(
+                    f'conflict- thought {k} would be {self.binding[k]} but another Evaluation said it should be {v}')
+            self.binding[k] = v
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