Filter for entries with dates specified by user in query

- Create Date filter
  - Users can pass dates in YYYY-MM-DD format in their query
- Use it to filter asymmetric search to user specified dates

src/search_filter/date_filter.py

@@ -0,0 +1,33 @@
+# Standard Packages
+import re
+
+# External Packages
+import torch
+
+
+def date_filter(query, entries, embeddings):
+    # extract date from query
+    date_regex = r'\d{4}-\d{2}-\d{2}'
+    dates_in_query = re.findall(date_regex, query)
+
+    # if no date in query, return all entries
+    if dates_in_query is None or len(dates_in_query) == 0:
+        return query, entries, embeddings
+
+    # remove dates from query
+    query = re.sub(date_regex, '', query)
+
+    # find entries with dates from query in them
+    entries_to_include = set()
+    for id, entry in enumerate(entries):
+        for date in dates_in_query:
+            if date in entry[1]:
+                entries_to_include.add(id)
+
+    # delete entries (and their embeddings) marked for exclusion
+    entries_to_exclude = set(range(len(entries))) - entries_to_include
+    for id in sorted(list(entries_to_exclude), reverse=True):
+        del entries[id]
+        embeddings = torch.cat((embeddings[:id], embeddings[id+1:]))
+
+    return query, entries, embeddings