add enostr->nostrdb filter conversions

Signed-off-by: William Casarin <jb55@jb55.com>

src/filter.rs

@@ -0,0 +1,37 @@
+impl From<enostr::Filter> for nostrdb::Filter {}
+    fn from(filter: enostr::Filter) -> Self {
+        let mut nfilter = nostrdb::Filter::new();
+
+        if let Some(ids) = filter.ids {
+            nfilter.ids(ids)
+        }
+
+        if let Some(authors) = filter.authors {
+            nfilter.authors(authors)
+        }
+
+        if let Some(kinds) = filter.kinds {
+            nfilter.kinds(kinds)
+        }
+
+        // #e
+        if let Some(events) = filter.events {
+            nfilter.tags(events, 'e')
+        }
+
+        // #p
+        if let Some(pubkeys) = filter.pubkeys {
+            nfilter.pubkeys(pubkeys)
+        }
+
+        if let Some(since) = filter.since {
+            nfilter.since(since)
+        }
+
+        if let Some(limit) = filter.limit {
+            nfilter.limit(limit)
+        }
+
+        nfilter
+    }
+}