1 files changed, 22 insertions, 0 deletions
diff --git a/lib/sql/match.ml b/lib/sql/match.ml
new file mode 100644
index 0000000..82fc1da
--- /dev/null
+++ b/lib/sql/match.ml
@@ -0,0 +1,22 @@
+let f : Sqlite3.Data.t -> Sqlite3.Data.t -> Sqlite3.Data.t =
+  let memo = Hashtbl.create 16 in
+  fun str data_1 ->
+    match (str, data_1) with
+    | Sqlite3.Data.TEXT s, Sqlite3.Data.TEXT content -> (
+        let regex =
+          match Hashtbl.find_opt memo s with
+          | None ->
+              let regex = Re.Posix.compile_pat s in
+              Hashtbl.add memo s regex;
+              regex
+          | Some v -> v
+        in
+
+        match Re.exec_opt regex content with
+        | None -> Sqlite3.Data.NULL
+        | Some g ->
+            let matched = Re.Group.get g 1 in
+            Sqlite3.Data.TEXT matched)
+    | _, _ -> data_1
+
+let register : Sqlite3.db -> unit = fun db -> Sqlite3.create_fun2 db "match" f