1 files changed, 64 insertions, 0 deletions
diff --git a/third_party/rust/sql-support/src/maybe_cached.rs b/third_party/rust/sql-support/src/maybe_cached.rs
new file mode 100644
index 0000000000..96f99f490c
--- /dev/null
+++ b/third_party/rust/sql-support/src/maybe_cached.rs
@@ -0,0 +1,64 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use rusqlite::{self, CachedStatement, Connection, Statement};
+
+use std::ops::{Deref, DerefMut};
+
+/// MaybeCached is a type that can be used to help abstract
+/// over cached and uncached rusqlite statements in a transparent manner.
+pub enum MaybeCached<'conn> {
+    Uncached(Statement<'conn>),
+    Cached(CachedStatement<'conn>),
+}
+
+impl<'conn> Deref for MaybeCached<'conn> {
+    type Target = Statement<'conn>;
+    #[inline]
+    fn deref(&self) -> &Statement<'conn> {
+        match self {
+            MaybeCached::Cached(cached) => Deref::deref(cached),
+            MaybeCached::Uncached(uncached) => uncached,
+        }
+    }
+}
+
+impl<'conn> DerefMut for MaybeCached<'conn> {
+    #[inline]
+    fn deref_mut(&mut self) -> &mut Statement<'conn> {
+        match self {
+            MaybeCached::Cached(cached) => DerefMut::deref_mut(cached),
+            MaybeCached::Uncached(uncached) => uncached,
+        }
+    }
+}
+
+impl<'conn> From<Statement<'conn>> for MaybeCached<'conn> {
+    #[inline]
+    fn from(stmt: Statement<'conn>) -> Self {
+        MaybeCached::Uncached(stmt)
+    }
+}
+
+impl<'conn> From<CachedStatement<'conn>> for MaybeCached<'conn> {
+    #[inline]
+    fn from(stmt: CachedStatement<'conn>) -> Self {
+        MaybeCached::Cached(stmt)
+    }
+}
+
+impl<'conn> MaybeCached<'conn> {
+    #[inline]
+    pub fn prepare(
+        conn: &'conn Connection,
+        sql: &str,
+        cached: bool,
+    ) -> rusqlite::Result<MaybeCached<'conn>> {
+        if cached {
+            Ok(MaybeCached::Cached(conn.prepare_cached(sql)?))
+        } else {
+            Ok(MaybeCached::Uncached(conn.prepare(sql)?))
+        }
+    }
+}