Add Result traits map_ref()/and_then_ref().

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/result.rs

@@ -1,3 +1,4 @@
+mod and_then_ref;
 mod debug_inspect;
 mod filter;
 mod flat_ok;
@@ -5,14 +6,16 @@ mod into_is_ok;
 mod log_debug_err;
 mod log_err;
 mod map_expect;
+mod map_ref;
 mod not_found;
 mod unwrap_infallible;
 mod unwrap_or_err;
 
 pub use self::{
-	debug_inspect::DebugInspect, filter::Filter, flat_ok::FlatOk, into_is_ok::IntoIsOk,
-	log_debug_err::LogDebugErr, log_err::LogErr, map_expect::MapExpect, not_found::NotFound,
-	unwrap_infallible::UnwrapInfallible, unwrap_or_err::UnwrapOrErr,
+	and_then_ref::AndThenRef, debug_inspect::DebugInspect, filter::Filter, flat_ok::FlatOk,
+	into_is_ok::IntoIsOk, log_debug_err::LogDebugErr, log_err::LogErr, map_expect::MapExpect,
+	map_ref::MapRef, not_found::NotFound, unwrap_infallible::UnwrapInfallible,
+	unwrap_or_err::UnwrapOrErr,
 };
 
 pub type Result<T = (), E = crate::Error> = std::result::Result<T, E>;

src/core/utils/result/and_then_ref.rs

@@ -0,0 +1,17 @@
+use super::Result;
+
+pub trait AndThenRef<T, E> {
+	fn and_then_ref<U, F>(self, op: F) -> Result<U, E>
+	where
+		F: FnOnce(&T) -> Result<U, E>;
+}
+
+impl<T, E> AndThenRef<T, E> for Result<T, E> {
+	#[inline]
+	fn and_then_ref<U, F>(self, op: F) -> Result<U, E>
+	where
+		F: FnOnce(&T) -> Result<U, E>,
+	{
+		self.and_then(|t| op(&t))
+	}
+}

src/core/utils/result/map_ref.rs

@@ -0,0 +1,17 @@
+use super::Result;
+
+pub trait MapRef<T, E> {
+	fn map_ref<U, F>(self, op: F) -> Result<U, E>
+	where
+		F: FnOnce(&T) -> U;
+}
+
+impl<T, E> MapRef<T, E> for Result<T, E> {
+	#[inline]
+	fn map_ref<U, F>(self, op: F) -> Result<U, E>
+	where
+		F: FnOnce(&T) -> U,
+	{
+		self.map(|t| op(&t))
+	}
+}