1 files changed, 58 insertions, 0 deletions
diff --git a/src/failable/ops/map.rs b/src/failable/ops/map.rs
new file mode 100644
index 0000000..8e1155c
--- /dev/null
+++ b/src/failable/ops/map.rs
@@ -0,0 +1,58 @@
+//
+// 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/.
+//
+
+//! Map implementation.
+//!
+//! Will be automatically included when incluing `filter::Filter`, so importing this module
+//! shouldn't be necessary.
+//!
+use std::marker::PhantomData;
+use std::borrow::Borrow;
+use std::error::Error;
+
+use failable::filter::FailableFilter;
+
+#[must_use = "filters are lazy and do nothing unless consumed"]
+#[derive(Clone)]
+pub struct FailableMapInput<F, M, FT, B>(F, M, PhantomData<FT>, PhantomData<B>);
+
+impl<F, M, FT, B> FailableMapInput<F, M, FT, B> {
+    pub fn new(a: F, m: M) -> FailableMapInput<F, M, FT, B> {
+        FailableMapInput(a, m, PhantomData, PhantomData)
+    }
+}
+
+impl<FT, E, F, T, B, M> FailableFilter<T, E> for FailableMapInput<F, M, FT, B>
+    where E: Error,
+          F: FailableFilter<FT, E>,
+          B: Borrow<FT> + Sized,
+          M: Fn(&T) -> B
+{
+    fn filter(&self, e: &T) -> Result<bool, E> {
+        self.0.filter(self.1(e).borrow())
+    }
+}
+
+#[must_use = "filters are lazy and do nothing unless consumed"]
+#[derive(Clone)]
+pub struct FailableMapErr<F, M, FE, E>(F, M, PhantomData<FE>, PhantomData<E>);
+
+impl<F, M, FE, E> FailableMapErr<F, M, FE, E> {
+    pub fn new(a: F, m: M) -> FailableMapErr<F, M, FE, E> {
+        FailableMapErr(a, m, PhantomData, PhantomData)
+    }
+}
+
+impl<FE, E, F, T, M> FailableFilter<T, E> for FailableMapErr<F, M, FE, E>
+    where E: Error,
+          FE: Error,
+          F: FailableFilter<T, FE>,
+          M: Fn(FE) -> E
+{
+    fn filter(&self, e: &T) -> Result<bool, E> {
+        self.0.filter(e).map_err(&self.1)
+    }
+}