1 files changed, 70 insertions, 0 deletions
diff --git a/serde_dhall/src/serde.rs b/serde_dhall/src/serde.rs
new file mode 100644
index 0000000..3dad2d8
--- /dev/null
+++ b/serde_dhall/src/serde.rs
@@ -0,0 +1,70 @@
+use crate::de::{Deserialize, Value};
+use dhall::error::{Error, Result};
+use dhall_syntax::{ExprF, SubExpr, X};
+use std::borrow::Cow;
+
+impl<'a, T> Deserialize for T
+where
+    T: serde::Deserialize<'a>,
+{
+    fn from_dhall(v: &Value) -> Result<Self> {
+        T::deserialize(Deserializer(Cow::Owned(v.to_expr())))
+    }
+}
+
+struct Deserializer<'a>(Cow<'a, SubExpr<X, X>>);
+
+// impl serde::de::Error for Error {
+//     fn custom<T>(msg: T) -> Self
+//     where
+//         T: std::fmt::Display,
+//     {
+//         Error::Deserialize(msg.to_string())
+//     }
+// }
+
+impl<'de: 'a, 'a> serde::de::IntoDeserializer<'de, Error> for Deserializer<'a> {
+    type Deserializer = Deserializer<'a>;
+    fn into_deserializer(self) -> Self::Deserializer {
+        self
+    }
+}
+
+impl<'de: 'a, 'a> serde::Deserializer<'de> for Deserializer<'a> {
+    type Error = Error;
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        use std::convert::TryInto;
+        use ExprF::*;
+        match self.0.as_ref().as_ref() {
+            NaturalLit(n) => match (*n).try_into() {
+                Ok(n64) => visitor.visit_u64(n64),
+                Err(_) => match (*n).try_into() {
+                    Ok(n32) => visitor.visit_u32(n32),
+                    Err(_) => unimplemented!(),
+                },
+            },
+            IntegerLit(n) => match (*n).try_into() {
+                Ok(n64) => visitor.visit_i64(n64),
+                Err(_) => match (*n).try_into() {
+                    Ok(n32) => visitor.visit_i32(n32),
+                    Err(_) => unimplemented!(),
+                },
+            },
+            RecordLit(m) => visitor.visit_map(
+                serde::de::value::MapDeserializer::new(m.iter().map(
+                    |(k, v)| (k.as_ref(), Deserializer(Cow::Borrowed(v))),
+                )),
+            ),
+            _ => unimplemented!(),
+        }
+    }
+
+    serde::forward_to_deserialize_any! {
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
+    }
+}