Add basic deserialization support

Closes #13

8 files changed, 98 insertions, 13 deletions

diff --git a/dhall/Cargo.toml b/dhall/Cargo.toml
index a7c21dd..7f695d4 100644
--- a/dhall/Cargo.toml
+++ b/dhall/Cargo.toml
@@ -5,9 +5,6 @@ authors = ["NanoTech <nanotech@nanotechcorp.net>", "Nadrieril <nadrieril@users.n
 edition = "2018"
 build = "build.rs"
 
-[lib]
-doctest = false
-
 [features]
 nothreads = [] # disable threads for tarpaulin
 
diff --git a/dhall/src/error.rs b/dhall/src/error.rs
index 9e64b7e..cfd6f09 100644
--- a/dhall/src/error.rs
+++ b/dhall/src/error.rs
@@ -25,5 +25,8 @@ quick_error! {
             from()
             display("{:?}", err)
         }
+        Deserialize(err: String) {
+            display("{}", err)
+        }
     }
 }
diff --git a/dhall/src/lib.rs b/dhall/src/lib.rs
index c218aeb..8af5af9 100644
--- a/dhall/src/lib.rs
+++ b/dhall/src/lib.rs
@@ -39,14 +39,13 @@
 //!
 //! #[derive(Debug, Deserialize, SimpleStaticType)]
 //! struct Point {
-//!     x: usize,
-//!     y: usize,
+//!     x: u64,
+//!     y: u64,
 //! }
 //!
 //! fn main() {
 //!     // Some dhall data
-//!     // ./Point can be populated using Point::get_type().to_string()
-//!     let data = "{ x = 1, y = 1 + 1 } : ./Point";
+//!     let data = "{ x = 1, y = 1 + 1 }";
 //!
 //!     // Convert the dhall string to a Point.
 //!     let point: Point =
diff --git a/dhall/src/serde.rs b/dhall/src/serde.rs
index 4ac4f3d..196bda1 100644
--- a/dhall/src/serde.rs
+++ b/dhall/src/serde.rs
@@ -1,9 +1,69 @@
-use crate::error::Result;
-use crate::expr::Type;
+use crate::error::{Error, Result};
+use crate::expr::{Normalized, Type};
 use crate::traits::Deserialize;
+use dhall_core::*;
+use std::borrow::Cow;
 
 impl<'a, T: serde::Deserialize<'a>> Deserialize<'a> for T {
-    fn from_str(_s: &'a str, _ty: Option<&Type>) -> Result<Self> {
-        unimplemented!()
+    fn from_str(s: &'a str, ty: Option<&Type>) -> Result<Self> {
+        let expr = Normalized::from_str(s, ty)?;
+        T::deserialize(Deserializer(Cow::Owned(expr.0)))
+    }
+}
+
+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
     }
 }
diff --git a/dhall/src/traits/deserialize.rs b/dhall/src/traits/deserialize.rs
index 5271a65..1fbdfe1 100644
--- a/dhall/src/traits/deserialize.rs
+++ b/dhall/src/traits/deserialize.rs
@@ -8,7 +8,7 @@ pub trait Deserialize<'a>: Sized {
 impl<'a> Deserialize<'a> for Parsed {
     /// Simply parses the provided string. Ignores the
     /// provided type.
-    fn from_str(s: &'a str, _ty: Option<&Type>) -> Result<Self> {
+    fn from_str(s: &'a str, _: Option<&Type>) -> Result<Self> {
         Ok(Parsed::parse_str(s)?)
     }
 }
diff --git a/dhall/src/traits/static_type.rs b/dhall/src/traits/static_type.rs
index b402ca9..6c41e3f 100644
--- a/dhall/src/traits/static_type.rs
+++ b/dhall/src/traits/static_type.rs
@@ -47,12 +47,36 @@ impl SimpleStaticType for Natural {
     }
 }
 
+impl SimpleStaticType for u32 {
+    fn get_simple_static_type() -> SimpleType {
+        mktype(dhall_expr!(Natural))
+    }
+}
+
+impl SimpleStaticType for u64 {
+    fn get_simple_static_type() -> SimpleType {
+        mktype(dhall_expr!(Natural))
+    }
+}
+
 impl SimpleStaticType for Integer {
     fn get_simple_static_type() -> SimpleType {
         mktype(dhall_expr!(Integer))
     }
 }
 
+impl SimpleStaticType for i32 {
+    fn get_simple_static_type() -> SimpleType {
+        mktype(dhall_expr!(Integer))
+    }
+}
+
+impl SimpleStaticType for i64 {
+    fn get_simple_static_type() -> SimpleType {
+        mktype(dhall_expr!(Integer))
+    }
+}
+
 impl SimpleStaticType for String {
     fn get_simple_static_type() -> SimpleType {
         mktype(dhall_expr!(Text))
diff --git a/dhall_core/src/core.rs b/dhall_core/src/core.rs
index 39dea37..03a34f1 100644
--- a/dhall_core/src/core.rs
+++ b/dhall_core/src/core.rs
@@ -3,7 +3,6 @@ use crate::*;
 use std::collections::BTreeMap;
 use std::rc::Rc;
 
-pub type Int = isize;
 pub type Integer = isize;
 pub type Natural = usize;
 pub type Double = NaiveDouble;
diff --git a/dhall_core/src/label.rs b/dhall_core/src/label.rs
index 9dc2816..43c3f53 100644
--- a/dhall_core/src/label.rs
+++ b/dhall_core/src/label.rs
@@ -28,4 +28,7 @@ impl Label {
     pub fn from_str(s: &str) -> Label {
         Label(s.into())
     }
+    pub fn as_ref(&self) -> &str {
+        self.0.as_ref()
+    }
 }