Implement serialization

1 files changed, 312 insertions, 0 deletions

diff --git a/serde_dhall/src/serialize.rs b/serde_dhall/src/serialize.rs
new file mode 100644
index 0000000..dd3e426
--- /dev/null
+++ b/serde_dhall/src/serialize.rs
@@ -0,0 +1,312 @@
+use serde::ser;
+use std::collections::BTreeMap;
+
+use dhall::syntax::NumKind;
+
+use crate::value::SimpleValue;
+use crate::{Error, ErrorKind, Result, SimpleType, Value};
+use SimpleValue::*;
+
+pub trait Sealed {}
+
+pub trait ToDhall: Sealed {
+    #[doc(hidden)]
+    fn to_dhall(&self, ty: &SimpleType) -> Result<Value>;
+}
+
+impl<T> Sealed for T where T: ser::Serialize {}
+
+impl<T> ToDhall for T
+where
+    T: ser::Serialize,
+{
+    fn to_dhall(&self, ty: &SimpleType) -> Result<Value> {
+        let sval: SimpleValue = self.serialize(Serializer)?;
+        sval.into_value(ty)
+    }
+}
+
+#[derive(Default, Clone, Copy)]
+struct Serializer;
+
+impl ser::Serializer for Serializer {
+    type Ok = SimpleValue;
+    type Error = Error;
+
+    type SerializeSeq = SeqSerializer;
+    type SerializeTuple = TupleSerializer;
+    type SerializeTupleStruct = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeTupleVariant = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeMap = MapSerializer;
+    type SerializeStruct = StructSerializer;
+    type SerializeStructVariant = ser::Impossible<Self::Ok, Self::Error>;
+
+    fn serialize_bool(self, v: bool) -> Result<Self::Ok> {
+        Ok(Num(NumKind::Bool(v)))
+    }
+
+    fn serialize_i8(self, v: i8) -> Result<Self::Ok> {
+        self.serialize_i64(i64::from(v))
+    }
+    fn serialize_i16(self, v: i16) -> Result<Self::Ok> {
+        self.serialize_i64(i64::from(v))
+    }
+    fn serialize_i32(self, v: i32) -> Result<Self::Ok> {
+        self.serialize_i64(i64::from(v))
+    }
+    fn serialize_i64(self, v: i64) -> Result<Self::Ok> {
+        Ok(Num(NumKind::Integer(v)))
+    }
+
+    fn serialize_u8(self, v: u8) -> Result<Self::Ok> {
+        self.serialize_u64(u64::from(v))
+    }
+    fn serialize_u16(self, v: u16) -> Result<Self::Ok> {
+        self.serialize_u64(u64::from(v))
+    }
+    fn serialize_u32(self, v: u32) -> Result<Self::Ok> {
+        self.serialize_u64(u64::from(v))
+    }
+    fn serialize_u64(self, v: u64) -> Result<Self::Ok> {
+        Ok(Num(NumKind::Natural(v)))
+    }
+
+    fn serialize_f32(self, v: f32) -> Result<Self::Ok> {
+        self.serialize_f64(f64::from(v))
+    }
+    fn serialize_f64(self, v: f64) -> Result<Self::Ok> {
+        Ok(Num(NumKind::Double(v.into())))
+    }
+
+    fn serialize_char(self, v: char) -> Result<Self::Ok> {
+        self.serialize_str(&v.to_string())
+    }
+    fn serialize_str(self, v: &str) -> Result<Self::Ok> {
+        Ok(Text(v.to_owned()))
+    }
+
+    fn serialize_bytes(self, _v: &[u8]) -> Result<Self::Ok> {
+        Err(ErrorKind::Serialize(
+            "Unsupported data for serialization: byte array".to_owned(),
+        )
+        .into())
+    }
+
+    fn serialize_none(self) -> Result<Self::Ok> {
+        Ok(Optional(None))
+    }
+    fn serialize_some<T>(self, v: &T) -> Result<Self::Ok>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        Ok(Optional(Some(Box::new(v.serialize(self)?))))
+    }
+
+    fn serialize_unit(self) -> Result<Self::Ok> {
+        Ok(Record(Default::default()))
+    }
+
+    fn serialize_unit_struct(self, _name: &'static str) -> Result<Self::Ok> {
+        self.serialize_unit()
+    }
+    fn serialize_newtype_struct<T>(
+        self,
+        _name: &'static str,
+        _value: &T,
+    ) -> Result<Self::Ok>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        Err(ErrorKind::Serialize(
+            "Unsupported data for serialization: newtype struct".to_owned(),
+        )
+        .into())
+    }
+    fn serialize_struct(
+        self,
+        _name: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeStruct> {
+        Ok(StructSerializer::default())
+    }
+
+    fn serialize_unit_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        variant: &'static str,
+    ) -> Result<Self::Ok> {
+        Ok(Union(variant.to_owned(), None))
+    }
+    fn serialize_newtype_variant<T>(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        variant: &'static str,
+        value: &T,
+    ) -> Result<Self::Ok>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        let value = value.serialize(self)?;
+        Ok(Union(variant.to_owned(), Some(Box::new(value))))
+    }
+    fn serialize_tuple_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeTupleVariant> {
+        Err(ErrorKind::Serialize(
+            "Unsupported data for serialization: tuple variant".to_owned(),
+        )
+        .into())
+    }
+    fn serialize_struct_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeStructVariant> {
+        Err(ErrorKind::Serialize(
+            "Unsupported data for serialization: struct variant".to_owned(),
+        )
+        .into())
+    }
+
+    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
+        Ok(TupleSerializer::default())
+    }
+    fn serialize_tuple_struct(
+        self,
+        _name: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeTupleStruct> {
+        Err(ErrorKind::Serialize(
+            "Unsupported data for serialization: tuple struct".to_owned(),
+        )
+        .into())
+    }
+
+    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
+        Ok(SeqSerializer::default())
+    }
+
+    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
+        Ok(MapSerializer::default())
+    }
+}
+
+#[derive(Default)]
+struct SeqSerializer(Vec<SimpleValue>);
+
+impl ser::SerializeSeq for SeqSerializer {
+    type Ok = SimpleValue;
+    type Error = Error;
+
+    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        self.0.push(value.serialize(Serializer)?);
+        Ok(())
+    }
+
+    fn end(self) -> Result<Self::Ok> {
+        Ok(List(self.0))
+    }
+}
+
+#[derive(Default)]
+struct TupleSerializer(Vec<SimpleValue>);
+
+impl ser::SerializeTuple for TupleSerializer {
+    type Ok = SimpleValue;
+    type Error = Error;
+
+    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        self.0.push(value.serialize(Serializer)?);
+        Ok(())
+    }
+
+    fn end(self) -> Result<Self::Ok> {
+        Ok(Record(
+            self.0
+                .into_iter()
+                .enumerate()
+                .map(|(i, x)| (format!("_{}", i + 1), x))
+                .collect(),
+        ))
+    }
+}
+
+#[derive(Default)]
+struct MapSerializer {
+    map: BTreeMap<String, SimpleValue>,
+    key: Option<String>,
+    val: Option<SimpleValue>,
+}
+
+impl ser::SerializeMap for MapSerializer {
+    type Ok = SimpleValue;
+    type Error = Error;
+
+    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        let key = match key.serialize(Serializer)? {
+            Text(key) => key,
+            _ => return Err(<Error as ser::Error>::custom("not a string")),
+        };
+        if let Some(val) = self.val.take() {
+            self.map.insert(key, val);
+        } else {
+            self.key = Some(key);
+        }
+        Ok(())
+    }
+
+    fn serialize_value<T>(&mut self, val: &T) -> Result<()>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        let val: SimpleValue = val.serialize(Serializer)?;
+        if let Some(key) = self.key.take() {
+            self.map.insert(key, val);
+        } else {
+            self.val = Some(val);
+        }
+        Ok(())
+    }
+
+    fn end(self) -> Result<Self::Ok> {
+        Ok(Record(self.map))
+    }
+}
+
+#[derive(Default)]
+struct StructSerializer(BTreeMap<String, SimpleValue>);
+
+impl ser::SerializeStruct for StructSerializer {
+    type Ok = SimpleValue;
+    type Error = Error;
+
+    fn serialize_field<T>(&mut self, key: &'static str, val: &T) -> Result<()>
+    where
+        T: ?Sized + ser::Serialize,
+    {
+        let val: SimpleValue = val.serialize(Serializer)?;
+        self.0.insert(key.into(), val);
+        Ok(())
+    }
+
+    fn end(self) -> Result<Self::Ok> {
+        Ok(Record(self.0))
+    }
+}