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Diffstat (limited to 'serde_dhall/src/serialize.rs')
| -rw-r--r-- | serde_dhall/src/serialize.rs | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/serde_dhall/src/serialize.rs b/serde_dhall/src/serialize.rs new file mode 100644 index 0000000..286c04d --- /dev/null +++ b/serde_dhall/src/serialize.rs @@ -0,0 +1,396 @@ +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 {} + +/// A data structure that can be serialized from a Dhall expression. +/// +/// This is automatically implemented for any type that [serde] can serialize. +/// In fact, this trait cannot be implemented manually. To implement it for your type, +/// use serde's derive mechanism. +/// +/// # Example +/// +/// ```rust +/// # fn main() -> serde_dhall::Result<()> { +/// use serde::Serialize; +/// +/// // Use serde's derive +/// #[derive(Serialize)] +/// struct Point { +/// x: u64, +/// y: u64, +/// } +/// +/// // Convert a Point to a Dhall string. +/// let point = Point { x: 0, y: 0 }; +/// let point_str = serde_dhall::serialize(&point).to_string()?; +/// assert_eq!(point_str, "{ x = 0, y = 0 }".to_string()); +/// # Ok(()) +/// # } +/// ``` +/// +/// [serde]: https://serde.rs +pub trait ToDhall: Sealed { + #[doc(hidden)] + fn to_dhall(&self, ty: Option<&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: Option<&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)) + } +} + +impl serde::ser::Serialize for SimpleValue { + fn serialize<S>( + &self, + serializer: S, + ) -> std::result::Result<S::Ok, S::Error> + where + S: serde::ser::Serializer, + { + use serde::ser::{SerializeMap, SerializeSeq}; + use NumKind::*; + use SimpleValue::*; + + match self { + Num(Bool(x)) => serializer.serialize_bool(*x), + Num(Natural(x)) => serializer.serialize_u64(*x), + Num(Integer(x)) => serializer.serialize_i64(*x), + Num(Double(x)) => serializer.serialize_f64((*x).into()), + Text(x) => serializer.serialize_str(x), + List(xs) => { + let mut seq = serializer.serialize_seq(Some(xs.len()))?; + for x in xs { + seq.serialize_element(x)?; + } + seq.end() + } + Optional(None) => serializer.serialize_none(), + Optional(Some(x)) => serializer.serialize_some(x), + Record(m) => { + let mut map = serializer.serialize_map(Some(m.len()))?; + for (k, v) in m { + map.serialize_entry(k, v)?; + } + map.end() + } + // serde's enum support is yet again really limited. We can't avoid a memleak here :(. + Union(field_name, None) => { + let field_name: Box<str> = field_name.clone().into(); + serializer.serialize_unit_variant( + "SimpleValue", + 0, + Box::leak(field_name), + ) + } + Union(field_name, Some(x)) => { + let field_name: Box<str> = field_name.clone().into(); + serializer.serialize_newtype_variant( + "SimpleValue", + 0, + Box::leak(field_name), + x, + ) + } + } + } +} |