ipld_nostd/ipld/serde/

ser.rs

// Parts of this code is based on
// https://github.com/serde-rs/json/blob/95f67a09399d546d9ecadeb747a845a77ff309b2/src/value/ser.rs
use {
	super::super::{serde::SerdeError, Ipld},
	crate::cid::{serde::CID_SERDE_PRIVATE_IDENTIFIER, Cid},
	alloc::{
		borrow::ToOwned,
		collections::BTreeMap,
		format,
		string::{String, ToString},
		vec::Vec,
	},
	core::convert::TryFrom,
	serde::ser,
};

/// Serialize into instances of [`crate::ipld::Ipld`].
///
/// All Rust types can be serialized to [`crate::ipld::Ipld`], here is a list of
/// how they are converted:
///
///  - bool -> `Ipld::Bool`
///  - i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, usize ->
///    `Ipld::Integer`
///  - f32, f64 -> `Ipld::Float`
///  - char, String -> `Ipld::String`
///  - slices -> `Ipld::List`
///  - struct
///    - struct -> `Ipld::Map`
///    - newtype struct -> the value the struct wraps
///    - tuple struct -> `Ipld::List`
///    - unit struct -> cannot be serialized, it errors
///  - enum:
///    - unit variant -> `Ipld::String` of the variant name
///    - newtype variant -> single element `Ipld::Map`, key: variant name,
///      value: the one the newtype wraps
///    - tuple variant -> single element `Ipld::Map`, key: variant name, value:
///      `Ipld::List`
///    - struct variant -> single element `Ipld::Map`, key: variant name, value:
///      `Ipld::Map`
///  - unit (`()`) -> cannot be serialized, it errors
///
/// There are also common compound types that are supported:
///
///  - [`std::option::Option`] -> eithe `Ipld::Null` or the value
///  - [`serde_bytes::ByteBuf`] -> `Ipld::Bytes`
///  - lists (like e.g. [`std::vec::Vec`]) -> `Ipld::List`
///  - maps (like e.g. [`std::collections::BTreeMap`]) -> `Ipld::Map`
///  - [`cid::Cid`] -> `Ipld::Link`
///
///
/// # Example
///
/// ```
/// use {
/// 	ipld_core::{ipld::Ipld, serde::to_ipld},
/// 	serde_derive::Serialize,
/// };
///
/// #[derive(Serialize)]
/// struct Person {
/// 	name: String,
/// 	age: u8,
/// 	hobbies: Vec<String>,
/// 	is_cool: bool,
/// }
///
/// let person = Person {
/// 	name: "Hello World!".into(),
/// 	age: 52,
/// 	hobbies: vec!["geography".into(), "programming".into()],
/// 	is_cool: true,
/// };
///
/// let ipld = to_ipld(person);
/// assert!(matches!(ipld, Ok(Ipld::Map(_))));
/// ```
pub fn to_ipld<T>(value: T) -> Result<Ipld, SerdeError>
where
	T: ser::Serialize,
{
	value.serialize(Serializer)
}

impl ser::Serialize for Ipld {
	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
	where
		S: ser::Serializer,
	{
		match &self {
			Self::Null => serializer.serialize_none(),
			Self::Bool(value) => serializer.serialize_bool(*value),
			Self::Integer(value) => serializer.serialize_i128(*value),
			Self::Float(value) => serializer.serialize_f64(*value),
			Self::String(value) => serializer.serialize_str(value),
			Self::Bytes(value) => serializer.serialize_bytes(value),
			Self::List(value) => serializer.collect_seq(value),
			Self::Map(value) => serializer.collect_map(value),
			Self::Link(value) => value.serialize(serializer),
		}
	}
}

/// The IPLD serializer.
pub struct Serializer;

impl serde::Serializer for Serializer {
	type Error = SerdeError;
	type Ok = Ipld;
	type SerializeMap = SerializeMap;
	type SerializeSeq = SerializeVec;
	type SerializeStruct = SerializeMap;
	type SerializeStructVariant = SerializeStructVariant;
	type SerializeTuple = SerializeVec;
	type SerializeTupleStruct = SerializeVec;
	type SerializeTupleVariant = SerializeTupleVariant;

	#[inline]
	fn serialize_bool(self, value: bool) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::Bool(value))
	}

	#[inline]
	fn serialize_i8(self, value: i8) -> Result<Self::Ok, Self::Error> {
		self.serialize_i64(i64::from(value))
	}

	#[inline]
	fn serialize_i16(self, value: i16) -> Result<Self::Ok, Self::Error> {
		self.serialize_i64(i64::from(value))
	}

	#[inline]
	fn serialize_i32(self, value: i32) -> Result<Self::Ok, Self::Error> {
		self.serialize_i64(i64::from(value))
	}

	#[inline]
	fn serialize_i64(self, value: i64) -> Result<Self::Ok, Self::Error> {
		self.serialize_i128(i128::from(value))
	}

	fn serialize_i128(self, value: i128) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::Integer(value))
	}

	#[inline]
	fn serialize_u8(self, value: u8) -> Result<Self::Ok, Self::Error> {
		self.serialize_i128(value.into())
	}

	#[inline]
	fn serialize_u16(self, value: u16) -> Result<Self::Ok, Self::Error> {
		self.serialize_i128(value.into())
	}

	#[inline]
	fn serialize_u32(self, value: u32) -> Result<Self::Ok, Self::Error> {
		self.serialize_i128(value.into())
	}

	#[inline]
	fn serialize_u64(self, value: u64) -> Result<Self::Ok, Self::Error> {
		self.serialize_i128(value.into())
	}

	#[inline]
	fn serialize_f32(self, value: f32) -> Result<Self::Ok, Self::Error> {
		self.serialize_f64(f64::from(value))
	}

	#[inline]
	fn serialize_f64(self, value: f64) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::Float(value))
	}

	#[inline]
	fn serialize_char(self, value: char) -> Result<Self::Ok, Self::Error> {
		self.serialize_str(&value.to_string())
	}

	#[inline]
	fn serialize_str(self, value: &str) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::String(value.to_owned()))
	}

	fn serialize_bytes(self, value: &[u8]) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::Bytes(value.to_vec()))
	}

	#[inline]
	fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
		Err(ser::Error::custom("Unit is not supported"))
	}

	#[inline]
	fn serialize_unit_struct(
		self,
		_name: &'static str,
	) -> Result<Self::Ok, Self::Error> {
		Err(ser::Error::custom("Unit structs are not supported"))
	}

	#[inline]
	fn serialize_unit_variant(
		self,
		_name: &'static str,
		_variant_index: u32,
		variant: &'static str,
	) -> Result<Self::Ok, Self::Error> {
		self.serialize_str(variant)
	}

	#[inline]
	fn serialize_newtype_struct<T>(
		self,
		name: &'static str,
		value: &T,
	) -> Result<Self::Ok, Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		let ipld = value.serialize(self);
		if name == CID_SERDE_PRIVATE_IDENTIFIER {
			if let Ok(Ipld::Bytes(bytes)) = ipld {
				let cid = Cid::try_from(bytes)
					.map_err(|err| ser::Error::custom(format!("Invalid CID: {}", err)))?;
				return Ok(Self::Ok::Link(cid));
			}
		}
		ipld
	}

	fn serialize_newtype_variant<T>(
		self,
		_name: &'static str,
		_variant_index: u32,
		variant: &'static str,
		value: &T,
	) -> Result<Self::Ok, Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		let values = BTreeMap::from([(variant.to_owned(), value.serialize(self)?)]);
		Ok(Self::Ok::Map(values))
	}

	#[inline]
	fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::Null)
	}

	#[inline]
	fn serialize_some<T>(self, value: &T) -> Result<Self::Ok, Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		value.serialize(self)
	}

	fn serialize_seq(
		self,
		len: Option<usize>,
	) -> Result<Self::SerializeSeq, Self::Error> {
		Ok(SerializeVec {
			vec: Vec::with_capacity(len.unwrap_or(0)),
		})
	}

	fn serialize_tuple(
		self,
		len: usize,
	) -> Result<Self::SerializeTuple, Self::Error> {
		self.serialize_seq(Some(len))
	}

	fn serialize_tuple_struct(
		self,
		_name: &'static str,
		len: usize,
	) -> Result<Self::SerializeTupleStruct, Self::Error> {
		self.serialize_tuple(len)
	}

	fn serialize_tuple_variant(
		self,
		_name: &'static str,
		_variant_index: u32,
		variant: &'static str,
		len: usize,
	) -> Result<Self::SerializeTupleVariant, Self::Error> {
		Ok(SerializeTupleVariant {
			name: String::from(variant),
			vec: Vec::with_capacity(len),
		})
	}

	fn serialize_map(
		self,
		_len: Option<usize>,
	) -> Result<Self::SerializeMap, Self::Error> {
		Ok(SerializeMap {
			map: BTreeMap::new(),
			next_key: None,
		})
	}

	fn serialize_struct(
		self,
		_name: &'static str,
		len: usize,
	) -> Result<Self::SerializeStruct, Self::Error> {
		self.serialize_map(Some(len))
	}

	fn serialize_struct_variant(
		self,
		_name: &'static str,
		_variant_index: u32,
		variant: &'static str,
		_len: usize,
	) -> Result<Self::SerializeStructVariant, Self::Error> {
		Ok(SerializeStructVariant {
			name: String::from(variant),
			map: BTreeMap::new(),
		})
	}

	#[inline]
	fn is_human_readable(&self) -> bool {
		false
	}
}

pub struct SerializeVec {
	vec: Vec<Ipld>,
}

pub struct SerializeTupleVariant {
	name: String,
	vec: Vec<Ipld>,
}

pub struct SerializeMap {
	map: BTreeMap<String, Ipld>,
	next_key: Option<String>,
}

pub struct SerializeStructVariant {
	name: String,
	map: BTreeMap<String, Ipld>,
}

impl ser::SerializeSeq for SerializeVec {
	type Error = SerdeError;
	type Ok = Ipld;

	fn serialize_element<T>(&mut self, value: &T) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		self.vec.push(value.serialize(Serializer)?);
		Ok(())
	}

	fn end(self) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::List(self.vec))
	}
}

impl ser::SerializeTuple for SerializeVec {
	type Error = SerdeError;
	type Ok = Ipld;

	fn serialize_element<T>(&mut self, value: &T) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		ser::SerializeSeq::serialize_element(self, value)
	}

	fn end(self) -> Result<Self::Ok, Self::Error> {
		ser::SerializeSeq::end(self)
	}
}

impl ser::SerializeTupleStruct for SerializeVec {
	type Error = SerdeError;
	type Ok = Ipld;

	fn serialize_field<T>(&mut self, value: &T) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		ser::SerializeSeq::serialize_element(self, value)
	}

	fn end(self) -> Result<Self::Ok, Self::Error> {
		ser::SerializeSeq::end(self)
	}
}

impl ser::SerializeTupleVariant for SerializeTupleVariant {
	type Error = SerdeError;
	type Ok = Ipld;

	fn serialize_field<T>(&mut self, value: &T) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		self.vec.push(value.serialize(Serializer)?);
		Ok(())
	}

	fn end(self) -> Result<Self::Ok, Self::Error> {
		let map = BTreeMap::from([(self.name, Self::Ok::List(self.vec))]);
		Ok(Self::Ok::Map(map))
	}
}

impl ser::SerializeMap for SerializeMap {
	type Error = SerdeError;
	type Ok = Ipld;

	fn serialize_key<T>(&mut self, key: &T) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		match key.serialize(Serializer)? {
			Ipld::String(string_key) => {
				self.next_key = Some(string_key);
				Ok(())
			}
			_ => Err(ser::Error::custom("Map keys must be strings".to_string())),
		}
	}

	fn serialize_value<T>(&mut self, value: &T) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		let key = self.next_key.take();
		// Panic because this indicates a bug in the program rather than an
		// expected failure.
		let key = key.expect("serialize_value called before serialize_key");
		self.map.insert(key, value.serialize(Serializer)?);
		Ok(())
	}

	fn end(self) -> Result<Self::Ok, Self::Error> {
		Ok(Self::Ok::Map(self.map))
	}
}

impl ser::SerializeStruct for SerializeMap {
	type Error = SerdeError;
	type Ok = Ipld;

	fn serialize_field<T>(
		&mut self,
		key: &'static str,
		value: &T,
	) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		serde::ser::SerializeMap::serialize_key(self, key)?;
		serde::ser::SerializeMap::serialize_value(self, value)
	}

	fn end(self) -> Result<Self::Ok, Self::Error> {
		serde::ser::SerializeMap::end(self)
	}
}

impl ser::SerializeStructVariant for SerializeStructVariant {
	type Error = SerdeError;
	type Ok = Ipld;

	fn serialize_field<T>(
		&mut self,
		key: &'static str,
		value: &T,
	) -> Result<(), Self::Error>
	where
		T: ser::Serialize + ?Sized,
	{
		self
			.map
			.insert(key.to_string(), value.serialize(Serializer)?);
		Ok(())
	}

	fn end(self) -> Result<Self::Ok, Self::Error> {
		let mut object = BTreeMap::new();

		object.insert(self.name, Self::Ok::Map(self.map));

		Ok(Self::Ok::Map(object))
	}
}