jasn-core 0.2.0

//! Serialization to JASN Value.
//!
//! This module provides serialization from Rust types to JASN `Value`.

use std::collections::BTreeMap;

use serde::{Serialize, ser};

use crate::{Binary, Value};

/// Error type for serialization.
#[derive(Debug, thiserror::Error)]
pub enum Error {
    /// Custom serialization error.
    #[error("custom error: {0}")]
    Custom(String),
    /// Maps with non-string keys are not supported.
    #[error("maps with non-string keys are not supported")]
    NonStringKey,
}

impl ser::Error for Error {
    fn custom<T: std::fmt::Display>(msg: T) -> Self {
        Error::Custom(msg.to_string())
    }
}

type Result<T> = std::result::Result<T, Error>;

/// Serialize a Rust value to a JASN [`Value`].
pub fn to_value<T>(value: &T) -> Result<Value>
where
    T: Serialize + ?Sized,
{
    value.serialize(Serializer)
}

/// Serializer whose output is a [`Value`].
pub struct Serializer;

impl ser::Serializer for Serializer {
    type Ok = Value;
    type Error = Error;

    type SerializeSeq = SerializeVec;
    type SerializeTuple = SerializeVec;
    type SerializeTupleStruct = SerializeVec;
    type SerializeTupleVariant = SerializeTupleVariant;
    type SerializeMap = SerializeMap;
    type SerializeStruct = SerializeMap;
    type SerializeStructVariant = SerializeStructVariant;

    fn serialize_bool(self, v: bool) -> Result<Value> {
        Ok(Value::Bool(v))
    }

    fn serialize_i8(self, v: i8) -> Result<Value> {
        Ok(Value::Int(v as i64))
    }

    fn serialize_i16(self, v: i16) -> Result<Value> {
        Ok(Value::Int(v as i64))
    }

    fn serialize_i32(self, v: i32) -> Result<Value> {
        Ok(Value::Int(v as i64))
    }

    fn serialize_i64(self, v: i64) -> Result<Value> {
        Ok(Value::Int(v))
    }

    fn serialize_u8(self, v: u8) -> Result<Value> {
        Ok(Value::Int(v as i64))
    }

    fn serialize_u16(self, v: u16) -> Result<Value> {
        Ok(Value::Int(v as i64))
    }

    fn serialize_u32(self, v: u32) -> Result<Value> {
        Ok(Value::Int(v as i64))
    }

    fn serialize_u64(self, v: u64) -> Result<Value> {
        if v > i64::MAX as u64 {
            Ok(Value::Float(v as f64))
        } else {
            Ok(Value::Int(v as i64))
        }
    }

    fn serialize_f32(self, v: f32) -> Result<Value> {
        Ok(Value::Float(v as f64))
    }

    fn serialize_f64(self, v: f64) -> Result<Value> {
        Ok(Value::Float(v))
    }

    fn serialize_char(self, v: char) -> Result<Value> {
        Ok(Value::String(v.to_string()))
    }

    fn serialize_str(self, v: &str) -> Result<Value> {
        Ok(Value::String(v.to_string()))
    }

    fn serialize_bytes(self, v: &[u8]) -> Result<Value> {
        Ok(Value::Binary(Binary(v.to_vec())))
    }

    fn serialize_none(self) -> Result<Value> {
        Ok(Value::Null)
    }

    fn serialize_some<T>(self, value: &T) -> Result<Value>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    fn serialize_unit(self) -> Result<Value> {
        Ok(Value::Null)
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<Value> {
        Ok(Value::Null)
    }

    fn serialize_unit_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
    ) -> Result<Value> {
        Ok(Value::String(variant.to_string()))
    }

    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<Value>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    fn serialize_newtype_variant<T>(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        value: &T,
    ) -> Result<Value>
    where
        T: ?Sized + Serialize,
    {
        let mut map = BTreeMap::new();
        map.insert(variant.to_string(), to_value(value)?);
        Ok(Value::Map(map))
    }

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

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

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

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

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

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

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

/// Helper for serializing sequences.
pub struct SerializeVec {
    vec: Vec<Value>,
}

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

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

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

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

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

    fn end(self) -> Result<Value> {
        ser::SerializeSeq::end(self)
    }
}

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

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

    fn end(self) -> Result<Value> {
        ser::SerializeSeq::end(self)
    }
}

/// Helper for serializing tuple variants.
pub struct SerializeTupleVariant {
    name: String,
    vec: Vec<Value>,
}

impl ser::SerializeTupleVariant for SerializeTupleVariant {
    type Ok = Value;
    type Error = Error;

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

    fn end(self) -> Result<Value> {
        let mut map = BTreeMap::new();
        map.insert(self.name, Value::List(self.vec));
        Ok(Value::Map(map))
    }
}

/// Helper for serializing maps and structs.
pub struct SerializeMap {
    map: BTreeMap<String, Value>,
    next_key: Option<String>,
}

impl ser::SerializeMap for SerializeMap {
    type Ok = Value;
    type Error = Error;

    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.next_key = Some(key.serialize(KeySerializer)?);
        Ok(())
    }

    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        let key = self
            .next_key
            .take()
            .expect("serialize_value called before serialize_key");
        self.map.insert(key, to_value(value)?);
        Ok(())
    }

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

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

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

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

/// Helper for serializing struct variants.
pub struct SerializeStructVariant {
    name: String,
    map: BTreeMap<String, Value>,
}

impl ser::SerializeStructVariant for SerializeStructVariant {
    type Ok = Value;
    type Error = Error;

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

    fn end(self) -> Result<Value> {
        let mut outer = BTreeMap::new();
        outer.insert(self.name, Value::Map(self.map));
        Ok(Value::Map(outer))
    }
}

struct KeySerializer;

impl ser::Serializer for KeySerializer {
    type Ok = String;
    type Error = Error;

    type SerializeSeq = ser::Impossible<String, Error>;
    type SerializeTuple = ser::Impossible<String, Error>;
    type SerializeTupleStruct = ser::Impossible<String, Error>;
    type SerializeTupleVariant = ser::Impossible<String, Error>;
    type SerializeMap = ser::Impossible<String, Error>;
    type SerializeStruct = ser::Impossible<String, Error>;
    type SerializeStructVariant = ser::Impossible<String, Error>;

    fn serialize_bool(self, _v: bool) -> Result<String> {
        Err(Error::NonStringKey)
    }

    fn serialize_i8(self, v: i8) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_i16(self, v: i16) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_i32(self, v: i32) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_i64(self, v: i64) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_u8(self, v: u8) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_u16(self, v: u16) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_u32(self, v: u32) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_u64(self, v: u64) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_f32(self, _v: f32) -> Result<String> {
        Err(Error::NonStringKey)
    }

    fn serialize_f64(self, _v: f64) -> Result<String> {
        Err(Error::NonStringKey)
    }

    fn serialize_char(self, v: char) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_str(self, v: &str) -> Result<String> {
        Ok(v.to_string())
    }

    fn serialize_bytes(self, _v: &[u8]) -> Result<String> {
        Err(Error::NonStringKey)
    }

    fn serialize_none(self) -> Result<String> {
        Err(Error::NonStringKey)
    }

    fn serialize_some<T>(self, _value: &T) -> Result<String>
    where
        T: ?Sized + Serialize,
    {
        Err(Error::NonStringKey)
    }

    fn serialize_unit(self) -> Result<String> {
        Err(Error::NonStringKey)
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<String> {
        Err(Error::NonStringKey)
    }

    fn serialize_unit_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
    ) -> Result<String> {
        Ok(variant.to_string())
    }

    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<String>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    fn serialize_newtype_variant<T>(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _value: &T,
    ) -> Result<String>
    where
        T: ?Sized + Serialize,
    {
        Err(Error::NonStringKey)
    }

    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
        Err(Error::NonStringKey)
    }

    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
        Err(Error::NonStringKey)
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleStruct> {
        Err(Error::NonStringKey)
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleVariant> {
        Err(Error::NonStringKey)
    }

    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
        Err(Error::NonStringKey)
    }

    fn serialize_struct(self, _name: &'static str, _len: usize) -> Result<Self::SerializeStruct> {
        Err(Error::NonStringKey)
    }

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeStructVariant> {
        Err(Error::NonStringKey)
    }
}