sonic_rs/value/
de.rs

use std::{mem::MaybeUninit, result::Result as StdResult, slice};

use ::serde::{
    de::{
        self, Deserialize, DeserializeSeed, EnumAccess, Expected, IntoDeserializer, MapAccess,
        SeqAccess, Unexpected, VariantAccess, Visitor,
    },
    forward_to_deserialize_any,
};

use super::node::ValueRef;
use crate::{
    error::{Error, ErrorCode},
    reader::Reader,
    serde::{number::N, tri},
    value::{node::Value, Object},
};

/// Interpret a `sonic_rs::Value` as an instance of type `T`.
///
/// # Example
///
/// ```
/// use serde::Deserialize;
/// use sonic_rs::json;
///
/// #[derive(Deserialize, Debug)]
/// struct User {
///     string: String,
///     number: i32,
///     array: Vec<String>,
/// }
///
///  // The type of `j` is `sonic_rs::Value`
///  let j = json!({
///      "string": "hello",
///      "number": 123,
///      "array": ["a", "b", "c"],
///  });
///  let u: User = sonic_rs::from_value(&j).unwrap();
///  assert_eq!(u.string, "hello");
///  assert_eq!(u.number, 123);
///  assert_eq!(u.array, vec!["a", "b", "c"]);
/// ```
///
/// # Errors
///
/// This conversion can fail if the structure of the Value does not match the
/// structure expected by `T`, for example if `T` is a struct type but the Value
/// contains something other than a JSON map. It can also fail if the structure
/// is correct but `T`'s implementation of `Deserialize` decides that something
/// is wrong with the data, for example required struct fields are missing from
/// the JSON map or some number is too big to fit in the expected primitive
/// type.
pub fn from_value<'de, T>(value: &'de Value) -> Result<T, Error>
where
    T: Deserialize<'de>,
{
    T::deserialize(value)
}

impl<'de> Deserialize<'de> for Value {
    /// Deserialize this value from a `Deserializer`.
    ///
    /// # Examples
    ///
    /// ```
    /// use sonic_rs::Value;
    ///
    /// let v: Value = sonic_rs::from_str(r#"{"a": 1, "b": 2}"#).unwrap();
    /// assert_eq!(v["a"], 1);
    /// assert_eq!(v["b"], 2);
    /// ```
    fn deserialize<D>(deserializer: D) -> StdResult<Self, D::Error>
    where
        D: ::serde::Deserializer<'de>,
    {
        deserializer.deserialize_newtype_struct(TOKEN, ValueVisitor)
    }
}

pub(crate) const TOKEN: &str = "$sonic_rs::private::Value";

pub(crate) struct ValueVisitor;

impl<'de> Visitor<'de> for ValueVisitor {
    type Value = Value;

    fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        formatter.write_str("a valid json")
    }

    fn visit_bytes<E>(self, value_binary: &[u8]) -> StdResult<Value, E>
    where
        E: de::Error,
    {
        // we pass the value from value_binary
        unsafe {
            assert!(
                value_binary.len() == std::mem::size_of::<Value>(),
                "invalid value size {}",
                value_binary.len()
            );
            let mut dom: MaybeUninit<Value> = MaybeUninit::zeroed();
            std::ptr::copy_nonoverlapping(
                value_binary.as_ptr() as *const Value,
                dom.as_mut_ptr(),
                1,
            );
            Ok(dom.assume_init())
        }
    }
}

struct SeqRefDeserializer<'de> {
    iter: slice::Iter<'de, Value>,
}

impl<'de> SeqRefDeserializer<'de> {
    fn new(slice: &'de [Value]) -> Self {
        SeqRefDeserializer { iter: slice.iter() }
    }
}

impl<'de> SeqAccess<'de> for SeqRefDeserializer<'de> {
    type Error = Error;

    fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Error>
    where
        T: DeserializeSeed<'de>,
    {
        match self.iter.next() {
            Some(value) => seed.deserialize(value).map(Some),
            None => Ok(None),
        }
    }

    fn size_hint(&self) -> Option<usize> {
        match self.iter.size_hint() {
            (lower, Some(upper)) if lower == upper => Some(upper),
            _ => None,
        }
    }
}

struct MapRefDeserializer<'de> {
    iter: <&'de Object as IntoIterator>::IntoIter,
    value: Option<&'de Value>,
}

impl<'de> MapRefDeserializer<'de> {
    fn new(map: &'de Object) -> Self {
        MapRefDeserializer {
            iter: map.into_iter(),
            value: None,
        }
    }
}

impl<'de> MapAccess<'de> for MapRefDeserializer<'de> {
    type Error = Error;

    fn next_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Error>
    where
        T: DeserializeSeed<'de>,
    {
        match self.iter.next() {
            Some((key, value)) => {
                self.value = Some(value);
                let key_de = MapKeyDeserializer { key };
                seed.deserialize(key_de).map(Some)
            }
            None => Ok(None),
        }
    }

    fn next_value_seed<T>(&mut self, seed: T) -> Result<T::Value, Error>
    where
        T: DeserializeSeed<'de>,
    {
        match self.value.take() {
            Some(value) => seed.deserialize(value),
            None => Err(serde::de::Error::custom("value is missing")),
        }
    }

    fn size_hint(&self) -> Option<usize> {
        match self.iter.size_hint() {
            (lower, Some(upper)) if lower == upper => Some(upper),
            _ => None,
        }
    }
}

struct MapKeyDeserializer<'de> {
    key: &'de str,
}

macro_rules! deserialize_numeric_key {
    ($method:ident) => {
        deserialize_numeric_key!($method, deserialize_number);
    };

    ($method:ident, $using:ident) => {
        fn $method<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            let mut de =
                crate::Deserializer::new(crate::reader::Read::new(self.key.as_bytes(), false));
            match de.parser.read.peek() {
                Some(b'0'..=b'9' | b'-') => {}
                _ => return Err(Error::syntax(ErrorCode::ExpectedNumericKey, b"", 0)),
            }
            let number = tri!(de.$using(visitor));
            Ok(number)
        }
    };
}

impl<'de> serde::Deserializer<'de> for MapKeyDeserializer<'de> {
    type Error = Error;

    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_borrowed_str(self.key)
    }

    deserialize_numeric_key!(deserialize_i8);
    deserialize_numeric_key!(deserialize_i16);
    deserialize_numeric_key!(deserialize_i32);
    deserialize_numeric_key!(deserialize_i64);
    deserialize_numeric_key!(deserialize_u8);
    deserialize_numeric_key!(deserialize_u16);
    deserialize_numeric_key!(deserialize_u32);
    deserialize_numeric_key!(deserialize_u64);
    // TODO: impl parsing f32
    deserialize_numeric_key!(deserialize_f32);
    deserialize_numeric_key!(deserialize_f64);
    deserialize_numeric_key!(deserialize_i128, deserialize_i128);
    deserialize_numeric_key!(deserialize_u128, deserialize_u128);

    fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        if self.key == "true" {
            visitor.visit_bool(true)
        } else if self.key == "false" {
            visitor.visit_bool(false)
        } else {
            Err(serde::de::Error::invalid_type(
                Unexpected::Str(self.key),
                &visitor,
            ))
        }
    }

    #[inline]
    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        // Map keys cannot be null.
        visitor.visit_some(self)
    }

    #[inline]
    fn deserialize_newtype_struct<V>(
        self,
        _name: &'static str,
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_newtype_struct(self)
    }

    fn deserialize_enum<V>(
        self,
        name: &'static str,
        variants: &'static [&'static str],
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.key
            .into_deserializer()
            .deserialize_enum(name, variants, visitor)
    }

    forward_to_deserialize_any! {
        char str string bytes byte_buf unit unit_struct seq tuple tuple_struct
        map struct identifier ignored_any
    }
}

fn visit_array_ref<'de, V>(array: &'de [Value], visitor: V) -> Result<V::Value, Error>
where
    V: Visitor<'de>,
{
    let len = array.len();
    let mut deserializer = SeqRefDeserializer::new(array);
    let seq = tri!(visitor.visit_seq(&mut deserializer));
    let remaining = deserializer.iter.len();
    if remaining == 0 {
        Ok(seq)
    } else {
        Err(serde::de::Error::invalid_length(
            len,
            &"fewer elements in array",
        ))
    }
}

fn visit_object_ref<'de, V>(object: &'de Object, visitor: V) -> Result<V::Value, Error>
where
    V: Visitor<'de>,
{
    let len = object.len();
    let mut deserializer = MapRefDeserializer::new(object);
    let map = tri!(visitor.visit_map(&mut deserializer));
    let remaining = deserializer.iter.len();
    if remaining == 0 {
        Ok(map)
    } else {
        Err(serde::de::Error::invalid_length(
            len,
            &"fewer elements in map",
        ))
    }
}

macro_rules! deserialize_number {
    ($method:ident) => {
        fn $method<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match self.as_ref() {
                ValueRef::Number(n) => n.deserialize_any(visitor),
                _ => Err(self.invalid_type(&visitor)),
            }
        }
    };
}

impl Value {
    #[cold]
    fn invalid_type<E>(&self, exp: &dyn Expected) -> E
    where
        E: serde::de::Error,
    {
        serde::de::Error::invalid_type(self.unexpected(), exp)
    }

    #[cold]
    fn unexpected(&self) -> Unexpected<'_> {
        self.as_ref().unexpected()
    }
}

impl<'a> ValueRef<'a> {
    #[cold]
    fn unexpected(&self) -> Unexpected<'a> {
        match self {
            ValueRef::Null => Unexpected::Unit,
            ValueRef::Bool(b) => Unexpected::Bool(*b),
            ValueRef::Number(n) => match n.n {
                N::PosInt(u) => Unexpected::Unsigned(u),
                N::NegInt(i) => Unexpected::Signed(i),
                N::Float(f) => Unexpected::Float(f),
            },
            ValueRef::String(s) => Unexpected::Str(s),
            ValueRef::Array(_) => Unexpected::Seq,
            ValueRef::Object(_) => Unexpected::Map,
        }
    }
}

struct EnumRefDeserializer<'de> {
    variant: &'de str,
    value: Option<&'de Value>,
}

impl<'de> EnumAccess<'de> for EnumRefDeserializer<'de> {
    type Error = Error;
    type Variant = VariantRefDeserializer<'de>;

    fn variant_seed<V>(self, seed: V) -> Result<(V::Value, Self::Variant), Error>
    where
        V: DeserializeSeed<'de>,
    {
        let variant = self.variant.into_deserializer();
        let visitor = VariantRefDeserializer { value: self.value };
        seed.deserialize(variant).map(|v| (v, visitor))
    }
}

struct VariantRefDeserializer<'de> {
    value: Option<&'de Value>,
}

impl<'de> VariantAccess<'de> for VariantRefDeserializer<'de> {
    type Error = Error;

    fn unit_variant(self) -> Result<(), Error> {
        match self.value {
            Some(value) => Deserialize::deserialize(value),
            None => Ok(()),
        }
    }

    fn newtype_variant_seed<T>(self, seed: T) -> Result<T::Value, Error>
    where
        T: DeserializeSeed<'de>,
    {
        match self.value {
            Some(value) => seed.deserialize(value),
            None => Err(serde::de::Error::invalid_type(
                Unexpected::UnitVariant,
                &"newtype variant",
            )),
        }
    }

    fn tuple_variant<V>(self, _len: usize, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.value.map(|v| v.as_ref()) {
            Some(ValueRef::Array(v)) => {
                if v.is_empty() {
                    visitor.visit_unit()
                } else {
                    visit_array_ref(v, visitor)
                }
            }
            Some(other) => Err(serde::de::Error::invalid_type(
                other.unexpected(),
                &"tuple variant",
            )),
            None => Err(serde::de::Error::invalid_type(
                Unexpected::UnitVariant,
                &"tuple variant",
            )),
        }
    }

    fn struct_variant<V>(
        self,
        _fields: &'static [&'static str],
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.value.map(|v| v.as_ref()) {
            Some(ValueRef::Object(v)) => visit_object_ref(v, visitor),
            Some(other) => Err(serde::de::Error::invalid_type(
                other.unexpected(),
                &"struct variant",
            )),
            None => Err(serde::de::Error::invalid_type(
                Unexpected::UnitVariant,
                &"struct variant",
            )),
        }
    }
}

impl<'de> IntoDeserializer<'de, Error> for &'de Value {
    type Deserializer = Self;

    fn into_deserializer(self) -> Self::Deserializer {
        self
    }
}

impl<'de> serde::Deserializer<'de> for &'de Value {
    type Error = Error;

    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::Null => visitor.visit_unit(),
            ValueRef::Bool(v) => visitor.visit_bool(v),
            ValueRef::Number(n) => n.deserialize_any(visitor),
            ValueRef::String(v) => visitor.visit_borrowed_str(v),
            ValueRef::Array(v) => visit_array_ref(v, visitor),
            ValueRef::Object(v) => visit_object_ref(v, visitor),
        }
    }

    deserialize_number!(deserialize_i8);
    deserialize_number!(deserialize_i16);
    deserialize_number!(deserialize_i32);
    deserialize_number!(deserialize_i64);
    deserialize_number!(deserialize_i128);
    deserialize_number!(deserialize_u8);
    deserialize_number!(deserialize_u16);
    deserialize_number!(deserialize_u32);
    deserialize_number!(deserialize_u64);
    deserialize_number!(deserialize_u128);
    deserialize_number!(deserialize_f32);
    deserialize_number!(deserialize_f64);

    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::Null => visitor.visit_none(),
            _ => visitor.visit_some(self),
        }
    }

    fn deserialize_enum<V>(
        self,
        _name: &str,
        _variants: &'static [&'static str],
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        let (variant, value) = match self.as_ref() {
            ValueRef::Object(value) => {
                let mut iter = value.into_iter();
                let (variant, value) = match iter.next() {
                    Some(v) => v,
                    None => {
                        return Err(serde::de::Error::invalid_value(
                            Unexpected::Map,
                            &"map with a single key",
                        ));
                    }
                };
                // enums are encoded in json as maps with a single key:value pair
                if iter.next().is_some() {
                    return Err(serde::de::Error::invalid_value(
                        Unexpected::Map,
                        &"map with a single key",
                    ));
                }
                (variant, Some(value))
            }
            ValueRef::String(variant) => (variant, None),
            other => {
                return Err(serde::de::Error::invalid_type(
                    other.unexpected(),
                    &"string or map",
                ));
            }
        };

        visitor.visit_enum(EnumRefDeserializer { variant, value })
    }

    #[inline]
    fn deserialize_newtype_struct<V>(
        self,
        _name: &'static str,
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_newtype_struct(self)
    }

    fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::Bool(v) => visitor.visit_bool(v),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_char<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.deserialize_str(visitor)
    }

    fn deserialize_str<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::String(v) => visitor.visit_borrowed_str(v),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_string<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.deserialize_str(visitor)
    }

    fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::String(v) => visitor.visit_borrowed_str(v),
            ValueRef::Array(v) => visit_array_ref(v, visitor),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_byte_buf<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.deserialize_bytes(visitor)
    }

    fn deserialize_unit<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::Null => visitor.visit_unit(),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_unit_struct<V>(self, _name: &'static str, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.deserialize_unit(visitor)
    }

    fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::Array(v) => visit_array_ref(v, visitor),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_tuple<V>(self, _len: usize, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.deserialize_seq(visitor)
    }

    fn deserialize_tuple_struct<V>(
        self,
        _name: &'static str,
        _len: usize,
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.deserialize_seq(visitor)
    }

    fn deserialize_map<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::Object(v) => visit_object_ref(v, visitor),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_struct<V>(
        self,
        _name: &'static str,
        _fields: &'static [&'static str],
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.as_ref() {
            ValueRef::Array(v) => visit_array_ref(v, visitor),
            ValueRef::Object(v) => visit_object_ref(v, visitor),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_identifier<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        self.deserialize_str(visitor)
    }

    fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_unit()
    }
}

#[cfg(test)]
mod test {

    #[test]
    fn test_value_as_deserializer() {
        // unimplemented!()
    }
}
sonic_rs/value/de.rs

sonic_rs/value/
de.rs
