fastnbt/value/

de.rs

use std::{borrow::Cow, collections::HashMap};

use serde::{
    de::{
        value::{BorrowedStrDeserializer, BytesDeserializer},
        DeserializeSeed, EnumAccess, Expected, IntoDeserializer, MapAccess, SeqAccess, Unexpected,
        VariantAccess, Visitor,
    },
    forward_to_deserialize_any, Deserialize, Deserializer,
};
use serde_bytes::ByteBuf;

use crate::{error::Error, ByteArray, IntArray, LongArray, Value};

impl<'de> Deserialize<'de> for Value {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        struct ValueVisitor;
        impl<'de> serde::de::Visitor<'de> for ValueVisitor {
            type Value = Value;

            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
                formatter.write_str("valid NBT")
            }

            fn visit_i8<E>(self, v: i8) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Value::Byte(v))
            }

            fn visit_i16<E>(self, v: i16) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Value::Short(v))
            }

            fn visit_i32<E>(self, v: i32) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Value::Int(v))
            }

            fn visit_i64<E>(self, v: i64) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Value::Long(v))
            }

            fn visit_f32<E>(self, v: f32) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Value::Float(v))
            }

            fn visit_f64<E>(self, v: f64) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Value::Double(v))
            }

            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Value::String(v.to_owned()))
            }

            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
            where
                A: serde::de::SeqAccess<'de>,
            {
                // I think I either need to do the same trick as I did for NBT
                // Arrays and have dedicated types to this, or just accept that
                // it's a Vec<Value> and that you can construct invalid NBT with
                // it (by adding values of different type).

                // Feel like the case of list of lists will break me if I try
                // the dedicated type.
                let mut v = Vec::<Value>::with_capacity(seq.size_hint().unwrap_or(0));

                while let Some(el) = seq.next_element()? {
                    v.push(el);
                }

                Ok(Value::List(v))
            }

            fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
            where
                A: serde::de::MapAccess<'de>,
            {
                match map.next_key_seed(KeyClassifier)? {
                    Some(KeyClass::Compound(first_key)) => {
                        let mut compound = HashMap::new();

                        compound.insert(first_key, map.next_value()?);
                        while let Some((key, value)) = map.next_entry()? {
                            compound.insert(key, value);
                        }

                        Ok(Value::Compound(compound))
                    }
                    Some(KeyClass::ByteArray) => {
                        let data = map.next_value::<ByteBuf>()?;
                        Ok(Value::ByteArray(ByteArray::from_buf(data.into_vec())))
                    }
                    Some(KeyClass::IntArray) => {
                        let data = map.next_value::<ByteBuf>()?;
                        IntArray::from_bytes(&data)
                            .map(Value::IntArray)
                            .map_err(|_| serde::de::Error::custom("could not read int array"))
                    }
                    Some(KeyClass::LongArray) => {
                        let data = map.next_value::<ByteBuf>()?;
                        LongArray::from_bytes(&data)
                            .map(Value::LongArray)
                            .map_err(|_| serde::de::Error::custom("could not read long array"))
                    }
                    // No keys just means an empty compound.
                    None => Ok(Value::Compound(Default::default())),
                }
            }
        }

        deserializer.deserialize_any(ValueVisitor)
    }
}

struct KeyClassifier;

enum KeyClass {
    Compound(String),
    ByteArray,
    IntArray,
    LongArray,
}

impl<'de> DeserializeSeed<'de> for KeyClassifier {
    type Value = KeyClass;

    fn deserialize<D>(self, deserializer: D) -> Result<KeyClass, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        deserializer.deserialize_str(self)
    }
}

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

    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        formatter.write_str("an nbt field string")
    }

    fn visit_string<E>(self, s: String) -> Result<Self::Value, E>
    where
        E: serde::de::Error,
    {
        match s.as_str() {
            crate::BYTE_ARRAY_TOKEN => Ok(KeyClass::ByteArray),
            crate::INT_ARRAY_TOKEN => Ok(KeyClass::IntArray),
            crate::LONG_ARRAY_TOKEN => Ok(KeyClass::LongArray),
            _ => Ok(KeyClass::Compound(s)),
        }
    }

    fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
    where
        E: serde::de::Error,
    {
        match s {
            crate::BYTE_ARRAY_TOKEN => Ok(KeyClass::ByteArray),
            crate::INT_ARRAY_TOKEN => Ok(KeyClass::IntArray),
            crate::LONG_ARRAY_TOKEN => Ok(KeyClass::LongArray),
            _ => Ok(KeyClass::Compound(s.to_string())),
        }
    }
}

/* ---------- Deserializer ---------- */

//
// Everything below is copied and modified from serde_json:
// https://github.com/serde-rs/json/blob/52a9c050f5dcc0dc3de4825b131b8ff05219cc82/src/value/de.rs
//
// For which the license is MIT:
//
// Permission is hereby granted, free of charge, to any
// person obtaining a copy of this software and associated
// documentation files (the "Software"), to deal in the
// Software without restriction, including without
// limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice
// shall be included in all copies or substantial portions
// of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//

macro_rules! deserialize_number {
    ($method:ident, $visit:ident, $primitive:ident, $variant:ident) => {
        fn $method<V>(self, visitor: V) -> Result<V::Value, Self::Error>
        where
            V: Visitor<'de>,
        {
            match self {
                Value::$variant(v) => visitor.$visit(*v as $primitive),
                _ => Err(self.invalid_type(&visitor)),
            }
        }
    };
}

fn visit_list<'de, V>(list: &'de Vec<Value>, visitor: V) -> Result<V::Value, Error>
where
    V: Visitor<'de>,
{
    let len = list.len();
    let mut deserializer = SeqDeserializer::new(list);
    let seq = 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 list",
        ))
    }
}

fn visit_compound<'de, V>(
    compound: &'de HashMap<String, Value>,
    visitor: V,
) -> Result<V::Value, Error>
where
    V: Visitor<'de>,
{
    let len = compound.len();
    let mut deserializer = MapDeserializer::new(compound);
    let map = 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",
        ))
    }
}

fn get_i128_value(de: &Value) -> Result<i128, Error> {
    match de {
        Value::IntArray(v) => {
            if v.len() != 4 {
                Err(Error::bespoke(format!(
                    "deserialize i128: expected IntArray of length 4, got length {}",
                    v.len()
                )))
            } else {
                Ok(v.iter()
                    .rev()
                    .flat_map(|n| (0..32).map(move |bit| n >> bit & 1))
                    .rev()
                    .fold(0, |acc, bit| acc << 1 | bit as i128))
            }
        }
        v => Err(Error::bespoke(format!(
            "deserialize i128: expected IntArray value {v:?}"
        ))),
    }
}

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

    #[inline]
    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match *self {
            Value::Byte(val) => visitor.visit_i8(val),
            Value::Short(val) => visitor.visit_i16(val),
            Value::Int(val) => visitor.visit_i32(val),
            Value::Long(val) => visitor.visit_i64(val),
            Value::Float(val) => visitor.visit_f32(val),
            Value::Double(val) => visitor.visit_f64(val),
            Value::String(ref val) => visitor.visit_borrowed_str(val),
            Value::ByteArray(_) => visitor.visit_map(ArrayAccess {
                token: crate::BYTE_ARRAY_TOKEN,
                value: self,
            }),
            Value::IntArray(_) => visitor.visit_map(ArrayAccess {
                token: crate::INT_ARRAY_TOKEN,
                value: self,
            }),
            Value::LongArray(_) => visitor.visit_map(ArrayAccess {
                token: crate::LONG_ARRAY_TOKEN,
                value: self,
            }),
            Value::List(ref val) => visit_list(val, visitor),
            Value::Compound(ref val) => visit_compound(val, visitor),
        }
    }

    deserialize_number!(deserialize_i8, visit_i8, i8, Byte);
    deserialize_number!(deserialize_i16, visit_i16, i16, Short);
    deserialize_number!(deserialize_i32, visit_i32, i32, Int);
    deserialize_number!(deserialize_i64, visit_i64, i64, Long);
    deserialize_number!(deserialize_u8, visit_u8, u8, Byte);
    deserialize_number!(deserialize_u16, visit_u16, u16, Short);
    deserialize_number!(deserialize_u32, visit_u32, u32, Int);
    deserialize_number!(deserialize_u64, visit_u64, u64, Long);
    deserialize_number!(deserialize_f32, visit_f32, f32, Float);
    deserialize_number!(deserialize_f64, visit_f64, f64, Double);

    fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_i128(get_i128_value(self)?)
    }

    fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_u128(get_i128_value(self)? as u128)
    }

    #[inline]
    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_some(self)
    }

    #[inline]
    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 {
            Value::Compound(value) => {
                let mut iter = value.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 nbt 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))
            }
            Value::String(variant) => (variant, None),
            other => {
                return Err(serde::de::Error::invalid_type(
                    other.unexpected(),
                    &"string or map",
                ));
            }
        };

        visitor.visit_enum(EnumDeserializer { 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 {
            Value::Byte(v) => visitor.visit_bool(v != &0),
            Value::Short(v) => visitor.visit_bool(v != &0),
            Value::Int(v) => visitor.visit_bool(v != &0),
            Value::Long(v) => visitor.visit_bool(v != &0),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

    fn deserialize_char<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self {
            Value::Int(v) => match char::from_u32(*v as u32) {
                Some(v) => visitor.visit_char(v),
                None => Err(serde::de::Error::invalid_value(
                    self.unexpected(),
                    &"invalid character code",
                )),
            },
            Value::String(ref v) => match v.chars().next() {
                Some(v) => visitor.visit_char(v),
                None => Err(serde::de::Error::invalid_value(
                    self.unexpected(),
                    &"string contains no character",
                )),
            },
            _ => Err(self.invalid_type(&visitor)),
        }
    }

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

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

    fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self {
            Value::List(v) => visit_list(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>,
    {
        self.deserialize_any(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 {
            Value::List(v) => visit_list(v, visitor),
            Value::Compound(v) => visit_compound(v, visitor),
            _ => Err(self.invalid_type(&visitor)),
        }
    }

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

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

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

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

pub struct ArrayAccess<'de> {
    pub token: &'static str,
    pub value: &'de Value,
}
impl<'de> MapAccess<'de> for ArrayAccess<'de> {
    type Error = Error;

    fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Self::Error>
    where
        K: DeserializeSeed<'de>,
    {
        seed.deserialize(BorrowedStrDeserializer::new(self.token))
            .map(Some)
    }

    fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Self::Error>
    where
        V: DeserializeSeed<'de>,
    {
        let data = match self.value {
            Value::ByteArray(v) => v.to_bytes(),
            Value::IntArray(v) => v.to_bytes(),
            Value::LongArray(v) => v.to_bytes(),
            _ => unreachable!(),
        };
        let dz = BytesDeserializer::new(&data);
        seed.deserialize(dz)
    }
}

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

impl<'de> EnumAccess<'de> for EnumDeserializer<'de> {
    type Error = Error;
    type Variant = VariantDeserializer<'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 = VariantDeserializer { value: self.value };
        seed.deserialize(variant).map(|v| (v, visitor))
    }
}

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

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

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

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

    fn unit_variant(self) -> Result<(), Error> {
        match self.value {
            Some(value) => serde::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 {
            Some(Value::List(v)) => {
                if v.is_empty() {
                    visitor.visit_unit()
                } else {
                    visit_list(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 {
            Some(Value::Compound(v)) => visit_compound(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",
            )),
        }
    }
}

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

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

impl<'de> SeqAccess<'de> for SeqDeserializer<'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 MapDeserializer<'de> {
    iter: <&'de HashMap<String, Value> as IntoIterator>::IntoIter,
    value: Option<&'de Value>,
}

impl<'de> MapDeserializer<'de> {
    fn new(map: &'de HashMap<String, Value>) -> Self {
        MapDeserializer {
            iter: map.iter(),
            value: None,
        }
    }
}

impl<'de> MapAccess<'de> for MapDeserializer<'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: Cow::Borrowed(&**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: Cow<'de, str>,
}

macro_rules! deserialize_integer_key {
    ($method:ident => $visit:ident) => {
        fn $method<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match (self.key.parse(), self.key) {
                (Ok(integer), _) => visitor.$visit(integer),
                (Err(_), Cow::Borrowed(s)) => visitor.visit_borrowed_str(s),
                (Err(_), Cow::Owned(s)) => visitor.visit_string(s),
            }
        }
    };
}

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>,
    {
        BorrowedCowStrDeserializer::new(self.key).deserialize_any(visitor)
    }

    deserialize_integer_key!(deserialize_i8 => visit_i8);
    deserialize_integer_key!(deserialize_i16 => visit_i16);
    deserialize_integer_key!(deserialize_i32 => visit_i32);
    deserialize_integer_key!(deserialize_i64 => visit_i64);
    deserialize_integer_key!(deserialize_u8 => visit_u8);
    deserialize_integer_key!(deserialize_u16 => visit_u16);
    deserialize_integer_key!(deserialize_u32 => visit_u32);
    deserialize_integer_key!(deserialize_u64 => visit_u64);
    deserialize_integer_key!(deserialize_i128 => visit_i128);
    deserialize_integer_key!(deserialize_u128 => visit_u128);

    #[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! {
        bool f32 f64 char str string bytes byte_buf unit unit_struct seq tuple
        tuple_struct map struct identifier ignored_any
    }
}

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<'_> {
        match self {
            Value::Byte(v) => Unexpected::Signed(*v as i64),
            Value::Short(v) => Unexpected::Signed(*v as i64),
            Value::Int(v) => Unexpected::Signed(*v as i64),
            Value::Long(v) => Unexpected::Signed(*v),
            Value::Float(v) => Unexpected::Float(*v as f64),
            Value::Double(v) => Unexpected::Float(*v),
            Value::String(v) => Unexpected::Str(v),
            Value::ByteArray(_) => Unexpected::Seq,
            Value::IntArray(_) => Unexpected::Seq,
            Value::LongArray(_) => Unexpected::Seq,
            Value::List(_) => Unexpected::Seq,
            Value::Compound(_) => Unexpected::Map,
        }
    }
}

struct BorrowedCowStrDeserializer<'de> {
    value: Cow<'de, str>,
}

impl<'de> BorrowedCowStrDeserializer<'de> {
    fn new(value: Cow<'de, str>) -> Self {
        BorrowedCowStrDeserializer { value }
    }
}

impl<'de> Deserializer<'de> for BorrowedCowStrDeserializer<'de> {
    type Error = Error;

    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.value {
            Cow::Borrowed(string) => visitor.visit_borrowed_str(string),
            Cow::Owned(string) => visitor.visit_string(string),
        }
    }

    fn deserialize_enum<V>(
        self,
        _name: &str,
        _variants: &'static [&'static str],
        visitor: V,
    ) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        visitor.visit_enum(self)
    }

    forward_to_deserialize_any! {
        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
        bytes byte_buf option unit unit_struct newtype_struct seq tuple
        tuple_struct map struct identifier ignored_any
    }
}

impl<'de> EnumAccess<'de> for BorrowedCowStrDeserializer<'de> {
    type Error = Error;
    type Variant = UnitOnly;

    fn variant_seed<T>(self, seed: T) -> Result<(T::Value, Self::Variant), Error>
    where
        T: DeserializeSeed<'de>,
    {
        let value = seed.deserialize(self)?;
        Ok((value, UnitOnly))
    }
}

struct UnitOnly;

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

    fn unit_variant(self) -> Result<(), Error> {
        Ok(())
    }

    fn newtype_variant_seed<T>(self, _seed: T) -> Result<T::Value, Error>
    where
        T: DeserializeSeed<'de>,
    {
        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>,
    {
        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>,
    {
        Err(serde::de::Error::invalid_type(
            Unexpected::UnitVariant,
            &"struct variant",
        ))
    }
}