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    use crate::error::Error;
    use crate::map::Map;
    use crate::number::Number;
    use crate::value::Value;
    use alloc::borrow::{Cow, ToOwned};
    use alloc::string::String;
    #[cfg(feature = "raw_value")]
    use alloc::string::ToString;
    use alloc::vec::{self, Vec};
    use core::fmt;
    use core::slice;
    use core::str::FromStr;
    use serde::de::{
        self, Deserialize, DeserializeSeed, EnumAccess, Expected, IntoDeserializer, MapAccess,
        SeqAccess, Unexpected, VariantAccess, Visitor,
    };
    use serde::forward_to_deserialize_any;

    #[cfg(feature = "arbitrary_precision")]
    use crate::number::NumberFromString;

    impl<'de> Deserialize<'de> for Value {
        #[inline]
        fn deserialize<D>(deserializer: D) -> Result<Value, D::Error>
        where
            D: serde::Deserializer<'de>,
        {
            struct ValueVisitor;

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

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

                #[inline]
                fn visit_bool<E>(self, value: bool) -> Result<Value, E> {
                    Ok(Value::Bool(value))
                }

                #[inline]
                fn visit_i64<E>(self, value: i64) -> Result<Value, E> {
                    Ok(Value::Number(value.into()))
                }

                #[inline]
                fn visit_u64<E>(self, value: u64) -> Result<Value, E> {
                    Ok(Value::Number(value.into()))
                }

                #[inline]
                fn visit_f64<E>(self, value: f64) -> Result<Value, E> {
                    Ok(Number::from_f64(value).map_or(Value::Null, Value::Number))
                }

                #[cfg(any(feature = "std", feature = "alloc"))]
                #[inline]
                fn visit_str<E>(self, value: &str) -> Result<Value, E>
                where
                    E: serde::de::Error,
                {
                    self.visit_string(String::from(value))
                }

                #[cfg(any(feature = "std", feature = "alloc"))]
                #[inline]
                fn visit_string<E>(self, value: String) -> Result<Value, E> {
                    Ok(Value::String(value))
                }

                #[inline]
                fn visit_none<E>(self) -> Result<Value, E> {
                    Ok(Value::Null)
                }

                #[inline]
                fn visit_some<D>(self, deserializer: D) -> Result<Value, D::Error>
                where
                    D: serde::Deserializer<'de>,
                {
                    Deserialize::deserialize(deserializer)
                }

                #[inline]
                fn visit_unit<E>(self) -> Result<Value, E> {
                    Ok(Value::Null)
                }

                #[inline]
                fn visit_seq<V>(self, mut visitor: V) -> Result<Value, V::Error>
                where
                    V: SeqAccess<'de>,
                {
                    let mut vec = Vec::new();

                    while let Some(elem) = tri!(visitor.next_element()) {
                        vec.push(elem);
                    }

                    Ok(Value::Array(vec))
                }

                #[cfg(any(feature = "std", feature = "alloc"))]
                fn visit_map<V>(self, mut visitor: V) -> Result<Value, V::Error>
                where
                    V: MapAccess<'de>,
                {
                    match visitor.next_key_seed(KeyClassifier)? {
                        #[cfg(feature = "arbitrary_precision")]
                        Some(KeyClass::Number) => {
                            let number: NumberFromString = visitor.next_value()?;
                            Ok(Value::Number(number.value))
                        }
                        #[cfg(feature = "raw_value")]
                        Some(KeyClass::RawValue) => {
                            let value = visitor.next_value_seed(crate::raw::BoxedFromString)?;
                            crate::from_str(value.get()).map_err(de::Error::custom)
                        }
                        Some(KeyClass::Map(first_key)) => {
                            let mut values = Map::new();

                            values.insert(first_key, tri!(visitor.next_value()));
                            while let Some((key, value)) = tri!(visitor.next_entry()) {
                                values.insert(key, value);
                            }

                            Ok(Value::Object(values))
                        }
                        None => Ok(Value::Object(Map::new())),
                    }
                }
            }

            deserializer.deserialize_any(ValueVisitor)
        }
    }

    impl FromStr for Value {
        type Err = Error;
        fn from_str(s: &str) -> Result<Value, Error> {
            super::super::de::from_str(s)
        }
    }

    macro_rules! deserialize_number {
        ($method:ident) => {
            #[cfg(not(feature = "arbitrary_precision"))]
            fn $method<V>(self, visitor: V) -> Result<V::Value, Error>
            where
                V: Visitor<'de>,
            {
                match self {
                    Value::Number(n) => n.deserialize_any(visitor),
                    _ => Err(self.invalid_type(&visitor)),
                }
            }

            #[cfg(feature = "arbitrary_precision")]
            fn $method<V>(self, visitor: V) -> Result<V::Value, Error>
            where
                V: Visitor<'de>,
            {
                match self {
                    Value::Number(n) => n.$method(visitor),
                    _ => self.deserialize_any(visitor),
                }
            }
        };
    }

    fn visit_array<'de, V>(array: Vec<Value>, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        let len = array.len();
        let mut deserializer = SeqDeserializer::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<'de, V>(object: Map<String, Value>, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        let len = object.len();
        let mut deserializer = MapDeserializer::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",
            ))
        }
    }

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

        #[inline]
        fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match self {
                Value::Null => visitor.visit_unit(),
                Value::Bool(v) => visitor.visit_bool(v),
                Value::Number(n) => n.deserialize_any(visitor),
                #[cfg(any(feature = "std", feature = "alloc"))]
                Value::String(v) => visitor.visit_string(v),
                Value::Array(v) => visit_array(v, visitor),
                Value::Object(v) => visit_object(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);

        #[inline]
        fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match self {
                Value::Null => visitor.visit_none(),
                _ => 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::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))
                }
                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>,
        {
            #[cfg(feature = "raw_value")]
            {
                if name == crate::raw::TOKEN {
                    return visitor.visit_map(crate::raw::OwnedRawDeserializer {
                        raw_value: Some(self.to_string()),
                    });
                }
            }

            let _ = name;
            visitor.visit_newtype_struct(self)
        }

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

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

        fn deserialize_string<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match self {
                #[cfg(any(feature = "std", feature = "alloc"))]
                Value::String(v) => visitor.visit_string(v),
                _ => Err(self.invalid_type(&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 {
                #[cfg(any(feature = "std", feature = "alloc"))]
                Value::String(v) => visitor.visit_string(v),
                Value::Array(v) => visit_array(v, visitor),
                _ => Err(self.invalid_type(&visitor)),
            }
        }

        fn deserialize_unit<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match self {
                Value::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 {
                Value::Array(v) => visit_array(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 {
                Value::Object(v) => visit_object(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 {
                Value::Array(v) => visit_array(v, visitor),
                Value::Object(v) => visit_object(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>,
        {
            drop(self);
            visitor.visit_unit()
        }
    }

    struct EnumDeserializer {
        variant: String,
        value: Option<Value>,
    }

    impl<'de> EnumAccess<'de> for EnumDeserializer {
        type Error = Error;
        type Variant = VariantDeserializer;

        fn variant_seed<V>(self, seed: V) -> Result<(V::Value, VariantDeserializer), 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 Value {
        type Deserializer = Self;

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

    struct VariantDeserializer {
        value: Option<Value>,
    }

    impl<'de> VariantAccess<'de> for VariantDeserializer {
        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 {
                Some(Value::Array(v)) => {
                    if v.is_empty() {
                        visitor.visit_unit()
                    } else {
                        visit_array(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::Object(v)) => visit_object(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 {
        iter: vec::IntoIter<Value>,
    }

    impl SeqDeserializer {
        fn new(vec: Vec<Value>) -> Self {
            SeqDeserializer {
                iter: vec.into_iter(),
            }
        }
    }

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

    impl MapDeserializer {
        fn new(map: Map<String, Value>) -> Self {
            MapDeserializer {
                iter: map.into_iter(),
                value: None,
            }
        }
    }

    impl<'de> MapAccess<'de> for MapDeserializer {
        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::Owned(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,
            }
        }
    }

    macro_rules! deserialize_value_ref_number {
        ($method:ident) => {
            #[cfg(not(feature = "arbitrary_precision"))]
            fn $method<V>(self, visitor: V) -> Result<V::Value, Error>
            where
                V: Visitor<'de>,
            {
                match self {
                    Value::Number(n) => n.deserialize_any(visitor),
                    _ => Err(self.invalid_type(&visitor)),
                }
            }

            #[cfg(feature = "arbitrary_precision")]
            fn $method<V>(self, visitor: V) -> Result<V::Value, Error>
            where
                V: Visitor<'de>,
            {
                match self {
                    Value::Number(n) => n.$method(visitor),
                    _ => self.deserialize_any(visitor),
                }
            }
        };
    }

    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 Map<String, Value>, 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",
            ))
        }
    }

    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 {
                Value::Null => visitor.visit_unit(),
                Value::Bool(v) => visitor.visit_bool(*v),
                Value::Number(n) => n.deserialize_any(visitor),
                Value::String(v) => visitor.visit_borrowed_str(v),
                Value::Array(v) => visit_array_ref(v, visitor),
                Value::Object(v) => visit_object_ref(v, visitor),
            }
        }

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

        fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match *self {
                Value::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 {
                Value::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))
                }
                Value::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>,
        {
            #[cfg(feature = "raw_value")]
            {
                if name == crate::raw::TOKEN {
                    return visitor.visit_map(crate::raw::OwnedRawDeserializer {
                        raw_value: Some(self.to_string()),
                    });
                }
            }

            let _ = name;
            visitor.visit_newtype_struct(self)
        }

        fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: Visitor<'de>,
        {
            match *self {
                Value::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 {
                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>,
        {
            match self {
                Value::String(v) => visitor.visit_borrowed_str(v),
                Value::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 {
                Value::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 {
                Value::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 {
                Value::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 {
                Value::Array(v) => visit_array_ref(v, visitor),
                Value::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()
        }
    }

    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 {
                Some(Value::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 {
                Some(Value::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",
                )),
            }
        }
    }

    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 Map<String, Value> as IntoIterator>::IntoIter,
        value: Option<&'de Value>,
    }

    impl<'de> MapRefDeserializer<'de> {
        fn new(map: &'de Map<String, Value>) -> 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: 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),
                    #[cfg(any(feature = "std", feature = "alloc"))]
                    (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_i128 => visit_i128);
        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_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
        }
    }

    struct KeyClassifier;

    enum KeyClass {
        Map(String),
        #[cfg(feature = "arbitrary_precision")]
        Number,
        #[cfg(feature = "raw_value")]
        RawValue,
    }

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

        fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, 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 fmt::Formatter) -> fmt::Result {
            formatter.write_str("a string key")
        }

        fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            match s {
                #[cfg(feature = "arbitrary_precision")]
                crate::number::TOKEN => Ok(KeyClass::Number),
                #[cfg(feature = "raw_value")]
                crate::raw::TOKEN => Ok(KeyClass::RawValue),
                _ => Ok(KeyClass::Map(s.to_owned())),
            }
        }

        #[cfg(any(feature = "std", feature = "alloc"))]
        fn visit_string<E>(self, s: String) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            match s.as_str() {
                #[cfg(feature = "arbitrary_precision")]
                crate::number::TOKEN => Ok(KeyClass::Number),
                #[cfg(feature = "raw_value")]
                crate::raw::TOKEN => Ok(KeyClass::RawValue),
                _ => Ok(KeyClass::Map(s)),
            }
        }
    }

    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::Null => Unexpected::Unit,
                Value::Bool(b) => Unexpected::Bool(*b),
                Value::Number(n) => n.unexpected(),
                Value::String(s) => Unexpected::Str(s),
                Value::Array(_) => Unexpected::Seq,
                Value::Object(_) => Unexpected::Map,
            }
        }
    }

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

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

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

        fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
        where
            V: de::Visitor<'de>,
        {
            match self.value {
                Cow::Borrowed(string) => visitor.visit_borrowed_str(string),
                #[cfg(any(feature = "std", feature = "alloc"))]
                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: de::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> 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: de::DeserializeSeed<'de>,
        {
            let value = seed.deserialize(self)?;
            Ok((value, UnitOnly))
        }
    }

    struct UnitOnly;

    impl<'de> 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: de::DeserializeSeed<'de>,
        {
            Err(de::Error::invalid_type(
                Unexpected::UnitVariant,
                &"newtype variant",
            ))
        }

        fn tuple_variant<V>(self, _len: usize, _visitor: V) -> Result<V::Value, Error>
        where
            V: de::Visitor<'de>,
        {
            Err(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: de::Visitor<'de>,
        {
            Err(de::Error::invalid_type(
                Unexpected::UnitVariant,
                &"struct variant",
            ))
        }
    }