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+use crate::error::Error;
+use alloc::borrow::ToOwned;
+use alloc::boxed::Box;
+use alloc::string::String;
+use core::fmt::{self, Debug, Display};
+use core::mem;
+use serde::de::value::BorrowedStrDeserializer;
+use serde::de::{
+ self, Deserialize, DeserializeSeed, Deserializer, IntoDeserializer, MapAccess, Unexpected,
+ Visitor,
+};
+use serde::forward_to_deserialize_any;
+use serde::ser::{Serialize, SerializeStruct, Serializer};
+
+/// Reference to a range of bytes encompassing a single valid JSON value in the
+/// input data.
+///
+/// A `RawValue` can be used to defer parsing parts of a payload until later,
+/// or to avoid parsing it at all in the case that part of the payload just
+/// needs to be transferred verbatim into a different output object.
+///
+/// When serializing, a value of this type will retain its original formatting
+/// and will not be minified or pretty-printed.
+///
+/// # Note
+///
+/// `RawValue` is only available if serde\_json is built with the `"raw_value"`
+/// feature.
+///
+/// ```toml
+/// [dependencies]
+/// serde_json = { version = "1.0", features = ["raw_value"] }
+/// ```
+///
+/// # Example
+///
+/// ```
+/// use serde::{Deserialize, Serialize};
+/// use serde_json::{Result, value::RawValue};
+///
+/// #[derive(Deserialize)]
+/// struct Input<'a> {
+/// code: u32,
+/// #[serde(borrow)]
+/// payload: &'a RawValue,
+/// }
+///
+/// #[derive(Serialize)]
+/// struct Output<'a> {
+/// info: (u32, &'a RawValue),
+/// }
+///
+/// // Efficiently rearrange JSON input containing separate "code" and "payload"
+/// // keys into a single "info" key holding an array of code and payload.
+/// //
+/// // This could be done equivalently using serde_json::Value as the type for
+/// // payload, but &RawValue will perform better because it does not require
+/// // memory allocation. The correct range of bytes is borrowed from the input
+/// // data and pasted verbatim into the output.
+/// fn rearrange(input: &str) -> Result<String> {
+/// let input: Input = serde_json::from_str(input)?;
+///
+/// let output = Output {
+/// info: (input.code, input.payload),
+/// };
+///
+/// serde_json::to_string(&output)
+/// }
+///
+/// fn main() -> Result<()> {
+/// let out = rearrange(r#" {"code": 200, "payload": {}} "#)?;
+///
+/// assert_eq!(out, r#"{"info":[200,{}]}"#);
+///
+/// Ok(())
+/// }
+/// ```
+///
+/// # Ownership
+///
+/// The typical usage of `RawValue` will be in the borrowed form:
+///
+/// ```
+/// # use serde::Deserialize;
+/// # use serde_json::value::RawValue;
+/// #
+/// #[derive(Deserialize)]
+/// struct SomeStruct<'a> {
+/// #[serde(borrow)]
+/// raw_value: &'a RawValue,
+/// }
+/// ```
+///
+/// The borrowed form is suitable when deserializing through
+/// [`serde_json::from_str`] and [`serde_json::from_slice`] which support
+/// borrowing from the input data without memory allocation.
+///
+/// When deserializing through [`serde_json::from_reader`] you will need to use
+/// the boxed form of `RawValue` instead. This is almost as efficient but
+/// involves buffering the raw value from the I/O stream into memory.
+///
+/// [`serde_json::from_str`]: ../fn.from_str.html
+/// [`serde_json::from_slice`]: ../fn.from_slice.html
+/// [`serde_json::from_reader`]: ../fn.from_reader.html
+///
+/// ```
+/// # use serde::Deserialize;
+/// # use serde_json::value::RawValue;
+/// #
+/// #[derive(Deserialize)]
+/// struct SomeStruct {
+/// raw_value: Box<RawValue>,
+/// }
+/// ```
+#[repr(C)]
+#[cfg_attr(docsrs, doc(cfg(feature = "raw_value")))]
+pub struct RawValue {
+ json: str,
+}
+
+impl RawValue {
+ fn from_borrowed(json: &str) -> &Self {
+ unsafe { mem::transmute::<&str, &RawValue>(json) }
+ }
+
+ fn from_owned(json: Box<str>) -> Box<Self> {
+ unsafe { mem::transmute::<Box<str>, Box<RawValue>>(json) }
+ }
+
+ fn into_owned(raw_value: Box<Self>) -> Box<str> {
+ unsafe { mem::transmute::<Box<RawValue>, Box<str>>(raw_value) }
+ }
+}
+
+impl Clone for Box<RawValue> {
+ fn clone(&self) -> Self {
+ (**self).to_owned()
+ }
+}
+
+impl ToOwned for RawValue {
+ type Owned = Box<RawValue>;
+
+ fn to_owned(&self) -> Self::Owned {
+ RawValue::from_owned(self.json.to_owned().into_boxed_str())
+ }
+}
+
+impl Default for Box<RawValue> {
+ fn default() -> Self {
+ RawValue::from_borrowed("null").to_owned()
+ }
+}
+
+impl Debug for RawValue {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_tuple("RawValue")
+ .field(&format_args!("{}", &self.json))
+ .finish()
+ }
+}
+
+impl Display for RawValue {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.write_str(&self.json)
+ }
+}
+
+impl RawValue {
+ /// Convert an owned `String` of JSON data to an owned `RawValue`.
+ ///
+ /// This function is equivalent to `serde_json::from_str::<Box<RawValue>>`
+ /// except that we avoid an allocation and memcpy if both of the following
+ /// are true:
+ ///
+ /// - the input has no leading or trailing whitespace, and
+ /// - the input has capacity equal to its length.
+ pub fn from_string(json: String) -> Result<Box<Self>, Error> {
+ {
+ let borrowed = crate::from_str::<&Self>(&json)?;
+ if borrowed.json.len() < json.len() {
+ return Ok(borrowed.to_owned());
+ }
+ }
+ Ok(Self::from_owned(json.into_boxed_str()))
+ }
+
+ /// Access the JSON text underlying a raw value.
+ ///
+ /// # Example
+ ///
+ /// ```
+ /// use serde::Deserialize;
+ /// use serde_json::{Result, value::RawValue};
+ ///
+ /// #[derive(Deserialize)]
+ /// struct Response<'a> {
+ /// code: u32,
+ /// #[serde(borrow)]
+ /// payload: &'a RawValue,
+ /// }
+ ///
+ /// fn process(input: &str) -> Result<()> {
+ /// let response: Response = serde_json::from_str(input)?;
+ ///
+ /// let payload = response.payload.get();
+ /// if payload.starts_with('{') {
+ /// // handle a payload which is a JSON map
+ /// } else {
+ /// // handle any other type
+ /// }
+ ///
+ /// Ok(())
+ /// }
+ ///
+ /// fn main() -> Result<()> {
+ /// process(r#" {"code": 200, "payload": {}} "#)?;
+ /// Ok(())
+ /// }
+ /// ```
+ pub fn get(&self) -> &str {
+ &self.json
+ }
+}
+
+impl From<Box<RawValue>> for Box<str> {
+ fn from(raw_value: Box<RawValue>) -> Self {
+ RawValue::into_owned(raw_value)
+ }
+}
+
+/// Convert a `T` into a boxed `RawValue`.
+///
+/// # Example
+///
+/// ```
+/// // Upstream crate
+/// # #[derive(Serialize)]
+/// pub struct Thing {
+/// foo: String,
+/// bar: Option<String>,
+/// extra_data: Box<RawValue>,
+/// }
+///
+/// // Local crate
+/// use serde::Serialize;
+/// use serde_json::value::{to_raw_value, RawValue};
+///
+/// #[derive(Serialize)]
+/// struct MyExtraData {
+/// a: u32,
+/// b: u32,
+/// }
+///
+/// let my_thing = Thing {
+/// foo: "FooVal".into(),
+/// bar: None,
+/// extra_data: to_raw_value(&MyExtraData { a: 1, b: 2 }).unwrap(),
+/// };
+/// # assert_eq!(
+/// # serde_json::to_value(my_thing).unwrap(),
+/// # serde_json::json!({
+/// # "foo": "FooVal",
+/// # "bar": null,
+/// # "extra_data": { "a": 1, "b": 2 }
+/// # })
+/// # );
+/// ```
+///
+/// # Errors
+///
+/// This conversion can fail if `T`'s implementation of `Serialize` decides to
+/// fail, or if `T` contains a map with non-string keys.
+///
+/// ```
+/// use std::collections::BTreeMap;
+///
+/// // The keys in this map are vectors, not strings.
+/// let mut map = BTreeMap::new();
+/// map.insert(vec![32, 64], "x86");
+///
+/// println!("{}", serde_json::value::to_raw_value(&map).unwrap_err());
+/// ```
+#[cfg_attr(docsrs, doc(cfg(feature = "raw_value")))]
+pub fn to_raw_value<T>(value: &T) -> Result<Box<RawValue>, Error>
+where
+ T: ?Sized + Serialize,
+{
+ let json_string = crate::to_string(value)?;
+ Ok(RawValue::from_owned(json_string.into_boxed_str()))
+}
+
+pub const TOKEN: &str = "$serde_json::private::RawValue";
+
+impl Serialize for RawValue {
+ fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+ where
+ S: Serializer,
+ {
+ let mut s = serializer.serialize_struct(TOKEN, 1)?;
+ s.serialize_field(TOKEN, &self.json)?;
+ s.end()
+ }
+}
+
+impl<'de: 'a, 'a> Deserialize<'de> for &'a RawValue {
+ fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+ where
+ D: Deserializer<'de>,
+ {
+ struct ReferenceVisitor;
+
+ impl<'de> Visitor<'de> for ReferenceVisitor {
+ type Value = &'de RawValue;
+
+ fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ write!(formatter, "any valid JSON value")
+ }
+
+ fn visit_map<V>(self, mut visitor: V) -> Result<Self::Value, V::Error>
+ where
+ V: MapAccess<'de>,
+ {
+ let value = visitor.next_key::<RawKey>()?;
+ if value.is_none() {
+ return Err(de::Error::invalid_type(Unexpected::Map, &self));
+ }
+ visitor.next_value_seed(ReferenceFromString)
+ }
+ }
+
+ deserializer.deserialize_newtype_struct(TOKEN, ReferenceVisitor)
+ }
+}
+
+impl<'de> Deserialize<'de> for Box<RawValue> {
+ fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+ where
+ D: Deserializer<'de>,
+ {
+ struct BoxedVisitor;
+
+ impl<'de> Visitor<'de> for BoxedVisitor {
+ type Value = Box<RawValue>;
+
+ fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ write!(formatter, "any valid JSON value")
+ }
+
+ fn visit_map<V>(self, mut visitor: V) -> Result<Self::Value, V::Error>
+ where
+ V: MapAccess<'de>,
+ {
+ let value = visitor.next_key::<RawKey>()?;
+ if value.is_none() {
+ return Err(de::Error::invalid_type(Unexpected::Map, &self));
+ }
+ visitor.next_value_seed(BoxedFromString)
+ }
+ }
+
+ deserializer.deserialize_newtype_struct(TOKEN, BoxedVisitor)
+ }
+}
+
+struct RawKey;
+
+impl<'de> Deserialize<'de> for RawKey {
+ fn deserialize<D>(deserializer: D) -> Result<RawKey, D::Error>
+ where
+ D: Deserializer<'de>,
+ {
+ struct FieldVisitor;
+
+ impl<'de> Visitor<'de> for FieldVisitor {
+ type Value = ();
+
+ fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter.write_str("raw value")
+ }
+
+ fn visit_str<E>(self, s: &str) -> Result<(), E>
+ where
+ E: de::Error,
+ {
+ if s == TOKEN {
+ Ok(())
+ } else {
+ Err(de::Error::custom("unexpected raw value"))
+ }
+ }
+ }
+
+ deserializer.deserialize_identifier(FieldVisitor)?;
+ Ok(RawKey)
+ }
+}
+
+pub struct ReferenceFromString;
+
+impl<'de> DeserializeSeed<'de> for ReferenceFromString {
+ type Value = &'de RawValue;
+
+ fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
+ where
+ D: Deserializer<'de>,
+ {
+ deserializer.deserialize_str(self)
+ }
+}
+
+impl<'de> Visitor<'de> for ReferenceFromString {
+ type Value = &'de RawValue;
+
+ fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter.write_str("raw value")
+ }
+
+ fn visit_borrowed_str<E>(self, s: &'de str) -> Result<Self::Value, E>
+ where
+ E: de::Error,
+ {
+ Ok(RawValue::from_borrowed(s))
+ }
+}
+
+pub struct BoxedFromString;
+
+impl<'de> DeserializeSeed<'de> for BoxedFromString {
+ type Value = Box<RawValue>;
+
+ fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
+ where
+ D: Deserializer<'de>,
+ {
+ deserializer.deserialize_str(self)
+ }
+}
+
+impl<'de> Visitor<'de> for BoxedFromString {
+ type Value = Box<RawValue>;
+
+ fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter.write_str("raw value")
+ }
+
+ fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+ where
+ E: de::Error,
+ {
+ Ok(RawValue::from_owned(s.to_owned().into_boxed_str()))
+ }
+
+ #[cfg(any(feature = "std", feature = "alloc"))]
+ fn visit_string<E>(self, s: String) -> Result<Self::Value, E>
+ where
+ E: de::Error,
+ {
+ Ok(RawValue::from_owned(s.into_boxed_str()))
+ }
+}
+
+struct RawKeyDeserializer;
+
+impl<'de> Deserializer<'de> for RawKeyDeserializer {
+ type Error = Error;
+
+ fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
+ where
+ V: de::Visitor<'de>,
+ {
+ visitor.visit_borrowed_str(TOKEN)
+ }
+
+ forward_to_deserialize_any! {
+ bool u8 u16 u32 u64 u128 i8 i16 i32 i64 i128 f32 f64 char str string seq
+ bytes byte_buf map struct option unit newtype_struct ignored_any
+ unit_struct tuple_struct tuple enum identifier
+ }
+}
+
+pub struct OwnedRawDeserializer {
+ pub raw_value: Option<String>,
+}
+
+impl<'de> MapAccess<'de> for OwnedRawDeserializer {
+ type Error = Error;
+
+ fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Error>
+ where
+ K: de::DeserializeSeed<'de>,
+ {
+ if self.raw_value.is_none() {
+ return Ok(None);
+ }
+ seed.deserialize(RawKeyDeserializer).map(Some)
+ }
+
+ fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Error>
+ where
+ V: de::DeserializeSeed<'de>,
+ {
+ seed.deserialize(self.raw_value.take().unwrap().into_deserializer())
+ }
+}
+
+pub struct BorrowedRawDeserializer<'de> {
+ pub raw_value: Option<&'de str>,
+}
+
+impl<'de> MapAccess<'de> for BorrowedRawDeserializer<'de> {
+ type Error = Error;
+
+ fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Error>
+ where
+ K: de::DeserializeSeed<'de>,
+ {
+ if self.raw_value.is_none() {
+ return Ok(None);
+ }
+ seed.deserialize(RawKeyDeserializer).map(Some)
+ }
+
+ fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Error>
+ where
+ V: de::DeserializeSeed<'de>,
+ {
+ seed.deserialize(BorrowedStrDeserializer::new(self.raw_value.take().unwrap()))
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-09 16:16:47 +0000