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Diffstat (limited to '')
-rw-r--r-- | third_party/rust/serde_json/src/raw.rs | 531 |
1 files changed, 531 insertions, 0 deletions
diff --git a/third_party/rust/serde_json/src/raw.rs b/third_party/rust/serde_json/src/raw.rs new file mode 100644 index 0000000000..6aa4ffcb61 --- /dev/null +++ b/third_party/rust/serde_json/src/raw.rs @@ -0,0 +1,531 @@ +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>, +/// } +/// ``` +#[cfg_attr(not(doc), repr(transparent))] +#[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())) + } +} |