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// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
//! Provides the [`DeserializingBufferProvider`] wrapper, which deserializes data using Serde.
//!
//! Providers that produce opaque buffers that need to be deserialized into concrete data structs,
//! such as `FsDataProvider`, should implement [`BufferProvider`]. These can be converted into
//! [`DeserializingBufferProvider`] using the [`as_deserializing`](AsDeserializingBufferProvider::as_deserializing)
//! convenience method.
//!
//! [`BufferProvider`]: crate::buf::BufferProvider
// Hidden for now, but could be made public-stable in the future.
#[doc(hidden)]
pub mod borrow_de_utils;
use crate::buf::BufferFormat;
use crate::buf::BufferProvider;
use crate::prelude::*;
use serde::de::Deserialize;
use yoke::trait_hack::YokeTraitHack;
use yoke::Yokeable;
/// A [`BufferProvider`] that deserializes its data using Serde.
#[derive(Debug)]
pub struct DeserializingBufferProvider<'a, P: ?Sized>(&'a P);
/// Blanket-implemented trait adding the [`Self::as_deserializing()`] function.
pub trait AsDeserializingBufferProvider {
/// Wrap this [`BufferProvider`] in a [`DeserializingBufferProvider`].
///
/// This requires enabling the deserialization Cargo feature
/// for the expected format(s):
///
/// - `deserialize_json`
/// - `deserialize_postcard_1`
/// - `deserialize_bincode_1`
fn as_deserializing(&self) -> DeserializingBufferProvider<Self>;
}
impl<P> AsDeserializingBufferProvider for P
where
P: BufferProvider + ?Sized,
{
/// Wrap this [`BufferProvider`] in a [`DeserializingBufferProvider`].
///
/// This requires enabling the deserialization Cargo feature
/// for the expected format(s):
///
/// - `deserialize_json`
/// - `deserialize_postcard_1`
/// - `deserialize_bincode_1`
fn as_deserializing(&self) -> DeserializingBufferProvider<Self> {
DeserializingBufferProvider(self)
}
}
fn deserialize_impl<'data, M>(
// Allow `bytes` to be unused in case all buffer formats are disabled
#[allow(unused_variables)] bytes: &'data [u8],
buffer_format: BufferFormat,
) -> Result<<M::Yokeable as Yokeable<'data>>::Output, DataError>
where
M: DataMarker,
// Actual bound:
// for<'de> <M::Yokeable as Yokeable<'de>>::Output: Deserialize<'de>,
// Necessary workaround bound (see `yoke::trait_hack` docs):
for<'de> YokeTraitHack<<M::Yokeable as Yokeable<'de>>::Output>: Deserialize<'de>,
{
match buffer_format {
#[cfg(feature = "deserialize_json")]
BufferFormat::Json => {
let mut d = serde_json::Deserializer::from_slice(bytes);
let data = YokeTraitHack::<<M::Yokeable as Yokeable>::Output>::deserialize(&mut d)?;
Ok(data.0)
}
#[cfg(feature = "deserialize_bincode_1")]
BufferFormat::Bincode1 => {
use bincode::Options;
let options = bincode::DefaultOptions::new()
.with_fixint_encoding()
.allow_trailing_bytes();
let mut d = bincode::de::Deserializer::from_slice(bytes, options);
let data = YokeTraitHack::<<M::Yokeable as Yokeable>::Output>::deserialize(&mut d)?;
Ok(data.0)
}
#[cfg(feature = "deserialize_postcard_1")]
BufferFormat::Postcard1 => {
let mut d = postcard::Deserializer::from_bytes(bytes);
let data = YokeTraitHack::<<M::Yokeable as Yokeable>::Output>::deserialize(&mut d)?;
Ok(data.0)
}
// Allowed for cases in which all features are enabled
#[allow(unreachable_patterns)]
_ => Err(DataErrorKind::UnavailableBufferFormat(buffer_format).into_error()),
}
}
impl DataPayload<BufferMarker> {
/// Deserialize a [`DataPayload`]`<`[`BufferMarker`]`>` into a [`DataPayload`] of a
/// specific concrete type.
///
/// This requires enabling the deserialization Cargo feature
/// for the expected format(s):
///
/// - `deserialize_json`
/// - `deserialize_postcard_1`
/// - `deserialize_bincode_1`
///
/// This function takes the buffer format as an argument. When a buffer payload is returned
/// from a data provider, the buffer format is stored in the [`DataResponseMetadata`].
///
/// # Examples
///
/// Requires the `deserialize_json` Cargo feature:
///
/// ```
/// use icu_provider::buf::BufferFormat;
/// use icu_provider::hello_world::*;
/// use icu_provider::prelude::*;
///
/// let buffer: &[u8] = br#"{"message":"Hallo Welt"}"#;
///
/// let buffer_payload = DataPayload::from_owned(buffer);
/// let payload: DataPayload<HelloWorldV1Marker> = buffer_payload
/// .into_deserialized(BufferFormat::Json)
/// .expect("Deserialization successful");
///
/// assert_eq!(payload.get().message, "Hallo Welt");
/// ```
pub fn into_deserialized<M>(
self,
buffer_format: BufferFormat,
) -> Result<DataPayload<M>, DataError>
where
M: DataMarker,
// Actual bound:
// for<'de> <M::Yokeable as Yokeable<'de>>::Output: Deserialize<'de>,
// Necessary workaround bound (see `yoke::trait_hack` docs):
for<'de> YokeTraitHack<<M::Yokeable as Yokeable<'de>>::Output>: Deserialize<'de>,
{
self.try_map_project(|bytes, _| deserialize_impl::<M>(bytes, buffer_format))
}
}
impl<P, M> DynamicDataProvider<M> for DeserializingBufferProvider<'_, P>
where
M: DataMarker,
P: BufferProvider + ?Sized,
// Actual bound:
// for<'de> <M::Yokeable as Yokeable<'de>>::Output: serde::de::Deserialize<'de>,
// Necessary workaround bound (see `yoke::trait_hack` docs):
for<'de> YokeTraitHack<<M::Yokeable as Yokeable<'de>>::Output>: Deserialize<'de>,
{
/// Converts a buffer into a concrete type by deserializing from a supported buffer format.
///
/// This requires enabling the deserialization Cargo feature
/// for the expected format(s):
///
/// - `deserialize_json`
/// - `deserialize_postcard_1`
/// - `deserialize_bincode_1`
fn load_data(&self, key: DataKey, req: DataRequest) -> Result<DataResponse<M>, DataError> {
let buffer_response = BufferProvider::load_buffer(self.0, key, req)?;
let buffer_format = buffer_response.metadata.buffer_format.ok_or_else(|| {
DataError::custom("BufferProvider didn't set BufferFormat").with_req(key, req)
})?;
Ok(DataResponse {
metadata: buffer_response.metadata,
payload: buffer_response
.payload
.map(|p| p.into_deserialized(buffer_format))
.transpose()
.map_err(|e| e.with_req(key, req))?,
})
}
}
impl<P, M> DataProvider<M> for DeserializingBufferProvider<'_, P>
where
M: KeyedDataMarker,
P: BufferProvider + ?Sized,
// Actual bound:
// for<'de> <M::Yokeable as Yokeable<'de>>::Output: Deserialize<'de>,
// Necessary workaround bound (see `yoke::trait_hack` docs):
for<'de> YokeTraitHack<<M::Yokeable as Yokeable<'de>>::Output>: Deserialize<'de>,
{
/// Converts a buffer into a concrete type by deserializing from a supported buffer format.
///
/// This requires enabling the deserialization Cargo feature
/// for the expected format(s):
///
/// - `deserialize_json`
/// - `deserialize_postcard_1`
/// - `deserialize_bincode_1`
fn load(&self, req: DataRequest) -> Result<DataResponse<M>, DataError> {
self.load_data(M::KEY, req)
}
}
#[cfg(feature = "deserialize_json")]
impl From<serde_json::error::Error> for crate::DataError {
fn from(e: serde_json::error::Error) -> Self {
crate::DataError::custom("JSON deserialize").with_display_context(&e)
}
}
#[cfg(feature = "deserialize_bincode_1")]
impl From<bincode::Error> for crate::DataError {
fn from(e: bincode::Error) -> Self {
crate::DataError::custom("Bincode deserialize").with_display_context(&e)
}
}
#[cfg(feature = "deserialize_postcard_1")]
impl From<postcard::Error> for crate::DataError {
fn from(e: postcard::Error) -> Self {
crate::DataError::custom("Postcard deserialize").with_display_context(&e)
}
}