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use derive_more::From;
use serde::{Deserialize, Serialize};
/// Represents a wrapper around a message, supporting single and batch payloads.
#[derive(Clone, Debug, From, PartialEq, Eq, Serialize, Deserialize)]
#[serde(untagged)]
pub enum Msg<T> {
Single(T),
Batch(Vec<T>),
}
impl<T> Msg<T> {
/// Creates a new msg with a singular payload.
#[inline]
pub fn single(payload: T) -> Self {
Self::Single(payload)
}
/// Creates a new msg with a batch payload.
pub fn batch<I>(payloads: I) -> Self
where
I: IntoIterator<Item = T>,
{
Self::Batch(payloads.into_iter().collect())
}
/// Returns true if msg has a single payload.
#[inline]
pub fn is_single(&self) -> bool {
matches!(self, Self::Single(_))
}
/// Returns reference to single value if msg is single variant.
#[inline]
pub fn as_single(&self) -> Option<&T> {
match self {
Self::Single(x) => Some(x),
_ => None,
}
}
/// Returns mutable reference to single value if msg is single variant.
#[inline]
pub fn as_mut_single(&mut self) -> Option<&T> {
match self {
Self::Single(x) => Some(x),
_ => None,
}
}
/// Returns the single value if msg is single variant.
#[inline]
pub fn into_single(self) -> Option<T> {
match self {
Self::Single(x) => Some(x),
_ => None,
}
}
/// Returns true if msg has a batch of payloads.
#[inline]
pub fn is_batch(&self) -> bool {
matches!(self, Self::Batch(_))
}
/// Returns reference to batch value if msg is batch variant.
#[inline]
pub fn as_batch(&self) -> Option<&[T]> {
match self {
Self::Batch(x) => Some(x),
_ => None,
}
}
/// Returns mutable reference to batch value if msg is batch variant.
#[inline]
pub fn as_mut_batch(&mut self) -> Option<&mut [T]> {
match self {
Self::Batch(x) => Some(x),
_ => None,
}
}
/// Returns the batch value if msg is batch variant.
#[inline]
pub fn into_batch(self) -> Option<Vec<T>> {
match self {
Self::Batch(x) => Some(x),
_ => None,
}
}
/// Convert into a collection of payload data.
#[inline]
pub fn into_vec(self) -> Vec<T> {
match self {
Self::Single(x) => vec![x],
Self::Batch(x) => x,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
mod single {
use super::*;
#[test]
fn should_be_able_to_serialize_to_json() {
let msg = Msg::single("hello world");
let value = serde_json::to_value(msg).unwrap();
assert_eq!(value, serde_json::json!("hello world"));
}
#[test]
fn should_be_able_to_deserialize_from_json() {
let value = serde_json::json!("hello world");
let msg: Msg<String> = serde_json::from_value(value).unwrap();
assert_eq!(msg, Msg::single(String::from("hello world")));
}
#[test]
fn should_be_able_to_serialize_to_msgpack() {
let msg = Msg::single("hello world");
// NOTE: We don't actually check the output here because it's an implementation detail
// and could change as we change how serialization is done. This is merely to verify
// that we can serialize since there are times when serde fails to serialize at
// runtime.
let _ = rmp_serde::encode::to_vec_named(&msg).unwrap();
}
#[test]
fn should_be_able_to_deserialize_from_msgpack() {
// NOTE: It may seem odd that we are serializing just to deserialize, but this is to
// verify that we are not corrupting or causing issues when serializing on a
// client/server and then trying to deserialize on the other side. This has happened
// enough times with minor changes that we need tests to verify.
let buf = rmp_serde::encode::to_vec_named(&Msg::single("hello world")).unwrap();
let msg: Msg<String> = rmp_serde::decode::from_slice(&buf).unwrap();
assert_eq!(msg, Msg::single(String::from("hello world")));
}
}
mod batch {
use super::*;
#[test]
fn should_be_able_to_serialize_to_json() {
let msg = Msg::batch(["hello world"]);
let value = serde_json::to_value(msg).unwrap();
assert_eq!(value, serde_json::json!(["hello world"]));
}
#[test]
fn should_be_able_to_deserialize_from_json() {
let value = serde_json::json!(["hello world"]);
let msg: Msg<String> = serde_json::from_value(value).unwrap();
assert_eq!(msg, Msg::batch([String::from("hello world")]));
}
#[test]
fn should_be_able_to_serialize_to_msgpack() {
let msg = Msg::batch(["hello world"]);
// NOTE: We don't actually check the output here because it's an implementation detail
// and could change as we change how serialization is done. This is merely to verify
// that we can serialize since there are times when serde fails to serialize at
// runtime.
let _ = rmp_serde::encode::to_vec_named(&msg).unwrap();
}
#[test]
fn should_be_able_to_deserialize_from_msgpack() {
// NOTE: It may seem odd that we are serializing just to deserialize, but this is to
// verify that we are not corrupting or causing issues when serializing on a
// client/server and then trying to deserialize on the other side. This has happened
// enough times with minor changes that we need tests to verify.
let buf = rmp_serde::encode::to_vec_named(&Msg::batch(["hello world"])).unwrap();
let msg: Msg<String> = rmp_serde::decode::from_slice(&buf).unwrap();
assert_eq!(msg, Msg::batch([String::from("hello world")]));
}
}
}