split / cleanup core utils.

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/json.rs

@@ -0,0 +1,39 @@
+use std::{fmt, str::FromStr};
+
+use ruma::{canonical_json::try_from_json_map, CanonicalJsonError, CanonicalJsonObject};
+
+use crate::Result;
+
+/// Fallible conversion from any value that implements `Serialize` to a
+/// `CanonicalJsonObject`.
+///
+/// `value` must serialize to an `serde_json::Value::Object`.
+pub fn to_canonical_object<T: serde::Serialize>(value: T) -> Result<CanonicalJsonObject, CanonicalJsonError> {
+	use serde::ser::Error;
+
+	match serde_json::to_value(value).map_err(CanonicalJsonError::SerDe)? {
+		serde_json::Value::Object(map) => try_from_json_map(map),
+		_ => Err(CanonicalJsonError::SerDe(serde_json::Error::custom("Value must be an object"))),
+	}
+}
+
+pub fn deserialize_from_str<'de, D: serde::de::Deserializer<'de>, T: FromStr<Err = E>, E: fmt::Display>(
+	deserializer: D,
+) -> Result<T, D::Error> {
+	struct Visitor<T: FromStr<Err = E>, E>(std::marker::PhantomData<T>);
+	impl<T: FromStr<Err = Err>, Err: fmt::Display> serde::de::Visitor<'_> for Visitor<T, Err> {
+		type Value = T;
+
+		fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+			write!(formatter, "a parsable string")
+		}
+
+		fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
+		where
+			E: serde::de::Error,
+		{
+			v.parse().map_err(serde::de::Error::custom)
+		}
+	}
+	deserializer.deserialize_str(Visitor(std::marker::PhantomData))
+}