Introduce typed Parts for the JID to enable unfallible JID construction

jid/src/parts.rs

@@ -0,0 +1,52 @@
+use stringprep::{nameprep, nodeprep, resourceprep};
+
+use crate::Error;
+
+/// The [`NodePart`] is the optional part before the (optional) `@` in any [`Jid`], whether [`BareJid`] or [`FullJid`].
+#[derive(Clone, Debug, PartialEq, Hash, PartialOrd)]
+pub struct NodePart(pub(crate) String);
+
+fn length_check(len: usize, error_empty: Error, error_too_long: Error) -> Result<(), Error> {
+    if len == 0 {
+        Err(error_empty)
+    } else if len > 1023 {
+        Err(error_too_long)
+    } else {
+        Ok(())
+    }
+}
+
+impl NodePart {
+    /// Build a new [`NodePart`] from a string slice. Will fail in case of stringprep validation error.
+    pub fn new(s: &str) -> Result<NodePart, Error> {
+        let node = nodeprep(s).map_err(|_| Error::NodePrep)?;
+        length_check(node.len(), Error::NodeEmpty, Error::NodeTooLong)?;
+        Ok(NodePart(node.to_string()))
+    }
+}
+
+/// The [`DomainPart`] is the part between the (optional) `@` and the (optional) `/` in any [`Jid`], whether [`BareJid`] or [`FullJid`].
+#[derive(Clone, Debug, PartialEq, Hash, PartialOrd)]
+pub struct DomainPart(pub(crate) String);
+
+impl DomainPart {
+    /// Build a new [`DomainPart`] from a string slice. Will fail in case of stringprep validation error.
+    pub fn new(s: &str) -> Result<DomainPart, Error> {
+        let domain = nameprep(s).map_err(|_| Error::NamePrep)?;
+        length_check(domain.len(), Error::DomainEmpty, Error::DomainTooLong)?;
+        Ok(DomainPart(domain.to_string()))
+    }
+}
+
+/// The [`ResourcePart`] is the optional part after the `/` in a [`Jid`]. It is mandatory in [`FullJid`].
+#[derive(Clone, Debug, PartialEq, Hash, PartialOrd)]
+pub struct ResourcePart(pub(crate) String);
+
+impl ResourcePart {
+    /// Build a new [`ResourcePart`] from a string slice. Will fail in case of stringprep validation error.
+    pub fn new(s: &str) -> Result<ResourcePart, Error> {
+        let resource = resourceprep(s).map_err(|_| Error::ResourcePrep)?;
+        length_check(resource.len(), Error::ResourceEmpty, Error::ResourceTooLong)?;
+        Ok(ResourcePart(resource.to_string()))
+    }
+}