feat: early interface with Python

src/home_assistant/object_id.rs

@@ -0,0 +1,35 @@
+use std::{str::FromStr, sync::Arc};
+
+use pyo3::{exceptions::PyValueError, PyErr};
+use snafu::Snafu;
+
+#[derive(Debug, Clone, derive_more::Display)]
+pub struct ObjectId(Arc<str>);
+
+#[derive(Debug, Clone, Snafu)]
+#[snafu(display("expected a lowercase ASCII alphabetical character (i.e. a through z) or an underscore (i.e. _) but encountered {encountered}"))]
+pub struct ObjectIdParsingError {
+    encountered: char,
+}
+
+impl FromStr for ObjectId {
+    type Err = ObjectIdParsingError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        for c in s.chars() {
+            match c {
+                'a'..='z' => {}
+                '_' => {}
+                _ => return Err(ObjectIdParsingError { encountered: c }),
+            }
+        }
+
+        Ok(Self(s.into()))
+    }
+}
+
+impl From<ObjectIdParsingError> for PyErr {
+    fn from(error: ObjectIdParsingError) -> Self {
+        PyValueError::new_err(error.to_string())
+    }
+}