Guess I should put this under version control LOL

lifecycle/src/rsx/style_keys.rs

@@ -0,0 +1,83 @@
+//! A valid CSS class.
+//!
+//! A CSS class is a non-empty string that starts with an alphanumeric character
+//! and is followed by any number of alphanumeric characters and the
+//! `_`, `-` and `.` characters.
+
+use std::fmt::{Display, Error, Formatter};
+use std::ops::Deref;
+use std::str::FromStr;
+
+/// A valid CSS class.
+///
+/// A CSS class is a non-empty string that starts with an alphanumeric character
+/// and is followed by any number of alphanumeric characters and the
+/// `_`, `-` and `.` characters.
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub struct StyleKey(String);
+
+impl StyleKey {
+    /// Construct a new styles list from a string.
+    ///
+    /// Returns `Err` if the provided string is invalid.
+    pub fn try_new<S: Into<String>>(id: S) -> Result<Self, &'static str> {
+        let id = id.into();
+        {
+            let mut chars = id.chars();
+            match chars.next() {
+                None => return Err("style keys cannot be empty"),
+                Some(c) if !c.is_alphabetic() => {
+                    return Err("style keys must start with an alphabetic character")
+                }
+                _ => (),
+            }
+            for c in chars {
+                if !c.is_alphanumeric() && c != '-' {
+                    return Err(
+                        "style keys can only contain alphanumerics (dash included)",
+                    );
+                }
+            }
+        }
+        Ok(StyleKey(id))
+    }
+
+    /// Construct a new class name from a string.
+    ///
+    /// Panics if the provided string is invalid.
+    pub fn new<S: Into<String>>(id: S) -> Self {
+        let id = id.into();
+        Self::try_new(id.clone()).unwrap_or_else(|err| {
+            panic!(
+                "alchemy::dom::types::StyleKey: {:?} is not a valid class name: {}",
+                id, err
+            )
+        })
+    }
+}
+
+impl FromStr for StyleKey {
+    type Err = &'static str;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        StyleKey::try_new(s)
+    }
+}
+
+impl<'a> From<&'a str> for StyleKey {
+    fn from(str: &'a str) -> Self {
+        StyleKey::from_str(str).unwrap()
+    }
+}
+
+impl Display for StyleKey {
+    fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
+        Display::fmt(&self.0, f)
+    }
+}
+
+impl Deref for StyleKey {
+    type Target = String;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}