support underscores

src/lib.rs

@@ -65,17 +65,32 @@ pub enum Error {
 
 /// A static type prefix
 pub trait StaticType: Default {
- /// must be lowercase ascii [a-z] only, under 64 characters
+ /// must be lowercase ascii [a-z_] only, under 64 characters.
+ /// first character cannot be an underscore
  const TYPE: &'static str;
 
  #[doc(hidden)]
  const __TYPE_PREFIX_IS_VALID: bool = {
  assert!(Self::TYPE.len() < 64);
  let mut i = 0;
  while i < Self::TYPE.len() {
- assert!(Self::TYPE.as_bytes()[i].is_ascii_lowercase());
+ let b = Self::TYPE.as_bytes()[i];
+ assert!(
+ matches!(b, b'a'..=b'z' | b'_'),
+ "type prefix must contain only lowercase ascii, or underscores"
+ );
  i += 1;
  }
+ if !Self::TYPE.is_empty() {
+ assert!(
+ Self::TYPE.as_bytes()[0] != b'_',
+ "type prefix must not start with an underscore"
+ );
+ assert!(
+ Self::TYPE.as_bytes()[i - 1] != b'_',
+ "type prefix must not end with an underscore"
+ );
+ }
  true
  };
 }
@@ -134,7 +149,11 @@ impl DynamicType {
  /// ```
  pub fn new(s: &str) -> Result<Self, Error> {
  let tag: ArrayString<63> = s.try_into().map_err(|_| Error::InvalidType)?;
- if tag.bytes().any(|x| !x.is_ascii_lowercase()) {
+
+ if tag.bytes().any(|b| !matches!(b, b'a'..=b'z' | b'_')) {
+ return Err(Error::InvalidType);
+ }
+ if !tag.is_empty() && (tag.as_bytes()[0] == b'_' || tag.as_bytes()[tag.len() - 1] == b'_') {
  return Err(Error::InvalidType);
  }
  Ok(Self(tag))
@@ -144,7 +163,10 @@ impl DynamicType {
 impl Type for DynamicType {
  fn try_from_type_prefix(tag: &str) -> Result<Self, Cow<'static, str>> {
  let tag: ArrayString<63> = tag.try_into().map_err(|_| tag[..63].to_owned())?;
- if tag.bytes().any(|x| !x.is_ascii_lowercase()) {
+ if tag.bytes().any(|b| !matches!(b, b'a'..=b'z' | b'_')) {
+ return Err(tag.to_lowercase().into());
+ }
+ if !tag.is_empty() && (tag.as_bytes()[0] == b'_' || tag.as_bytes()[tag.len() - 1] == b'_') {
  return Err(tag.to_lowercase().into());
  }
  Ok(Self(tag))
@@ -278,7 +300,7 @@ impl<T: Type> FromStr for TypeSafeId<T> {
 
  fn from_str(id: &str) -> Result<Self, Self::Err> {
  let (tag, id) = match id.rsplit_once('_') {
- Some((tag, _)) if tag.is_empty() => return Err(Error::InvalidType),
+ Some(("", _)) => return Err(Error::InvalidType),
  Some((tag, id)) => (tag, id),
  None => ("", id),
  };