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/// `Id` is a Graphviz `ID`.
pub struct Id<'a> {
pub(crate) name: std::borrow::Cow<'a, str>,
}
impl<'a> Id<'a> {
/// Creates an `Id` named `name`.
///
/// The caller must ensure that the input conforms to an
/// identifier format: it must be a non-empty string made up of
/// alphanumeric or underscore characters, not beginning with a
/// digit (i.e., the regular expression `[a-zA-Z_][a-zA-Z_0-9]*`).
///
/// (Note: this format is a strict subset of the `ID` format
/// defined by the DOT language. This function may change in the
/// future to accept a broader subset, or the entirety, of DOT's
/// `ID` format.)
///
/// Passing an invalid string (containing spaces, brackets,
/// quotes, ...) will return an empty `Err` value.
pub fn new<Name: Into<std::borrow::Cow<'a, str>>>(name: Name) -> crate::Result<Self> {
let name = name.into();
match name.chars().next() {
Some(c) if c.is_ascii_alphabetic() || c == '_' => {}
_ => return Err(crate::Error::InvalidId),
}
if !name.chars().all(|c| c.is_ascii_alphanumeric() || c == '_') {
return Err(crate::Error::InvalidId);
}
Ok(Self { name })
}
}
impl<'a> std::fmt::Display for Id<'a> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", self.name)
}
}