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//! This file implements the error type for the crate.
use graph::error::Error as GraphError;
use core::fmt::{Display, Formatter};
/// The error type for NFA operations.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
#[non_exhaustive]
pub enum Error {
/// An unknown node id is encountered.
UnknownNode(usize),
/// Some operations are not supported by the implementations.
///
/// Everything is a trade-off, wink wink.
UnsupportedOperation,
/// There is no root in the underlying regular expression.
NoRoot,
/// This error comes from some underlying graph operation.
Graph(GraphError),
/// A cycle is found when constructing regular expressions.
Cycle,
}
impl Display for Error {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
match self {
Error::UnknownNode(id) => write!(f, "unknown node: {id}"),
Error::UnsupportedOperation => write!(f, "unsupported operation"),
Error::Graph(e) => write!(f, "graph error: {e}"),
Error::NoRoot => write!(f, "no root found"),
Error::Cycle => write!(f, "a cycle is found when constructing regular expressions"),
}
}
}
impl std::error::Error for Error {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
if let Self::Graph(gerr) = self {
Some(gerr)
} else {
None
}
}
}
impl From<GraphError> for Error {
fn from(e: GraphError) -> Self {
Self::Graph(e)
}
}
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