1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48

use std::fmt;

/// An error encountered while parsing or executing a selector.
#[derive(Debug)]
pub struct Error {
    kind: ErrorKind,
}

impl Error {
    fn new(kind: ErrorKind) -> Self {
        Error { kind }
    }

    /// Create an error indicating the caller provided an empty path to search.
    pub(crate) fn empty_path() -> Self {
        Error::new(ErrorKind::EmptyPath)
    }

    /// Create an error indicating the caller provided a non-empty string that
    /// couldn't be parsed to a searchable path.
    pub(crate) fn invalid_segment(segment: String) -> Self {
        Error::new(ErrorKind::InvalidSegment(segment))
    }
}

impl std::error::Error for Error {}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match &self.kind {
            ErrorKind::EmptyPath => f.write_str("Empty path"),
            ErrorKind::InvalidSegment(segment) => write!(
                f,
                "Invalid path segment: `{}` is not an identifier",
                segment
            ),
        }
    }
}

#[derive(Debug)]
enum ErrorKind {
    /// The selector parser was passed an empty string.
    EmptyPath,
    /// The selector parser was passed a non-empty string that had
    /// an invalid part after being split by the path separator.
    InvalidSegment(String),
}