css_to_xpath/translate/
error.rs

1//! Error types for selector translation.
2//!
3//! Errors always name the selector and the construct. The exact wording
4//! here is part of this crate's output contract and is pinned by tests.
5
6#[derive(Clone, Debug, Eq, PartialEq)]
7pub enum Error {
8    /// The selector is not valid CSS (as judged by Servo's parser).
9    /// The second field is the 1-indexed byte column of the error within the
10    /// selector string, used to render a caret pointer.
11    Parse(String, u32),
12    /// The selector is valid CSS, but uses a construct outside the
13    /// supported set: this crate errors rather than approximating.
14    Unsupported(String),
15}
16
17impl Error {
18    /// Render the user-facing message, naming the offending selector.
19    pub fn into_message(self, selector: &str) -> String {
20        match self {
21            Error::Parse(detail, column) => {
22                let caret_pos = (column as usize).saturating_sub(1).min(selector.len());
23                let caret_line = format!("{}{}", " ".repeat(caret_pos), "^");
24                format!(
25                    "Unable to parse the CSS selector {selector:?}: {detail}\n  |\n  | {selector}\n  | {caret_line}"
26                )
27            }
28            Error::Unsupported(construct) => format!(
29                "The CSS selector {selector:?} uses {construct}, which this translator does not support"
30            ),
31        }
32    }
33}
css_to_xpath/translate/error.rs

css_to_xpath/translate/
error.rs
