Enum Error 

#[non_exhaustive]
pub enum Error {
    Parse {
        kind: ParseErrorKind,
        offset: usize,
    },
    Unsupported {
        construct: String,
        offset: Option<usize>,
    },
}

Why a CSS selector could not be translated.

The variants split by whose rules were broken: Error::Parse for a selector CSS itself rejects, Error::Unsupported for a valid selector this crate declines to approximate.

A Error::Parse always knows the offending byte position, so it always renders a caret. A Error::Unsupported knows one for the constructs the pre-parse scan of the source text finds, and not for the ones the translator finds, because Servo’s parsed components carry no source offsets to map a component back to the selector text. Its offset is therefore an Option, and its message grows a caret only when it is Some.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Parse

The selector is not valid CSS (as judged by Servo’s parser).

Fields

kind: ParseErrorKind

What is wrong with the selector.

offset: usize

The 0-indexed byte offset of the error within the selector string, used to render a caret pointer. It is selector.len() for an error at end of input.

Unsupported

The selector is valid CSS, but uses a construct outside the supported set: this crate errors rather than approximating.

Fields

construct: String

The offending construct, as a noun phrase (the `||` column combinator) that reads as the object of “uses …”.

offset: Option<usize>

The 0-indexed byte offset of the construct within the selector string, when it is known; None when it is not. See the variant split above for which constructs know it.

Implementations

impl Error

pub fn message(&self, selector: &str) -> String

Render the full user-facing message, naming the offending selector — and, whenever the error carries a position, pointing a caret at it.

Display is the one-line form for callers that no longer hold the selector; this is the form to print when they do.

pub fn into_message(self, selector: &str) -> String

👎Deprecated since 0.3.0:

use Error::message, which takes &self

Deprecated alias for Error::message, which borrows the error rather than consuming it.

Trait Implementations

impl Clone for Error

fn clone(&self) -> Error

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Error

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Error

fn fmt(&self, f: &mut Formatter<'_>) -> Result

The one-line form, which does not need the selector: enough to identify the fault when the error is all a caller still has.

impl Eq for Error

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for Error

fn eq(&self, other: &Error) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Error