Enum RecoveryError 

pub enum RecoveryError {
    Eof,
    AlreadyRecovered,
    RecoveryDisabled,
}

Variants

Eof

Recovery failed because the parser reached the end of file

AlreadyRecovered

Recovery failed because it didn’t eat any tokens. Meaning, the parser is already in a recovered state. This is an error because: a) It shouldn’t create a completed marker wrapping no tokens b) This results in an infinite-loop if the recovery is used inside a while loop. For example, it’s common that list parsing also recovers at the end of a statement or block. However, list elements don’t start with a ; or } which is why parsing, for example, an array element fails again and the array expression triggers another recovery. Handling this as an error ensures that list parsing rules break out of the loop the same way as they would at the EOF.

RecoveryDisabled

Returned if there’s an unexpected token and the parser is speculatively parsing a syntax. Error-recovery is disabled when doing speculative parsing because it can then make the impression that the parser was able to correctly parse a syntax when, in fact, it only skipped over the tokens.

For example the syntax (a, b, c) ... in JavaScript can either be a parenthesized expression or an arrow function, depending on what kind of token ... is. Thus, the parer’s only option is to make the following assumption: “Let’s assume (a, b, c) ...” is an arrow function expression“

The parser then tries to parse (a, b, c) as an arrow function parameters and validates that ... indeed is the =>. The parser rewinds and re-parses the syntax as a parenthesized expression if it turns out that ... isn’t the => token or if any element in (a, b, c) isn’t a valid parameter (for example 5 + 3 isn’t valid).

Trait Implementations

impl Debug for RecoveryError

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

Formats the value using the given formatter.

impl Display for RecoveryError

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

Formats the value using the given formatter.

impl Error for RecoveryError

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 RecoveryError

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for RecoveryError

impl StructuralPartialEq for RecoveryError