Enum LanguageError 

#[non_exhaustive]
pub enum LanguageError {
    ParseError {
        expr: String,
        reason: String,
    },
    EvalError(String),
    UnknownVariable(String),
    NotFound(String),
    NotSupported {
        feature: String,
        language: String,
    },
    EvalFailure {
        class: ExpressionErrorClass,
        position: Option<ErrorPosition>,
        detail: Option<String>,
    },
    TypeMismatch {
        expected: String,
        actual: String,
        position: Option<ErrorPosition>,
    },
    ConversionError {
        source_type: String,
        target: String,
    },
}

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.

ParseError

Fields

expr: String

reason: String

EvalError(String)

UnknownVariable(String)

NotFound(String)

NotSupported

Fields

feature: String

language: String

EvalFailure

Structured evaluation failure with a typed class and an optional engine-reported position inside the expression source.

detail is optional already-redacted diagnostic text: the emitting crate MUST strip exchange data before storing it here. The Display output stays short and carries no value text.

Fields

class: ExpressionErrorClass

position: Option<ErrorPosition>

detail: Option<String>

TypeMismatch

A value’s type did not match the type expected by the destination. expected/actual are TYPE names, never runtime values.

Fields

expected: String

actual: String

position: Option<ErrorPosition>

ConversionError

The evaluation result could not be converted to the declared destination type. source_type/target are type/destination names, never runtime values (see crate::eval::to_expression_failed for the trusted-target rewrite).

Fields

source_type: String

target: String

Implementations

impl LanguageError

pub fn eval_error(expr: &str, message: impl Display) -> Self

Create an EvalError that includes the expression being evaluated.

This preserves the expression context in the error message for easier debugging.

pub fn class(&self) -> Option<ExpressionErrorClass>

Typed failure classification for structured transport (see crate::eval::to_expression_failed).

Registry/lifecycle variants (UnknownVariable, NotFound, NotSupported) are not evaluation classes and yield None.

pub fn position(&self) -> Option<ErrorPosition>

Engine-reported 1-based position inside the expression source, when the variant carries one.

Trait Implementations

impl Debug for LanguageError

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

Formats the value using the given formatter.

impl Display for LanguageError

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

Formats the value using the given formatter.

impl Error for LanguageError

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.