Struct BuildError

pub struct BuildError { /* private fields */ }

An error that occurred during the construction of a DFA.

This error does not provide many introspection capabilities. There are generally only two things you can do with it:

• Obtain a human readable message via its std::fmt::Display impl.
• Access an underlying nfa::thompson::BuildError type from its source method via the std::error::Error trait. This error only occurs when using convenience routines for building a DFA directly from a pattern string.

When the std feature is enabled, this implements the std::error::Error trait.

Implementations

impl BuildError

pub fn is_size_limit_exceeded(&self) -> bool

Returns true if and only if this error corresponds to an error with DFA construction that occurred because of exceeding a size limit.

While this can occur when size limits like Config::dfa_size_limit or Config::determinize_size_limit are exceeded, this can also occur when the number of states or patterns exceeds a hard-coded maximum. (Where these maximums are derived based on the values representable by StateID and PatternID.)

This predicate is useful in contexts where you want to distinguish between errors related to something provided by an end user (for example, an invalid regex pattern) and errors related to configured heuristics. For example, building a DFA might be an optimization that you want to skip if construction fails because of an exceeded size limit, but where you want to bubble up an error if it fails for some other reason.

Example

use regex_automata::{dfa::{dense, Automaton}, Input};

let err = dense::Builder::new()
    .configure(dense::Config::new()
        .determinize_size_limit(Some(100_000))
    )
    .build(r"\w{20}")
    .unwrap_err();
// This error occurs because a size limit was exceeded.
// But things are otherwise valid.
assert!(err.is_size_limit_exceeded());

let err = dense::Builder::new()
    .build(r"\bxyz\b")
    .unwrap_err();
// This error occurs because a Unicode word boundary
// was used without enabling heuristic support for it.
// So... not related to size limits.
assert!(!err.is_size_limit_exceeded());

let err = dense::Builder::new()
    .build(r"(xyz")
    .unwrap_err();
// This error occurs because the pattern is invalid.
// So... not related to size limits.
assert!(!err.is_size_limit_exceeded());

Trait Implementations

impl Clone for BuildError

fn clone(&self) -> BuildError

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for BuildError

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

Formats the value using the given formatter.

impl Display for BuildError

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

Formats the value using the given formatter.

impl Error for BuildError

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.