pub enum Err<E> {
    Incomplete(Needed),
    Error(E),
    Failure(E),
}
Expand description

The Err enum indicates the parser was not successful

It has three cases:

  • Incomplete indicates that more data is needed to decide. The Needed enum can contain how many additional bytes are necessary. If you are sure your parser is working on full data, you can wrap your parser with the complete combinator to transform that case in Error
  • Error means some parser did not succeed, but another one might (as an example, when testing different branches of an alt combinator)
  • Failure indicates an unrecoverable error. As an example, if you recognize a prefix to decide on the next parser to apply, and that parser fails, you know there’s no need to try other parsers, you were already in the right branch, so the data is invalid

Variants

Incomplete(Needed)

There was not enough data

Error(E)

The parser had an error (recoverable)

Failure(E)

The parser had an unrecoverable error: we got to the right branch and we know other branches won’t work, so backtrack as fast as possible

Implementations

Tests if the result is Incomplete

Applies the given function to the inner error

Automatically converts between errors if the underlying type supports it

Maps Err<(T, ErrorKind)> to Err<(U, ErrorKind)> with the given F: T -> U

Maps Err<error::Error<T>> to Err<error::Error<U>> with the given F: T -> U

Obtaining ownership

Obtaining ownership

Obtaining ownership

Obtaining ownership

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Formats the value using the given formatter. Read more

The lower-level source of this error, if any. Read more

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

Returns a stack backtrace, if available, of where this error occurred. Read more

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

Converts to this type from the input type.

Converts to this type from the input type.

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

Uses borrowed data to replace owned data, usually by cloning. Read more

Converts the given value to a String. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.