Module error

Error management

Errors are designed with multiple needs in mind:

• Accumulate more context as the error goes up the parser chain
• Distinguish between recoverable errors, unrecoverable errors, and more data is needed
• Have a very low overhead, as errors are often discarded by the calling parser (examples: repeat, alt)
• Can be modified according to the user’s needs, because some languages need a lot more information
• Help thread-through the stream

To abstract these needs away from the user, generally winnow parsers use the PResult alias, rather than Result. Parser::parse is a top-level operation that can help convert to a Result for integrating with your application’s error reporting.

Error types include:

• ()
• ErrorKind
• InputError (mostly for testing)
• ContextError
• TreeError (mostly for testing)
• [Custom errors][crate::_topic::error]

Structs

ContextError

Accumulate context while backtracking errors

InputError

Capture input on error

ParseError

See Parser::parse

TreeErrorBasestd

See TreeErrorFrame::Kind, ParserError::append

TreeErrorContextstd

See TreeErrorFrame::Context, AddContext::add_context

Enums

ErrMode

Add parse error state to ParserErrors

ErrorKind

Provide some minor debug context for errors

Needed

Contains information on needed data if a parser returned Incomplete

StrContext

Additional parse context for ContextError added via Parser::context

StrContextValue

See StrContext

TreeErrorstd

Trace all error paths, particularly for tests

TreeErrorFramestd

See TreeError::Stack

Traits

AddContext

Used by Parser::context to add custom data to error while backtracking

ErrorConvert

Equivalent of From implementation to avoid orphan rules in bits parsers

FromExternalError

Create a new error with an external error, from std::str::FromStr

ParserError

The basic Parser trait for errors

Type Aliases

IResult

For use with Parser::parse_peek which allows the input stream to be threaded through a parser.

PResult

For use with Parser::parse_next