Module stream 

Available on crate feature unstable-doc only.

Custom Stream

winnow is batteries included with support for

• Basic inputs like &str, newtypes with
• Improved debug output like Bytes
• Stateful for passing state through your parser, like tracking recursion depth
• LocatingSlice for looking up the absolute position of a token

Implementing a custom token

The first level of customization is parsing &[MyItem] or TokenSlice<MyItem>.

The basic traits you may want for a custom token type are:

trait	usage
AsChar	Transforms common types to a char for basic token parsing
ContainsToken	Look for the token in the given set

See also TokenSlice<MyItem>, lexing.

Implementing a custom stream

Let’s assume we have an input type we’ll call MyStream. MyStream is a sequence of MyItem tokens.

The goal is to define parsers with this signature: &mut MyStream -> ModalResult<Output>.

fn parser<'s>(i: &mut MyStream<'s>) -> ModalResult<Output<'s>> {
    "test".parse_next(i)
}

Like above, you’ll need to implement the related token traits for MyItem.

The traits you may want to implement for MyStream include:

trait	usage
Stream	Core trait for driving parsing
StreamIsPartial	Marks the input as being the complete buffer or a partial buffer for streaming input
AsBytes	Casts the input type to a byte slice
AsBStr	Casts the input type to a slice of ASCII / UTF-8-like bytes
Compare	Character comparison operations
FindSlice	Look for a substring in self
Location	Calculate location within initial input
Offset	Calculate the offset between slices

And for &[MyItem] (slices returned by Stream):

trait	usage
SliceLen	Calculate the input length
ParseSlice	Used to integrate &str’s parse() method