Function parse_prefix 

pub fn parse_prefix<'arena>(
    arena: &'arena Bump,
    span: Span,
    input: &'arena [u8],
) -> Result<(Type<'arena>, Position), ParseError>

Parses the longest valid type prefix of input and reports the absolute position just past the consumed bytes.

Unlike parse_str, this does not require the entire input to be a single type. It is the handoff point for embedding callers (e.g. the phpdoc-syntax parser): they parse one type, fast-forward their own scanner to the returned position, and keep going with their own tokens from there.

Arguments

• arena - The arena that will own every AST node.
• span - The absolute span covering input within its source file.
• input - The slice to parse; only the prefix that forms a complete type expression is consumed.

Errors

Returns a ParseError if the prefix does not start with a valid type.