Trait UserPosn

Source

pub trait UserPosn:
    Sized
    + Debug
    + Copy
    + Default
    + PartialEq
    + Eq
    + Hash {
    // Provided methods
    fn advance_cols(self, _num_bytes: usize, _num_chars: usize) -> Self { ... }
    fn advance_line(self, _num_bytes: usize) -> Self { ... }
    fn line(&self) -> usize { ... }
    fn column(&self) -> usize { ... }
    fn error_fmt(&self, fmt: &mut Formatter<'_>) -> Result<(), Error> { ... }
}

Expand description

Trait for location within a stream

This base trait is used to enable tracking the position of a token parser within a stream in a manner that is useful for human-readable error messages

A simple implementation can be null, if the position is not critical for error messages for the token parser - for example, parsing a simple string in a test.

For a single file implementation see crate::LineColumn

Provided Methods§

Source

fn advance_cols(self, _num_bytes: usize, _num_chars: usize) -> Self

Advance the state of the stream by a number of bytes and a number of characters; the characters are guaranteed to not be newlines

For character streams (where num_bytes is not the same as num_char) this must only be invoked to move on to a new UTF8 character boundary - hence num_bytes must be a (sum of) len_utf8 values for the text at byte offset of self.

Source

fn advance_line(self, _num_bytes: usize) -> Self

Advance the state of the stream by a number of bytes and to the start of the next line

For character streams this must only be invoked to move on to a new UTF8 character boundary - hence num_bytes must be a (sum of) len_utf8 values for the text at byte offset of self, the last character of which is a newline

Source