The find callback: preparations

We'll have to break the code for the find callback in pieces somehow.

We also need some additional preparations.

Pos type

We need a type that represents a position in the buffer.

/// A position in the buffer.
pub const Pos = struct {
    lnr: usize = 0,
    col: usize = 0,
};

wrapscan option

We need an option for the searching behavior: should the search continue when the end of file is reached, by repeating the search from the start of the file? This also works while searching backwards:

/// Searches wrap around the end of the file
pub var wrapscan = true;

Constants

We need two new constants:

const lastIndexOf = mem.lastIndexOf;
const indexOf = mem.indexOf;