Type of zippers. A zipper allow to naviguate in a rope in a convenient and efficient manner. Note that a zipper points to a position between two glyphs, not to a glyph, so in a rope of length len there is len + 1 positions.
make_b rope pos creates a new zipper pointing to positon length rope - pos of rope.
val offset : t -> intReturns the position of the zipper in the rope.
val next : t -> Zed_char.t * tnext zipper returns the glyph at the right of the zipper and a zipper to the next position. It raises Out_of_bounds if the zipper points to the end of the rope.
val prev : t -> Zed_char.t * tprev zipper returns the glyph at the left of the zipper and a zipper to the previous position. It raises Out_of_bounds if the zipper points to the beginning of the rope.
move n zip moves the zipper by n glyphs. If n is negative it is moved to the left and if it is positive it is moved to the right. It raises Out_of_bounds if the result is outside the bounds of the rope.
val at_bos : t -> boolat_bos zipper returns true if zipper points to the beginning of the rope.
val at_eos : t -> boolat_eos zipper returns true if zipper points to the end of the rope.
val find_f : (Zed_char.t -> bool) -> t -> tfind_f f zip search forward for a glyph to satisfy f. It returns a zipper pointing to the left of the first glyph to satisfy f, or a zipper pointing to the end of the rope if no such glyph exists.
val find_b : (Zed_char.t -> bool) -> t -> tfind_b f zip search backward for a glyph to satisfy f. It returns a zipper pointing to the right of the first glyph to satisfy f, or a zipper pointing to the beginning of the rope if no such glyph exists.