Module Blit_intf

module Blit_intf: sig .. end

Standard type for blit functions, and reusable code for validating blit arguments.

type ('src, 'dst) blit = src:'src -> src_pos:int -> dst:'dst -> dst_pos:int -> len:int -> unit

If blit : (src, dst) blit, then blit ~src ~src_pos ~len ~dst ~dst_pos blits len values from src starting at position src_pos to dst at position dst_pos. Furthermore, blit raises if src_pos, len, and dst_pos don't specify valid slices of src and dst.

type ('src, 'dst) blito = src:'src ->
       ?src_pos:int -> ?src_len:int -> dst:'dst -> ?dst_pos:int -> unit -> unit

type ('src, 'dst) sub = 'src -> pos:int -> len:int -> 'dst

If sub : (src, dst) sub, then sub ~src ~pos ~len returns a sequence of type dst containing len characters of src starting at pos.

subo is like sub, except pos and len are optional.

type ('src, 'dst) subo = ?pos:int -> ?len:int -> 'src -> 'dst

module type S = sig .. end

module type S1 = sig .. end

module type S_distinct = sig .. end

Users of modules matching the blit signatures S, S1, and S1_distinct only need to understand the code above. The code below is only for those that need to implement modules that match those signatures.

module type Elt = sig .. end

module type Sequence = sig .. end

module type Blit = sig .. end

Standard type for blit functions, and reusable code for validating blit arguments.

If blit : (src, dst) blit, then blit ~src ~src_pos ~len ~dst ~dst_pos blits len values from src starting at position src_pos to dst at position dst_pos. Furthermore, blit raises if src_pos, len, and dst_pos don't specify valid slices of src and dst.

default is 0

default is length src - src_pos

default is 0

If sub : (src, dst) sub, then sub ~src ~pos ~len returns a sequence of type dst containing len characters of src starting at pos.

subo is like sub, except pos and len are optional.

default is 0

default is length src - pos

Users of modules matching the blit signatures S, S1, and S1_distinct only need to understand the code above. The code below is only for those that need to implement modules that match those signatures.

of_bool is used to generate two distinct values of type t, used in unit tests. It is required that of_bool false <> of_bool true.

There are various Make* functors that turn an unsafe_blit function into a blit function. The functors differ in whether the sequence type is monomorphic or polymorphic, and whether the src and dst types are distinct or are the same.

The blit functions make sure the slices are valid and then call unsafe_blit. They guarantee at a call unsafe_blit ~src ~src_pos ~dst ~dst_pos ~len that:

        len > 0
        && src_pos >= 0
        && src_pos + len <= get_src_len src
        && dst_pos >= 0
        && dst_pos + len <= get_dst_len dst

The Make* functors also automatically create unit tests.

Make is for blitting between two values of the same monomorphic type.

Make_distinct is for blitting between values of disinct monomorphic types.

Make1 is for blitting between two values of the same polymorphic type.

Make1 guarantees to only call create_like ~len t with len > 0 if length t > 0.