@spec apply_mapping((non_neg_integer() -> non_neg_integer()) | nil, non_neg_integer()) ::
  non_neg_integer()

Apply a reorder mapping to a primary weight.

Arguments

• mapping_fn - a reorder mapping function from build_mapping/1, or nil.

• primary - the primary weight to remap.

Returns

The remapped primary weight, or the original if mapping_fn is nil.

@spec build_mapping([atom()]) :: (non_neg_integer() -> non_neg_integer()) | nil

Build a reorder mapping function from the given script codes.

Arguments

• reorder_codes - a list of script code atoms (e.g., [:Grek, :Latn]).

Returns

• A function (primary :: integer()) -> integer() that remaps primary weights.

• nil if the list is empty or no valid mappings were found.

@spec load_primary_to_fractional_lead() :: %{
  required(integer() | {:sub, integer()}) => non_neg_integer()
}

Load a mapping from allkeys integer primary weights to their fractional lead bytes and sub-bytes.

Returns

A map %{integer() | {:sub, integer()} => non_neg_integer()}.

@spec load_script_ranges() :: %{
  required(String.t()) => {non_neg_integer(), non_neg_integer()}
}

Load the script-to-lead-byte-range mapping from FractionalUCA.txt.

Returns

A map %{String.t() => {start_byte, end_byte}}.