module HexaPDF::Font::TrueType::Table::Kern::Format0

def self.parse(io, _length)

{left_char: {right_char: kern_value}}
Parses the format 0 subtable and returns a hash of the form

Format0.parse(io, length) -> pairs
:call-seq: 
def self.parse(io, _length)
  number_of_pairs = io.read(8).unpack1('n')
  pairs = Hash.new {|h, k| h[k] = {} }
  io.read(number_of_pairs * 6).unpack('n*').each_slice(3) do |left, right, value|
    pairs[left][right] = (value < 0x8000 ? value : -(value ^ 0xffff) - 1)
  end
  pairs
end