lib/mb_string/core_ext/string.rb
require "unicode/display_width"
require "unicode/display_width/string_ext"
class String
def mb_ljust(width, pad_str = " ")
return ljust(width, pad_str) if ascii_only? && pad_str.ascii_only?
mb_execute(width) do |pad_size|
self + mb_build_padding(pad_size, pad_str)
end
end
def mb_rjust(width, pad_str = " ")
return rjust(width, pad_str) if ascii_only? && pad_str.ascii_only?
mb_execute(width) do |pad_size|
mb_build_padding(pad_size, pad_str, is_append_right: false) + self
end
end
def mb_center(width, pad_str = " ")
return center(width, pad_str) if ascii_only? && pad_str.ascii_only?
mb_execute(width) do |pad_size|
left_pad_size = pad_size / 2
right_pad_size = pad_size - left_pad_size
right_padding = mb_build_padding(right_pad_size, pad_str)
left_padding = mb_build_padding(left_pad_size, pad_str, is_append_right: false)
left_padding + self + right_padding
end
end
def mb_truncate(truncate_at, options = {})
return dup unless display_width > truncate_at
omission = options[:omission] || "..."
length_with_room_for_omission = truncate_at - omission.display_width
size = 0
slice = ""
each_char do |c|
char_size = c.display_width
if size + char_size > length_with_room_for_omission
slice << omission
break
end
size += char_size
slice << c
end
slice
end
private
def mb_execute(width)
pad_size = [width - display_width, 0].max
return self if pad_size.zero?
yield(pad_size)
end
def mb_build_padding(pad_size, pad_str, is_append_right: true)
pad_display_width = pad_str.display_width
pad_num, mod = pad_size.divmod(pad_display_width)
padding = pad_str * pad_num
if mod > 0
padding = mb_tweak_reminder(pad_str, mod, padding)
padding = append_reminder_space(padding, is_append_right) if pad_size > padding.display_width
end
padding
end
def mb_tweak_reminder(pad_str, mod, padding)
pad_str.each_char do |c|
char_display_width = c.display_width
if mod >= char_display_width
padding << c
mod -= char_display_width
end
end
padding
end
def append_reminder_space(padding, is_append_right)
if is_append_right
padding + " "
else
" " + padding
end
end
end