Lua wcwidth implementation

Pure Lua implementation of wcwidth function. This function determines the number of column positions required for the character to display. The value passed must be a character code.

local wcwidth = require 'wcwidth'
print( wcwidth( 0 ))      -- prints 0
print( wcwidth( 32 ))     -- prints 1, ASCII space
print( wcwidth( 0x0410 )) -- prints 1, cyrillic "A"
print( wcwidth( 0x30b3 )) -- prints 2, katakana "コ"

wcwidth( wc )

The function either returns 0 (if wc is a null wide-character code), or returns the number of column positions to be occupied by the wide-character code wc, or returns −1 (if wc does not correspond to a printing wide-character code)