LZW Compression In Lua

Question

Here is the Pseudocode for Lempel-Ziv-Welch Compression.

 pattern = get input character
 while ( not end-of-file ) {
     K = get input character
     if (          


        

Answer 1

You should also take a look here to download the source for a high-performance LZW compression algorithm in Lua...

Answer 2

Assuming uncompressed is a string, you'll need to use something like this to iterate over it:

for i = 1, #uncompressed do
  local c = string.sub(uncompressed, i, i)
  -- etc
end   

There's another issue on line 10; .. is used for string concatenation in Lua, so this line should be local wc = w .. c.

You may also want to read this with regard to the performance of string concatenation. Long story short, it's often more efficient to keep each element in a table and return it with table.concat().