LuaDiffer: A simple lua diff library

This is a simple lua module that performs a diff on two strings and returns a table of string chunks, or a diff of two lists and returns a list of list subsets.

Example

   1 make_diff = require "diff"
   2 s1 = [[hello
   3 ...
   4 to the
   5 world]]
   6 s2 = [[hello
   7 ...
   8 *at* the
   9 world]]
  10 diff = make_diff(s1, s2)

returns the table:

   1 {
   2   {old="hello\n...\n", old_first=1, old_last=2,
   3    new="hello\n...\n", new_first=1, new_last=2},
   4   {old="to the\n", old_first=3, old_last=3,
   5    new="*at* the\n", new_first=3, new_last=3},
   6   {old="world", old_first=4, old_last=4,
   7    new="world", new_first=4, new_last=4},
   8 }

and running:

   1 diff:print{color=false}

produces the output:

   1   hello
   2   ...
   3 - to the
   4 + *at* the
   5   world

You can also diff tables:

   1 diff({1,2,3,4,5},{99,2,4,5,6})

returns:

   1 {{old={1},    old_first=1, old_last=1, new={99},   new_first=1, new_last=1},
   2  {old={2},    old_first=2, old_last=2, new={2},    new_first=2, new_last=2},
   3  {old={3},    old_first=3, old_last=3, new={},     new_first=3, new_last=2},
   4  {old={4, 5}, old_first=4, old_last=5, new={4, 5}, new_first=3, new_last=4},
   5  {old={},     old_first=6, old_last=5, new={6},    new_first=5, new_last=5}}

(when diffing tables, it is guaranteed that for matching chunks, .old and .new refer to the same table, so chunk.old == chunk.new will succeed)