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

make_diff = require "diff"
s1 = [[hello
...
to the
world]]
s2 = [[hello
...
*at* the
world]]
diff = make_diff(s1, s2)

returns the table:

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

and running:

diff:print{color=false}

produces the output:

  hello
  ...
- to the
+ *at* the
  world

You can also diff tables:

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

returns:

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