Difference in last line does not get handled

[Alien426]

Bug Description

See title.
getChangedLines() does return the correct line numbers.

Steps To Reproduce

Put a difference in the last line.

Expected Behavior

The change in the last line should be displayed when calling getDiff() or renderDiff().

Possible Solution

$captureLine only gets pushed onto $return when a line is equal. When the last line is reached and differs, the for loop is already ending and the capture buffer is not checked anymore.

Seems to work when putting a copy of the if ($captureBuffer !== []) block before the return.

[janbarasek]

Thanks for the detailed report — the analysis is very helpful.

Based on a review (with the help of AI-assisted code analysis), the issue is not fully resolved in the current version. The root cause you described is valid:
$captureBuffer is only flushed when an equal line is encountered. If the last processed line differs, the loop ends and the buffer is never flushed, so the diff is missing.

To properly fix this, could you please open a pull request with the following changes?

Requested fixes

1. Flush $captureBuffer after the for loop, before returning the Diff object
   (this handles differences in the last line).

2. (Recommended) Iterate over the maximum length of both inputs, not only $from, e.g.

   $max = max(count($from), count($to));
   for ($i = 0; $i < $max; $i++) {
       $original = $from[$i] ?? '';
       $target = $to[$i] ?? '';
       ...
   }

   This ensures added lines at the end of the right-hand input are handled correctly.

3. The note about $lineNumber being a string (sprintf vs concatenation) is valid, but optional and unrelated to this bug — feel free to include it if you want.

If you can submit a PR with these adjustments, I’ll be happy to review and merge it.

Thanks again for the report and the thoughtful investigation.