wp-includes/Text/Diff.php:80returns the number of new (added) lines in a given diff.
int function countAddedLines() { $count = 0; foreach ($this->_edits as $edit) { if (is_a($edit, 'Text_Diff_Op_add') || is_a($edit, 'Text_Diff_Op_change')) { $count += $edit->nfinal(); } } return $count; }Introduced in Text_Diff 1.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/Text/Diff.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.