wp-includes/Text/Diff.php:161Computes the length of the Longest Common Subsequence (LCS).
int function lcs() { $lcs = 0; foreach ($this->_edits as $edit) { if (is_a($edit, 'Text_Diff_Op_copy')) { $lcs += count($edit->orig); } } return $lcs; }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.