zendframework/zf2 — pull request #4058 by zburnham (2013-03-18 02:24:42+00:00)
Title: Currently InputFilter cannot use context to validate empty fields.

There are cases in which an empty field is not automatically valid or invalid, but instead may need to have further validation based on context. This adds a "continueIfEmpty" property to the Input class, and modifies the InputFilter and Factory classes.