(regex target-string &optional result-form &key start end sharedp) &body body)
|Function: Iterates over TARGET-STRING and tries to match REGEX as often as possible evaluating BODY with the variables in VAR-LIST bound to the corresponding register groups for each match in turn, i.e. each variable is either bound to a string or to NIL. For each element of VAR-LIST which is NIL there's no binding to the corresponding register group. The number of variables in VAR-LIST must not be greater than the number of register groups. After the last match, returns RESULT-FORM if provided or NIL otherwise. An implicit block named NIL surrounds DO-REGISTER-GROUPS; RETURN may be used to terminate the loop immediately. If REGEX matches an empty string the scan is continued one position behind this match. If SHAREDP is true, the substrings may share structure with TARGET-STRING. BODY may start with declarations.