ABAP Regexp

REPORT  ZCA_PROGRAM2.
 
SELECTION-SCREEN BEGIN OF SCREEN 100 AS WINDOW.
  PARAMETERS email TYPE c LENGTH 30 LOWER CASE.
SELECTION-SCREEN END OF SCREEN 100.
 
CLASS demo DEFINITION.
  PUBLIC SECTION.
  CLASS-METHODS main.
  ENDCLASS.
 
CLASS demo IMPLEMENTATION.
  METHOD main.
    DATA: regex TYPE REF TO cl_abap_regex,
          matcher TYPE REF TO cl_abap_matcher.
 
    CREATE OBJECT regex EXPORTING pattern ='\w+(\.\w+)*@(\w+\.)+(\w{2,4})' ignore_case = 'X'.
    DO.
      CALL SELECTION-SCREEN 100 STARTING AT 10 10.      
 
      matcher = regex->create_matcher( text = email ).
      IF matcher->match( ) IS INITIAL.
        MESSAGE 'wrong format' TYPE 'S' DISPLAY LIKE 'E'        .
      ELSE.
        MESSAGE 'Format ok' TYPE 'S'.
        EXIT.
      ENDIF.
    ENDDO.
  ENDMETHOD.    
ENDCLASS.
START-OF-SELECTION.
  demo=>main( ).