Demeter Law Violation Detector

*&---------------------------------------------------------------------*
*& Report  ZZ_CHECK_DEMETER_LAW
*&---------------------------------------------------------------------*
*& Checks ABAP method code for the easiest type of LoD violation
*& Extensible by more cases
*&---------------------------------------------------------------------*

report  zz_check_demeter_law.

parameters: p_class type seomtdkey-clsname,  " Structure has F4 attached!
            p_meth  type seomtdkey-mtdname.  " Structure has F4 attached!

start-of-selection.
  perform start.

* ---
class lcl_scanner definition.
  public section.
    methods:
      constructor importing it_source type stringtab
                  raising cx_abap_error_analyze,
      get_first_token importing is_stmnt type sstmnt
                      returning value(ev_token) type char30,
      get_second_token importing is_stmnt type sstmnt
                       returning value(ev_token) type char30,
      get_nth_token importing iv_n type i
                              is_stmnt type sstmnt
                    returning value(ev_token) type char30,
      get_first_stmnt importing iv_first_token type char30
                returning value(es_stmnt) type sstmnt,
      get_stmnts importing iv_first_token type char30
                returning value(et_stmnt) type sstmnt_tab,
      to_string importing is_stmnt type sstmnt
                exporting ev_stmnt type string.
    data: gt_token type stokes_tab read-only,
          gt_stmnt type sstmnt_tab read-only.
endclass.                    "lcl_scanner DEFINITION

* ---
class lcl_check_demeter definition.
  public section.
    data: gs_key       type seocpdkey,
          go_descr     type ref to cl_abap_classdescr read-only,
          gt_methcode  type stringtab read-only,
          go_scanner   type ref to lcl_scanner.
    methods:
      constructor importing iv_class type seoclsname
                            iv_meth  type seocpdname
                  raising cx_abap_error_analyze,
      get_classdescr returning value(eo_descr) type ref to cl_abap_typedescr
                     raising cx_abap_error_analyze,
      read_method raising cx_abap_error_analyze,
      read_source exporting et_methcode type stringtab
                  raising cx_abap_error_analyze,
      scan_source importing it_methcode type stringtab
                  exporting eo_scanner type ref to lcl_scanner
                  raising cx_abap_error_analyze,
      check raising cx_abap_error_analyze .
endclass.                    "lcl_check_demeter DEFINITION

* ---
form start.

  data: lo_demeter type ref to lcl_check_demeter,
        lo_ex      type ref to cx_abap_error_analyze .

  try.
      create object lo_demeter
        exporting
          iv_class = p_class
          iv_meth  = p_meth.

      lo_demeter->check( ).

    catch cx_abap_error_analyze  into lo_ex.
      message lo_ex->message type 'I'.
  endtry.


endform.                    "start


* ---
class lcl_check_demeter implementation.
  method constructor.
    gs_key-clsname = iv_class.
    gs_key-cpdname = iv_meth.
    go_descr ?= get_classdescr( ).
    read_method(  ).
  endmethod.                    "constructor
  method get_classdescr.
    call method cl_abap_classdescr=>describe_by_name
      exporting
        p_name      = gs_key-clsname
      receiving
        p_descr_ref = eo_descr
      exceptions
        others      = 1.
    if sy-subrc ne 0.
      raise exception type cx_abap_error_analyze
        exporting
          message = 'Class not found'.
    endif.
  endmethod.                    "get_classdescr
  method read_method.
    read_source( importing et_methcode = gt_methcode ).
    scan_source( exporting it_methcode = gt_methcode
                 importing eo_scanner  = go_scanner ).
  endmethod.                    "read_method
  method read_source.

    data: lv_msg type string.

    call function 'SEO_METHOD_GET_SOURCE'
      exporting
        mtdkey                        = gs_key
      importing
        source_expanded               = et_methcode
      exceptions
        _internal_method_not_existing = 1
        _internal_class_not_existing  = 2
        version_not_existing          = 3
        inactive_new                  = 4
        inactive_deleted              = 5
        others                        = 6.

    if sy-subrc <> 0.
      message id sy-msgid type sy-msgty number sy-msgno
        with sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4
        into lv_msg.
      raise exception type cx_abap_error_analyze
        exporting
          message = lv_msg.
    endif.

  endmethod.                    "read_method
  method scan_source.
    create object eo_scanner
      exporting
        it_source = it_methcode.
  endmethod.                    "scan_source
  method check.

    data: lv_stmnt type string,
          lv_msg   type string.

    field-symbols: <ls_stmnt> type sstmnt,
                   <ls_token> type stokes.

    loop at go_scanner->gt_token assigning <ls_token>.
      if <ls_token>-str cp '*->*->*'.
        concatenate `'` <ls_token>-str `'` into lv_msg.
        concatenate 'Demeter violation' lv_msg into lv_msg
          separated by space.
        raise exception type cx_abap_error_analyze
          exporting
            message = lv_msg.
      endif.
    endloop.

  endmethod.                    "check
endclass.                    "lcl_check_demeter IMPLEMENTATION


* ---
class lcl_scanner implementation.
  method get_nth_token.
    field-symbols: <ls_token> type stokes.
    data: lv_index type i.
    lv_index = iv_n - 1 + is_stmnt-from.
    read table gt_token assigning <ls_token> index lv_index.
    if sy-subrc eq 0.
      ev_token = <ls_token>-str.
    endif.
  endmethod.                    "get_nth_token
  method get_first_token.
    ev_token = get_nth_token( iv_n = 1 is_stmnt = is_stmnt ).
  endmethod.                    "get_first_token
  method get_second_token.
    ev_token = get_nth_token( iv_n = 2 is_stmnt = is_stmnt ).
  endmethod.                    "get_second_token
  method constructor.
    data: lv_msg type string.
    scan abap-source it_source
      tokens into gt_token
      statements into gt_stmnt
      message into lv_msg.

    if sy-subrc ne 0.
      if lv_msg is initial.
        lv_msg = 'Scanner error'.
      endif.
      raise exception type cx_abap_error_analyze
        exporting
          message = lv_msg.
    endif.
  endmethod.                    "constructor
  method get_first_stmnt.
    data: lt_stmnts type sstmnt_tab.
    lt_stmnts = get_stmnts( iv_first_token ).
    read table lt_stmnts into es_stmnt index 1.
  endmethod.                    "get_first_stmnt
  method get_stmnts.
    field-symbols: <ls_stmnt> type sstmnt.
    loop at gt_stmnt assigning <ls_stmnt>.
      if get_first_token( <ls_stmnt> ) cp iv_first_token. " cp, not eq, for being case-insensitive
        insert <ls_stmnt> into table et_stmnt.
      endif.
    endloop.
  endmethod.                    "get_stmnts
  method to_string.
    field-symbols: <ls_token> type stokes.
    clear ev_stmnt.
    loop at gt_token assigning <ls_token>
                     from is_stmnt-from
                       to is_stmnt-to.
      concatenate ev_stmnt <ls_token>-str into ev_stmnt
        separated by space.
    endloop.
  endmethod.
endclass.                    "lcl_scanner IMPLEMENTATION