Create ALV tree main program including Data & Event declaration

 *&-------------------------------------------------------------*
*& Report  ZDEMO_ALVTREE                                       *
*&                                                             *
*&-------------------------------------------------------------*
*&                                                             *
*& Example of a simple ALV Grid Report                         *
*& ...................................                         *
*&                                                             *
*& The basic requirement for this demo is to display a number  *
*& of fields from the EKPO and EKKO table in a tree structure. *
*&                                                             *
*&-------------------------------------------------------------*
*                          Amendment History                   *
*--------------------------------------------------------------*
report  zdemo_alvgrid                 .
*Data Declaration
*----------------
tables:     ekko.
type-pools: slis.                                 "ALV Declarations
types: begin of t_ekko,
  ebeln type ekpo-ebeln,
  ebelp type ekpo-ebelp,
  statu type ekpo-statu,
  aedat type ekpo-aedat,
  matnr type ekpo-matnr,
  menge type ekpo-menge,
  meins type ekpo-meins,
  netpr type ekpo-netpr,
  peinh type ekpo-peinh,
 end of t_ekko.
data: it_ekko     type standard table of t_ekko initial size 0,
      it_ekpo     type standard table of t_ekko initial size 0,
      it_emptytab type standard table of t_ekko initial size 0,
      wa_ekko     type t_ekko,
      wa_ekpo     type t_ekko.
data: ok_code like sy-ucomm,           "OK-Code
      save_ok like sy-ucomm.
*ALV data declarations
data: fieldcatalog  type lvc_t_fcat with header line.
data: gd_fieldcat   type lvc_t_fcat,
      gd_tab_group  type slis_t_sp_group_alv,
      gd_layout     type slis_layout_alv.
*ALVtree data declarations
class cl_gui_column_tree definition load.
class cl_gui_cfw definition load.
data: gd_tree             type ref to cl_gui_alv_tree,
      gd_hierarchy_header type treev_hhdr,
      gd_report_title     type slis_t_listheader,
      gd_logo             type sdydo_value,
      gd_variant          type disvariant.
*Create container for alv-tree
data: gd_tree_container_name(30) type c,
      gd_custom_container        type ref to cl_gui_custom_container.
************************************************************************
*Includes
*include zdemo_alvtreeo01. "Screen PBO Modules
*include zdemo_alvtreei01. "Screen PAI Modules
*include zdemo_alvtreef01. "ABAP Subroutines(FORMS)
************************************************************************
*Start-of-selection.
start-of-selection.
* Display ALVtree report
  call screen 100.