CLASS zcl_demo_01 DEFINITION
  PUBLIC FINAL
  CREATE PUBLIC.

  PUBLIC SECTION.
    METHODS replace_text_in
      IMPORTING
        mailtext        TYPE string
        with            TYPE clike
        if              TYPE clike
        text            TYPE clike OPTIONAL
      RETURNING
        VALUE(r_result) TYPE string.

  PRIVATE SECTION.
    TYPES: BEGIN OF _changed_parts,
             one   TYPE abap_bool,
             two   TYPE abap_bool,
             three TYPE abap_bool,
           END OF _changed_parts.

    DATA changed_parts TYPE _changed_parts.
ENDCLASS.


CLASS zcl_demo_01 IMPLEMENTATION.
  METHOD replace_text_in.
    ASSIGN COMPONENT if OF STRUCTURE changed_parts TO FIELD-SYMBOL(<field>).
    IF sy-subrc > 0.
      RETURN.
    ENDIF.

    " TODO: variable is assigned but never used (ABAP cleaner)
    DATA(findstr) = |${ if }%|.
    r_result = mailtext.
    DATA(replacestr) = |<p>{ with }{ COND #( WHEN text IS SUPPLIED THEN |: <b>{ text }</b>| ELSE `` ) }</p>|.
    IF <field> IS NOT INITIAL.
      REPLACE findstr WITH replacestr INTO r_result.
    ELSE.
      REPLACE findstr WITH `` INTO r_result.
    ENDIF.
  ENDMETHOD.
ENDCLASS.