函數裡面嵌套過程和函數，這樣的要怎麼使用，起什麼作用？（代碼在裡面。）

function SQL_Display(sin:String;TSout:TStrings):Integer;
var sout:string;
    indent_Stack:TStack;
    Indent_Space:Integer;
    Execpt_Flag:Boolean;
//------------------------------------------------------------------------
  procedure check_Except(sin:string);
  begin
     if pos(D_Except_KeyWords,sin)<>0 then
     begin
        Execpt_Flag:=true;
      //  Dont_Care_Flag:=True;
     end;
  end;
//------------------------------------------------------------------------
  function Recursive_Normalize(var sin:String;var Sout:String):Integer;
  var ss:String;
      Dont_care_Flag:Boolean;
      Found_dont_care_Ends:Boolean;
      Bracket_Stack:TStack;
  //============================================================================
  procedure do_Prefix_Keywords;
  begin
     Found_dont_care_Ends:=False;
     Dont_Care_Flag:=False;
     if sout=''
       then Sout:=Sout+LPad(ss,Indent_Space+K_Indent_Space,#32)+#32
       else Sout:=Sout+#13+#10+LPad(ss,Indent_Space+K_Indent_Space,#32)+#32;
  end;
  //============================================================================
  procedure Do_Active_Dont_Care;
  begin
     Dont_Care_Flag:=True;
     Found_dont_care_Ends:=False;
     Sout:=Sout+#13+#10+LPad(ss,Indent_Space+K_Indent_Space,#32)+#32;
  end;
  //============================================================================
  procedure Do_DontCare_begs;
  begin
     if (Dont_Care_Flag) and (not Found_dont_care_Ends) and (not Execpt_Flag) then
     begin
        Found_dont_care_Ends:=True;
        //
        if not indent_Stack.Push(IntToStr(K_Indent_Space)) then
        begin
           result:=EV_ERR_Stack_Push_Error;
           exit;
        end;
        //
        Indent_Space:=Indent_Space+K_Indent_Space;
        Sout:=Sout+#13+#10+LPad(ss,Indent_Space,#32)+#32;
        result:=Recursive_Normalize(sin,sout);
        if result<>0 then
        begin
           sout:='';
           exit;
        end;
     end
     else
     if (not Found_dont_care_Ends) and (Execpt_Flag) then
     begin
        Found_dont_care_Ends:=True;
        Sout:=Sout+#13+#10+LPad(ss,Indent_Space,#32)+#13+#10+LPad(#32,K_Field_Indent_Space,#32);
     end
     else
     begin
        Sout:=Sout+ss+' ';
        if not Bracket_Stack.Push(ss) then
        begin
           result:=EV_ERR_Stack_Push_Error;
           exit;
        end;
     end;
  end;
  //============================================================================
  procedure Do_DontCare_ends;
  var temp:String;
  begin
     if Bracket_Stack.Stack_Index>=1 then
     begin
        if not Bracket_Stack.POP(temp) then
        begin
           result:=EV_ERR_Stack_POP_Error;
           exit;
        end;
        Sout:=Sout+ss+#32;
     end
     else
     begin
        Found_dont_care_Ends:=False;
        Dont_Care_Flag:=True;
        Sout:=Sout+#13+#10+LPad(ss,Indent_Space,#32)+#32;
        //
        if not Execpt_Flag then
        begin
           if not indent_Stack.POP(temp) then
           begin
              result:=EV_ERR_Stack_POP_Error;
              exit;
           end;
           Indent_Space:=Indent_Space-strToInt(temp);
        end;
     end;
  end;
  //============================================================================
  procedure Do_Posfix_Keywords;
  begin
        if (Dont_Care_Flag) or (Bracket_Stack.Stack_Index>=1) then
        begin
           Sout:=Sout+ss+#32;
        end
        else
        begin
           Sout:=Sout+ss+#13+#10+LPad(#32,Indent_Space+K_Field_Indent_Space,#32);
        end;
    // end;
  end;
  //============================================================================
  procedure Do_None;
  begin
     Sout:=Sout+ss+' ';
  end;
  //============================================================================
  procedure Initial;
  begin
     Found_dont_care_Ends:=False;
     Dont_care_Flag:=False;
     //
     Bracket_Stack:=TStack.Create;
     Bracket_Stack.Initial;
  end;
  //============================================================================
  begin
     Initial;
     result:=0;
     //
     while (sin <>'') and (result=0) do
     begin
        ss:=StringTok(sin,' ');
        if InStringCheck(ss,D_Prefix_Keywords,K_Separator)<>0 then
        begin
           do_Prefix_Keywords;
        end
        else
        if InStringCheck(ss,D_Active_Dont_Care,K_Separator)<>0 then
        begin
           Do_Active_Dont_Care;
        end
        else
        if InStringCheck(ss,D_DontCare_begs,K_Separator)<>0 then
        begin
           Do_DontCare_begs;
        end
        else
        if InStringCheck(ss,D_DontCare_ends,K_Separator)<>0 then
        begin
           Do_DontCare_ends;
        end
        else
        if InStringCheck(ss,D_Posfix_Keywords,K_Separator)<>0 then
        begin
           Do_Posfix_Keywords;
        end
        else
           Do_None;
     end;
  end;
  //============================================================================
begin
   result:=SQL_Normalize(sin);
   //
   if result<>0
     then exit;   indent_Stack:=TStack.Create;
   indent_Stack.Initial;
   TSout.Clear;
   //
   Execpt_Flag:=False;
   Indent_Space:=0;
   check_Except(sin);
   //
   result:=Recursive_Normalize(sin,Sout);
   TSout.add(Sout);
end;