XML: Bubble Sort utilizing XMLVARs

Recently, a question about sorting has come up. The context was an ICAO Search of Facility types which returns ICAO strings in alphabetical order. However, each ICAO represents a Facility that has a certain distance from the user's aircraft, and a sort according to distance is needed.

Acknowledgements are owed to Robbie McElrath who provided the Bubble Sort XML (thank you, Robbie) and Tom Aguilo, for providing XMLVARs. The sort script that follows makes use of the array-forming capabilities of XMLVARS. Thanks, Tom.

 MACROS:
   <Macro Name="sort">
     @2 (>L:sort_len, number)
     :127
        0 (>L:sort_swapped, bool)
        0 sp0
        :128
           l0 ++ s0 (L:sort_len, number) >= if{ g129 }
           @1 l0 -- scat s10 (>C:XMLVARS:SearchVarName, string) (C:XMLVARS:NumberValue, number) s11
           @1 l0    scat     (>C:XMLVARS:SearchVarName, string) (C:XMLVARS:NumberValue, number) s12 & gt;
               if{
                 l11 (>C:XMLVARS:NumberValue, number)
                 l10 (>C:XMLVARS:SearchVarName, string) l12 (>C:XMLVARS:NumberValue, number)
                 1 (>L:sort_swapped, bool)
               }
           g128
        :129
        (L:sort_swapped, bool) if{ g127 }
   </Macro>
   
   <Macro Name="store">
     @1 @2 scat (>C:XMLVARS:StoreVarName, string) (>C:XMLVARS:NumberValue, number)
   </Macro>  

 UPDATE:
   <Update Frequency="18" Hidden="No">      
   (L:SortInit, bool) 0 ==
       if{
           2 @store('sort_test', 0)
           1 @store('sort_test', 1)
           4 @store('sort_test', 2)
           8 @store('sort_test', 3)
           7 @store('sort_test', 4)
           0 @store('sort_test', 5)
           1 (>L:SortInit, bool)
       }  
                  
       'sort_test0' (>C:XMLVARS:SearchVarName,string) (C:XMLVARS:NumberValue,number) (>L:SortTest0, number)       
       'sort_test1' (>C:XMLVARS:SearchVarName,string) (C:XMLVARS:NumberValue,number) (>L:SortTest1, number)  
       'sort_test2' (>C:XMLVARS:SearchVarName,string) (C:XMLVARS:NumberValue,number) (>L:SortTest2, number)  
       'sort_test3' (>C:XMLVARS:SearchVarName,string) (C:XMLVARS:NumberValue,number) (>L:SortTest3, number)  
       'sort_test4' (>C:XMLVARS:SearchVarName,string) (C:XMLVARS:NumberValue,number) (>L:SortTest4, number)  
       'sort_test5' (>C:XMLVARS:SearchVarName,string) (C:XMLVARS:NumberValue,number) (>L:SortTest5, number)  
   </Update>

 MOUSE:
   <Area Left="150" Top="130" Width="16" Height="16">
       <Cursor Type="Hand" />
           <Click Kind="LeftSingle+RightSingle">
               @sort('sort_test', 6)
           </Click>
   </Area>    

Notes:

- (L:sort_len, number) is the array length. For example, IcaoSearchMatchedIcaosNumber

- The SortInit sequence was used for testing purposes only. It stores 2, 1, 4, 8, 7, and 0 into XMLVARs named 'sort_test0' through 'sort_test5'. In a real application, GeoCalcDistance information would actually generate the values to be stored in these XMLVARs and a SortInit sequence would probably never be needed.

- The bottom 6 lines in the Update section simply read the XMLVARs and store then into traditional L:Vars so that BlackBox can display them (so you can see what is happening before and after the sort is applied)

- A Mouse Area 'click area' is used to execute the sort macro, @sort('sort_test', 6). The number 6 is the array length to be sorted. In the real example I postulated, it would be written @sort('sort_test',C:fs9gps:IcaoSearchMatchedIcaosNumber).

- The script requires use of XMLVARs. Specifically, the array-forming capability of XMLVARs in which an array of variables can be named dynamically, for example, sort_test0, sort_test1, sort_test2, ... sort_testn, is needed.

- The algorithm sorts in ascending order. To reverse it to sort in descending order, change the & gt; to & lt; in this line:

 @1 l0 scat (>C:XMLVARS:SearchVarName, string) (C:XMLVARS:NumberValue, number) s12 & lt;

 FINALLY - Note that I placed a space after the ampersand & in 4 places above (one in the Code and three in the Notes) so that it would display properly in the wiki.  Please remove that space in your XML

Bob