XML for Data storage

by LaurenceBoyd Mar 20, 2014 6:21 am 497095900

XML

XML is a flexible, convenient, way of storing data, once you understand how.
Programs typically evolve thru several versions. This often results in different data items being stored. This has meant careful tracking of data version vs program versions, as programs could not correctly read data from the wrong data version.
XML is flexible as names are stored with the data. Names which are understood can be read, while others are ignored. The downside is that missing variables may require defaults.
XML is a very convenient to use. The rules are quite simple.
XML consists of elements:

<name> text </name>

Every opening <name> is paired with a closing </name).
Names can be almost anything but are case sensitive.
Elements can be wholly contained within other elements.
Elements cannot overlap.
<name1> <XYZ> </XYZ> </name1> legal
<name1> <XYZ> </name1> </XYZ> not legal


for more details visit: http://www.w3schools.com/xml/xml_syntax.asp

Saving Data

The following example shows only the code to open and write a file.

 sub FileSaveAs 
 filedialog "Save file", FilePath$+"*.Sudoku", FullName$ 
 call GetFileName$ 
 if FileName$="" then notice "No file chosen!": end 
 call FileSave 
 end sub 
 
 sub FileSave 
 open FullName$ for output as #File 
 FileOpen = True 
 #File "<XML>" 
 #File "<!-- "; Date$();" "; Time$();" ";FullName$;" -->" 'XML comment 
 #File " <Sudoku>" 
 call SaveOptions 
 call SaveCells 
 #File " </Sudoku>" 
 #File "</XML>" 
 close #File 
 FileOpen = False 
 notice "Puzzle Saved ";chr$(13);_ 
 "File Name ";FileName$;chr$(13);_ 
 "at ";FilePath$ 
 end sub 
 
 sub SaveCells 
 for row = 1 to 9: for col = 1 to 9 
 if CellValue(row,col) <> 0 then 
 call SaveOneCell row, col, CellValue(row,col), CellStage(row,col) 
 end if 
 next col: next row 
 end sub 
 
 sub SaveOneCell row,col,value,stage 
 #File " <Cell> "; 
 #File "<Row> ";row; 
 #File " </Row>"; 
 #File "<Col> ";col; 
 #File " </Col>"; 
 #File "<Value> ";value; 
 #File " </Value>"; 
 if stage <> 1 then 
 #File "<Stage> ";right$(" ";str$(stage),2); 
 #File " </Stage>"; 
 end if 
 #File " </Cell>" 
 end sub 
 
 sub SaveOptions 
 #File " <Size> ";9;" </Size>" 
 #File " <Diagonal>"; 
 if DiagActive then #File " On "; else #File " Off "; 
 #File "</Diagonal>" 
 #File " <Possible>"; 
 if PossibleShow then #File " On "; else #File " Off "; 
 #File "</Possible>" 
 #File " <Reduce> "; 
 if ReduceActive then #File " On "; else #File " Off "; 
 #File "</Reduce>" 
 end sub 
 
 sub GetFileName$ 
 for pos = len(FullName$) to 1 step -1 
 if mid$(FullName$, pos, 1) = "\" then exit for 
 next pos 
 FileName$ = mid$(FullName$,pos+1) 
 FilePath$ = left$(FullName$,pos) 
 end sub 

Example data file:

 <XML> 
 <!-- Mar 12, 2014 10:56:25 C:\Data\Sudoku\3.40.88.Sudoku --> 
 <Sudoku> 
 <Size> 9 </Size> 
 <Diagonal> Off </Diagonal> 
 <Possible> Off </Possible> 
 <Reduce> Off </Reduce> 
 <Cell> <Row> 1 </Row><Col> 1 </Col><Value> 7 </Value> </Cell> 
 <Cell> <Row> 1 </Row><Col> 7 </Col><Value> 9 </Value> </Cell> 
 <Cell> <Row> 1 </Row><Col> 8 </Col><Value> 3 </Value> </Cell> 
 <Cell> <Row> 2 </Row><Col> 4 </Col><Value> 6 </Value> </Cell> 
 <Cell> <Row> 2 </Row><Col> 5 </Col><Value> 4 </Value> </Cell> 
 <Cell> <Row> 2 </Row><Col> 6 </Col><Value> 7 </Value><Stage> 2 </Stage> </Cell> 
 <Cell> <Row> 3 </Row><Col> 1 </Col><Value> 1 </Value> </Cell> 
 <Cell> <Row> 9 </Row><Col> 2 </Col><Value> 4 </Value> </Cell> 
 <Cell> <Row> 9 </Row><Col> 3 </Col><Value> 1 </Value> </Cell> 
 </Sudoku> 
 </XML> 

Reading Data

Reading XML data is a little more work than writing it, but still not difficult. Since you wrote the file, you only need to be able to read what you wrote.
For this code segment, variable names with initial letter capitalized are assumed to have been declared global.

 sub FileLoad 
 filedialog "Load file...", FilePath$+"*.Sudoku", FullName$ 
 call GetFileName$ 
 if FileName$="" then notice "No file chosen!": end 
 open FullName$ for input as #File 
 FileOpen = True 
 call ProcessFile 
 end sub 
 
 sub GetFileName$ 
 for pos = len(FullName$) to 1 step -1 
 if mid$(FullName$, pos, 1) = "\" then exit for 
 next pos 
 FileName$ = mid$(FullName$,pos+1) 
 FilePath$ = left$(FullName$,pos) 
 end sub 
 
 sub ProcessFile 
 do 
 call FindTag 
 select case Tag$ 
 case "<XML>" 
 case "<Sudoku>":call InitCellArrays :call LoadPuzzle 
 case "</XML>" :close #File: FileOpen = False 
 end select 
 loop until FileOpen = False 
 end sub 
 
 sub LoadPuzzle 
 do 
 call FindTag 
 select case Tag$ 
 case "<Cell>" :call LoadCell 
 case "<Diagonal>" :DiagActive = FindContentLogic() 
 case "</Diagonal>" 
 case "<Possible>" :PossibleShow = FindContentLogic() 
 case "</Possible>" 
 case "<Reduce>" :ReduceActive = FindContentLogic() 
 case "</Reduce>" 
 case "<Size>" :call CheckSize 
 case "</Size>" 
 case "</Sudoku>" :call ShowRefresh: exit sub 
 end select 
 loop until FileOpen = False 
 end sub 
 
 sub LoadCell 
 stage = 1 
 do 
 call FindTag 
 select case Tag$ 
 case "<Row>" :row = FindContentValue() 
 case "</Row>" 
 case "<Col>" :col = FindContentValue() 
 case "</Col>" 
 case "<Value>" :val = FindContentValue() 
 case "</Value>" 
 case "<Stage>" :stage = FindContentValue() 
 case "</Stage>" 
 case "</Cell>" :CellValue(row,col) = val: CellStage(row,col) = stage 
 exit sub 
 end select 
 loop until FileOpen = False 
 end sub 
 
 sub LoadInputBuffer 
 if eof(#File) <> 0 then close #File: FileOpen = False: exit sub 
 do until (len(InputBuffer$) > 0 ) or (eof(#File) <> 0 ) 'skip blank lines 
 line input #File, InputBuffer$ 
 loop 
 end sub 
 
 sub FindTag 
 if len(InputBuffer$) = 0 then call LoadInputBuffer 
 for i = 1 to len(InputBuffer$) 
 if mid$(InputBuffer$, i, 1) = "<" then exit for 
 next 
 for j=i+1 to len(InputBuffer$) 
 if mid$(InputBuffer$, j, 1) = ">" then exit for 
 next 
 Tag$ = mid$(InputBuffer$, i, j-i+1) 
 InputBuffer$ = mid$(InputBuffer$, j+1) 'remove tag 
 end sub 
 
 function FindContentString$() 
 for i = 1 to len(InputBuffer$) 
 if mid$(InputBuffer$, i, 1) = "<" then exit for 
 next 
 FindContentString$ = trim$(mid$(InputBuffer$, 1, i-1)) 
 InputBuffer$ = mid$(InputBuffer$, i) 'remove content 
 end function 
 
 function FindContentValue() 
 for i = 1 to len(InputBuffer$) 
 if mid$(InputBuffer$, i, 1) = "<" then exit for 
 next 
 FindContentValue = val(mid$(InputBuffer$, 1, i-1)) 
 InputBuffer$ = mid$(InputBuffer$, i) 'remove content 
 end function 
 
 function FindContentLogic() 
 FindContentLogic = False 
 if FindContentString$() = "on" then FindContentLogic = True 
 end function 

19 Mar 2014 9:14