[Richard Suchenwirth] 2002-11-24 - Reading "[XML] in a Nutshell", I was
happy to see Tcl mentioned at least in one place (though not in the
index). Code examples in that book are mostly in [Java]. However, their
example 19-3, where, on little more than two pages of code, an XML document
statistics program based on SAX (Simple API for XML) (counting elements, attributes, 
processing
instructions, text characters) is developed, prompted me to remake it in
Tcl (on half a page of code, of course ;-) The code below uses the ''[expat]'' SAX parser delivered with [tDOM], but should run with little modifications with [TclXML]'s parser too.
}
 package require tdom

 #--- Callbacks for certain parser events
 proc el {name attlist} {
    incr ::nEl
    incr ::nAtt [llength $attlist]
 }
 proc ch data {
    incr ::nChar [string length $data]
 }
 proc pi {target data} {
    incr ::nPi
 }
 #--- "main" loop
 if [llength $argv] {puts "usage: $argv0 file..."}
 foreach file $argv {
     foreach i {nEl nAtt nChar nPi} {set $i 0} ;# reset counters
     set p [expat -elementstartcommand el \
	    -characterdatacommand          ch \
	    -processinginstructioncommand  pi ]
	if [catch {$p parsefile $file} res] {
		puts "error:$res"
    } else {
        puts "$file: $nEl elements, $nAtt attributes, $nChar characters,\
            $nPi processing instructions"
    }
	$p free
 }