[Tclxml-users] Possible fix for "-final 0" in pure Tcl 2.5?

[Ted N. S. A. GA <te...@ag...>]

Hello folks,

You may recall that back in December, I had found a bug in using the
pure Tcl version of tclxml to parse XML streams with the "-final 0" option.

I think someone suggested diking out the Rose patch for bug #596959, but
there were others saying that would break something else, and there was
no real resolution to the issue.

I recently had a rare spare day to look at it again.  I certainly can't
claim to understand the code which uses regular expressions in a much more
heavy duty fashion than anything else I have seen in Tcl.

However, after hours of playing around with "puts", I was drawn back to
the Rose patch.  It seems to be intended to insert a null XML element
into the stream for some reason, but I question the way it does this.

The tokenized xml seems to be put into a list in 4-tuples, as in the
loop at line 332 of sgmlparser.tcl:

	foreach {tag close param text} $sgml 

The rose patch on line 175 of sgmlparse.tcl inserts -5- empty tuples
into the tokenized xml:

	set sgml [linsert $sgml 0 {} {} {} {} {}]

This pushes what was a "tag" into being a "close".

Should this not be -4- empty tuples?

If I apply the following patch:

-----CUT HERE-----
*** sgmlparser.tcl.bak	Tue Feb  4 13:34:40 2003
--- sgmlparser.tcl	Tue Feb  4 13:40:16 2003
***************
*** 172,178 ****
  
  	# Patch from bug report #596959, Marshall Rose
  	if {[string compare [lindex $sgml 4] ""]} {
! 	    set sgml [linsert $sgml 0 {} {} {} {} {}]
  	}
  
      } else {
--- 172,178 ----
  
  	# Patch from bug report #596959, Marshall Rose
  	if {[string compare [lindex $sgml 4] ""]} {
! 	    set sgml [linsert $sgml 0 {} {} {} {} ]
  	}
  
      } else {
-----CUT HERE---

Then my test program seems to run OK.

Comments?


			Ted

PS:

Here's my test program.  Run it with no args to do a piecemeal parse
with -final 0.  Run it with 1 arg to do a all at once parse with
-final 0, and run it with 2 args to do an all at once parse with -final 1.

Before the "patch", case 1 will error out, case 2 will produce no output
and case 3 will work OK.  After the patch, all 3 cases produce the same
output.

----CUT HERE----
#!/usr/local/bin/tclsh8.4

package require xml

proc xml_el_start {name attrs args} {
	puts "Start name ($name) attrs ($attrs) args ($args)"
}

proc xml_el_end {name args} {
	puts "End name ($name) args ($args)"
}

proc xml_char_data {data} {
	if { [string length $data] } {
		puts "Cdata data ($data)"
	}
}

set parser [ ::xml::parser \
	-elementstartcommand xml_el_start \
	-elementendcommand xml_el_end \
	-characterdatacommand xml_char_data \
	-defaultcommand xml_default \
	-final 0 \
]
      

if { [llength $argv]  == 0 } {
	$parser parse "<fooby>"
	$parser parse "<hello>"
	$parser parse "world"
	$parser parse "</hello>"
	$parser parse "</fooby>"
} else {
	if { [llength $argv] == 2} {
		$parser configure -final 1
	}
	$parser parse {<fooby><hello>world</hello></fooby>}
}
----CUT HERE---