XML Spec CharData doubt

[Manish Tomar]

Hi All,

I have a doubt in "CharData" grammar given XML 1.0 spec (http://
www.w3.org/TR/REC-xml/#NT-CharData).

[14] CharData ::= [^<&]* - ([^<&]* ']]>' [^<&]*)

The text above [14] (in spec) describing CharData says that char data
must not have following chars: ^,<,& and it must not have ']]>' (CDATA
ending section) inside it. The grammar is given above. I was wondering
if the grammar can be written as

CharData ::= [^<&]* - ']]>'

Wouldnt this mean the same thing as the text describing [14]?

Thanks in advance,
Manish

PS: I am sorry if the message doesn't fit in this group.

 

[Bjoern Hoehrmann]

* Manish Tomar wrote in comp.text.xml:

I have a doubt in "CharData" grammar given XML 1.0 spec (http://
www.w3.org/TR/REC-xml/#NT-CharData).

[14] CharData ::= [^<&]* - ([^<&]* ']]>' [^<&]*)

The text above [14] (in spec) describing CharData says that char data
must not have following chars: ^,<,& and it must not have ']]>' (CDATA
ending section) inside it. The grammar is given above. I was wondering
if the grammar can be written as

CharData ::= [^<&]* - ']]>'

Wouldnt this mean the same thing as the text describing [14]?

No, a string like "...]]>..." is not allowed by the original production
but is allowed by your rewrite. The productions match the whole string,
they don't look at whether a string contains something that matches, un-
less you write it as the original does.

 

[Richard Tobin]

[14] CharData ::= [^<&]* - ([^<&]* ']]>' [^<&]*)

The text above [14] (in spec) describing CharData says that char data
must not have following chars: ^,<,& and it must not have ']]>' (CDATA
ending section) inside it. The grammar is given above. I was wondering
if the grammar can be written as

CharData ::= [^<&]* - ']]>'

Wouldnt this mean the same thing as the text describing [14]?

A production "A - B" means all the strings that match A, but which don't
match B. If we used your production, we would accept strings like

xyz]]>xyz

because it matches A and doesn't match B. The production could have been
more concisely written as

[^<&]* - ( .* ']]>' .* )

but presumably it was thought clearer to restrict the second part to
be a subset of the first. (In fact, I don't think the XML spec uses
"." at all.)

-- Richard

 

[Manish Tomar]

Thanks a lot guys!
I also checked out the the Notation section in the spec and your
explanations were clear.

 

[Manish Tomar]

Thanks a lot guys!
I also checked out the the Notation section in the spec and your
explanations were clear.