Re: [xml] Degenerate case

[Liam R E Quin <liam holoweb net>]

On Tue, 2019-09-17 at 00:47 -0400, Webb Scales wrote:
> Would a file containing just an XML comment, e.g.,
>
> <!-- My comment. -->
>
>
> be an acceptable input to LibXML2?

Let's look at  the specification of XML,
https://www.w3.org/TR/REC-xml/

We see in section 2.1,
[[
 [Definition: A textual object is a well-formed XML document if:]

    Taken as a whole, it matches the production labeled document.

    It meets all the well-formedness constraints given in this
specification.

    Each of the parsed entities which is referenced directly or
indirectly within the document is well-formed.
]]

So we need our input to match Document.

The immediately following text in the spec has,
[[

Document
[1]     document           ::=          prolog element Misc*
]]

If you follow these you find "element" means we need exactly one top-
level element, <foo>...</foo>, and your example has a comment but no
element. So, it is not well-formed.

You will find it helpful to become moer familiar with the grammar in
the XML specification.

Best,

Liam


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