The old XPath "position() = 1" would work in Nokogiri due to the way they
retrieve descendants. In Oga however this would simply always return the first
node.
To fix this Oga now counts the amount of preceding siblings that match the same
full name.
This means that "foo[1]" uses this AST:
(predicate (test nil "foo") (int 1))
Instead of this AST:
(test nil "foo" (int 1))
This makes it easier for the XPath evaluator to process predicates correctly.
This method can be used to compare two NodeSet instances. By using
XML::NodeSet#equal_nodes?() the need for exposing the "nodes" instance variable
is also removed.
This expression could be used to get all elements that _don't_ have any
namespace. The problem is that this can't be expressed as just a node test,
instead the resulting XPath would have to look something like the following:
X[local-name() = name()]
However, since the XPath predicates are already created for pseudo classes and
such, also injecting the above into it would be a real big pain. As such I've
decided not to support it.
Instead of using "descendant-or-self" Oga will use "descendant". This ensures
that expressions such as "foo *" don't return a set also including the "foo"
element.
Nokogiri solves this problem in a somewhat different way by using //foo//* for
the CSS expression "foo *". While this works in Nokogiri the expression
"descendant-or-self::node()" is slow as a snail in Oga (due to its nature of
retrieving _all_ nodes first). By using "descendant" we can work around this
problem.
When running XPath queries such as "self::node()" the result should be a set
containing the document itself. This in turn fixes expressions such as
descendant-or-self::node()/a.
This removes parsing support for selectors such as :nth-child(-n-6). According
to the CSS spec this isn't valid anyway (confirmed by testing it in Chromium).
As a result there's no point in supporting it in any way.
When lexing multi-line strings everything used to work fine as long as the input
were to be read as a whole. However, when using an IO instance all hell would
break loose. Due to the lexer reading IO instances on a per line basis,
sometimes Ragel would end up setting "ts" to NULL. For example, the following
input would break the lexer:
<foo class="\nbar" />
Due to the input being read per line, the following data would be sent to the
lexer:
<foo class="\n
bar" />
This would result in different (or NULL) pointers being used for building a
string, in turn resulting in memory allocation errors.
To work around this the string lexing setup has been broken into separate
machines for single and double quoted strings. The tokens used have also been
changed so that instead of just "T_STRING" there are now the following tokens:
* T_STRING_SQUOTE
* T_STRING_DQUOTE
* T_STRING_BODY
A string can have multiple T_STRING_BODY tokens (= multi-line strings, only the
case for IO inputs). These strings are stitched back together by the parser.
This fixes#58.
Processing of this axis along with a predicate wouldn't quite work out. Even if
the predicate returned false the node would still be matched (which should not
be the case).
Previously input such as "x > y" would result in the following token sequences:
T_IDENT, T_CHILD, T_IDENT
This commit changes this to the following:
T_IDENT, T_SPACE, T_CHILD, T_IDENT
This allows the parser to use T_SPACE as a terminal token, this in turn prevents
around 16 shift/reduce conflicts from arising.
This does mean that input such as " > y" or " x > y" is now invalid. This
however can be solved by simply _not_ adding leading/trailing whitespace to CSS
queries.
The new setup will not involve a separate transformation stage, instead the CSS
parser will directly emit an XPath AST. This reduces the overhead needed for
parsing/evaluating CSS selectors while also simplifying the code. The downside
is that I basically have to re-write 80% of the parser.
This uses stricter (and more correct) rules in both the lexer and the parser.
The resulting AST has also received a small rework to make it more compact and
less confusing.
This includes support for the crazy 2n+1 syntax you can use with selectors such
as :nth-child().
CSS selectors: doing what XPath already does using an even crazier syntax,
because screw you.
When lexing XML entities such as & and < these sequences are now
converted into their "actual" forms. In turn, Oga::XML::Text#to_xml ensures they
are encoded when the method is called.
Performance wise this puts some strain on the lexer, for every T_TEXT/T_STRING
node now potentially has to have its content modified. In the benchmark
xml/lexer/string_average_bench.rb the average processing time is now about the
same as before the improvements made in
8db77c0a09. I was hoping that the lexer would
still be a bit faster, but alas this is not the case. Doing this in native code
would be a nightmare as C doesn't have a proper string replacement function. I'm
not old/sadistic enough to write on myself just yet.
This fixes#49
This was a gimmick in the first place. It doesn't work well with IO instances
(= requires re-reading of the input), the code was too complex and it wasn't
that useful in the end. Lets just get rid of it.
This fixes#53.
Instead of relying on String#count for counting newlines in text nodes, Oga now
does this in C/Java. String#count isn't exactly the fastest way of counting
characters. Performance was measured using
benchmark/xml/lexer/string_average_bench.rb. Before this patch the results were
as following:
MRI: 0.529s
Rbx: 4.965s
JRuby: 0.622s
After this patch:
MRI: 0.424s
Rbx: 1.942s
JRuby: 0.665s => numbers vary a bit, seem roughly the same as before
The commands used for benchmarking:
$ rake clean # to make sure that C exts aren't shared between MRI/Rbx
$ rake generate
$ rake fixtures
$ ruby benchmark/xml/lexer/string_average_bench.rb
The big difference for Rbx is probably due to the implementation of String#count
not being super fast. Some changes were made
(https://github.com/rubinius/rubinius/pull/3133) to the method, but this hasn't
been released yet.
JRuby seems to perform in a similar way, so either it was already optimizing
things for me or I suck at writing well performing Java code.
This fixes#51.
This ensures we only call String#downcase if we can't find an all lowercased
*and* all uppercased version of the element name. This in turn can save as many
object allocations as there are HTML opening tags.
This fixes#52.
Instead of using `namespace.name` lets just use `namespace_name`. This fixes the
problem of serializing attributes where the namespace prefix is "xmlns" as the
namespace for this isn't registered by default.
This fixes#47.
This API is a little bit dodgy (similar to Nokogiri's API) due to the use of
separate parser and handler classes. This is done to ensure that the return
values of callback methods (e.g. on_element) aren't used by Racc for building
AST trees. This also ensures that whatever variables are set by the handler
don't conflict with any variables of the parser.
This fixes#42.
While still a bit cryptic this is probably as best as we can get it. An example:
Oga.parse_xml("<namefoo:bar=\"10\"")
parser.rb:116:in `on_error': Unexpected string on line 1: (Racc::ParseError)
=> 1: <namefoo:bar="10"
This fixes#43.
When an XML element has no child nodes a self-closing tag is used. When parsing
documents/elements in HTML mode this is only done if the element is a so called
"void element" (e.g. <link> tags).
This fixes#46.
When the default namespace is registered (using xmlns="...") Oga now properly
sets the namespace of the container and all child elements.
This fixes#44.
Yorick Peterse
Tero Tasanen