NEWS file for the selectr package

Changes in version 0.5-1

BUG FIXES

• Fixed handling of CSS unicode escapes in attribute values. This would be observed when the attribute value contained hexadecimal sequences like (abcdef) where the characters inside the parentheses were not properly escaped. This fix ensures that such sequences are correctly translated to their XPath equivalents. Thanks to André Veríssimo for reporting the issue.

Changes in version 0.5-0

NEW FEATURES

• Added support for CSS Selectors Level 4 pseudo-classes :is(), :where(), and :has(). The :is() pseudo-class matches elements against a list of selectors, taking the maximum specificity from its arguments. The :where() pseudo-class works similarly to :is() but always has zero specificity. The :has() pseudo-class represents an element if any of the relative selectors match when anchored against that element, with specificity calculated from the maximum of its arguments.

• Added support for complex selectors in :nth-child() and :nth-last-child() using the of S syntax (e.g., :nth-child(2 of .foo)). This allows matching the nth child that matches a specific selector or selector list.

• Extended :not() to accept multiple selectors separated by commas (e.g., :not(.foo, #bar)), following CSS Selectors Level 4. Specificity is now calculated as the maximum specificity among all arguments, rather than the sum.

• Added support for additional CSS Selectors Level 4 pseudo-classes: :any-link, :target-within, and :local-link. These pseudo-classes do not match any elements in static XML/HTML documents and translate to XPath expressions that always evaluate to false. For now, most of the new Level 4 pseudo-classes that depend on dynamic document state e.g. :user-valid and :placeholder-shown are not implemented, but may be at a future date to be non-matching selectors.

• The :lang() and :dir() pseudo-classes now support multiple comma-separated arguments (e.g., :lang(en, fr, de)).

• Added :matches() as a backwards-compatible alias for :is().

MINOR CHANGES

• Improved sibling selector translation to use a more compact form. For the adjacent sibling combinator a + b, the generated XPath now uses a/following-sibling::*[1][self::b] instead of a/following-sibling::*[(name() = 'b') and (position() = 1)].

• The descendant combinator a b now uses a//b instead of a/descendant::b for a more concise XPath. Unfortunately a similar optimisation cannot be applied to in general when attempting to replace descendant-or-self:: with .//a as it would prevent root nodes being matched correctly.

• Improved validation of CSS selector arguments. Better error messages are now provided when pseudo-elements appear inside functional pseudo-classes where they are not permitted (e.g., inside :is(), :matches(), :where(), or :has()).

• Enhanced input validation for :lang() and :dir() pseudo-classes to ensure proper argument formatting and to reject invalid or empty language tags.

• Improved handling of edge cases in selector parsing, including better validation of class selector syntax and more robust handling of null or missing element components.

• Simplified method registration for XML and xml2 objects. No longer necessary to hook into package load/unload events.

Changes in version 0.4-2

MINOR CHANGES

• Improve handling of vectors of length > 1 in logical comparison. Contributed by Garrick Aden-Buie.

• Minor improvements to error message construction. Contributed by Michael Chirico.

Changes in version 0.4-1

BUG FIXES

• When the R.oo package is attached, the use of class selectors no longer worked. This is due to the use of the Class name for R.oo's base class object, where selectr was also using it (but not exporting) the same name of Class for representing a class selector. Consequently, selectr's code was changed to rename the class to avoid any clashing. Because it was not exported, this is purely an internal change. Thanks to Francois Lemaire-Sicre for reporting the issue.

Changes in version 0.4-0

MINOR CHANGES

• Large rewrite of internals to use the R6 OO system instead of Reference Classes. This does not affect any external facing code as the results should be identical to the previous implementation, which is why this change is marked as minor. Initial and crude performance testing (by running the test suite) indicates that the R6 implementation is approximately twice as fast at generating XPath as the Reference Classes implementation.

• The minimum required version of R for selectr has been increased from 2.15.2 to 3.0 as that is the minimum required version of R6.

• Minor performance enhancements have been made. Not only is R6 faster than Reference Classes, the use of string formatting has been replaced with string concatenation. Additionally dynamic calling of methods via do.call() has been replaced with direct method calls.

BUG FIXES

• The issues in previous releases where methods can sometimes be missing should now be resolved. The bug appeared to lie in core Reference Classes code. By switching to R6, this type of issue should no longer be possible.

Changes in version 0.3-2

MINOR CHANGES

• Improved method registration for XML and xml2 objects. Avoids checks on each use and is only performed once per dependent package load/unload.

BUG FIXES

• In some environments, reference class methods were missing at runtime. This appears to be due to some internal behaviour in them methods package where methods are registered on an objects when the $ operator is used for a field or method. Instead, when a method is missing, they are manually bound to the object.

Changes in version 0.3-1

MINOR CHANGES

• Enabled partial matching on the translator argument to css_to_xpath(). Instead of defaulting to a generic translator, a non-matching argument will be returned with an error.

• Introduced many more unit tests via the covr package. This enabled dead code to be trimmed and also identified areas of code which needed improvement. Minor enhancements include: tolerate whitespace within a :not(), more consistent results returned from parser methods, improvements to argument parsing.

BUG FIXES

• The |= attribute matching operator was not being parsed correctly for the generic translator.

• Handle scenario where a CSS comment is unclosed. Results in everything after the comment start to be removed (which may or may not result in a valid selector).

Changes in version 0.3-0

MAJOR CHANGES

• Added support for documents from the xml2 package.

• selectr now also does not strictly depend on the XML package. If either the XML or xml2 packages are present (which are required for the querySelector methods to work) then querySelector will begin to work for them. This also enables selectr to be used for translation-only.

BUG FIXES

• Improve support for nth-*(an+b) selectors. Ported from cssselect.

Changes in version 0.2-3

MINOR CHANGES

• Code cleanup contributed by Kun Ren (#1).

• Updated DESCRIPTION to include URL and BugReports fields. Also update email address.

BUG FIXES

• Fix behaviour for nth-*(an+b) pseudo-class selectors for negative a's. Contributed to cssselect by Paul Tremberth, ported to R.

• Escape delimiting characters to support new version of the stringr package. Probably should have been done in the first place. Reported by Hadley Wickham (#5).

Changes in version 0.2-2

MINOR CHANGES

• Corrected licence to BSD 3 clause. This was the licence in use previously, but has now been made more explicit.

• Removed 'Enhances' field because we import functions from XML. This choice is made because XML is a required package, rather than an optional package that can be worked with. This and the previous change have been made to keep up with recent changes in R-devel.

Changes in version 0.2-1

MINOR FEATURES

• Added a 'CITATION' file which cites a technical report on the package.

• show() methods are now available on internal objects, making interactive extensibility and bug-fixing easier. This is simply wrapping the repr() methods (mirroring the Python source) that the same objects have.

BUG FIXES

• Use the session character encoding to determine whether to run unicode tests. Tests break in non-unicode sessions otherwise.

Changes in version 0.2-0

NEW FEATURES

• Introduced new functions querySelectorNS() and querySelectorAllNS() to ease the use of namespaces within a document. Previously this would have required knowledge of XPath.

BUG FIXES

• Fix meaning of :empty, whitespace is not empty.

• Use lang() for XML documents with the :lang() CSS selector.

• |ident no longer produces a parsing error, but is now equivalent to just 'ident'.

Changes in version 0.1-1

BUG FIXES

• Now testing unicode only in non-Windows platforms on package check. Output should still be consistent, just depends on the current charset being unicode.

Changes in version 0.1-0

NEW FEATURES

• Initial port of the Python 'cssselect' package. Code is very literally ported, including the test suite.

• Wrapped translation functionality into a single function, css_to_xpath().

• Created two convenience functions, querySelector() and querySelectorAll(). These mirror the behaviour of the same functions present in a web browser. querySelector() returns a node, while querySelectorAll() returns a list of nodes.