Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/1690
New procedural operator: `:matches-path(...)`
Description: this is a all-or-nothing passthrough operator, which
on/off behavior is dictated by whether the argument match the
path of the current location. The argument can be either plain
text to be found at any position in the path, or a literal regex
against which the path is tested.
Whereas cosmetic filters can be made specific to whole domain,
the new `:matches-path()` operator allows to further narrow
the specificity according to the path of the current document
lcoation.
Typically this procedural operator is used as first operator in
a procedural cosmetic filter, so as to ensure that no further
matching work is performed should there be no match against the
current path of the current document location.
Example of usage:
example.com##:matches-path(/shop) p
Will hide all `p` elements when visiting `https://example.com/shop/stuff`,
but not when visiting `https://example.com/` or any other page
on `example.com` which has no instance of `/shop` in the path part
of the URL.
The procedural cosmetic filtering code has been split from
the content script code injected unconditionally and will
from now on be injected only when it is needed, i.e. when
there are procedural cosmetic filters to enforce.
The motivation for this is:
https://www.debugbear.com/blog/2020-chrome-extension-performance-report#what-can-extension-developers-do-to-keep-their-extensions-fast
Though uBO's content script injected unconditionally in all
pages/frames is relatively small, I still wanted to further
reduce the amount of content script code injected
unconditionally: The procedural cosmetic filtering code
represents roughly 14KB of code the browser won't have to
parse/execute unconditionally unless there exists procedural
cosmetic filters to enforce for a page or frame.
At the time the above article was published, the total
size of unconditional content scripts injected by uBO was
~101 KB, while after this commit, the total size will be
~57 KB (keeping in mind uBO does not minify and does not
remove comments from its JavaScript code).
Additionally, some refactoring on how user stylesheets are
injected so as to ensure that `:style`-based procedural
filters which are essentially declarative are injected
earlier along with plain, non-procedural cosmetic filters.
