Instead of relying on GScanner and its idea of syntax, code up a parser
that obeys the CSS spec.
This also has the great side effect of reporting correct line numbers
and positions.
Also included is a reorganization of the returned error values. Instead
of error values describing what type of syntax error was returned, the
code just returns SYNTAX_ERROR. Other messages exist for when actual
values don't work or when errors shouldn't be fatal due to backwards
compatibility.
This is pretty important, because otherwise recursions cause crashes.
And if you accidentally change your theme to one that crashes on load,
all your gonna SEGV and then on reboot, gdm tries to load the theme...
Call gtk_css_provider_load_from_file() instead of the internal function.
This has two advantages:
1) It simplifies the code a lot
2) It gets rid of GMappedFile usage. GMappedFile does not work
everywhere, so this is finally portable.
This way, we achieve two things:
1) We can unify file loading to one location
2) We can emit the error from file loading using the parsing-error
signal. This is very useful for @import handling in particular.
Emits the error without the need for a scanner. Also simplifies
gtk_css_provider_take_error() because we now can assert an available
scanner at all times.
Instead of having an error member in the CSS provider's private struct,
connect a signal handler when an error is passed in. This has two
advantages:
1) It makes the code clearer as we don't have to keep track of an error
member anywhere.
2) It causes a non-emission of the g_warning() when an error was passed
in, because it only triggers when no signal handlers are connected.
So we get identical behavior to GTK 3.0 where warnings where only
emitted when no error was passed in.
Instead of aborting a parse whenever we encounter an error, parse to the
end. But if a GError was passed in, reset the provider completely as if
nothing had been parsed.
Value parsing only sometimes emitted errors. Sometimes it didn't emit
errors but ignored the value, sometimes it took a default, sometimes it
converted it to something it deemed suitable.
While refactoring, I moved the whole GValue <=> char * conversion
routines to a separate file, to make navigating the core css provider
easier.
