Commit 9e2ad88455 improved app search results by allowing to differentiate
their match_type: prefix match or substring match; while giving more priority
to prefix matches over substring matches, but only when they are in the same
match_category[1].
This was a step forward but, as outlined in #3082, still not enough to get
most relevant results first to the user, because apparently (and for the
specific case of desktop app searching) a prefix match in a lower category
is more relevant to the user than a substring match in a higher category.
So that's what this commit implements, i.e. it makes sure prefix matches
are still preferred over substring matches but this time not only when
in the same category but also across different categories.
[1] Match category is the Desktop file key where the match happened.
They are shown below from top to lesser priority.
DESKTOP_KEY_Name
DESKTOP_KEY_Exec
DESKTOP_KEY_Keywords
DESKTOP_KEY_GenericName
DESKTOP_KEY_X_GNOME_FullName
DESKTOP_KEY_Comment
Fixes#3082
· Add a usage output that is printed when called with no argument
or with '--help' argument. This is helpful as it avoids having
to read the source code to know how to run the different options.
· Adds new '--should-show-only' option to 'search' command, to
better mimick the gnome-shell app search, by not returning
apps with NoDisplay=true.
Example for running a desktop app search with the new option from
inside the GLib build dir:
$ gio/tests/apps search --should-show-only settings
