Map the type CLASS to a list of variable settings.
CLASS is the project class, a symbol. VARIABLES is a list
that declares directory-local variables for the class.
An element in VARIABLES is either of the form:
(MAJOR-MODE . ALIST)
or
(DIRECTORY . LIST)
In the first form, MAJOR-MODE is a symbol, and ALIST is an alist
whose elements are of the form (VARIABLE . VALUE).
In the second form, DIRECTORY is a directory name (a string), and
LIST is a list of the form accepted by the function.
When a file is visited, the file's class is found. A directory
may be assigned a class using `dir-locals-set-directory-class'.
Then variables are set in the file's buffer according to the
VARIABLES list of the class. The list is processed in order.
* If the element is of the form (MAJOR-MODE . ALIST), and the
buffer's major mode is derived from MAJOR-MODE (as determined
by `derived-mode-p'), then all the variables in ALIST are
applied. A MAJOR-MODE of nil may be used to match any buffer.
`make-local-variable' is called for each variable before it is
set.
* If the element is of the form (DIRECTORY . LIST), and DIRECTORY
is an initial substring of the file's directory, then LIST is
applied by recursively following these rules.