Add simple conditional processing and file include

Can now use C-style include declarations to include files within other sail files. This is done in such a way that all the location information is preserved in error messages. As an example:

$include "aarch64/prelude.sail"
$define SYM
$ifndef SYM
$include <../util.sail>
$endif

would include the file aarch64/prelude.sail relative to the file where the include is contained. It then defines a symbol SYM and includes another file if it is not defined. The <../util.sail> include will be accessed relative to $SAIL_DIR/lib, so $SAIL_DIR/lib/../util.sail in this case.

This can be used with the standard C trick of

$ifndef ONCE
$define ONCE
val f : unit -> unit
$endif

so no matter how many sail files include the above file, the valspec for f will only appear once.

Currently we just have $include, $define, $ifdef and $ifndef (with $else and $endif). We're using $ rather than # because # is already used in internal identifiers, although this could be switched.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/util.ml b/src/util.ml
index 94bbc6dc..6d4b3726 100644
--- a/src/util.ml
+++ b/src/util.ml
@@ -413,3 +413,5 @@ let zchar c =
 let zencode_string str = "z" ^ List.fold_left (fun s1 s2 -> s1 ^ s2) "" (List.map zchar (string_to_list str))
 
 let zencode_upper_string str = "Z" ^ List.fold_left (fun s1 s2 -> s1 ^ s2) "" (List.map zchar (string_to_list str))
+
+let warn str = prerr_endline (("Warning" |> yellow |> clear) ^ ": " ^ str)