From d87d4ad3a6d2ec2804cb7b20128fecb6d9df4e6e Mon Sep 17 00:00:00 2001
From: Alasdair Armstrong
Date: Thu, 25 Jan 2018 00:30:24 +0000
Subject: 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.
---
 src/lexer.mll | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'src/lexer.mll')

diff --git a/src/lexer.mll b/src/lexer.mll
index 21b70c5f..77fba70b 100644
--- a/src/lexer.mll
+++ b/src/lexer.mll
@@ -186,9 +186,10 @@ let alphanum = letter|digit
 let startident = letter|'_'
 let ident = alphanum|['_''\'''#']
 let tyvar_start = '\''
-let oper_char = ['!''$''%''&''*''+''-''.''/'':''<''=''>''@''^''|']
+let oper_char = ['!''%''&''*''+''-''.''/'':''<''=''>''@''^''|']
 let operator = (oper_char+ ('_' ident)?)
 let escape_sequence = ('\\' ['\\''\"''\'''n''t''b''r']) | ('\\' digit digit digit) | ('\\' 'x' hexdigit hexdigit)
+let lchar = [^'\n']
 
 rule token = parse
   | ws
@@ -236,6 +237,8 @@ rule token = parse
   | "//"        { line_comment (Lexing.lexeme_start_p lexbuf) lexbuf; token lexbuf }
   | "/*"        { comment (Lexing.lexeme_start_p lexbuf) 0 lexbuf; token lexbuf }
   | "*/"        { raise (LexError("Unbalanced comment", Lexing.lexeme_start_p lexbuf)) }
+  | "$" (ident+ as i) (lchar* as f) "\n"
+    { Lexing.new_line lexbuf; Pragma(i, String.trim f) }
   | "infix" ws (digit as p) ws (operator as op)
     { operators := M.add op (mk_operator Infix (int_of_string (Char.escaped p)) op) !operators;
       Fixity (Infix, Big_int.of_string (Char.escaped p), op) }
-- 
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