tweaks the grammar to handle empty files (#18)

also adds a tests to prevent regressions.

Author: ivg

frontc/cparser.mly

@@ -185,9 +185,11 @@ AND_EQ PIPE_EQ CIRC_EQ INF_INF_EQ SUP_SUP_EQ
 
 %%
 
-interpret: file EOF {$1};
+interpret: file {$1};
 
-file: globals EOF {List.rev $1};
+file:
+  | EOF   {[]}
+  | globals EOF {List.rev $1};
 
 globals:
   | global						{[$1]}

test.t/empty.c

@@ -1,3 +1,6 @@
+  $ ../printc/printc_bin.exe empty.c
+
+
   $ ../printc/printc_bin.exe volatile.c
 
   typedef int  const t1;
@@ -32,6 +35,8 @@
 
 
 
+
+
   $ ../printc/printc_bin.exe for.c
 
   void main()
@@ -53,6 +58,8 @@
 
 
 
+
+
   $ ../printc/printc_bin.exe from.c
 
   void main()
@@ -85,6 +92,8 @@
 
 
 
+
+
   $ ../printc/printc_bin.exe okp.c
 
   typedef int j_decompress_ptr, boolean, my_main_ptr, j_decompress_ptr, size_t,