#
# Check for Bison. 
#
# This macro verifies that Bison is installed.  If successful, then
# 1) YACC is set to bison -y (to emulate YACC calls)
# 2) BISON is set to bison
#
AC_DEFUN([AC_PROG_BISON],
[AC_CACHE_CHECK(,
ac_cv_has_bison,
[AC_PROG_YACC()
])
if test "$YACC" != "bison -y"; then
  AC_MSG_ERROR([bison not found but required])
else
  AC_SUBST(BISON,[bison],[location of bison])
fi
])