1AC_DEFUN([PDNS_CHECK_BISON], [
2  AC_REQUIRE([AC_PROG_YACC])
3  AC_REQUIRE([AC_PROG_EGREP])
4
5  AC_CACHE_CHECK([if bison is the parser generator],[pdns_cv_prog_bison],[
6    AS_IF([$YACC --version 2>/dev/null | $EGREP -q '^bison '],
7      [pdns_cv_prog_bison=yes], [pdns_cv_prog_bison=no])
8  ])
9
10  AS_IF([test "x$pdns_cv_prog_bison" = "xno"], [
11    AS_IF([test ! -f "${srcdir}/pdns/bindparser.cc"],
12      [AC_MSG_ERROR([bison is missing and you don't have ${srcdir}/pdns/bindparser.cc. Please install bison])]
13    )]
14  )
15])
16