# onceonly.m4 serial 3

dnl Copyright (C) 2002, 2003 Free Software Foundation, Inc.

dnl This file is free software, distributed under the terms of the GNU

dnl General Public License.  As a special exception to the GNU General

dnl Public License, this file may be distributed as part of a program

dnl that contains a configuration script generated by Autoconf, under

dnl the same distribution terms as the rest of that program.

dnl This file defines some "once only" variants of standard autoconf macros.

dnl   AC_CHECK_HEADERS_ONCE         like  AC_CHECK_HEADERS

dnl   AC_CHECK_FUNCS_ONCE           like  AC_CHECK_FUNCS

dnl   AC_CHECK_DECLS_ONCE           like  AC_CHECK_DECLS

dnl   AC_REQUIRE([AC_HEADER_STDC])  like  AC_HEADER_STDC

dnl The advantage is that the check for each of the headers/functions/decls

dnl will be put only once into the 'configure' file. It keeps the size of

dnl the 'configure' file down, and avoids redundant output when 'configure'

dnl is run.

dnl The drawback is that the checks cannot be conditionalized. If you write

dnl   if some_condition; then gl_CHECK_HEADERS(stdlib.h); fi

dnl inside an AC_DEFUNed function, the gl_CHECK_HEADERS macro call expands to

dnl empty, and the check will be inserted before the body of the AC_DEFUNed

dnl function.

dnl Autoconf version 2.57 or newer is recommended.

AC_PREREQ(2.54)

# AC_CHECK_HEADERS_ONCE(HEADER1 HEADER2 ...) is a once-only variant of

# AC_CHECK_HEADERS(HEADER1 HEADER2 ...).

AC_DEFUN([AC_CHECK_HEADERS_ONCE], [

  :

  AC_FOREACH([gl_HEADER_NAME], [$1], [

    AC_DEFUN([gl_CHECK_HEADER_]m4_quote(translit(defn([gl_HEADER_NAME]),

                                                 [-./], [___])), [

      AC_CHECK_HEADERS(gl_HEADER_NAME)

    ])

    AC_REQUIRE([gl_CHECK_HEADER_]m4_quote(translit(gl_HEADER_NAME,

                                                   [-./], [___])))

  ])

])

# AC_CHECK_FUNCS_ONCE(FUNC1 FUNC2 ...) is a once-only variant of

# AC_CHECK_FUNCS(FUNC1 FUNC2 ...).

AC_DEFUN([AC_CHECK_FUNCS_ONCE], [

  :

  AC_FOREACH([gl_FUNC_NAME], [$1], [

    AC_DEFUN([gl_CHECK_FUNC_]defn([gl_FUNC_NAME]), [

      AC_CHECK_FUNCS(defn([gl_FUNC_NAME]))

    ])

    AC_REQUIRE([gl_CHECK_FUNC_]defn([gl_FUNC_NAME]))

  ])

])

# AC_CHECK_DECLS_ONCE(DECL1 DECL2 ...) is a once-only variant of

# AC_CHECK_DECLS(DECL1, DECL2, ...).

AC_DEFUN([AC_CHECK_DECLS_ONCE], [

  :

  AC_FOREACH([gl_DECL_NAME], [$1], [

    AC_DEFUN([gl_CHECK_DECL_]defn([gl_DECL_NAME]), [

      AC_CHECK_DECLS(defn([gl_DECL_NAME]))

    ])

    AC_REQUIRE([gl_CHECK_DECL_]defn([gl_DECL_NAME]))

  ])

])