new submission: AX_CONFIG_PREFIXED_HEADER

[Matto Marjanovic]

Hiya,

Appended is my submission for a new pair of macros:

    AX_CONFIG_PREFIXED_HEADER(OUTPUT, PREFIX, INPUT)
    AX_PREFIXED_DEFINE(PREFIX, SYMBOL)

 for release under the "GPLv2 with Autoconf exception" license.

These were inspired by the AX_PREFIX_CONFIG_H macro to solve the
 same basic problem:  create an installable version of the generated 
 "config.h" header by prefixing the defined symbols with a PREFIX.

However, instead of copying/prefixing the *entire* input header file,
 this new pair of macros allows the developer to select exactly which
 symbols she needs in the installable header file.  AX_PREFIXED_DEFINE
 is used to schedule a SYMBOL (which should already have a corresponding
 AC_DEFINE) for prefixing with PREFIX.  AX_CONFIG_PREFIXED_HEADER
 specifies that the OUTPUT header is generated from the INPUT header
 using all the symbols scheduled under PREFIX.

It's nice because it creates an installable config header with only
 the symbols one absolutely needs (and none of the extraneous cruft
 which may be broken anyhow).

The macros currently have no defaults for the parameters; each parameter
 is required.  I'm happy to take suggestions for how to improve this,
 or pointers to examples of the right way to do this, or anything else
 in the macros.  (This is my first autoconf macro, and I must admit I'd
 like to take a break from pouring over m4 source code for a while.)

-matt m.

===8<========================================================================

dnl *************************************************************************
dnl AX_CONFIG_PREFIXED_HEADER and AX_PREFIXED_DEFINE
dnl
dnl @synopsis AX_CONFIG_PREFIXED_HEADER(OUTPUT, PREFIX, INPUT)
dnl @synopsis AX_PREFIXED_DEFINE(PREFIX, SYMBOL)
dnl
dnl This pair of macros is used to create an installable version of a
dnl configure-generated config file (such as the usual 'config.h', which
dnl itself should never be installed by a package).
dnl
dnl The classic example is the creation of a "mypkg-config.h" file
dnl which will be installed along with mypkg's other header files.
dnl Your configure.ac should contain:
dnl
dnl    AC_CONFIG_HEADERS([config.h])
dnl    ...
dnl    AX_CONFIG_PREFIXED_HEADER([mypkg-config.h], [MYPKG], [config.h])
dnl
dnl This declares that 'mypkg-config.h' will be generated at the end of
dnl config.status from 'config.h' by prefixing the desired symbols with
dnl "MYPKG_".  To schedule symbols for inclusion in 'mypkg-config.h',
dnl you would add the following to configure.ac:
dnl
dnl    AX_PREFIXED_DEFINE([MYPKG], [HAVE_FEATURE_Q])
dnl    ...
dnl    AX_PREFIXED_DEFINE([MYPKG], [HAVE_ALLOCA_H])
dnl    ...
dnl    AX_PREFIXED_DEFINE([MYPKG], [SPECIAL_PRINTING_STRING])
dnl        etc.
dnl
dnl Each instance of AX_PREFIXED_DEFINE() should correspond to an instance
dnl of the usual AC_DEFINE(); the AX_PREFIXED_DEFINE() merely declares that
dnl the DEFINE'd symbol should be prefixed with "MYPKG_" and added to the
dnl 'mypkg-config.h' output file.  
dnl
dnl AX_CONFIG_PREFIXED_HEADER will only transfer over "#define SYMBOL ..."
dnl and "/* #undef SYMBOL ... */" declarations.  It will also attempt to
dnl transfer an immediately preceding (no intervening blank lines) C-style
dnl comment block.
dnl
dnl The mutual ordering of AC_CONFIG_PREFIXED_HEADER, AC_CONFIG_HEADERS,
dnl AX_PREFIXED_DEFINE, and AC_DEFINE is unimportant.  All the real work
dnl is done at AC_OUTPUT and during execution of config.status.
dnl
dnl @version v1.0 (last modified: 2004-08-08)
dnl @author Matthew Marjanovic <address@hidden>
dnl
dnl *************************************************************************
AC_DEFUN([AX_CONFIG_PREFIXED_HEADER],[dnl
AC_CONFIG_COMMANDS([$1],[dnl
AS_VAR_PUSHDEF([_OUT],[ax_config_prefixed_OUT])dnl
AS_VAR_PUSHDEF([_PFX],[ax_config_prefixed_PFX])dnl
AS_VAR_PUSHDEF([_INP],[ax_config_prefixed_INP])dnl
AS_VAR_PUSHDEF([_DFN],[ax_config_prefixed_DFN])dnl
AS_VAR_PUSHDEF([_TMP],[ax_config_prefixed_TMP])dnl
AS_VAR_PUSHDEF([_SCRIPT],[ax_config_prefixed_SCRIPT])dnl
_OUT="$1"
_PFX=AS_TR_CPP([$2])
_INP=`echo "$3" | sed -e 's/ *//'`
_DFN=AS_TR_CPP([_$_OUT])
_TMP="$tmp/$_OUT"
_SCRIPT="$tmp/${_OUT}.sed"
if test -z "$_PFX" ; then
   AC_MSG_ERROR([missing prefix in [$0]])
else
  if test ! -f "$_INP" ; then 
    if test -f "$srcdir/$_INP" ; then
       _INP="$srcdir/$_INP"
    fi
  fi
  AC_MSG_NOTICE([creating $_OUT (prefix $_PFX for $_INP)])
  if test ! -f $_INP ; then
    AC_MSG_ERROR([input file $_INP does not exist])
  else
    # Create the transformation script
    cat <<_EOF >$_SCRIPT
@%:@ look for requested keywords and prefix them
m4_ifdef([_AX_PREFIXED_DEFINE_VARS($2)],
         [AC_FOREACH([AC_Var], m4_defn([_AX_PREFIXED_DEFINE_VARS($2)]),
[s/@%:@\\( *\\)\\(def[]ine\\|undef\\)  *\\(AC_Var\\)\\(.*\\)/@%:@\\1\\2 
${_PFX}_\\3 \\4/
])])dnl
@%:@ successful?  then go print
tPrint
@%:@ else, try to collect a comment
\\,/\\*, bCommentBegin
@%:@ else, clear comment if a blank li[]ne is encountered
/ */ h
d
@%:@ Comments:  collect lines in hold buffer until end marker found.
:CommentBegin
\\,\\*/, bCommentEnd
N; bCommentBegin
:CommentEnd
h; d
@%:@ append pattern/nl to hold buffer, remove any blank, print, clear hold.
:Print
s/\\(.*\\)/\\1\\n/
H; x; s/^\\n//; p
s/.*//; x; d
_EOF
    # Run _INP through _SCRIPT to create _TMP
    cat <<_EOF >$_TMP
/*
   $_OUT
   This is an architecture-specific fi[]le which was generated
   automatically by configure.

   Do not edit it manually.
*/

@%:@ifndef $_DFN
@%:@def[]ine $_DFN

_EOF
    sed -nf $_SCRIPT $_INP >>$_TMP
    cat <<_EOF >>$_TMP

@%:@endif /* $_DFN */
_EOF
    # Check if new output is different from existing...
    # ...move to destination if so.
    if cmp -s $_OUT $_TMP 2>/dev/null; then
      AC_MSG_NOTICE([$_OUT is unchanged])
    else
      ac_dir=`AS_DIRNAME(["$_OUT"])`
      AS_MKDIR_P(["$ac_dir"])
      rm -f "$_OUT"
      mv "$_TMP" "$_OUT"
    fi
  fi
fi
AS_VAR_POPDEF([_SCRIPT])dnl
AS_VAR_POPDEF([_TMP])dnl
AS_VAR_POPDEF([_DFN])dnl
AS_VAR_POPDEF([_INP])dnl
AS_VAR_POPDEF([_PFX])dnl
AS_VAR_POPDEF([_OUT])dnl
],[PACKAGE_TARNAME="$PACKAGE_TARNAME"])])# AX_CONFIG_PREFIXED_HEADER

AC_DEFUN([AX_PREFIXED_DEFINE],
[m4_append_uniq([_AX_PREFIXED_DEFINE_VARS($1)], [$2], [ ])dnl
])# AX_PREFIXED_DEFINE

===8<========================================================================