[p5sagit/p5-mst-13.2.git] / lib / ExtUtils / Constant.pm

package ExtUtils::Constant;
use vars qw (@ISA $VERSION @EXPORT_OK %EXPORT_TAGS);
$VERSION = 0.16;

=head1 NAME

ExtUtils::Constant - generate XS code to import C header constants

=head1 SYNOPSIS

    use ExtUtils::Constant qw (WriteConstants);
    WriteConstants(
        NAME => 'Foo',
        NAMES => [qw(FOO BAR BAZ)],
    );
    # Generates wrapper code to make the values of the constants FOO BAR BAZ
    #  available to perl

=head1 DESCRIPTION

ExtUtils::Constant facilitates generating C and XS wrapper code to allow
perl modules to AUTOLOAD constants defined in C library header files.
It is principally used by the C<h2xs> utility, on which this code is based.
It doesn't contain the routines to scan header files to extract these
constants.

=head1 USAGE

Generally one only needs to call the C<WriteConstants> function, and then

    #include "const-c.inc"

in the C section of C<Foo.xs>

    INCLUDE: const-xs.inc

in the XS section of C<Foo.xs>.

For greater flexibility use C<constant_types()>, C<C_constant> and
C<XS_constant>, with which C<WriteConstants> is implemented.

Currently this module understands the following types. h2xs may only know
a subset. The sizes of the numeric types are chosen by the C<Configure>
script at compile time.

=over 4

=item IV

signed integer, at least 32 bits.

=item UV

unsigned integer, the same size as I<IV>

=item NV

floating point type, probably C<double>, possibly C<long double>

=item PV

NUL terminated string, length will be determined with C<strlen>

=item PVN

A fixed length thing, given as a [pointer, length] pair. If you know the
length of a string at compile time you may use this instead of I<PV>

=item SV

A B<mortal> SV.

=item YES

Truth.  (C<PL_sv_yes>)  The value is not needed (and ignored).

=item NO

Defined Falsehood.  (C<PL_sv_no>)  The value is not needed (and ignored).

=item UNDEF

C<undef>.  The value of the macro is not needed.

=back

=head1 FUNCTIONS

=over 4

=cut

if ($] >= 5.006) {
  eval "use warnings; 1" or die $@;
}
use strict;
use Carp qw(croak cluck);

use Exporter;
use ExtUtils::Constant::Utils qw(C_stringify);
use ExtUtils::Constant::XS qw(%XS_Constant %XS_TypeSet);

@ISA = 'Exporter';

%EXPORT_TAGS = ( 'all' => [ qw(
	XS_constant constant_types return_clause memEQ_clause C_stringify
	C_constant autoload WriteConstants WriteMakefileSnippet
) ] );

@EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );

=item constant_types

A function returning a single scalar with C<#define> definitions for the
constants used internally between the generated C and XS functions.

=cut

sub constant_types {
  ExtUtils::Constant::XS->header();
}

sub memEQ_clause {
  cluck "ExtUtils::Constant::memEQ_clause is deprecated";
  ExtUtils::Constant::XS->memEQ_clause({name=>$_[0], checked_at=>$_[1],
					indent=>$_[2]});
}

sub return_clause ($$) {
  cluck "ExtUtils::Constant::return_clause is deprecated";
  my $indent = shift;
  ExtUtils::Constant::XS->return_clause({indent=>$indent}, @_);
}

sub switch_clause {
  cluck "ExtUtils::Constant::switch_clause is deprecated";
  my $indent = shift;
  my $comment = shift;
  ExtUtils::Constant::XS->switch_clause({indent=>$indent, comment=>$comment},
					@_);
}

sub C_constant {
  my ($package, $subname, $default_type, $what, $indent, $breakout, @items)
    = @_;
  ExtUtils::Constant::XS->C_constant({package => $package, subname => $subname,
				      default_type => $default_type,
				      types => $what, indent => $indent,
				      breakout => $breakout}, @items);
}

=item XS_constant PACKAGE, TYPES, SUBNAME, C_SUBNAME

A function to generate the XS code to implement the perl subroutine
I<PACKAGE>::constant used by I<PACKAGE>::AUTOLOAD to load constants.
This XS code is a wrapper around a C subroutine usually generated by
C<C_constant>, and usually named C<constant>.

I<TYPES> should be given either as a comma separated list of types that the
C subroutine C<constant> will generate or as a reference to a hash. It should
be the same list of types as C<C_constant> was given.
[Otherwise C<XS_constant> and C<C_constant> may have different ideas about
the number of parameters passed to the C function C<constant>]

You can call the perl visible subroutine something other than C<constant> if
you give the parameter I<SUBNAME>. The C subroutine it calls defaults to
the name of the perl visible subroutine, unless you give the parameter
I<C_SUBNAME>.

=cut

sub XS_constant {
  my $package = shift;
  my $what = shift;
  my $subname = shift;
  my $C_subname = shift;
  $subname ||= 'constant';
  $C_subname ||= $subname;

  if (!ref $what) {
    # Convert line of the form IV,UV,NV to hash
    $what = {map {$_ => 1} split /,\s*/, ($what)};
  }
  my $params = ExtUtils::Constant::XS->params ($what);
  my $type;

  my $xs = <<"EOT";
void
$subname(sv)
    PREINIT:
#ifdef dXSTARG
	dXSTARG; /* Faster if we have it.  */
#else
	dTARGET;
#endif
	STRLEN		len;
        int		type;
EOT

  if ($params->{IV}) {
    $xs .= "	IV		iv;\n";
  } else {
    $xs .= "	/* IV\t\tiv;\tUncomment this if you need to return IVs */\n";
  }
  if ($params->{NV}) {
    $xs .= "	NV		nv;\n";
  } else {
    $xs .= "	/* NV\t\tnv;\tUncomment this if you need to return NVs */\n";
  }
  if ($params->{PV}) {
    $xs .= "	const char	*pv;\n";
  } else {
    $xs .=
      "	/* const char\t*pv;\tUncomment this if you need to return PVs */\n";
  }

  $xs .= << 'EOT';
    INPUT:
	SV *		sv;
        const char *	s = SvPV(sv, len);
EOT
  if ($params->{''}) {
  $xs .= << 'EOT';
    INPUT:
	int		utf8 = SvUTF8(sv);
EOT
  }
  $xs .= << 'EOT';
    PPCODE:
EOT

  if ($params->{IV} xor $params->{NV}) {
    $xs .= << "EOT";
        /* Change this to $C_subname(aTHX_ s, len, &iv, &nv);
           if you need to return both NVs and IVs */
EOT
  }
  $xs .= "	type = $C_subname(aTHX_ s, len";
  $xs .= ', utf8' if $params->{''};
  $xs .= ', &iv' if $params->{IV};
  $xs .= ', &nv' if $params->{NV};
  $xs .= ', &pv' if $params->{PV};
  $xs .= ', &sv' if $params->{SV};
  $xs .= ");\n";

  $xs .= << "EOT";
      /* Return 1 or 2 items. First is error message, or undef if no error.
           Second, if present, is found value */
        switch (type) {
        case PERL_constant_NOTFOUND:
          sv = sv_2mortal(newSVpvf("%s is not a valid $package macro", s));
          PUSHs(sv);
          break;
        case PERL_constant_NOTDEF:
          sv = sv_2mortal(newSVpvf(
	    "Your vendor has not defined $package macro %s, used", s));
          PUSHs(sv);
          break;
EOT

  foreach $type (sort keys %XS_Constant) {
    # '' marks utf8 flag needed.
    next if $type eq '';
    $xs .= "\t/* Uncomment this if you need to return ${type}s\n"
      unless $what->{$type};
    $xs .= "        case PERL_constant_IS$type:\n";
    if (length $XS_Constant{$type}) {
      $xs .= << "EOT";
          EXTEND(SP, 1);
          PUSHs(&PL_sv_undef);
          $XS_Constant{$type};
EOT
    } else {
      # Do nothing. return (), which will be correctly interpreted as
      # (undef, undef)
    }
    $xs .= "          break;\n";
    unless ($what->{$type}) {
      chop $xs; # Yes, another need for chop not chomp.
      $xs .= " */\n";
    }
  }
  $xs .= << "EOT";
        default:
          sv = sv_2mortal(newSVpvf(
	    "Unexpected return type %d while processing $package macro %s, used",
               type, s));
          PUSHs(sv);
        }
EOT

  return $xs;
}


=item autoload PACKAGE, VERSION, AUTOLOADER

A function to generate the AUTOLOAD subroutine for the module I<PACKAGE>
I<VERSION> is the perl version the code should be backwards compatible with.
It defaults to the version of perl running the subroutine.  If I<AUTOLOADER>
is true, the AUTOLOAD subroutine falls back on AutoLoader::AUTOLOAD for all
names that the constant() routine doesn't recognise.

=cut

# ' # Grr. syntax highlighters that don't grok pod.

sub autoload {
  my ($module, $compat_version, $autoloader) = @_;
  $compat_version ||= $];
  croak "Can't maintain compatibility back as far as version $compat_version"
    if $compat_version < 5;
  my $func = "sub AUTOLOAD {\n"
  . "    # This AUTOLOAD is used to 'autoload' constants from the constant()\n"
  . "    # XS function.";
  $func .= "  If a constant is not found then control is passed\n"
  . "    # to the AUTOLOAD in AutoLoader." if $autoloader;


  $func .= "\n\n"
  . "    my \$constname;\n";
  $func .=
    "    our \$AUTOLOAD;\n"  if ($compat_version >= 5.006);

  $func .= <<"EOT";
    (\$constname = \$AUTOLOAD) =~ s/.*:://;
    croak "&${module}::constant not defined" if \$constname eq 'constant';
    my (\$error, \$val) = constant(\$constname);
EOT

  if ($autoloader) {
    $func .= <<'EOT';
    if ($error) {
	if ($error =~  /is not a valid/) {
	    $AutoLoader::AUTOLOAD = $AUTOLOAD;
	    goto &AutoLoader::AUTOLOAD;
	} else {
	    croak $error;
	}
    }
EOT
  } else {
    $func .=
      "    if (\$error) { croak \$error; }\n";
  }

  $func .= <<'END';
    {
	no strict 'refs';
	# Fixed between 5.005_53 and 5.005_61
#XXX	if ($] >= 5.00561) {
#XXX	    *$AUTOLOAD = sub () { $val };
#XXX	}
#XXX	else {
	    *$AUTOLOAD = sub { $val };
#XXX	}
    }
    goto &$AUTOLOAD;
}

END

  return $func;
}


=item WriteMakefileSnippet

WriteMakefileSnippet ATTRIBUTE =E<gt> VALUE [, ...] 

A function to generate perl code for Makefile.PL that will regenerate
the constant subroutines.  Parameters are named as passed to C<WriteConstants>,
with the addition of C<INDENT> to specify the number of leading spaces
(default 2).

Currently only C<INDENT>, C<NAME>, C<DEFAULT_TYPE>, C<NAMES>, C<C_FILE> and
C<XS_FILE> are recognised.

=cut

sub WriteMakefileSnippet {
  my %args = @_;
  my $indent = $args{INDENT} || 2;

  my $result = <<"EOT";
ExtUtils::Constant::WriteConstants(
                                   NAME         => '$args{NAME}',
                                   NAMES        => \\\@names,
                                   DEFAULT_TYPE => '$args{DEFAULT_TYPE}',
EOT
  foreach (qw (C_FILE XS_FILE)) {
    next unless exists $args{$_};
    $result .= sprintf "                                   %-12s => '%s',\n",
      $_, $args{$_};
  }
  $result .= <<'EOT';
                                );
EOT

  $result =~ s/^/' 'x$indent/gem;
  return ExtUtils::Constant::XS->dump_names({default_type=>$args{DEFAULT_TYPE},
					     indent=>$indent,},
					    @{$args{NAMES}})
    . $result;
}

=item WriteConstants ATTRIBUTE =E<gt> VALUE [, ...]

Writes a file of C code and a file of XS code which you should C<#include>
and C<INCLUDE> in the C and XS sections respectively of your module's XS
code.  You probably want to do this in your C<Makefile.PL>, so that you can
easily edit the list of constants without touching the rest of your module.
The attributes supported are

=over 4

=item NAME

Name of the module.  This must be specified

=item DEFAULT_TYPE

The default type for the constants.  If not specified C<IV> is assumed.

=item BREAKOUT_AT

The names of the constants are grouped by length.  Generate child subroutines
for each group with this number or more names in.

=item NAMES

An array of constants' names, either scalars containing names, or hashrefs
as detailed in L<"C_constant">.

=item C_FILE

The name of the file to write containing the C code.  The default is
C<const-c.inc>.  The C<-> in the name ensures that the file can't be
mistaken for anything related to a legitimate perl package name, and
not naming the file C<.c> avoids having to override Makefile.PL's
C<.xs> to C<.c> rules.

=item XS_FILE

The name of the file to write containing the XS code.  The default is
C<const-xs.inc>.

=item SUBNAME

The perl visible name of the XS subroutine generated which will return the
constants. The default is C<constant>.

=item C_SUBNAME

The name of the C subroutine generated which will return the constants.
The default is I<SUBNAME>.  Child subroutines have C<_> and the name
length appended, so constants with 10 character names would be in
C<constant_10> with the default I<XS_SUBNAME>.

=back

=cut

sub WriteConstants {
  my %ARGS =
    ( # defaults
     C_FILE =>       'const-c.inc',
     XS_FILE =>      'const-xs.inc',
     SUBNAME =>      'constant',
     DEFAULT_TYPE => 'IV',
     @_);

  $ARGS{C_SUBNAME} ||= $ARGS{SUBNAME}; # No-one sane will have C_SUBNAME eq '0'

  croak "Module name not specified" unless length $ARGS{NAME};

  open my $c_fh, ">$ARGS{C_FILE}" or die "Can't open $ARGS{C_FILE}: $!";
  open my $xs_fh, ">$ARGS{XS_FILE}" or die "Can't open $ARGS{XS_FILE}: $!";

  # As this subroutine is intended to make code that isn't edited, there's no
  # need for the user to specify any types that aren't found in the list of
  # names.
  my $types = {};

  print $c_fh constant_types(); # macro defs
  print $c_fh "\n";

  # indent is still undef. Until anyone implements indent style rules with it.
  foreach (ExtUtils::Constant::XS->C_constant({package => $ARGS{NAME},
					       subname => $ARGS{C_SUBNAME},
					       default_type =>
					       $ARGS{DEFAULT_TYPE},
					       types => $types,
					       breakout => $ARGS{BREAKOUT_AT}},
					       @{$ARGS{NAMES}})) {
    print $c_fh $_, "\n"; # C constant subs
  }
  print $xs_fh XS_constant ($ARGS{NAME}, $types, $ARGS{XS_SUBNAME},
                            $ARGS{C_SUBNAME});

  close $c_fh or warn "Error closing $ARGS{C_FILE}: $!";
  close $xs_fh or warn "Error closing $ARGS{XS_FILE}: $!";
}

1;
__END__

=back

=head1 AUTHOR

Nicholas Clark <nick@ccl4.org> based on the code in C<h2xs> by Larry Wall and
others

=cut
Commit	Line	Data
af6c647e	1	package ExtUtils::Constant;
af6ca1d0	2	use vars qw (@ISA $VERSION @EXPORT_OK %EXPORT_TAGS);
af6ca1d0	3	$VERSION = 0.16;
af6c647e	4
	5	=head1 NAME
	6
	7	ExtUtils::Constant - generate XS code to import C header constants
	8
	9	=head1 SYNOPSIS
	10
0552bf3a	11	use ExtUtils::Constant qw (WriteConstants);
	12	WriteConstants(
	13	NAME => 'Foo',
	14	NAMES => [qw(FOO BAR BAZ)],
0552bf3a	15	);
	16	# Generates wrapper code to make the values of the constants FOO BAR BAZ
	17	# available to perl
af6c647e	18
	19	=head1 DESCRIPTION
	20
	21	ExtUtils::Constant facilitates generating C and XS wrapper code to allow
	22	perl modules to AUTOLOAD constants defined in C library header files.
	23	It is principally used by the C<h2xs> utility, on which this code is based.
	24	It doesn't contain the routines to scan header files to extract these
	25	constants.
	26
	27	=head1 USAGE
	28
0552bf3a	29	Generally one only needs to call the C<WriteConstants> function, and then
0552bf3a	30
1cb0fb50	31	#include "const-c.inc"
0552bf3a	32
	33	in the C section of C<Foo.xs>
	34
ac7de224	35	INCLUDE: const-xs.inc
0552bf3a	36
	37	in the XS section of C<Foo.xs>.
	38
	39	For greater flexibility use C<constant_types()>, C<C_constant> and
	40	C<XS_constant>, with which C<WriteConstants> is implemented.
af6c647e	41
	42	Currently this module understands the following types. h2xs may only know
	43	a subset. The sizes of the numeric types are chosen by the C<Configure>
	44	script at compile time.
	45
	46	=over 4
	47
	48	=item IV
	49
	50	signed integer, at least 32 bits.
	51
	52	=item UV
	53
	54	unsigned integer, the same size as I<IV>
	55
	56	=item NV
	57
	58	floating point type, probably C<double>, possibly C<long double>
	59
	60	=item PV
	61
	62	NUL terminated string, length will be determined with C<strlen>
	63
	64	=item PVN
	65
	66	A fixed length thing, given as a [pointer, length] pair. If you know the
	67	length of a string at compile time you may use this instead of I<PV>
	68
9a7df4f2	69	=item SV
cea00dc5	70
	71	A B<mortal> SV.
	72
3414cef0	73	=item YES
	74
	75	Truth. (C<PL_sv_yes>) The value is not needed (and ignored).
	76
	77	=item NO
	78
	79	Defined Falsehood. (C<PL_sv_no>) The value is not needed (and ignored).
	80
	81	=item UNDEF
	82
	83	C<undef>. The value of the macro is not needed.
	84
af6c647e	85	=back
	86
	87	=head1 FUNCTIONS
	88
	89	=over 4
	90
	91	=cut
	92
d7f97632	93	if ($] >= 5.006) {
	94	eval "use warnings; 1" or die $@;
	95	}
af6c647e	96	use strict;
af6ca1d0	97	use Carp qw(croak cluck);
4f2c4fd8	98
af6c647e	99	use Exporter;
af6ca1d0	100	use ExtUtils::Constant::Utils qw(C_stringify);
af6ca1d0	101	use ExtUtils::Constant::XS qw(%XS_Constant %XS_TypeSet);
af6c647e	102
af6c647e	103	@ISA = 'Exporter';
af6c647e	104
	105	%EXPORT_TAGS = ( 'all' => [ qw(
	106	XS_constant constant_types return_clause memEQ_clause C_stringify
9a7df4f2	107	C_constant autoload WriteConstants WriteMakefileSnippet
af6c647e	108	) ] );
	109
	110	@EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
	111
af6c647e	112	=item constant_types
	113
	114	A function returning a single scalar with C<#define> definitions for the
	115	constants used internally between the generated C and XS functions.
	116
	117	=cut
	118
af6ca1d0	119	sub constant_types {
af6ca1d0	120	ExtUtils::Constant::XS->header();
af6c647e	121	}
af6c647e	122
af6c647e	123	sub memEQ_clause {
af6ca1d0	124	cluck "ExtUtils::Constant::memEQ_clause is deprecated";
	125	ExtUtils::Constant::XS->memEQ_clause({name=>$_[0], checked_at=>$_[1],
	126	indent=>$_[2]});
af6c647e	127	}
af6c647e	128
6557ab03	129	sub return_clause ($$) {
af6ca1d0	130	cluck "ExtUtils::Constant::return_clause is deprecated";
	131	my $indent = shift;
	132	ExtUtils::Constant::XS->return_clause({indent=>$indent}, @_);
af6c647e	133	}
af6c647e	134
8ac27563	135	sub switch_clause {
af6ca1d0	136	cluck "ExtUtils::Constant::switch_clause is deprecated";
	137	my $indent = shift;
	138	my $comment = shift;
	139	ExtUtils::Constant::XS->switch_clause({indent=>$indent, comment=>$comment},
	140	@_);
6d79cad2	141	}
6d79cad2	142
af6c647e	143	sub C_constant {
8ac27563	144	my ($package, $subname, $default_type, $what, $indent, $breakout, @items)
8ac27563	145	= @_;
af6ca1d0	146	ExtUtils::Constant::XS->C_constant({package => $package, subname => $subname,
	147	default_type => $default_type,
	148	types => $what, indent => $indent,
	149	breakout => $breakout}, @items);
af6c647e	150	}
	151
	152	=item XS_constant PACKAGE, TYPES, SUBNAME, C_SUBNAME
	153
	154	A function to generate the XS code to implement the perl subroutine
	155	I<PACKAGE>::constant used by I<PACKAGE>::AUTOLOAD to load constants.
	156	This XS code is a wrapper around a C subroutine usually generated by
	157	C<C_constant>, and usually named C<constant>.
	158
	159	I<TYPES> should be given either as a comma separated list of types that the
	160	C subroutine C<constant> will generate or as a reference to a hash. It should
	161	be the same list of types as C<C_constant> was given.
	162	[Otherwise C<XS_constant> and C<C_constant> may have different ideas about
	163	the number of parameters passed to the C function C<constant>]
	164
	165	You can call the perl visible subroutine something other than C<constant> if
d1be9408	166	you give the parameter I<SUBNAME>. The C subroutine it calls defaults to
af6c647e	167	the name of the perl visible subroutine, unless you give the parameter
	168	I<C_SUBNAME>.
	169
	170	=cut
	171
	172	sub XS_constant {
	173	my $package = shift;
	174	my $what = shift;
	175	my $subname = shift;
	176	my $C_subname = shift;
	177	$subname \|\|= 'constant';
	178	$C_subname \|\|= $subname;
	179
	180	if (!ref $what) {
	181	# Convert line of the form IV,UV,NV to hash
	182	$what = {map {$_ => 1} split /,\s*/, ($what)};
	183	}
af6ca1d0	184	my $params = ExtUtils::Constant::XS->params ($what);
af6c647e	185	my $type;
	186
	187	my $xs = <<"EOT";
	188	void
	189	$subname(sv)
	190	PREINIT:
	191	#ifdef dXSTARG
	192	dXSTARG; /* Faster if we have it. */
	193	#else
	194	dTARGET;
	195	#endif
	196	STRLEN len;
	197	int type;
	198	EOT
	199
72f7b9a1	200	if ($params->{IV}) {
af6c647e	201	$xs .= " IV iv;\n";
	202	} else {
	203	$xs .= " /* IV\t\tiv;\tUncomment this if you need to return IVs */\n";
	204	}
72f7b9a1	205	if ($params->{NV}) {
af6c647e	206	$xs .= " NV nv;\n";
	207	} else {
	208	$xs .= " /* NV\t\tnv;\tUncomment this if you need to return NVs */\n";
	209	}
72f7b9a1	210	if ($params->{PV}) {
af6c647e	211	$xs .= " const char *pv;\n";
	212	} else {
	213	$xs .=
	214	" /* const char\tpv;\tUncomment this if you need to return PVs /\n";
	215	}
	216
	217	$xs .= << 'EOT';
	218	INPUT:
	219	SV * sv;
	220	const char * s = SvPV(sv, len);
6557ab03	221	EOT
	222	if ($params->{''}) {
	223	$xs .= << 'EOT';
	224	INPUT:
	225	int utf8 = SvUTF8(sv);
	226	EOT
	227	}
	228	$xs .= << 'EOT';
af6c647e	229	PPCODE:
	230	EOT
	231
72f7b9a1	232	if ($params->{IV} xor $params->{NV}) {
af6c647e	233	$xs .= << "EOT";
a2c454fa	234	/* Change this to $C_subname(aTHX_ s, len, &iv, &nv);
af6c647e	235	if you need to return both NVs and IVs */
	236	EOT
	237	}
a2c454fa	238	$xs .= " type = $C_subname(aTHX_ s, len";
6557ab03	239	$xs .= ', utf8' if $params->{''};
72f7b9a1	240	$xs .= ', &iv' if $params->{IV};
	241	$xs .= ', &nv' if $params->{NV};
	242	$xs .= ', &pv' if $params->{PV};
	243	$xs .= ', &sv' if $params->{SV};
af6c647e	244	$xs .= ");\n";
	245
	246	$xs .= << "EOT";
	247	/* Return 1 or 2 items. First is error message, or undef if no error.
	248	Second, if present, is found value */
	249	switch (type) {
	250	case PERL_constant_NOTFOUND:
	251	sv = sv_2mortal(newSVpvf("%s is not a valid $package macro", s));
6d79cad2	252	PUSHs(sv);
af6c647e	253	break;
	254	case PERL_constant_NOTDEF:
	255	sv = sv_2mortal(newSVpvf(
8ac27563	256	"Your vendor has not defined $package macro %s, used", s));
6d79cad2	257	PUSHs(sv);
af6c647e	258	break;
	259	EOT
	260
	261	foreach $type (sort keys %XS_Constant) {
6557ab03	262	# '' marks utf8 flag needed.
6557ab03	263	next if $type eq '';
af6c647e	264	$xs .= "\t/* Uncomment this if you need to return ${type}s\n"
af6c647e	265	unless $what->{$type};
8ac27563	266	$xs .= " case PERL_constant_IS$type:\n";
	267	if (length $XS_Constant{$type}) {
	268	$xs .= << "EOT";
af6c647e	269	EXTEND(SP, 1);
	270	PUSHs(&PL_sv_undef);
	271	$XS_Constant{$type};
af6c647e	272	EOT
8ac27563	273	} else {
	274	# Do nothing. return (), which will be correctly interpreted as
	275	# (undef, undef)
	276	}
	277	$xs .= " break;\n";
af6c647e	278	unless ($what->{$type}) {
	279	chop $xs; # Yes, another need for chop not chomp.
	280	$xs .= " */\n";
	281	}
	282	}
	283	$xs .= << "EOT";
	284	default:
	285	sv = sv_2mortal(newSVpvf(
8ac27563	286	"Unexpected return type %d while processing $package macro %s, used",
af6c647e	287	type, s));
6d79cad2	288	PUSHs(sv);
af6c647e	289	}
	290	EOT
	291
	292	return $xs;
	293	}
	294
	295
6d79cad2	296	=item autoload PACKAGE, VERSION, AUTOLOADER
af6c647e	297
	298	A function to generate the AUTOLOAD subroutine for the module I<PACKAGE>
	299	I<VERSION> is the perl version the code should be backwards compatible with.
6d79cad2	300	It defaults to the version of perl running the subroutine. If I<AUTOLOADER>
	301	is true, the AUTOLOAD subroutine falls back on AutoLoader::AUTOLOAD for all
	302	names that the constant() routine doesn't recognise.
af6c647e	303
	304	=cut
	305
6d79cad2	306	# ' # Grr. syntax highlighters that don't grok pod.
6d79cad2	307
af6c647e	308	sub autoload {
6d79cad2	309	my ($module, $compat_version, $autoloader) = @_;
af6c647e	310	$compat_version \|\|= $];
	311	croak "Can't maintain compatibility back as far as version $compat_version"
	312	if $compat_version < 5;
6d79cad2	313	my $func = "sub AUTOLOAD {\n"
	314	. " # This AUTOLOAD is used to 'autoload' constants from the constant()\n"
	315	. " # XS function.";
	316	$func .= " If a constant is not found then control is passed\n"
	317	. " # to the AUTOLOAD in AutoLoader." if $autoloader;
	318
	319
	320	$func .= "\n\n"
	321	. " my \$constname;\n";
a2c454fa	322	$func .=
6d79cad2	323	" our \$AUTOLOAD;\n" if ($compat_version >= 5.006);
	324
	325	$func .= <<"EOT";
af6c647e	326	(\$constname = \$AUTOLOAD) =~ s/.*:://;
	327	croak "&${module}::constant not defined" if \$constname eq 'constant';
	328	my (\$error, \$val) = constant(\$constname);
6d79cad2	329	EOT
	330
	331	if ($autoloader) {
	332	$func .= <<'EOT';
	333	if ($error) {
	334	if ($error =~ /is not a valid/) {
	335	$AutoLoader::AUTOLOAD = $AUTOLOAD;
af6c647e	336	goto &AutoLoader::AUTOLOAD;
af6c647e	337	} else {
6d79cad2	338	croak $error;
af6c647e	339	}
af6c647e	340	}
6d79cad2	341	EOT
	342	} else {
	343	$func .=
	344	" if (\$error) { croak \$error; }\n";
	345	}
	346
	347	$func .= <<'END';
af6c647e	348	{
	349	no strict 'refs';
	350	# Fixed between 5.005_53 and 5.005_61
6d79cad2	351	#XXX if ($] >= 5.00561) {
6d79cad2	352	#XXX *$AUTOLOAD = sub () { $val };
af6c647e	353	#XXX }
af6c647e	354	#XXX else {
6d79cad2	355	*$AUTOLOAD = sub { $val };
af6c647e	356	#XXX }
af6c647e	357	}
6d79cad2	358	goto &$AUTOLOAD;
af6c647e	359	}
	360
	361	END
	362
6d79cad2	363	return $func;
af6c647e	364	}
0552bf3a	365
0552bf3a	366
9a7df4f2	367	=item WriteMakefileSnippet
	368
	369	WriteMakefileSnippet ATTRIBUTE =E<gt> VALUE [, ...]
	370
d1be9408	371	A function to generate perl code for Makefile.PL that will regenerate
9a7df4f2	372	the constant subroutines. Parameters are named as passed to C<WriteConstants>,
	373	with the addition of C<INDENT> to specify the number of leading spaces
	374	(default 2).
	375
	376	Currently only C<INDENT>, C<NAME>, C<DEFAULT_TYPE>, C<NAMES>, C<C_FILE> and
	377	C<XS_FILE> are recognised.
	378
	379	=cut
	380
	381	sub WriteMakefileSnippet {
	382	my %args = @_;
	383	my $indent = $args{INDENT} \|\| 2;
	384
	385	my $result = <<"EOT";
	386	ExtUtils::Constant::WriteConstants(
	387	NAME => '$args{NAME}',
	388	NAMES => \\\@names,
	389	DEFAULT_TYPE => '$args{DEFAULT_TYPE}',
	390	EOT
	391	foreach (qw (C_FILE XS_FILE)) {
	392	next unless exists $args{$_};
	393	$result .= sprintf " %-12s => '%s',\n",
	394	$_, $args{$_};
	395	}
	396	$result .= <<'EOT';
	397	);
	398	EOT
	399
	400	$result =~ s/^/' 'x$indent/gem;
af6ca1d0	401	return ExtUtils::Constant::XS->dump_names({default_type=>$args{DEFAULT_TYPE},
	402	indent=>$indent,},
	403	@{$args{NAMES}})
	404	. $result;
9a7df4f2	405	}
9a7df4f2	406
0552bf3a	407	=item WriteConstants ATTRIBUTE =E<gt> VALUE [, ...]
	408
	409	Writes a file of C code and a file of XS code which you should C<#include>
	410	and C<INCLUDE> in the C and XS sections respectively of your module's XS
4f2c4fd8	411	code. You probably want to do this in your C<Makefile.PL>, so that you can
0552bf3a	412	easily edit the list of constants without touching the rest of your module.
	413	The attributes supported are
	414
	415	=over 4
	416
	417	=item NAME
	418
	419	Name of the module. This must be specified
	420
	421	=item DEFAULT_TYPE
	422
	423	The default type for the constants. If not specified C<IV> is assumed.
	424
	425	=item BREAKOUT_AT
	426
	427	The names of the constants are grouped by length. Generate child subroutines
	428	for each group with this number or more names in.
	429
	430	=item NAMES
	431
	432	An array of constants' names, either scalars containing names, or hashrefs
	433	as detailed in L<"C_constant">.
	434
	435	=item C_FILE
	436
	437	The name of the file to write containing the C code. The default is
1cb0fb50	438	C<const-c.inc>. The C<-> in the name ensures that the file can't be
	439	mistaken for anything related to a legitimate perl package name, and
	440	not naming the file C<.c> avoids having to override Makefile.PL's
	441	C<.xs> to C<.c> rules.
0552bf3a	442
	443	=item XS_FILE
	444
	445	The name of the file to write containing the XS code. The default is
1cb0fb50	446	C<const-xs.inc>.
0552bf3a	447
	448	=item SUBNAME
	449
	450	The perl visible name of the XS subroutine generated which will return the
9a7df4f2	451	constants. The default is C<constant>.
0552bf3a	452
	453	=item C_SUBNAME
	454
	455	The name of the C subroutine generated which will return the constants.
	456	The default is I<SUBNAME>. Child subroutines have C<_> and the name
	457	length appended, so constants with 10 character names would be in
	458	C<constant_10> with the default I<XS_SUBNAME>.
	459
	460	=back
	461
	462	=cut
	463
	464	sub WriteConstants {
	465	my %ARGS =
	466	( # defaults
1cb0fb50	467	C_FILE => 'const-c.inc',
1cb0fb50	468	XS_FILE => 'const-xs.inc',
0552bf3a	469	SUBNAME => 'constant',
	470	DEFAULT_TYPE => 'IV',
	471	@_);
	472
	473	$ARGS{C_SUBNAME} \|\|= $ARGS{SUBNAME}; # No-one sane will have C_SUBNAME eq '0'
	474
	475	croak "Module name not specified" unless length $ARGS{NAME};
	476
	477	open my $c_fh, ">$ARGS{C_FILE}" or die "Can't open $ARGS{C_FILE}: $!";
	478	open my $xs_fh, ">$ARGS{XS_FILE}" or die "Can't open $ARGS{XS_FILE}: $!";
	479
	480	# As this subroutine is intended to make code that isn't edited, there's no
	481	# need for the user to specify any types that aren't found in the list of
	482	# names.
	483	my $types = {};
	484
	485	print $c_fh constant_types(); # macro defs
	486	print $c_fh "\n";
	487
4f2c4fd8	488	# indent is still undef. Until anyone implements indent style rules with it.
af6ca1d0	489	foreach (ExtUtils::Constant::XS->C_constant({package => $ARGS{NAME},
	490	subname => $ARGS{C_SUBNAME},
	491	default_type =>
	492	$ARGS{DEFAULT_TYPE},
	493	types => $types,
	494	breakout => $ARGS{BREAKOUT_AT}},
	495	@{$ARGS{NAMES}})) {
0552bf3a	496	print $c_fh $_, "\n"; # C constant subs
	497	}
	498	print $xs_fh XS_constant ($ARGS{NAME}, $types, $ARGS{XS_SUBNAME},
	499	$ARGS{C_SUBNAME});
	500
	501	close $c_fh or warn "Error closing $ARGS{C_FILE}: $!";
	502	close $xs_fh or warn "Error closing $ARGS{XS_FILE}: $!";
	503	}
	504
af6c647e	505	1;
	506	__END__
	507
	508	=back
	509
	510	=head1 AUTHOR
	511
	512	Nicholas Clark <nick@ccl4.org> based on the code in C<h2xs> by Larry Wall and
	513	others
	514
	515	=cut