package ExtUtils::Constant; use vars qw (@ISA $VERSION @EXPORT_OK %EXPORT_TAGS); $VERSION = 0.23; =head1 NAME ExtUtils::Constant - generate XS code to import C header constants =head1 SYNOPSIS use ExtUtils::Constant qw (WriteConstants); WriteConstants( NAME => 'Foo', NAMES => [qw(FOO BAR BAZ)], ); # Generates wrapper code to make the values of the constants FOO BAR BAZ # available to perl =head1 DESCRIPTION ExtUtils::Constant facilitates generating C and XS wrapper code to allow perl modules to AUTOLOAD constants defined in C library header files. It is principally used by the C utility, on which this code is based. It doesn't contain the routines to scan header files to extract these constants. =head1 USAGE Generally one only needs to call the C function, and then #include "const-c.inc" in the C section of C INCLUDE: const-xs.inc in the XS section of C. For greater flexibility use C, C and C, with which C is implemented. Currently this module understands the following types. h2xs may only know a subset. The sizes of the numeric types are chosen by the C script at compile time. =over 4 =item IV signed integer, at least 32 bits. =item UV unsigned integer, the same size as I =item NV floating point type, probably C, possibly C =item PV NUL terminated string, length will be determined with C =item PVN A fixed length thing, given as a [pointer, length] pair. If you know the length of a string at compile time you may use this instead of I =item SV A B SV. =item YES Truth. (C) The value is not needed (and ignored). =item NO Defined Falsehood. (C) The value is not needed (and ignored). =item UNDEF C. The value of the macro is not needed. =back =head1 FUNCTIONS =over 4 =cut if ($] >= 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, XS_SUBNAME, C_SUBNAME A function to generate the XS code to implement the perl subroutine I::constant used by I::AUTOLOAD to load constants. This XS code is a wrapper around a C subroutine usually generated by C, and usually named C. I should be given either as a comma separated list of types that the C subroutine C will generate or as a reference to a hash. It should be the same list of types as C was given. [Otherwise C and C may have different ideas about the number of parameters passed to the C function C] You can call the perl visible subroutine something other than C if you give the parameter I. The C subroutine it calls defaults to the name of the perl visible subroutine, unless you give the parameter I. =cut sub XS_constant { my $package = shift; my $what = shift; my $XS_subname = shift; my $C_subname = shift; $XS_subname ||= 'constant'; $C_subname ||= $XS_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 $XS_subname(sv) PREINIT: #ifdef dXSTARG dXSTARG; /* Faster if we have it. */ #else dTARGET; #endif STRLEN len; int type; EOT if ($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"; # If anyone is insane enough to suggest a package name containing % my $package_sprintf_safe = $package; $package_sprintf_safe =~ s/%/%%/g; $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_sprintf_safe macro", s)); PUSHs(sv); break; case PERL_constant_NOTDEF: sv = sv_2mortal(newSVpvf( "Your vendor has not defined $package_sprintf_safe 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_sprintf_safe macro %s, used", type, s)); PUSHs(sv); } EOT return $xs; } =item autoload PACKAGE, VERSION, AUTOLOADER A function to generate the AUTOLOAD subroutine for the module I I is the perl version the code should be backwards compatible with. It defaults to the version of perl running the subroutine. If I is true, the AUTOLOAD subroutine falls back on AutoLoader::AUTOLOAD for all names that the constant() routine doesn't recognise. =cut # ' # Grr. syntax highlighters that don't grok pod. sub autoload { my ($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 VALUE [, ...] A function to generate perl code for Makefile.PL that will regenerate the constant subroutines. Parameters are named as passed to C, with the addition of C to specify the number of leading spaces (default 2). Currently only C, C, C, C, C and C 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 VALUE [, ...] Writes a file of C code and a file of XS code which you should C<#include> and C in the C and XS sections respectively of your module's XS code. You probably want to do this in your C, 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 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 PROXYSUBS If true, uses proxy subs. See L. =item C_FH A filehandle to write the C code to. If not given, then I is opened for writing. =item C_FILE The name of the file to write containing the C code. The default is C. 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_FH A filehandle to write the XS code to. If not given, then I is opened for writing. =item XS_FILE The name of the file to write containing the XS code. The default is C. =item XS_SUBNAME The perl visible name of the XS subroutine generated which will return the constants. The default is C. =item C_SUBNAME The name of the C subroutine generated which will return the constants. The default is I. Child subroutines have C<_> and the name length appended, so constants with 10 character names would be in C with the default I. =back =cut sub WriteConstants { my %ARGS = ( # defaults C_FILE => 'const-c.inc', XS_FILE => 'const-xs.inc', XS_SUBNAME => 'constant', DEFAULT_TYPE => 'IV', @_); $ARGS{C_SUBNAME} ||= $ARGS{XS_SUBNAME}; # No-one sane will have C_SUBNAME eq '0' croak "Module name not specified" unless length $ARGS{NAME}; # Do this before creating (empty) files, in case it fails: require ExtUtils::Constant::ProxySubs if $ARGS{PROXYSUBS}; my $c_fh = $ARGS{C_FH}; if (!$c_fh) { if ($] <= 5.008) { # We need these little games, rather than doing things # unconditionally, because we're used in core Makefile.PLs before # IO is available (needed by filehandle), but also we want to work on # older perls where undefined scalars do not automatically turn into # anonymous file handles. require FileHandle; $c_fh = FileHandle->new(); } open $c_fh, ">$ARGS{C_FILE}" or die "Can't open $ARGS{C_FILE}: $!"; } my $xs_fh = $ARGS{XS_FH}; if (!$xs_fh) { if ($] <= 5.008) { require FileHandle; $xs_fh = FileHandle->new(); } open $xs_fh, ">$ARGS{XS_FILE}" or die "Can't open $ARGS{XS_FILE}: $!"; } # As this subroutine is intended to make code that isn't edited, there's no # need for the user to specify any types that aren't found in the list of # names. if ($ARGS{PROXYSUBS}) { $ARGS{C_FH} = $c_fh; $ARGS{XS_FH} = $xs_fh; ExtUtils::Constant::ProxySubs->WriteConstants(%ARGS); } else { 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}: $!" unless $ARGS{C_FH}; close $xs_fh or warn "Error closing $ARGS{XS_FILE}: $!" unless $ARGS{XS_FH}; } 1; __END__ =back =head1 AUTHOR Nicholas Clark based on the code in C by Larry Wall and others =cut