summaryrefslogtreecommitdiff
path: root/lib/Exporter/Heavy.pm
blob: d1c4a10e51caa014d432b075ee5af9e3a7d4cc0c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
package Exporter::Heavy;

use strict;
no strict 'refs';

# On one line so MakeMaker will see it.
require Exporter;  our $VERSION = $Exporter::VERSION;
$Carp::Internal{"Exporter::Heavy"} = 1;
our $Verbose;

=head1 NAME

Exporter::Heavy - Exporter guts

=head1 SYNOPSIS

(internal use only)

=head1 DESCRIPTION

No user-serviceable parts inside.

=cut

#
# We go to a lot of trouble not to 'require Carp' at file scope,
#  because Carp requires Exporter, and something has to give.
#

sub heavy_export {

    # First make import warnings look like they're coming from the "use".
    local $SIG{__WARN__} = sub {
	my $text = shift;
	if ($text =~ s/ at \S*Exporter\S*.pm line \d+.*\n//) {
	    require Carp;
	    local $Carp::CarpLevel = 1;	# ignore package calling us too.
	    Carp::carp($text);
	}
	else {
	    warn $text;
	}
    };
    local $SIG{__DIE__} = sub {
	require Carp;
	local $Carp::CarpLevel = 1;	# ignore package calling us too.
	Carp::croak("$_[0]Illegal null symbol in \@${1}::EXPORT")
	    if $_[0] =~ /^Unable to create sub named "(.*?)::"/;
    };

    my($pkg, $callpkg, @imports) = @_;
    my($type, $sym, $oops);
    my($exports, $export_cache) = (\@{"${pkg}::EXPORT"},
                                   \%{"${pkg}::EXPORT"});

    if (@imports) {
	if (!%$export_cache) {
	    s/^&// foreach @$exports;
	    @{$export_cache}{@$exports} = (1) x @$exports;
	    my $ok = \@{"${pkg}::EXPORT_OK"};
	    if (@$ok) {
		s/^&// foreach @$ok;
		@{$export_cache}{@$ok} = (1) x @$ok;
	    }
	}

	if ($imports[0] =~ m#^[/!:]#){
	    my $tagsref = \%{"${pkg}::EXPORT_TAGS"};
	    my $tagdata;
	    my %imports;
	    my($remove, $spec, @names, @allexports);
	    # negated first item implies starting with default set:
	    unshift @imports, ':DEFAULT' if $imports[0] =~ m/^!/;
	    foreach $spec (@imports){
		$remove = $spec =~ s/^!//;

		if ($spec =~ s/^://){
		    if ($spec eq 'DEFAULT'){
			@names = @$exports;
		    }
		    elsif ($tagdata = $tagsref->{$spec}) {
			@names = @$tagdata;
		    }
		    else {
			warn qq["$spec" is not defined in %${pkg}::EXPORT_TAGS];
			++$oops;
			next;
		    }
		}
		elsif ($spec =~ m:^/(.*)/$:){
		    my $patn = $1;
		    @allexports = keys %$export_cache unless @allexports; # only do keys once
		    @names = grep(/$patn/, @allexports); # not anchored by default
		}
		else {
		    @names = ($spec); # is a normal symbol name
		}

		warn "Import ".($remove ? "del":"add").": @names "
		    if $Verbose;

		if ($remove) {
		   foreach $sym (@names) { delete $imports{$sym} } 
		}
		else {
		    @imports{@names} = (1) x @names;
		}
	    }
	    @imports = keys %imports;
	}

        my @carp;
	foreach $sym (@imports) {
	    if (!$export_cache->{$sym}) {
		if ($sym =~ m/^\d/) {
		    $pkg->VERSION($sym); # inherit from UNIVERSAL
		    # If the version number was the only thing specified
		    # then we should act as if nothing was specified:
		    if (@imports == 1) {
			@imports = @$exports;
			last;
		    }
		    # We need a way to emulate 'use Foo ()' but still
		    # allow an easy version check: "use Foo 1.23, ''";
		    if (@imports == 2 and !$imports[1]) {
			@imports = ();
			last;
		    }
		} elsif ($sym !~ s/^&// || !$export_cache->{$sym}) {
		    # accumulate the non-exports
		    push @carp,
		        qq["$sym" is not exported by the $pkg module\n];
		    $oops++;
		}
	    }
	}
	if ($oops) {
	    require Carp;
	    Carp::croak("@{carp}Can't continue after import errors");
	}
    }
    else {
	@imports = @$exports;
    }

    my($fail, $fail_cache) = (\@{"${pkg}::EXPORT_FAIL"},
                              \%{"${pkg}::EXPORT_FAIL"});

    if (@$fail) {
	if (!%$fail_cache) {
	    # Build cache of symbols. Optimise the lookup by adding
	    # barewords twice... both with and without a leading &.
	    # (Technique could be applied to $export_cache at cost of memory)
	    my @expanded = map { /^\w/ ? ($_, '&'.$_) : $_ } @$fail;
	    warn "${pkg}::EXPORT_FAIL cached: @expanded" if $Verbose;
	    @{$fail_cache}{@expanded} = (1) x @expanded;
	}
	my @failed;
	foreach $sym (@imports) { push(@failed, $sym) if $fail_cache->{$sym} }
	if (@failed) {
	    @failed = $pkg->export_fail(@failed);
	    foreach $sym (@failed) {
                require Carp;
		Carp::carp(qq["$sym" is not implemented by the $pkg module ],
			"on this architecture");
	    }
	    if (@failed) {
		require Carp;
		Carp::croak("Can't continue after import errors");
	    }
	}
    }

    warn "Importing into $callpkg from $pkg: ",
		join(", ",sort @imports) if $Verbose;

    foreach $sym (@imports) {
	# shortcut for the common case of no type character
	(*{"${callpkg}::$sym"} = \&{"${pkg}::$sym"}, next)
	    unless $sym =~ s/^(\W)//;
	$type = $1;
	*{"${callpkg}::$sym"} =
	    $type eq '&' ? \&{"${pkg}::$sym"} :
	    $type eq '$' ? \${"${pkg}::$sym"} :
	    $type eq '@' ? \@{"${pkg}::$sym"} :
	    $type eq '%' ? \%{"${pkg}::$sym"} :
	    $type eq '*' ?  *{"${pkg}::$sym"} :
	    do { require Carp; Carp::croak("Can't export symbol: $type$sym") };
    }
}

sub heavy_export_to_level
{
      my $pkg = shift;
      my $level = shift;
      (undef) = shift;			# XXX redundant arg
      my $callpkg = caller($level);
      $pkg->export($callpkg, @_);
}

# Utility functions

sub _push_tags {
    my($pkg, $var, $syms) = @_;
    my @nontag = ();
    my $export_tags = \%{"${pkg}::EXPORT_TAGS"};
    push(@{"${pkg}::$var"},
	map { $export_tags->{$_} ? @{$export_tags->{$_}} 
                                 : scalar(push(@nontag,$_),$_) }
		(@$syms) ? @$syms : keys %$export_tags);
    if (@nontag and $^W) {
	# This may change to a die one day
	require Carp;
	Carp::carp(join(", ", @nontag)." are not tags of $pkg");
    }
}


sub require_version {
    my($self, $wanted) = @_;
    my $pkg = ref $self || $self;
    return ${pkg}->VERSION($wanted);
}

1;