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=head1 NAME |
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|
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Perl::Strip - reduce file size by stripping whitespace, comments, pod etc. |
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|
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=head1 SYNOPSIS |
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|
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use Perl::Strip; |
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|
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=head1 DESCRIPTION |
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|
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This module transforms perl sources into a more compact format. It does |
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this by removing most whitespace, comments, pod, and by some other means. |
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|
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The resulting code looks obfuscated, but perl (and the deparser) don't |
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have any problems with that. Depending on the source file you can expect |
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about 30-60% "compression". |
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|
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The main target for this module is low-diskspace environments, such as |
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L<App::Staticperl>, boot floppy/CDs/flash environments and so on. |
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|
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See also the commandline utility L<perlstrip>. |
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|
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=head1 METHODS |
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|
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The C<Perl::Strip> class is a subclsass of L<PPI::Transform>, and as such |
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inherits all of it's methods, even the ones not documented here. |
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|
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=over 4 |
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|
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=cut |
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|
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package Perl::Strip; |
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|
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our $VERSION = '1.2'; |
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our $CACHE_VERSION = 3; |
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|
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use common::sense; |
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|
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use PPI; |
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|
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use base PPI::Transform::; |
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|
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=item my $transform = new Perl::Strip key => value... |
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|
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Creates a new Perl::Strip transform object. It supports the following |
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parameters: |
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|
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=over 4 |
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|
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=item optimise_size => $bool |
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|
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By default, this module optimises I<compressability>, not raw size. This |
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switch changes that (and makes it slower). |
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|
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=item keep_nl => $bool |
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|
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By default, whitespace will either be stripped or replaced by a space. If |
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this option is enabled, then newlines will not be removed. This has the |
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advantage of keeping line number information intact (e.g. for backtraces), |
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but of course doesn't compress as well. |
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|
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=item cache => $path |
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|
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Since this module can take a very long time (minutes for the larger files |
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in the perl distribution), it can utilise a cache directory. The directory |
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will be created if it doesn't exist, and can be deleted at any time. |
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|
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=back |
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|
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=cut |
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|
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# PPI::Transform compatible |
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sub document { |
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my ($self, $doc) = @_; |
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|
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$self->{optimise_size} = 1; # more research is needed |
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|
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# special stripping for unicore/ files |
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if (eval { $doc->child (1)->content =~ /^# .* (build by mktables|machine-generated .*mktables) / }) { |
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|
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for my $heredoc (@{ $doc->find (PPI::Token::HereDoc::) }) { |
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my $src = join "", $heredoc->heredoc; |
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|
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# special stripping for unicore swashes and properties |
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# much more could be done by going binary |
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for ($src) { |
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s/^(?:0*([0-9a-fA-F]+))?\t(?:0*([0-9a-fA-F]+))?\t(?:0*([0-9a-fA-F]+))?/$1\t$2\t$3/gm |
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if $self->{optimise_size}; |
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|
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# s{ |
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# ^([0-9a-fA-F]+)\t([0-9a-fA-F]*)\t |
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# }{ |
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# # ww - smaller filesize, UU - compress better |
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# pack "C0UU", |
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# hex $1, |
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# length $2 ? (hex $2) - (hex $1) : 0 |
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# }gemx; |
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|
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s/#.*\n/\n/mg; |
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s/\s+\n/\n/mg; |
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} |
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|
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# PPI seems to be mostly undocumented |
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$heredoc->{_heredoc} = [split /$/, $src]; |
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} |
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} |
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|
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$doc->prune (PPI::Token::Comment::); |
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$doc->prune (PPI::Token::Pod::); |
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|
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# prune END stuff |
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for (my $last = $doc->last_element; $last; ) { |
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my $prev = $last->previous_token; |
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|
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if ($last->isa (PPI::Token::Whitespace::)) { |
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$last->delete; |
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} elsif ($last->isa (PPI::Statement::End::)) { |
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$last->delete; |
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last; |
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} elsif ($last->isa (PPI::Token::Pod::)) { |
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$last->delete; |
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} else { |
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last; |
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} |
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|
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$last = $prev; |
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} |
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|
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# prune some but not all insignificant whitespace |
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for my $ws (@{ $doc->find (PPI::Token::Whitespace::) }) { |
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my $prev = $ws->previous_token; |
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my $next = $ws->next_token; |
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|
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if (!$prev || !$next) { |
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$ws->delete; |
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} else { |
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if ($next->isa (PPI::Token::Whitespace::)) { |
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$ws->delete; |
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} elsif ( |
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$next->isa (PPI::Token::Operator::) && $next->{content} =~ /^(?:,|=|!|!=|==|=>)$/ # no ., because of digits. == float |
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or $prev->isa (PPI::Token::Operator::) && $prev->{content} =~ /^(?:,|=|\.|!|!=|==|=>)$/ |
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or $prev->isa (PPI::Token::Structure::) |
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or ($self->{optimise_size} && |
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($prev->isa (PPI::Token::Word::) |
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&& (PPI::Token::Symbol:: eq ref $next |
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|| $next->isa (PPI::Structure::Block::) |
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|| $next->isa (PPI::Structure::List::) |
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|| $next->isa (PPI::Structure::Condition::))) |
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) |
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) { |
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# perl has some idiotic warnings about nonexisting operators |
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if ($prev->isa (PPI::Token::Operator::) && $prev->{content} eq "=" |
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&& $next->isa (PPI::Token::Operator::) && $next->{content} =~ /[+\-]/ |
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) { |
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# avoid "Reverse %s operator" diagnostic |
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} else { |
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$ws->delete; |
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} |
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} else { |
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$ws->{content} = ' '; |
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} |
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} |
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} |
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|
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# prune whitespace around blocks, also ";" at end of blocks |
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if ($self->{optimise_size}) { |
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# these usually decrease size, but decrease compressability more |
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for my $struct (PPI::Structure::Block::, PPI::Structure::Condition::, PPI::Structure::List::) { |
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for my $node (@{ $doc->find ($struct) }) { |
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my $n1 = $node->first_token; |
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# my $n2 = $n1->previous_token; |
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my $n3 = $n1->next_token; |
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$n1->delete if $n1->isa (PPI::Token::Whitespace::); |
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# $n2->delete if $n2 && $n2->isa (PPI::Token::Whitespace::); # unsafe! AE::timer $MAX_SIGNAL_LATENCY -($NOW - int$NOW) |
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$n3->delete if $n3 && $n3->isa (PPI::Token::Whitespace::); |
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my $n1 = $node->last_token; |
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my $n2 = $n1->next_token; |
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my $n3 = $n1->previous_token; |
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$n1->delete if $n1->isa (PPI::Token::Whitespace::); |
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$n2->delete if $n2 && $n2->isa (PPI::Token::Whitespace::); |
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$n3->{content} = "" # delete seems to trigger a bug inside PPI |
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if $n3 && ($n3->isa (PPI::Token::Whitespace::) |
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|| ($n3->isa (PPI::Token::Structure::) && $n3->content eq ";")); |
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} |
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} |
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} |
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|
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# foreach => for |
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for my $node (@{ $doc->find (PPI::Statement::Compound::) }) { |
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if (my $n = $node->first_token) { |
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$n->{content} = "for" if $n->{content} eq "foreach" && $n->isa (PPI::Token::Word::); |
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} |
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} |
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|
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# reformat qw() lists which often have lots of whitespace |
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for my $node (@{ $doc->find (PPI::Token::QuoteLike::Words::) }) { |
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if ($node->{content} =~ /^qw(.)(.*)(.)$/s) { |
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my ($a, $qw, $b) = ($1, $2, $3); |
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$qw =~ s/^\s+//; |
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$qw =~ s/\s+$//; |
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$qw =~ s/\s+/ /g; |
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$node->{content} = "qw$a$qw$b"; |
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} |
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} |
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|
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# prune return at end of sub-blocks |
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#TODO: |
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# PPI::Document |
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# PPI::Statement::Sub |
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# PPI::Token::Word 'sub' |
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# PPI::Token::Whitespace ' ' |
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# PPI::Token::Word 'f' |
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# PPI::Structure::Block { ... } |
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# PPI::Statement |
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# PPI::Token::Word 'sub' |
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# PPI::Structure::Block { ... } |
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# PPI::Statement::Break |
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# PPI::Token::Word 'return' |
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# PPI::Token::Whitespace ' ' |
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# PPI::Token::Number '5' |
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# PPI::Token::Structure ';' |
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# PPI::Statement::Compound |
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# PPI::Structure::Block { ... } |
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# PPI::Statement::Break |
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# PPI::Token::Word 'return' |
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# PPI::Token::Whitespace ' ' |
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# PPI::Token::Number '8' |
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# PPI::Statement::Break |
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# PPI::Token::Word 'return' |
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# PPI::Token::Whitespace ' ' |
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# PPI::Token::Number '7' |
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|
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1 |
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} |
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|
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=item $perl = $transform->strip ($perl) |
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|
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Strips the perl source in C<$perl> and returns the stripped source. |
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|
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=cut |
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|
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sub strip { |
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my ($self, $src) = @_; |
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|
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my $filter = sub { |
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my $ppi = new PPI::Document \$src |
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or return; |
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|
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$self->document ($ppi) |
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or return; |
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|
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$src = $ppi->serialize; |
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}; |
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|
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if (exists $self->{cache} && (2048 <= length $src)) { |
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my $file = "$self->{cache}/" . Digest::MD5::md5_hex "$CACHE_VERSION \n" . (!!$self->{optimise_size}) . "\n\x00$src"; |
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|
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if (open my $fh, "<:perlio", $file) { |
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# zero size means unchanged |
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if (-s $fh) { |
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local $/; |
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$src = <$fh> |
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} |
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} else { |
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my $oldsrc = $src; |
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|
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$filter->(); |
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|
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mkdir $self->{cache}; |
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|
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if (open my $fh, ">:perlio", "$file~") { |
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# write a zero-byte file if source is unchanged |
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if ($oldsrc eq $src or (syswrite $fh, $src) == length $src) { |
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close $fh; |
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rename "$file~", $file; |
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} |
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} |
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} |
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} else { |
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$filter->(); |
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} |
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|
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$src |
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} |
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|
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=back |
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|
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=head1 SEE ALSO |
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|
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L<App::Staticperl>, L<Perl::Squish>. |
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|
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=head1 AUTHOR |
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|
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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|
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=cut |
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|
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1; |
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|
