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=head1 NAME |
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Compress::LZF - extremely light-weight Lempel-Ziv-Free compression |
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=head1 SYNOPSIS |
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# import compress/decompress functions |
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use Compress::LZF; |
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# the same as above |
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use Compress::LZF ':compress'; |
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$compressed = compress $uncompressed_data; |
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$original_data = decompress $compressed; |
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# import sfreeze, sfreeze_cref and sfreeze_c |
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use Compress::LZF ':freeze'; |
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$serialized = sfreeze_c [4,5,6]; |
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$original_data = sthaw $serialized; |
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=head1 DESCRIPTION |
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LZF is an extremely fast (not that much slower than a pure memcpy) |
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compression algorithm. It is ideal for applications where you want to save |
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I<some> space but not at the cost of speed. It is ideal for repetitive |
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data as well. The module is self-contained and very small (no large |
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library to be pulled in). It is also free, so there should be no problems |
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incorporating this module into commercial programs. |
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I have no idea wether any patents in any countries apply to this |
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algorithm, but at the moment it is believed that it is free from any |
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patents. |
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=head1 FUNCTIONS |
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=head2 $compressed = compress $uncompressed |
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Try to compress the given string as quickly and as much as possible. In |
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the worst case, the string can enlarge by 1 byte, but that should be the |
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absolute exception. You can expect a 45% compression ratio on large, |
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binary strings. |
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=head2 $decompressed = decompress $compressed |
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Uncompress the string (compressed by C<compress>) and return the original |
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data. Decompression errors can result in either broken data (there is no |
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checksum kept) or a runtime error. |
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=head2 $serialized = sfreeze $value (simplified freeze) |
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Often there is the need to serialize data into a string. This function does that, by using the Storable |
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module. It does the following transforms: |
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undef (the perl undefined value) |
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=> a special cookie (undef'ness is being preserved) |
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IV, NV, PV (i.e. a _plain_ perl scalar): |
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=> stays as is when it contains normal text/numbers |
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=> gets serialized into a string |
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RV, undef, other funny objects (magical ones for example): |
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=> data structure is freeze'd into a string. |
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That is, it tries to leave "normal", human-readable data untouched but |
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still serializes complex data structures into strings. The idea is to keep |
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readability as high as possible, and in cases readability can't be helped |
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anyways, it tries to compress the string. |
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The C<sfreeze> functions will enlarge the original data one byte at most |
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and will only load the Storable method when neccessary. |
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=head2 $serialized = sfreeze_c $value (sfreeze and compress) |
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Similar to C<sfreeze>, but always tries to C<c>ompress the resulting |
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string. This still leaves most small objects (most numbers) untouched. |
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=head2 $serialized = sfreeze_cr $value (sfreeze and compress references) |
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Similar to C<sfreeze>, but tries to C<c>ompress the resulting string |
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unless it's a "simple" string. References for example are not "simple" and |
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as such are being compressed. |
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=head2 $original_data = sthaw $serialized |
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Recreate the original object from it's serialized representation. This |
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function automatically detects all the different sfreeze formats. |
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=head2 Compress::LZF::set_serializer $package, $freeze, $thaw |
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Set the serialize module and functions to use. The default is "Storable", |
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"Storable::net_mstore" and "Storable::mretrieve", which should be fine for |
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most purposes. |
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=head1 SEE ALSO |
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Other Compress::* modules, especially Compress::LZV1 (an older, less |
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speedy module that guarentees only 1 byte overhead worst case) and |
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Compress::Zlib. |
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http://liblzf.plan9.de/ |
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=head1 AUTHOR |
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This perl extension and the underlying liblzf were written by Marc Lehmann |
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<schmorp@schmorp.de> (See also http://liblzf.plan9.de/). |
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=head1 BUGS |
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=cut |
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package Compress::LZF; |
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require Exporter; |
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require DynaLoader; |
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$VERSION = '1.9'; |
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@ISA = qw/Exporter DynaLoader/; |
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%EXPORT_TAGS = ( |
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freeze => [qw(sfreeze sfreeze_cr sfreeze_c sthaw)], |
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compress => [qw(compress decompress)], |
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); |
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Exporter::export_tags('compress'); |
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Exporter::export_ok_tags('freeze'); |
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bootstrap Compress::LZF $VERSION; |
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1; |
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