PPMD Streaming String Compression

Demonstrates streaming string compression using PPMD. Data may be compressed in chunks by initially calling one of the BeginCompress* methods, followed by 0 or more calls to a MoreCompress* method, and terminating with a call to an EndCompress* method.

Likewise, data may be decompressed by calling a BeginDecompress* method, followed by 0 or more MoreDecompress* calls, and ending with an EndDecompress* method call.

This example demonstrates string-to-string compression and decompression in chunks.

The functionality in this example is available in pre-release only:

Chilkat Module for Perl 5.8.* (Pre-Release)

Chilkat Module for Perl 5.10.* (Pre-Release)

use chilkat;

$compress = new chilkat::CkCompression();

#  Any string argument automatically begins a 30-day trial.
$success = $compress->UnlockComponent("30-day trial");
if ($success != 1) {
    print "Compression component unlock failed" . "\n";
    exit;
}

$compress->put_Algorithm("ppmd");
$compress->put_Charset("ansi");
$compress->put_EncodingMode("base64");

#  Create a long string to compress.
$strData = "abcdefg1122334455667788";
$strData = $strData . "\r\n";

#  Note: BeginCompressStringENC may return a zero-length
#  string.  This is normal if the input is buffered and no
#  compressed data is yet available.
#  However, a null reference indicates an error -- which is
#  generally only possible if the component was never unlocked.
$strCompressed = $compress->beginCompressStringENC($strData);
if ($strCompressed eq null ) {
    print $compress->lastErrorText() . "\n";
    exit;
}

#  Compress 100 more chunks of data.  Each call to
#  MoreCompressStringENC may or may not produce additional
#  compressed output.
for ($i = 0; $i <= 99; $i++) {
    $strData = "abcdefg1122334455667788";
    $strData = $strData . "\r\n";

    $strCompressed = $strCompressed . $compress->moreCompressStringENC($strData);
}

#  Finalize the compression with a single call to EndCompressStringENC:
$strCompressed = $strCompressed . $compress->endCompressStringENC();

#  Display the compressed string.
#  The result will be:
#  ec8YZ5vk9za18d0plwuV7R65em9OZge9gJXht/QAAAAAAAAAABNOZQAAKw==

print $strCompressed . "\r\n";

#  Decompress back to the original in a single call.

$strOriginal = $compress->decompressStringENC($strCompressed);

#  Display the uncompressed original:
print "--- Original ---" . "\r\n";
print $strOriginal . "\r\n";

#  Decompress in multiple calls.  It doesn't matter how the
#  compressed data is split -- it could be fed to the decompressor
#  one char at a time if desired.
$chunk1 = "ec8YZ5vk9za1";
$chunk2 = "8d0p";
$chunk3 = "lwuV7R65em9OZge9gJXht/QAAAA";
$chunk4 = "AAAAAABNOZQAAKw==";

$strOriginal = "";
$strOriginal = $compress->beginDecompressStringENC($chunk1);
$strOriginal = $strOriginal . $compress->moreDecompressStringENC($chunk2);
$strOriginal = $strOriginal . $compress->moreDecompressStringENC($chunk3);
$strOriginal = $strOriginal . $compress->moreDecompressStringENC($chunk4);
$strOriginal = $strOriginal . $compress->endDecompressStringENC();

#  Display the uncompressed original after decompressing in chunks:
print "--- Original after Decompressing from Chunks ---" . "\r\n";
print $strOriginal . "\r\n";