TestRLEDecompressingInputStream.java
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package org.apache.poi.util;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.commons.io.output.UnsynchronizedByteArrayOutputStream;
import org.junit.jupiter.api.Test;
class TestRLEDecompressingInputStream {
/**
* Section 3.2.1 No Compression Example
*
* The following string illustrates an ASCII text string with a set of characters that cannot be compressed
* by the compression algorithm specified in section 2.4.1.
*
* abcdefghijklmnopqrstuv.
*
* This example is provided to demonstrate the results of compressing and decompressing the string
* using an interoperable implementation of the algorithm specified in section 2.4.1.
*
* The following hex array represents the compressed byte array of the example string as compressed by
* the compression algorithm.
*
* 01 19 B0 00 61 62 63 64 65 66 67 68 00 69 6A 6B 6C
* 6D 6E 6F 70 00 71 72 73 74 75 76 2E
*
* The following hex array represents the decompressed byte array of the example string as
* decompressed by the decompression algorithm.
*
* 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70 71
* 72 73 74 75 76 2E
*
*/
@Test
void noCompressionExample() throws IOException {
final byte[] compressed = {
0x01, 0x19, (byte)0xB0, 0x00, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x00, 0x69, 0x6A, 0x6B, 0x6C,
0x6D, 0x6E, 0x6F, 0x70, 0x00, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x2E
};
final String expected = "abcdefghijklmnopqrstuv.";
checkRLEDecompression(expected, compressed);
}
/**
* Section 3.2.2 Normal Compression Example
*
* The following string illustrates an ASCII text string with a typical set of characters that can be
* compressed by the compression algorithm.
*
* #aaabcdefaaaaghijaaaaaklaaamnopqaaaaaaaaaaaarstuvwxyzaaa
*
* This example is provided to demonstrate the results of compressing and decompressing the example
* string using an interoperable implementation of the algorithm specified in section 2.4.1.
*
* The following hex array represents the compressed byte array of the example string as compressed by
* the compression algorithm:
*
* 01 2F B0 00 23 61 61 61 62 63 64 65 82 66 00 70
* 61 67 68 69 6A 01 38 08 61 6B 6C 00 30 6D 6E 6F
* 70 06 71 02 70 04 10 72 73 74 75 76 10 77 78 79
* 7A 00 3C
*
* The following hex array represents the decompressed byte array of the example string as
* decompressed by the decompression algorithm:
*
* 23 61 61 61 62 63 64 65 66 61 61 61 61 67 68 69
* 6a 61 61 61 61 61 6B 6C 61 61 61 6D 6E 6F 70 71
* 61 61 61 61 61 61 61 61 61 61 61 61 72 73 74 75
* 76 77 78 79 7A 61 61 61
*/
@Test
void normalCompressionExample() throws IOException {
final byte[] compressed = {
0x01, 0x2F, (byte)0xB0, 0x00, 0x23, 0x61, 0x61, 0x61, 0x62, 0x63, 0x64, 0x65, (byte)0x82, 0x66, 0x00, 0x70,
0x61, 0x67, 0x68, 0x69, 0x6A, 0x01, 0x38, 0x08, 0x61, 0x6B, 0x6C, 0x00, 0x30, 0x6D, 0x6E, 0x6F,
0x70, 0x06, 0x71, 0x02, 0x70, 0x04, 0x10, 0x72, 0x73, 0x74, 0x75, 0x76, 0x10, 0x77, 0x78, 0x79,
0x7A, 0x00, 0x3C
};
final String expected = "#aaabcdefaaaaghijaaaaaklaaamnopqaaaaaaaaaaaarstuvwxyzaaa";
checkRLEDecompression(expected, compressed);
}
/**
* Section 3.2.3 Maximum Compression Example
*
* The following string illustrates an ASCII text string with a typical set of characters that can be
* compressed by the compression algorithm.
*
* aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
*
* This example is provided to demonstrate the results of compressing and decompressing the example
* string using an interoperable implementation of the algorithm specified in section 2.4.1.
*
* The following hex array represents the compressed byte array of the example string as compressed by
* the compression algorithm:
*
* 01 03 B0 02 61 45 00
*
* The following hex array represents the decompressed byte array of the example string as
* decompressed by the decompression algorithm:
*
* 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61
* 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61
* 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61
* 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61
* 61 61 61 61 61 61 61 61 61
*/
@Test
void maximumCompressionExample() throws IOException {
final byte[] compressed = {
0x01, 0x03, (byte)0xB0, 0x02, 0x61, 0x45, 0x00
};
final String expected = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
checkRLEDecompression(expected, compressed);
}
@Test
void decompress() throws IOException {
final byte[] compressed = {
0x01, 0x03, (byte)0xB0, 0x02, 0x61, 0x45, 0x00
};
final byte[] expanded = RLEDecompressingInputStream.decompress(compressed);
final byte[] expected = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa".getBytes(StringUtil.UTF8);
assertArrayEquals(expected, expanded);
}
private static void checkRLEDecompression(String expected, byte[] runLengthEncodedData) throws IOException {
InputStream compressedStream = new ByteArrayInputStream(runLengthEncodedData);
UnsynchronizedByteArrayOutputStream out = UnsynchronizedByteArrayOutputStream.builder().get();
try (InputStream stream = new RLEDecompressingInputStream(compressedStream)) {
IOUtils.copy(stream, out);
}
String expanded = out.toString(StringUtil.UTF8);
assertEquals(expected, expanded);
}
}