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/*

* Reference Huffman coding

* Copyright (c) Project Nayuki

*

* https://www.nayuki.io/page/reference-huffman-coding

* https://github.com/nayuki/Reference-Huffman-coding

*/

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

/**

* Tests {@link HuffmanCompress} coupled with {@link HuffmanDecompress}.

*/

public class HuffmanCompressTest extends HuffmanCodingTest {

protected byte[] compress(byte[] b) throws IOException {

FrequencyTable freqs = new FrequencyTable(new int[257]);

for (byte x : b)

freqs.increment(x & 0xFF);

freqs.increment(256); // EOF symbol gets a frequency of 1

CodeTree code = freqs.buildCodeTree();

CanonicalCode canonCode = new CanonicalCode(code, 257);

code = canonCode.toCodeTree();

InputStream in = new ByteArrayInputStream(b);

ByteArrayOutputStream out = new ByteArrayOutputStream();

BitOutputStream bitOut = new BitOutputStream(out);

HuffmanCompress.writeCodeLengthTable(bitOut, canonCode);

HuffmanCompress.compress(code, in, bitOut);

bitOut.close();

return out.toByteArray();

}

protected byte[] decompress(byte[] b) throws IOException {

InputStream in = new ByteArrayInputStream(b);

ByteArrayOutputStream out = new ByteArrayOutputStream();

BitInputStream bitIn = new BitInputStream(in);

CanonicalCode canonCode = HuffmanDecompress.readCodeLengthTable(bitIn);

CodeTree code = canonCode.toCodeTree();

HuffmanDecompress.decompress(code, bitIn, out);

return out.toByteArray();

}

}