com.aliasi.lm.BitTrieWriter Maven / Gradle / Ivy
Show all versions of aliasi-lingpipe Show documentation
/*
* LingPipe v. 4.1.0
* Copyright (C) 2003-2011 Alias-i
*
* This program is licensed under the Alias-i Royalty Free License
* Version 1 WITHOUT ANY WARRANTY, without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the Alias-i
* Royalty Free License Version 1 for more details.
*
* You should have received a copy of the Alias-i Royalty Free License
* Version 1 along with this program; if not, visit
* http://alias-i.com/lingpipe/licenses/lingpipe-license-1.txt or contact
* Alias-i, Inc. at 181 North 11th Street, Suite 401, Brooklyn, NY 11211,
* +1 (718) 290-9170.
*/
package com.aliasi.lm;
import com.aliasi.io.BitOutput;
import java.io.IOException;
/**
* A BitTrieWriter provides a trie writer that wraps a
* bit-level output.
*
* The reader for the output of a bit trie writer is {@link
* BitTrieReader}.
*
*
Counts of trie nodes and differences between
* successive symbols on transitions are delta coded for compression
* (see {@link BitOutput#writeDelta(long)}).
*
*
The method {@link #copy(TrieReader,TrieWriter)} is available to
* copy the contents of a reader to a writer.
*
* @author Bob Carpenter
* @version 2.3
* @since LingPipe2.3
*/
public class BitTrieWriter extends BitTrie implements TrieWriter {
private final BitOutput mBitOutput;
/**
* Construct a bit trie writer from the specified bit output
* with the specified maximum n-gram.
*
* @param bitOutput Underlying bit output.
*/
public BitTrieWriter(BitOutput bitOutput) {
mBitOutput = bitOutput;
}
public void writeCount(long count) throws IOException {
checkCount(count);
// System.out.println(" TrieWriter.writeCount(" + count + ")");
// System.out.println("CODE: " + count);
mBitOutput.writeDelta(count);
pushValue(-1L);
}
public void writeSymbol(long symbol) throws IOException {
if (symbol == -1L) {
// encode -1 as 1L
mBitOutput.writeDelta(1L);
// System.out.println("TrieWriter.writeSymbol(-1)");
// System.out.println("CODE: " + 1L);
popValue();
} else {
long code = symbol - popValue() + 1L; // >= 2
mBitOutput.writeDelta(code);
// System.out.println("TrieWriter.writeSymbol(" + symbol + ") char=" + ((char)symbol));
// System.out.println("CODE: " + code);
pushValue(symbol);
}
}
/**
* Copies the content of the specified trie reader to the specified
* trie writer.
*
* @param reader Reader from which to read.
* @param writer Writer to which to write.
*/
public static void copy(TrieReader reader, TrieWriter writer)
throws IOException {
long count = reader.readCount();
// System.out.println("count=" + count);
writer.writeCount(count);
long symbol;
while ((symbol = reader.readSymbol()) != -1L) {
// System.out.println("symbol=" + symbol + "[" + ((char)symbol) + "]");
writer.writeSymbol(symbol);
copy(reader,writer);
}
// System.out.println("symbol=-1");
writer.writeSymbol(-1L);
}
}