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Fork of https://github.com/airlift/aircompressor (zstd only). This module is temporary until we get an official release that includes the ZstdInputStream API (which is already implemented by two different people but neither PR shows any progress).

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/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package ai.vespa.airlift.zstd;

class HuffmanCompressionContext
{
    private final HuffmanTableWriterWorkspace tableWriterWorkspace = new HuffmanTableWriterWorkspace();
    private final HuffmanCompressionTableWorkspace compressionTableWorkspace = new HuffmanCompressionTableWorkspace();

    private HuffmanCompressionTable previousTable = new HuffmanCompressionTable(Huffman.MAX_SYMBOL_COUNT);
    private HuffmanCompressionTable temporaryTable = new HuffmanCompressionTable(Huffman.MAX_SYMBOL_COUNT);

    private HuffmanCompressionTable previousCandidate = previousTable;
    private HuffmanCompressionTable temporaryCandidate = temporaryTable;

    public HuffmanCompressionTable getPreviousTable()
    {
        return previousTable;
    }

    public HuffmanCompressionTable borrowTemporaryTable()
    {
        previousCandidate = temporaryTable;
        temporaryCandidate = previousTable;

        return temporaryTable;
    }

    public void discardTemporaryTable()
    {
        previousCandidate = previousTable;
        temporaryCandidate = temporaryTable;
    }

    public void saveChanges()
    {
        temporaryTable = temporaryCandidate;
        previousTable = previousCandidate;
    }

    public HuffmanCompressionTableWorkspace getCompressionTableWorkspace()
    {
        return compressionTableWorkspace;
    }

    public HuffmanTableWriterWorkspace getTableWriterWorkspace()
    {
        return tableWriterWorkspace;
    }
}