org.ttzero.excel.reader.ShareStringParser Maven / Gradle / Ivy

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/*
 * Copyright (c) 2019-2020, [email protected] All Rights Reserved.
 *
 * 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 org.ttzero.excel.reader;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.ttzero.excel.entity.e3.Context;
import org.ttzero.excel.entity.e3.ParserIdentifier;
import org.ttzero.excel.entity.e3.StringParser;
import org.ttzero.excel.entity.e3.Block;

import java.io.IOException;

/**
 * 5.100 SST – Shared String Table
 * 
 * A BIFF8 workbook collects the strings of all text cells
 * in a global list, the Shared String Table. This table is
 * located in the record SST in the Workbook Globals Sub-stream
 * (➜4.2.5).
 *
 * @author guanquan.wang on 2019-02-05
 */
public class ShareStringParser {
    private static final Logger LOGGER = LoggerFactory.getLogger(ShareStringParser.class);

    public static SharedStrings get(Block block) {
        block.ready();
        // Total number of strings in the workbook (see below)
        int ts = block.nextInt();
        // Number of following strings (nm)
        int nm = block.nextInt();
        LOGGER.debug("SharedString Count: {} Unique: {}", ts, nm);

        // List of nm Unicode strings, 16-bit string length (➜2.5.3)
        int page = 1 << 9;
        SharedStrings sst;
        if (nm > page << 1) {
            // Store value as `IndexSharedStringTable` file format
            Context context = block.getContext();
            try {
                IndexSharedStringTable isst = new IndexSharedStringTable();

                for (int i = 0; i < nm; i++) {
                    isst.push(StringParser.get16Bit(block));
                }
                sst = new SharedStrings(isst, context.cacheSize, context.hotSize);
            } catch (IOException e) {
                throw new ExcelReadException("Error. Create SharedStringTable failed.", e);
            }
        } else {
            String[] data = new String[nm];
            for (int i = 0; i < nm; i++) {
                data[i] = StringParser.get16Bit(block);
            }
            sst = new SharedStrings(data);
        }

        block.commit();
        return sst;
    }

    public static short getId() {
        return ParserIdentifier.SST;
    }
}