org.ttzero.excel.entity.e3.SheetSubStream 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.entity.e3;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.ttzero.excel.reader.BIFF8Row;
import org.ttzero.excel.reader.Dimension;
import org.ttzero.excel.reader.ExcelReadException;
import org.ttzero.excel.reader.RowBlock;
import org.ttzero.excel.reader.RowBlockParser;

/**
 * 2.3.4 Sub-streams
 * 
 * A sub-stream that describes a sheet in a workbook
 * is called Sheet Sub-stream. It is part of the BIFF5-BIFF8
 * Workbook Stream as well as the BIFF4W Workspace Stream.
 *
 * @author guanquan.wang at 2019-03-02 11:29
 */
public class SheetSubStream {
    protected static final Logger LOGGER = LoggerFactory.getLogger(SheetSubStream.class);

    protected GlobalsSetting gs;
    protected SheetInfo sheet;

    protected Index index;
    protected Dimension range;
    protected Block block;
    protected RowBlock rowBlock;
    protected BIFF8Row firstRow;
    protected boolean eof;

    public SheetSubStream(GlobalsSetting gs, SheetInfo sheet) {
        this.gs = gs;
        this.sheet = sheet;
    }

    /**
     * @return sheet name
     */
    public String getName() {
        return sheet.getName();
    }

    public void get(Block block) {
        int sid = gs.firstSid;
        int n = sheet.position >> block.context.ssz, m = sheet.position - (n << block.context.ssz);
        block.context.sectorTable.moveTo(sid);
        for (; n-- > 0; sid = block.context.sectorTable.nextSecID()) ;
        block.testShouldLoad(sid);

        block.skip(m);

        // Check Beginning of File
        short id = block.nextIdentifier();
        if (id != ParserIdentifier.BOF) {
            throw new ExcelReadException("Miss the BOF.");
        }

        // BOF
        BOFParser.BOF bof = BOFParser.get(block);
        LOGGER.debug(bof.toString());

        for ( ; ; ) {
            short nextId = block.nextIdentifier();

            if (nextId == ParserIdentifier.EOF) {
                break;
            }
            // Check the identify
            if (!ParserIdentifier.contains(nextId)) {
                IgnoreParser.get(block);
                continue;
            }

            // Only parse the record in whitelist
            if (parseWhiteListRecord(nextId, block)) {
                break;
            }
        }

        // Empty worksheet
        if (range.lastRow - range.firstRow < 0) {
            eof = true;
        }

        if (!eof && beforeParseRowBlock()) {
            startReadRowBlock();
        }

    }

    /**
     * Begin to parse rows
     */
    protected void startReadRowBlock() {
        // Parse the first row block
        rowBlock = RowBlockParser.get(this.block);
        rowBlock.setGlobalEntry(gs.sst, gs.styles);

        // The first row block's first row
        if (rowBlock.hasNext()) {
            firstRow = rowBlock.firstRow();
            rowBlock.setHeaderRow(firstRow.asHeader());
        } else {
            eof = true;
        }
    }

    /**
     * Parse whitelist record
     *
     * @param id the record id
     * @param block block data
     * @return true if abort all parse
     */
    protected boolean parseWhiteListRecord(int id, Block block) {
        switch (id) {
            // 4.7 Cell Table and Row Blocks
            case ParserIdentifier.INDEX:
                index = IndexParser.get(block);
                break;
            // 5.35 DIMENSION
            case ParserIdentifier.DIMENSION:
                block.ready();
                // Index to first used row
                int fr = block.nextInt() + 1;
                // Index to last used row, increased by 1
                int lr = block.nextInt();
                // Index to first used column
                short fc = (short) (block.nextShort() + 1);
                // Index to last used column, increased by 1
                short lc = block.nextShort();
                range = new Dimension(fr, fc, lr, lc);
                block.commit();
                break;
            // 4.7 Cell Table and Row Blocks
            case ParserIdentifier.ROW:
                block.cacheIdentifier(); // rollback
                this.block = block.deepClone();
                return true;
            // 5.29
            case ParserIdentifier.DBCELL:
                // Empty sheet
                return eof = true;
            default:
                IgnoreParser.get(block);
        }
        return false;
    }

    /**
     * Do something before parse RowBlock
     *
     * @return boolean value, abort if returns false
     */
    protected boolean beforeParseRowBlock() {
        return this.block != null;
    }

    public Dimension getRange() {
        return range;
    }

    public BIFF8Row firstRow() {
        return firstRow;
    }

    /**
     * iterator rows
     *
     * @return Row
     */
    public BIFF8Row nextRow() {
        if (eof) return null;
        if (!rowBlock.hasNext()) {
            BIFF8Row row = rowBlock.lastRow();
            if (row.getRowNumber() < range.lastRow - 1) {
                rowBlock = RowBlockParser.get(block);
                if (!rowBlock.hasNext()) {
                    return null;
                }
                // End loop
            } else {
                eof = true;
                return null;
            }
        }
        return rowBlock.next();
    }
}