com.healthmarketscience.jackcess.impl.ComplexColumnSupport.java Source code

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/*
Copyright (c) 2013 James Ahlborn
    
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
    
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.
    
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
USA
*/

package com.healthmarketscience.jackcess.impl;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.EnumSet;
import java.util.List;
import java.util.Set;

import com.healthmarketscience.jackcess.Column;
import com.healthmarketscience.jackcess.CursorBuilder;
import com.healthmarketscience.jackcess.DataType;
import com.healthmarketscience.jackcess.IndexCursor;
import com.healthmarketscience.jackcess.Row;
import com.healthmarketscience.jackcess.Table;
import com.healthmarketscience.jackcess.complex.ComplexColumnInfo;
import com.healthmarketscience.jackcess.complex.ComplexValue;
import com.healthmarketscience.jackcess.impl.complex.AttachmentColumnInfoImpl;
import com.healthmarketscience.jackcess.impl.complex.MultiValueColumnInfoImpl;
import com.healthmarketscience.jackcess.impl.complex.UnsupportedColumnInfoImpl;
import com.healthmarketscience.jackcess.impl.complex.VersionHistoryColumnInfoImpl;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Utility code for loading complex columns.
 *
 * @author James Ahlborn
 */
public class ComplexColumnSupport {
    private static final Log LOG = LogFactory.getLog(ComplexColumnSupport.class);

    private static final String COL_COMPLEX_TYPE_OBJECT_ID = "ComplexTypeObjectID";
    private static final String COL_TABLE_ID = "ConceptualTableID";
    private static final String COL_FLAT_TABLE_ID = "FlatTableID";

    private static final Set<DataType> MULTI_VALUE_TYPES = EnumSet.of(DataType.BYTE, DataType.INT, DataType.LONG,
            DataType.FLOAT, DataType.DOUBLE, DataType.GUID, DataType.NUMERIC, DataType.TEXT);

    /**
     * Creates a ComplexColumnInfo for a complex column.
     */
    public static ComplexColumnInfo<? extends ComplexValue> create(ColumnImpl column, ByteBuffer buffer, int offset)
            throws IOException {
        int complexTypeId = buffer.getInt(offset + column.getFormat().OFFSET_COLUMN_COMPLEX_ID);

        DatabaseImpl db = column.getDatabase();
        TableImpl complexColumns = db.getSystemComplexColumns();
        IndexCursor cursor = CursorBuilder.createCursor(complexColumns.getPrimaryKeyIndex());
        if (!cursor.findFirstRowByEntry(complexTypeId)) {
            throw new IOException("Could not find complex column info for complex column with id " + complexTypeId);
        }
        Row cColRow = cursor.getCurrentRow();
        int tableId = cColRow.getInt(COL_TABLE_ID);
        if (tableId != column.getTable().getTableDefPageNumber()) {
            throw new IOException("Found complex column for table " + tableId + " but expected table "
                    + column.getTable().getTableDefPageNumber());
        }
        int flatTableId = cColRow.getInt(COL_FLAT_TABLE_ID);
        int typeObjId = cColRow.getInt(COL_COMPLEX_TYPE_OBJECT_ID);

        TableImpl typeObjTable = db.getTable(typeObjId);
        TableImpl flatTable = db.getTable(flatTableId);

        if ((typeObjTable == null) || (flatTable == null)) {
            throw new IOException("Could not find supporting tables (" + typeObjId + ", " + flatTableId
                    + ") for complex column with id " + complexTypeId);
        }

        // we inspect the structore of the "type table" to determine what kind of
        // complex info we are dealing with
        if (isMultiValueColumn(typeObjTable)) {
            return new MultiValueColumnInfoImpl(column, complexTypeId, typeObjTable, flatTable);
        } else if (isAttachmentColumn(typeObjTable)) {
            return new AttachmentColumnInfoImpl(column, complexTypeId, typeObjTable, flatTable);
        } else if (isVersionHistoryColumn(typeObjTable)) {
            return new VersionHistoryColumnInfoImpl(column, complexTypeId, typeObjTable, flatTable);
        }

        LOG.warn("Unsupported complex column type " + typeObjTable.getName());
        return new UnsupportedColumnInfoImpl(column, complexTypeId, typeObjTable, flatTable);
    }

    public static boolean isMultiValueColumn(Table typeObjTable) {
        // if we found a single value of a "simple" type, then we are dealing with
        // a multi-value column
        List<? extends Column> typeCols = typeObjTable.getColumns();
        return ((typeCols.size() == 1) && MULTI_VALUE_TYPES.contains(typeCols.get(0).getType()));
    }

    public static boolean isAttachmentColumn(Table typeObjTable) {
        // attachment data has these columns FileURL(MEMO), FileName(TEXT),
        // FileType(TEXT), FileData(OLE), FileTimeStamp(SHORT_DATE_TIME),
        // FileFlags(LONG)
        List<? extends Column> typeCols = typeObjTable.getColumns();
        if (typeCols.size() < 6) {
            return false;
        }

        int numMemo = 0;
        int numText = 0;
        int numDate = 0;
        int numOle = 0;
        int numLong = 0;

        for (Column col : typeCols) {
            switch (col.getType()) {
            case TEXT:
                ++numText;
                break;
            case LONG:
                ++numLong;
                break;
            case SHORT_DATE_TIME:
                ++numDate;
                break;
            case OLE:
                ++numOle;
                break;
            case MEMO:
                ++numMemo;
                break;
            default:
                // ignore
            }
        }

        // be flexible, allow for extra columns...
        return ((numMemo >= 1) && (numText >= 2) && (numOle >= 1) && (numDate >= 1) && (numLong >= 1));
    }

    public static boolean isVersionHistoryColumn(Table typeObjTable) {
        // version history data has these columns <value>(MEMO),
        // <modified>(SHORT_DATE_TIME)
        List<? extends Column> typeCols = typeObjTable.getColumns();
        if (typeCols.size() < 2) {
            return false;
        }

        int numMemo = 0;
        int numDate = 0;

        for (Column col : typeCols) {
            switch (col.getType()) {
            case SHORT_DATE_TIME:
                ++numDate;
                break;
            case MEMO:
                ++numMemo;
                break;
            default:
                // ignore
            }
        }

        // be flexible, allow for extra columns...
        return ((numMemo >= 1) && (numDate >= 1));
    }
}