poi/src/java/org/apache/poi/hssf/record/aggregates/SharedValueManager.java

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   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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   See the License for the specific language governing permissions and
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package org.apache.poi.hssf.record.aggregates;

import java.util.Arrays;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

import org.apache.poi.hssf.record.ArrayRecord;
import org.apache.poi.hssf.record.FormulaRecord;
import org.apache.poi.hssf.record.SharedFormulaRecord;
import org.apache.poi.hssf.record.SharedValueRecordBase;
import org.apache.poi.hssf.record.TableRecord;
import org.apache.poi.hssf.record.formula.ExpPtg;
import org.apache.poi.hssf.util.CellRangeAddress8Bit;
import org.apache.poi.ss.util.CellReference;

/**
 * Manages various auxiliary records while constructing a
 * {@link RowRecordsAggregate}:
 * <ul>
 * <li>{@link SharedFormulaRecord}s</li>
 * <li>{@link ArrayRecord}s</li>
 * <li>{@link TableRecord}s</li>
 * </ul>
 *
 * @author Josh Micich
 */
public final class SharedValueManager {

	private static final class SharedFormulaGroup {
		private final SharedFormulaRecord _sfr;
		private final FormulaRecordAggregate[] _frAggs;
		private int _numberOfFormulas;
		/**
		 * Coordinates of the first cell having a formula that uses this shared formula.
		 * This is often <i>but not always</i> the top left cell in the range covered by
		 * {@link #_sfr}
		 */
		private final CellReference _firstCell;

		public SharedFormulaGroup(SharedFormulaRecord sfr, CellReference firstCell) {
			if (!sfr.isInRange(firstCell.getRow(), firstCell.getCol())) {
				throw new IllegalArgumentException("First formula cell " + firstCell.formatAsString()
						+ " is not shared formula range " + sfr.getRange().toString() + ".");
			}
			_sfr = sfr;
			_firstCell = firstCell;
			int width = sfr.getLastColumn() - sfr.getFirstColumn() + 1;
			int height = sfr.getLastRow() - sfr.getFirstRow() + 1;
			_frAggs = new FormulaRecordAggregate[width * height];
			_numberOfFormulas = 0;
		}

		public void add(FormulaRecordAggregate agg) {
			if (_numberOfFormulas == 0) {
				if (_firstCell.getRow() != agg.getRow() || _firstCell.getCol() != agg.getColumn()) {
					throw new IllegalStateException("shared formula coding error");
				}
			}
			if (_numberOfFormulas >= _frAggs.length) {
				throw new RuntimeException("Too many formula records for shared formula group");
			}
			_frAggs[_numberOfFormulas++] = agg;
		}

		public void unlinkSharedFormulas() {
			for (int i = 0; i < _numberOfFormulas; i++) {
				_frAggs[i].unlinkSharedFormula();
			}
		}

		public SharedFormulaRecord getSFR() {
			return _sfr;
		}

		public final String toString() {
			StringBuffer sb = new StringBuffer(64);
			sb.append(getClass().getName()).append(" [");
			sb.append(_sfr.getRange().toString());
			sb.append("]");
			return sb.toString();
		}

		/**
		 * Note - the 'first cell' of a shared formula group is not always the top-left cell
		 * of the enclosing range.
		 * @return <code>true</code> if the specified coordinates correspond to the 'first cell'
		 * of this shared formula group.
		 */
		public boolean isFirstCell(int row, int column) {
			return _firstCell.getRow() == row && _firstCell.getCol() == column;
		}
	}

	/**
	 * @return a new empty {@link SharedValueManager}.
	 */
	public static final SharedValueManager createEmpty() {
		// Note - must create distinct instances because they are assumed to be mutable.
		return new SharedValueManager(
			new SharedFormulaRecord[0], new CellReference[0], new ArrayRecord[0], new TableRecord[0]);
	}
	private final ArrayRecord[] _arrayRecords;
	private final TableRecord[] _tableRecords;
	private final Map<SharedFormulaRecord, SharedFormulaGroup> _groupsBySharedFormulaRecord;
	/** cached for optimization purposes */
	private SharedFormulaGroup[] _groups;

	private SharedValueManager(SharedFormulaRecord[] sharedFormulaRecords,
			CellReference[] firstCells, ArrayRecord[] arrayRecords, TableRecord[] tableRecords) {
		int nShF = sharedFormulaRecords.length;
		if (nShF != firstCells.length) {
			throw new IllegalArgumentException("array sizes don't match: " + nShF + "!=" + firstCells.length + ".");
		}
		_arrayRecords = arrayRecords;
		_tableRecords = tableRecords;
		Map<SharedFormulaRecord, SharedFormulaGroup> m = new HashMap<SharedFormulaRecord, SharedFormulaGroup>(nShF * 3 / 2);
		for (int i = 0; i < nShF; i++) {
			SharedFormulaRecord sfr = sharedFormulaRecords[i];
			m.put(sfr, new SharedFormulaGroup(sfr, firstCells[i]));
		}
		_groupsBySharedFormulaRecord = m;
	}

	/**
	 * @param firstCells
	 * @param recs list of sheet records (possibly contains records for other parts of the Excel file)
	 * @param startIx index of first row/cell record for current sheet
	 * @param endIx one past index of last row/cell record for current sheet.  It is important
	 * that this code does not inadvertently collect <tt>SharedFormulaRecord</tt>s from any other
	 * sheet (which could happen if endIx is chosen poorly).  (see bug 44449)
	 */
	public static SharedValueManager create(SharedFormulaRecord[] sharedFormulaRecords,
			CellReference[] firstCells, ArrayRecord[] arrayRecords, TableRecord[] tableRecords) {
		if (sharedFormulaRecords.length + firstCells.length + arrayRecords.length + tableRecords.length < 1) {
			return createEmpty();
		}
		return new SharedValueManager(sharedFormulaRecords, firstCells, arrayRecords, tableRecords);
	}


	/**
	 * @param firstCell as extracted from the {@link ExpPtg} from the cell's formula.
	 * @return never <code>null</code>
	 */
	public SharedFormulaRecord linkSharedFormulaRecord(CellReference firstCell, FormulaRecordAggregate agg) {

		SharedFormulaGroup result = findFormulaGroup(getGroups(), firstCell);
		result.add(agg);
		return result.getSFR();
	}

	private static SharedFormulaGroup findFormulaGroup(SharedFormulaGroup[] groups, CellReference firstCell) {
		int row = firstCell.getRow();
		int column = firstCell.getCol();
		// Traverse the list of shared formulas and try to find the correct one for us

		// perhaps this could be optimised to some kind of binary search
		for (int i = 0; i < groups.length; i++) {
			SharedFormulaGroup svg = groups[i];
			if (svg.isFirstCell(row, column)) {
				return svg;
			}
		}
		// TODO - fix file "15228.xls" so it opens in Excel after rewriting with POI
		throw new RuntimeException("Failed to find a matching shared formula record");
	}

	private SharedFormulaGroup[] getGroups() {
		if (_groups == null) {
			SharedFormulaGroup[] groups = new SharedFormulaGroup[_groupsBySharedFormulaRecord.size()];
			_groupsBySharedFormulaRecord.values().toArray(groups);
			Arrays.sort(groups, SVGComparator); // make search behaviour more deterministic
			_groups = groups;
		}
		return _groups;
	}

	private static final Comparator<SharedFormulaGroup> SVGComparator = new Comparator<SharedFormulaGroup>() {

		public int compare(SharedFormulaGroup a, SharedFormulaGroup b) {
			CellRangeAddress8Bit rangeA = a.getSFR().getRange();
			CellRangeAddress8Bit rangeB = b.getSFR().getRange();

			int cmp;
			cmp = rangeA.getFirstRow() - rangeB.getFirstRow();
			if (cmp != 0) {
				return cmp;
			}
			cmp = rangeA.getFirstColumn() - rangeB.getFirstColumn();
			if (cmp != 0) {
				return cmp;
			}
			return 0;
		}
	};

	/**
	 * Gets the {@link SharedValueRecordBase} record if it should be encoded immediately after the
	 * formula record contained in the specified {@link FormulaRecordAggregate} agg.  Note - the
	 * shared value record always appears after the first formula record in the group.  For arrays
	 * and tables the first formula is always the in the top left cell.  However, since shared
	 * formula groups can be sparse and/or overlap, the first formula may not actually be in the
	 * top left cell.
	 *
	 * @return the SHRFMLA, TABLE or ARRAY record for the formula cell, if it is the first cell of
	 * a table or array region. <code>null</code> if the formula cell is not shared/array/table,
	 * or if the specified formula is not the the first in the group.
	 */
	public SharedValueRecordBase getRecordForFirstCell(FormulaRecordAggregate agg) {
		CellReference firstCell = agg.getFormulaRecord().getFormula().getExpReference();
		// perhaps this could be optimised by consulting the (somewhat unreliable) isShared flag
		// and/or distinguishing between tExp and tTbl.
		if (firstCell == null) {
			// not a shared/array/table formula
			return null;
		}


		int row = firstCell.getRow();
		int column = firstCell.getCol();
		if (agg.getRow() != row || agg.getColumn() != column) {
			// not the first formula cell in the group
			return null;
		}
		SharedFormulaGroup[] groups = getGroups();
		for (int i = 0; i < groups.length; i++) {
			// note - logic for finding correct shared formula group is slightly
			// more complicated since the first cell
			SharedFormulaGroup sfg = groups[i];
			if (sfg.isFirstCell(row, column)) {
				return sfg.getSFR();
			}
		}

		// Since arrays and tables cannot be sparse (all cells in range participate)
		// The first cell will be the top left in the range.  So we can match the
		// ARRAY/TABLE record directly.

		for (int i = 0; i < _tableRecords.length; i++) {
			TableRecord tr = _tableRecords[i];
			if (tr.isFirstCell(row, column)) {
				return tr;
			}
		}
		for (int i = 0; i < _arrayRecords.length; i++) {
			ArrayRecord ar = _arrayRecords[i];
			if (ar.isFirstCell(row, column)) {
				return ar;
			}
		}
		return null;
	}

	/**
	 * Converts all {@link FormulaRecord}s handled by <tt>sharedFormulaRecord</tt>
	 * to plain unshared formulas
	 */
	public void unlink(SharedFormulaRecord sharedFormulaRecord) {
		SharedFormulaGroup svg = _groupsBySharedFormulaRecord.remove(sharedFormulaRecord);
		_groups = null; // be sure to reset cached value
		if (svg == null) {
			throw new IllegalStateException("Failed to find formulas for shared formula");
		}
		svg.unlinkSharedFormulas();
	}
}