poi/src/java/org/apache/poi/ss/formula/BaseFormulaEvaluator.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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package org.apache.poi.ss.formula;

import java.util.Map;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.CellValue;
import org.apache.poi.ss.usermodel.FormulaEvaluator;
import org.apache.poi.ss.usermodel.RichTextString;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;

/**
 * Common functionality across file formats for evaluating formula cells.<p/>
 */
public abstract class BaseFormulaEvaluator implements FormulaEvaluator, WorkbookEvaluatorProvider {
    protected final WorkbookEvaluator _bookEvaluator;

    protected BaseFormulaEvaluator(WorkbookEvaluator bookEvaluator) {
        this._bookEvaluator = bookEvaluator;
    }

    /**
     * Coordinates several formula evaluators together so that formulas that involve external
     * references can be evaluated.
     * @param workbookNames the simple file names used to identify the workbooks in formulas
     * with external links (for example "MyData.xls" as used in a formula "[MyData.xls]Sheet1!A1")
     * @param evaluators all evaluators for the full set of workbooks required by the formulas.
     */
    public static void setupEnvironment(String[] workbookNames, BaseFormulaEvaluator[] evaluators) {
        WorkbookEvaluator[] wbEvals = new WorkbookEvaluator[evaluators.length];
        for (int i = 0; i < wbEvals.length; i++) {
            wbEvals[i] = evaluators[i]._bookEvaluator;
        }
        CollaboratingWorkbooksEnvironment.setup(workbookNames, wbEvals);
    }

    @Override
    public void setupReferencedWorkbooks(Map<String, FormulaEvaluator> evaluators) {
        CollaboratingWorkbooksEnvironment.setupFormulaEvaluator(evaluators);
    }

    @Override
    public WorkbookEvaluator _getWorkbookEvaluator() {
        return _bookEvaluator;
    }

    /**
     * Should be called whenever there are major changes (e.g. moving sheets) to input cells
     * in the evaluated workbook.  If performance is not critical, a single call to this method
     * may be used instead of many specific calls to the notify~ methods.
     *
     * Failure to call this method after changing cell values will cause incorrect behaviour
     * of the evaluate~ methods of this class
     */
    @Override
    public void clearAllCachedResultValues() {
        _bookEvaluator.clearAllCachedResultValues();
    }

    /**
     * If cell contains a formula, the formula is evaluated and returned,
     * else the CellValue simply copies the appropriate cell value from
     * the cell and also its cell type. This method should be preferred over
     * evaluateInCell() when the call should not modify the contents of the
     * original cell.
     *
     * @param cell may be <code>null</code> signifying that the cell is not present (or blank)
     * @return <code>null</code> if the supplied cell is <code>null</code> or blank
     */
    @Override
    public CellValue evaluate(Cell cell) {
        if (cell == null) {
            return null;
        }

        switch (cell.getCellTypeEnum()) {
            case BOOLEAN:
                return CellValue.valueOf(cell.getBooleanCellValue());
            case ERROR:
                return CellValue.getError(cell.getErrorCellValue());
            case FORMULA:
                return evaluateFormulaCellValue(cell);
            case NUMERIC:
                return new CellValue(cell.getNumericCellValue());
            case STRING:
                return new CellValue(cell.getRichStringCellValue().getString());
            case BLANK:
                return null;
            default:
                throw new IllegalStateException("Bad cell type (" + cell.getCellTypeEnum() + ")");
        }
    }
    
    /**
     * If cell contains formula, it evaluates the formula, and
     *  puts the formula result back into the cell, in place
     *  of the old formula.
     * Else if cell does not contain formula, this method leaves
     *  the cell unchanged.
     * Note that the same instance of HSSFCell is returned to
     * allow chained calls like:
     * <pre>
     * int evaluatedCellType = evaluator.evaluateInCell(cell).getCellType();
     * </pre>
     * Be aware that your cell value will be changed to hold the
     *  result of the formula. If you simply want the formula
     *  value computed for you, use {@link #evaluateFormulaCellEnum(Cell)}}
     * @param cell
     * @return the {@code cell} that was passed in, allowing for chained calls
     */
    @Override
    public Cell evaluateInCell(Cell cell) {
        if (cell == null) {
            return null;
        }
        Cell result = cell;
        if (cell.getCellTypeEnum() == CellType.FORMULA) {
            CellValue cv = evaluateFormulaCellValue(cell);
            setCellValue(cell, cv);
            setCellType(cell, cv); // cell will no longer be a formula cell
        }
        return result;
    }

    protected abstract CellValue evaluateFormulaCellValue(Cell cell);

    /**
     * If cell contains formula, it evaluates the formula, and saves the result of the formula. The
     * cell remains as a formula cell. If the cell does not contain formula, this method returns -1
     * and leaves the cell unchanged.
     *
     * Note that the type of the <em>formula result</em> is returned, so you know what kind of
     * cached formula result is also stored with  the formula.
     * <pre>
     * int evaluatedCellType = evaluator.evaluateFormulaCell(cell);
     * </pre>
     * Be aware that your cell will hold both the formula, and the result. If you want the cell
     * replaced with the result of the formula, use {@link #evaluateInCell(org.apache.poi.ss.usermodel.Cell)}
     * @param cell The cell to evaluate
     * @return -1 for non-formula cells, or the type of the <em>formula result</em>
     * @deprecated 3.15. Will return a {@link CellType} enum in the future.
     */
    @Override
    public int evaluateFormulaCell(Cell cell) {
        return evaluateFormulaCellEnum(cell).getCode();
    }
    
    /**
     * If cell contains formula, it evaluates the formula,
     *  and saves the result of the formula. The cell
     *  remains as a formula cell.
     * Else if cell does not contain formula, this method leaves
     *  the cell unchanged.
     * Note that the type of the formula result is returned,
     *  so you know what kind of value is also stored with
     *  the formula.
     * <pre>
     * CellType evaluatedCellType = evaluator.evaluateFormulaCellEnum(cell);
     * </pre>
     * Be aware that your cell will hold both the formula,
     *  and the result. If you want the cell replaced with
     *  the result of the formula, use {@link #evaluate(org.apache.poi.ss.usermodel.Cell)} }
     * @param cell The cell to evaluate
     * @return The type of the formula result (the cell's type remains as CellType.FORMULA however)
     *         If cell is not a formula cell, returns {@link CellType#_NONE} rather than throwing an exception.
     * @since POI 3.15 beta 3
     * @deprecated POI 3.15 beta 3. Will be deleted when we make the CellType enum transition. See bug 59791.
     */
    @Override
    public CellType evaluateFormulaCellEnum(Cell cell) {
        if (cell == null || cell.getCellTypeEnum() != CellType.FORMULA) {
            return CellType._NONE;
        }
        CellValue cv = evaluateFormulaCellValue(cell);
        // cell remains a formula cell, but the cached value is changed
        setCellValue(cell, cv);
        return cv.getCellTypeEnum();
    }

    protected static void setCellType(Cell cell, CellValue cv) {
        CellType cellType = cv.getCellTypeEnum();
        switch (cellType) {
            case BOOLEAN:
            case ERROR:
            case NUMERIC:
            case STRING:
                cell.setCellType(cellType);
                return;
            case BLANK:
                // never happens - blanks eventually get translated to zero
                throw new IllegalArgumentException("This should never happen. Blanks eventually get translated to zero.");
            case FORMULA:
                // this will never happen, we have already evaluated the formula
                throw new IllegalArgumentException("This should never happen. Formulas should have already been evaluated.");
            default:
                throw new IllegalStateException("Unexpected cell value type (" + cellType + ")");
        }
    }
    
    protected abstract RichTextString createRichTextString(String str);
    
    protected void setCellValue(Cell cell, CellValue cv) {
        CellType cellType = cv.getCellTypeEnum();
        switch (cellType) {
            case BOOLEAN:
                cell.setCellValue(cv.getBooleanValue());
                break;
            case ERROR:
                cell.setCellErrorValue(cv.getErrorValue());
                break;
            case NUMERIC:
                cell.setCellValue(cv.getNumberValue());
                break;
            case STRING:
                cell.setCellValue(createRichTextString(cv.getStringValue()));
                break;
            case BLANK:
                // never happens - blanks eventually get translated to zero
            case FORMULA:
                // this will never happen, we have already evaluated the formula
            default:
                throw new IllegalStateException("Unexpected cell value type (" + cellType + ")");
        }
    }
    

    /**
     * Loops over all cells in all sheets of the supplied
     *  workbook.
     * For cells that contain formulas, their formulas are
     *  evaluated, and the results are saved. These cells
     *  remain as formula cells.
     * For cells that do not contain formulas, no changes
     *  are made.
     * This is a helpful wrapper around looping over all
     *  cells, and calling evaluateFormulaCell on each one.
     */
    public static void evaluateAllFormulaCells(Workbook wb) {
        FormulaEvaluator evaluator = wb.getCreationHelper().createFormulaEvaluator();
        evaluateAllFormulaCells(wb, evaluator);
    }
    protected static void evaluateAllFormulaCells(Workbook wb, FormulaEvaluator evaluator) {
        for(int i=0; i<wb.getNumberOfSheets(); i++) {
            Sheet sheet = wb.getSheetAt(i);

            for(Row r : sheet) {
                for (Cell c : r) {
                    if (c.getCellTypeEnum() == CellType.FORMULA) {
                        evaluator.evaluateFormulaCellEnum(c);
                    }
                }
            }
        }
    }

    /** {@inheritDoc} */
    @Override
    public void setIgnoreMissingWorkbooks(boolean ignore){
        _bookEvaluator.setIgnoreMissingWorkbooks(ignore);
    }

    /** {@inheritDoc} */
    @Override
    public void setDebugEvaluationOutputForNextEval(boolean value){
        _bookEvaluator.setDebugEvaluationOutputForNextEval(value);
    }
}