poi/src/testcases/org/apache/poi/hssf/record/formula/eval/TestExternalFunction.java

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package org.apache.poi.hssf.record.formula.eval;

import java.io.IOException;

import junit.framework.TestCase;

import org.apache.poi.hssf.HSSFTestDataSamples;
import org.apache.poi.hssf.record.formula.functions.FreeRefFunction;
import org.apache.poi.hssf.record.formula.toolpack.DefaultToolPack;
import org.apache.poi.hssf.record.formula.toolpack.MainToolPacksHandler;
import org.apache.poi.hssf.record.formula.toolpack.ToolPack;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFFormulaEvaluator;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.formula.OperationEvaluationContext;
import org.apache.poi.ss.usermodel.Workbook;

/**
 * 
 * @author Josh Micich
 * 
 * Modified 09/14/09 by Petr Udalau - Test of registering UDFs in workbook and
 * using ToolPacks.
 */
public final class TestExternalFunction extends TestCase {

    private static class MyFunc implements FreeRefFunction {
        public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
            if (args.length != 1 || !(args[0] instanceof StringEval)) {
                return ErrorEval.VALUE_INVALID;
            } else {
                StringEval input = (StringEval) args[0];
                return new StringEval(input.getStringValue() + "abc");
            }
        }
    }

    private static class MyFunc2 implements FreeRefFunction {
        public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
            if (args.length != 1 || !(args[0] instanceof StringEval)) {
                return ErrorEval.VALUE_INVALID;
            } else {
                StringEval input = (StringEval) args[0];
                return new StringEval(input.getStringValue() + "abc2");
            }
        }
    }

    /**
     * Creates and registers user-defined function "MyFunc()" directly with POI.
     * This is VB function defined in "testNames.xls". In future there must be
     * some parser of VBA scripts which will register UDFs.
     */
    private void registerMyFunc(Workbook workbook) {
        workbook.registerUserDefinedFunction("myFunc", new MyFunc());
    }

    /**
     * Creates example ToolPack which contains function "MyFunc2()".
     */
    private void createExampleToolPack() {
        ToolPack exampleToolPack = new DefaultToolPack();
        exampleToolPack.addFunction("myFunc2", new MyFunc2());
        MainToolPacksHandler.instance().addToolPack(exampleToolPack);
    }

    /**
     * Checks that an external function can get invoked from the formula
     * evaluator.
     * 
     * @throws IOException
     * 
     */
    public void testInvoke() {
        HSSFWorkbook wb = HSSFTestDataSamples.openSampleWorkbook("testNames.xls");
        HSSFSheet sheet = wb.getSheetAt(0);

        registerMyFunc(wb);
        createExampleToolPack();

        HSSFRow row = sheet.getRow(0);
        HSSFCell myFuncCell = row.getCell(1); //=myFunc("_")

        HSSFCell myFunc2Cell = row.getCell(2); //=myFunc2("_")

        HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
        try {
            assertEquals("_abc", fe.evaluate(myFuncCell).getStringValue());
            assertEquals("_abc2", fe.evaluate(myFunc2Cell).getStringValue());
        } catch (Exception e) {
            assertFalse(true);
        }
    }
}