yearfrac.java

来自「EXCEL read and write」· Java 代码 · 共 161 行

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   this work for additional information regarding copyright ownership.
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package org.apache.poi.hssf.record.formula.atp;

import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.regex.Pattern;

import org.apache.poi.hssf.record.formula.eval.ErrorEval;
import org.apache.poi.hssf.record.formula.eval.Eval;
import org.apache.poi.hssf.record.formula.eval.EvaluationException;
import org.apache.poi.hssf.record.formula.eval.NumberEval;
import org.apache.poi.hssf.record.formula.eval.OperandResolver;
import org.apache.poi.hssf.record.formula.eval.StringEval;
import org.apache.poi.hssf.record.formula.eval.ValueEval;
import org.apache.poi.hssf.record.formula.functions.FreeRefFunction;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.ss.formula.EvaluationWorkbook;
/**
 * Implementation of Excel 'Analysis ToolPak' function YEARFRAC()<br/>
 * 
 * Returns the fraction of the year spanned by two dates.<p/>
 * 
 * <b>Syntax</b><br/>
 * <b>YEARFRAC</b>(<b>startDate</b>, <b>endDate</b>, basis)<p/>
 * 
 * The <b>basis</b> optionally specifies the behaviour of YEARFRAC as follows:
 * 
 * <table border="0" cellpadding="1" cellspacing="0" summary="basis parameter description">
 *   <tr><th>Value</th><th>Days per Month</th><th>Days per Year</th></tr>
 *   <tr align='center'><td>0 (default)</td><td>30</td><td>360</td></tr>
 *   <tr align='center'><td>1</td><td>actual</td><td>actual</td></tr>
 *   <tr align='center'><td>2</td><td>actual</td><td>360</td></tr>
 *   <tr align='center'><td>3</td><td>actual</td><td>365</td></tr>
 *   <tr align='center'><td>4</td><td>30</td><td>360</td></tr>
 * </table>
 * 
 */
final class YearFrac implements FreeRefFunction {

	public static final FreeRefFunction instance = new YearFrac();
	
	private YearFrac() {
		// enforce singleton
	}

	public ValueEval evaluate(Eval[] args, EvaluationWorkbook workbook, int srcCellSheet, int srcCellRow,
			int srcCellCol) {

		double result;
		try {
			int basis = 0; // default
			switch(args.length) {
				case 3:
					basis = evaluateIntArg(args[2], srcCellRow, srcCellCol);
				case 2:
					break;
				default:
					return ErrorEval.VALUE_INVALID;  
			}
			double startDateVal = evaluateDateArg(args[0], srcCellRow, srcCellCol);
			double endDateVal = evaluateDateArg(args[1], srcCellRow, srcCellCol);
			result = YearFracCalculator.calculate(startDateVal, endDateVal, basis);
		} catch (EvaluationException e) {
			return e.getErrorEval();
		}
		
		return new NumberEval(result);
	}

	private static double evaluateDateArg(Eval arg, int srcCellRow, int srcCellCol) throws EvaluationException {
		ValueEval ve = OperandResolver.getSingleValue(arg, srcCellRow, (short) srcCellCol);

		if (ve instanceof StringEval) {
			String strVal = ((StringEval) ve).getStringValue();
			Double dVal = OperandResolver.parseDouble(strVal);
			if (dVal != null) {
				return dVal.doubleValue();
			}
			Calendar date = parseDate(strVal);
			return HSSFDateUtil.getExcelDate(date, false);
		}
		return OperandResolver.coerceValueToDouble(ve);
	}

	private static Calendar parseDate(String strVal) throws EvaluationException {
		String[] parts = Pattern.compile("/").split(strVal);
		if (parts.length != 3) {
			throw new EvaluationException(ErrorEval.VALUE_INVALID);
		}
		String part2 = parts[2];
		int spacePos = part2.indexOf(' ');
		if (spacePos > 0) {
			// drop time portion if present
			part2 = part2.substring(0, spacePos);
		}
		int f0;
		int f1;
		int f2;
		try {
			f0 = Integer.parseInt(parts[0]);
			f1 = Integer.parseInt(parts[1]);
			f2 = Integer.parseInt(part2);
		} catch (NumberFormatException e) {
			throw new EvaluationException(ErrorEval.VALUE_INVALID);
		}
		if (f0<0 || f1<0 || f2<0 || (f0>12 && f1>12 && f2>12)) {
			// easy to see this cannot be a valid date
			throw new EvaluationException(ErrorEval.VALUE_INVALID);
		}
		
		if (f0 >= 1900 && f0 < 9999) {
			// when 4 digit value appears first, the format is YYYY/MM/DD, regardless of OS settings
			return makeDate(f0, f1, f2);
		}
		// otherwise the format seems to depend on OS settings (default date format)
		if (false) {
			// MM/DD/YYYY is probably a good guess, if the in the US
			return makeDate(f2, f0, f1);
		}
		// TODO - find a way to choose the correct date format
		throw new RuntimeException("Unable to determine date format for text '" + strVal + "'");
	}

	/**
	 * @param month 1-based
	 */
	private static Calendar makeDate(int year, int month, int day) throws EvaluationException {
		if (month < 1 || month > 12) {
			throw new EvaluationException(ErrorEval.VALUE_INVALID);
		}
		Calendar cal = new GregorianCalendar(year, month-1, 1, 0, 0, 0);
		cal.set(Calendar.MILLISECOND, 0);
		if (day <1 || day>cal.getActualMaximum(Calendar.DAY_OF_MONTH)) {
			throw new EvaluationException(ErrorEval.VALUE_INVALID);
		}
		cal.set(Calendar.DAY_OF_MONTH, day);
		return cal;
	}

	private static int evaluateIntArg(Eval arg, int srcCellRow, int srcCellCol) throws EvaluationException {
		ValueEval ve = OperandResolver.getSingleValue(arg, srcCellRow, (short) srcCellCol);
		return OperandResolver.coerceValueToInt(ve);
	}
}