poi/src/main/java/org/apache/poi/ss/formula/functions/Sumproduct.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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   distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.poi.ss.formula.functions;

import java.util.Arrays;

import org.apache.poi.ss.formula.TwoDEval;
import org.apache.poi.ss.formula.eval.AreaEval;
import org.apache.poi.ss.formula.eval.BlankEval;
import org.apache.poi.ss.formula.eval.ErrorEval;
import org.apache.poi.ss.formula.eval.EvaluationException;
import org.apache.poi.ss.formula.eval.NumberEval;
import org.apache.poi.ss.formula.eval.NumericValueEval;
import org.apache.poi.ss.formula.eval.RefEval;
import org.apache.poi.ss.formula.eval.StringEval;
import org.apache.poi.ss.formula.eval.ValueEval;


/**
 * Implementation for the Excel function SUMPRODUCT<p>
 *
 * Syntax : <br>
 *  SUMPRODUCT ( array1[, array2[, array3[, ...]]])
 *    <table border="0" cellpadding="1" cellspacing="0" summary="Parameter descriptions">
 *      <tr><th>array1, ... arrayN&nbsp;&nbsp;</th><td>typically area references,
 *      possibly cell references or scalar values</td></tr>
 *    </table><br>
 *
 * Let A<b>n</b><sub>(<b>i</b>,<b>j</b>)</sub> represent the element in the <b>i</b>th row <b>j</b>th column
 * of the <b>n</b>th array<br>
 * Assuming each array has the same dimensions (W, H), the result is defined as:<br>
 * SUMPRODUCT = &Sigma;<sub><b>i</b>: 1..H</sub> &nbsp;
 * 	(&nbsp; &Sigma;<sub><b>j</b>: 1..W</sub> &nbsp;
 * 	  (&nbsp; &Pi;<sub><b>n</b>: 1..N</sub>
 * 			A<b>n</b><sub>(<b>i</b>,<b>j</b>)</sub>&nbsp;
 *    )&nbsp;
 *  )
 */
public final class Sumproduct implements Function {


	public ValueEval evaluate(ValueEval[] args, int srcCellRow, int srcCellCol) {

		int maxN = args.length;

		if(maxN < 1) {
			return ErrorEval.VALUE_INVALID;
		}
		ValueEval firstArg = args[0];
		try {
			if(firstArg instanceof NumericValueEval) {
				return evaluateSingleProduct(args);
			}
			if(firstArg instanceof RefEval) {
				return evaluateSingleProduct(args);
			}
			if (firstArg instanceof TwoDEval) {
				TwoDEval ae = (TwoDEval) firstArg;
				if(ae.isRow() && ae.isColumn()) {
					return evaluateSingleProduct(args);
				}
				return evaluateAreaSumProduct(args);
			}
		} catch (EvaluationException e) {
			return e.getErrorEval();
		}
		throw new RuntimeException("Invalid arg type for SUMPRODUCT: ("
				+ firstArg.getClass().getName() + ")");
	}

	private static ValueEval evaluateSingleProduct(ValueEval[] evalArgs) throws EvaluationException {
		int maxN = evalArgs.length;

		double term = 1D;
		for(int n=0; n<maxN; n++) {
			double val = getScalarValue(evalArgs[n]);
			term *= val;
		}
		return new NumberEval(term);
	}

	private static double getScalarValue(ValueEval arg) throws EvaluationException {

		ValueEval eval;
		if (arg instanceof RefEval) {
			RefEval re = (RefEval) arg;
			if (re.getNumberOfSheets() > 1) {
                throw new EvaluationException(ErrorEval.VALUE_INVALID);
			}
			eval = re.getInnerValueEval(re.getFirstSheetIndex());
		} else {
			eval = arg;
		}

		if (eval == null) {
			throw new RuntimeException("parameter may not be null");
		}
		if (eval instanceof AreaEval) {
			AreaEval ae = (AreaEval) eval;
			// an area ref can work as a scalar value if it is 1x1
			if(!ae.isColumn() || !ae.isRow()) {
				throw new EvaluationException(ErrorEval.VALUE_INVALID);
			}
			eval = ae.getRelativeValue(0, 0);
		}

		return getProductTerm(eval, true);
	}

	private static ValueEval evaluateAreaSumProduct(ValueEval[] evalArgs) throws EvaluationException {
		int maxN = evalArgs.length;
		TwoDEval[] args;
		try {
			args = Arrays.copyOf(evalArgs, maxN, TwoDEval[].class);
		} catch (ArrayStoreException e) {
			// one of the other args was not an AreaRef
			return ErrorEval.VALUE_INVALID;
		}


		TwoDEval firstArg = args[0];

		int height = firstArg.getHeight();
		int width = firstArg.getWidth(); // TODO - junit

		// first check dimensions
		if (!areasAllSameSize(args, height, width)) {
			// normally this results in #VALUE!,
			// but errors in individual cells take precedence
			for (int i = 1; i < args.length; i++) {
				throwFirstError(args[i]);
			}
			return ErrorEval.VALUE_INVALID;
		}

		double acc = 0;

		for (int rrIx=0; rrIx<height; rrIx++) {
			for (int rcIx=0; rcIx<width; rcIx++) {
				double term = 1D;
				for(int n=0; n<maxN; n++) {
					double val = getProductTerm(args[n].getValue(rrIx, rcIx), false);
					term *= val;
				}
				acc += term;
			}
		}

		return new NumberEval(acc);
	}

	private static void throwFirstError(TwoDEval areaEval) throws EvaluationException {
		int height = areaEval.getHeight();
		int width = areaEval.getWidth();
		for (int rrIx=0; rrIx<height; rrIx++) {
			for (int rcIx=0; rcIx<width; rcIx++) {
				ValueEval ve = areaEval.getValue(rrIx, rcIx);
				if (ve instanceof ErrorEval) {
					throw new EvaluationException((ErrorEval) ve);
				}
			}
		}
	}

	private static boolean areasAllSameSize(TwoDEval[] args, int height, int width) {
		for (int i = 0; i < args.length; i++) {
			TwoDEval areaEval = args[i];
			// check that height and width match
			if(areaEval.getHeight() != height) {
				return false;
			}
			if(areaEval.getWidth() != width) {
				return false;
			}
		}
		return true;
	}


	/**
	 * Determines a <code>double</code> value for the specified <code>ValueEval</code>.
	 * @param isScalarProduct <code>false</code> for SUMPRODUCTs over area refs.
	 * @throws EvaluationException if <code>ve</code> represents an error value.
	 * <p>
	 * Note - string values and empty cells are interpreted differently depending on
	 * <code>isScalarProduct</code>.  For scalar products, if any term is blank or a string, the
	 * error (#VALUE!) is raised.  For area (sum)products, if any term is blank or a string, the
	 * result is zero.
	 */
	private static double getProductTerm(ValueEval ve, boolean isScalarProduct) throws EvaluationException {

		if(ve instanceof BlankEval || ve == null) {
			// TODO - shouldn't BlankEval.INSTANCE be used always instead of null?
			// null seems to occur when the blank cell is part of an area ref (but not reliably)
			if(isScalarProduct) {
				throw new EvaluationException(ErrorEval.VALUE_INVALID);
			}
			return 0;
		}

		if(ve instanceof ErrorEval) {
			throw new EvaluationException((ErrorEval)ve);
		}
		if(ve instanceof StringEval) {
			if(isScalarProduct) {
				throw new EvaluationException(ErrorEval.VALUE_INVALID);
			}
			// Note for area SUMPRODUCTs, string values are interpreted as zero
			// even if they would parse as valid numeric values
			return 0;
		}
		if(ve instanceof NumericValueEval) {
			NumericValueEval nve = (NumericValueEval) ve;
			return nve.getNumberValue();
		}
		throw new RuntimeException("Unexpected value eval class ("
				+ ve.getClass().getName() + ")");
	}
}