poi/poi/src/main/java/org/apache/poi/ss/formula/functions/Subtotal.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 static org.apache.poi.ss.formula.functions.AggregateFunction.subtotalInstance;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import org.apache.poi.ss.formula.LazyRefEval;
import org.apache.poi.ss.formula.eval.ErrorEval;
import org.apache.poi.ss.formula.eval.EvaluationException;
import org.apache.poi.ss.formula.eval.NotImplementedFunctionException;
import org.apache.poi.ss.formula.eval.OperandResolver;
import org.apache.poi.ss.formula.eval.ValueEval;

/**
 * Implementation for the Excel function SUBTOTAL<p>
 *
 * <b>Syntax :</b> <br>
 *  SUBTOTAL ( <b>functionCode</b>, <b>ref1</b>, ref2 ... ) <br>
 *    <table>
 *      <caption>Parameter descriptions</caption>
 *      <tr><td><b>functionCode</b></td><td>(1-11) Selects the underlying aggregate function to be used (see table below)</td></tr>
 *      <tr><td><b>ref1</b>, ref2 ...</td><td>Arguments to be passed to the underlying aggregate function</td></tr>
 *    </table><br>
 *
 *  <table>
 *      <caption>Parameter descriptions</caption>
 *      <tr><th>functionCode</th><th>Aggregate Function</th></tr>
 *      <tr><td>1</td><td>AVERAGE</td></tr>
 *      <tr><td>2</td><td>COUNT</td></tr>
 *      <tr><td>3</td><td>COUNTA</td></tr>
 *      <tr><td>4</td><td>MAX</td></tr>
 *      <tr><td>5</td><td>MIN</td></tr>
 *      <tr><td>6</td><td>PRODUCT</td></tr>
 *      <tr><td>7</td><td>STDEV</td></tr>
 *      <tr><td>8</td><td>STDEVP *</td></tr>
 *      <tr><td>9</td><td>SUM</td></tr>
 *      <tr><td>10</td><td>VAR *</td></tr>
 *      <tr><td>11</td><td>VARP *</td></tr>
 *      <tr><td>101</td><td>AVERAGE</td></tr>
 *      <tr><td>102</td><td>COUNT</td></tr>
 *      <tr><td>103</td><td>COUNTA</td></tr>
 *      <tr><td>104</td><td>MAX</td></tr>
 *      <tr><td>105</td><td>MIN</td></tr>
 *      <tr><td>106</td><td>PRODUCT</td></tr>
 *      <tr><td>107</td><td>STDEV</td></tr>
 *      <tr><td>108</td><td>STDEVP *</td></tr>
 *      <tr><td>109</td><td>SUM</td></tr>
 *      <tr><td>110</td><td>VAR *</td></tr>
 *      <tr><td>111</td><td>VARP *</td></tr>
 *  </table><br>
 * * Not implemented in POI yet. Functions 101-111 are the same as functions 1-11 but with
 * the option 'ignore hidden values'.
 */
public class Subtotal implements Function {

	private static Function findFunction(int functionCode) throws EvaluationException {
        switch (functionCode) {
			case 1: return subtotalInstance(AggregateFunction.AVERAGE, true);
			case 2: return Count.subtotalInstance(true);
			case 3: return Counta.subtotalInstance(true);
			case 4: return subtotalInstance(AggregateFunction.MAX, true);
			case 5: return subtotalInstance(AggregateFunction.MIN, true);
			case 6: return subtotalInstance(AggregateFunction.PRODUCT, true);
			case 7: return subtotalInstance(AggregateFunction.STDEV, true);
			case 8: throw new NotImplementedFunctionException("STDEVP");
			case 9: return subtotalInstance(AggregateFunction.SUM, true);
			case 10: throw new NotImplementedFunctionException("VAR");
			case 11: throw new NotImplementedFunctionException("VARP");
			case 101: return subtotalInstance(AggregateFunction.AVERAGE, false);
			case 102: return Count.subtotalInstance(false);
			case 103: return Counta.subtotalInstance(false);
			case 104: return subtotalInstance(AggregateFunction.MAX, false);
			case 105: return subtotalInstance(AggregateFunction.MIN, false);
			case 106: return subtotalInstance(AggregateFunction.PRODUCT, false);
			case 107: return subtotalInstance(AggregateFunction.STDEV, false);
			case 108: throw new NotImplementedFunctionException("STDEVP SUBTOTAL with 'exclude hidden values' option");
			case 109: return subtotalInstance(AggregateFunction.SUM, false);
			case 110: throw new NotImplementedFunctionException("VAR SUBTOTAL with 'exclude hidden values' option");
			case 111: throw new NotImplementedFunctionException("VARP SUBTOTAL with 'exclude hidden values' option");
		}
		throw EvaluationException.invalidValue();
	}

	@Override
	public ValueEval evaluate(ValueEval[] args, int srcRowIndex, int srcColumnIndex) {
		int nInnerArgs = args.length-1; // -1: first arg is used to select from a basic aggregate function
		if (nInnerArgs < 1) {
			return ErrorEval.VALUE_INVALID;
		}

		final Function innerFunc;
		int functionCode;
		try {
			ValueEval ve = OperandResolver.getSingleValue(args[0], srcRowIndex, srcColumnIndex);
            functionCode = OperandResolver.coerceValueToInt(ve);
			innerFunc = findFunction(functionCode);
		} catch (EvaluationException e) {
			return e.getErrorEval();
		}

		// ignore the first arg, this is the function-type, we check for the length above
		final List<ValueEval> list = new ArrayList<>(Arrays.asList(args).subList(1, args.length));

		Iterator<ValueEval> it = list.iterator();

		// See https://support.office.com/en-us/article/SUBTOTAL-function-7b027003-f060-4ade-9040-e478765b9939
		// "If there are other subtotals within ref1, ref2,... (or nested subtotals), these nested subtotals are ignored to avoid double counting."
		// For array references it is handled in other evaluation steps, but we need to handle this here for references to subtotal-functions
		while(it.hasNext()) {
			ValueEval eval = it.next();
			if(eval instanceof LazyRefEval) {
				LazyRefEval lazyRefEval = (LazyRefEval) eval;
				if(lazyRefEval.isSubTotal()) {
					it.remove();
				}
				if (functionCode > 100 && lazyRefEval.isRowHidden()) {
				    it.remove();
				}
			}
		}

		return innerFunc.evaluate(list.toArray(new ValueEval[0]), srcRowIndex, srcColumnIndex);
	}
}