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- /* ====================================================================
- Licensed to the Apache Software Foundation (ASF) under one or more
- contributor license agreements. See the NOTICE file distributed with
- 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
- the License. You may obtain a copy of the License at
-
- http://www.apache.org/licenses/LICENSE-2.0
-
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
- ==================================================================== */
-
- package org.apache.poi.ss.formula.functions;
-
- import org.apache.poi.ss.formula.OperationEvaluationContext;
- 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.OperandResolver;
- import org.apache.poi.ss.formula.eval.ValueEval;
-
- /**
- * Implementation for Excel DELTA() function.<p>
- * <p>
- * <b>Syntax</b>:<br> <b>DELTA </b>(<b>number1</b>,<b>number2</b> )<br>
- * <p>
- * Tests whether two values are equal. Returns 1 if number1 = number2; returns 0 otherwise.
- * Use this function to filter a set of values. For example, by summing several DELTA functions
- * you calculate the count of equal pairs. This function is also known as the Kronecker Delta function.
- *
- * <ul>
- * <li>If number1 is nonnumeric, DELTA returns the #VALUE! error value.</li>
- * <li>If number2 is nonnumeric, DELTA returns the #VALUE! error value.</li>
- * </ul>
- *
- * @author cedric dot walter @ gmail dot com
- */
- public final class Delta extends Fixed2ArgFunction implements FreeRefFunction {
-
- public static final FreeRefFunction instance = new Delta();
-
- private static final NumberEval ONE = new NumberEval(1);
- private static final NumberEval ZERO = new NumberEval(0);
-
- public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg1, ValueEval arg2) {
- try {
- Double number1 = evaluateValue(arg1, srcRowIndex, srcColumnIndex);
- if (number1 == null) {
- return ErrorEval.VALUE_INVALID;
- }
- Double number2 = evaluateValue(arg2, srcRowIndex, srcColumnIndex);
- if (number2 == null) {
- return ErrorEval.VALUE_INVALID;
- }
-
- return (number1.compareTo(number2) == 0) ? ONE : ZERO;
- } catch (EvaluationException e) {
- return e.getErrorEval();
- }
- }
-
- public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
- if (args.length == 2) {
- return evaluate(ec.getRowIndex(), ec.getColumnIndex(), args[0], args[1]);
- }
-
- return ErrorEval.VALUE_INVALID;
- }
-
- private static Double evaluateValue(ValueEval arg, int srcRowIndex, int srcColumnIndex) throws EvaluationException {
- ValueEval veText = OperandResolver.getSingleValue(arg, srcRowIndex, srcColumnIndex);
- String strText1 = OperandResolver.coerceValueToString(veText);
- return OperandResolver.parseDouble(strText1);
- }
- }
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