/**
* Copyright (C) 2001-2017 by RapidMiner and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapidminer.com
*
* This program is free software: you can redistribute it and/or modify it under the terms of the
* GNU Affero General Public License as published by the Free Software Foundation, either version 3
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
* even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License along with this program.
* If not, see http://www.gnu.org/licenses/.
*/
package com.rapidminer.tools.expression.internal.function.conversion;
import java.util.concurrent.Callable;
import com.rapidminer.tools.Ontology;
import com.rapidminer.tools.Tools;
import com.rapidminer.tools.expression.DoubleCallable;
import com.rapidminer.tools.expression.ExpressionEvaluator;
import com.rapidminer.tools.expression.ExpressionParsingException;
import com.rapidminer.tools.expression.ExpressionType;
import com.rapidminer.tools.expression.FunctionDescription;
import com.rapidminer.tools.expression.FunctionInputException;
import com.rapidminer.tools.expression.internal.SimpleExpressionEvaluator;
import com.rapidminer.tools.expression.internal.function.AbstractFunction;
/**
*
* A {@link Function} parsing a number to a string.
*
* @author Marcel Seifert
*
*/
public class NumericalToString extends AbstractFunction {
/**
* Constructs an AbstractFunction with {@link FunctionDescription} generated from the arguments
* and the function name generated from the description.
*/
public NumericalToString() {
super("conversion.str", 1, Ontology.NOMINAL);
}
@Override
public ExpressionEvaluator compute(ExpressionEvaluator... inputEvaluators) {
if (inputEvaluators.length != 1) {
throw new FunctionInputException("expression_parser.function_wrong_input", getFunctionName(), 1,
inputEvaluators.length);
}
ExpressionType type = getResultType(inputEvaluators);
ExpressionEvaluator input = inputEvaluators[0];
return new SimpleExpressionEvaluator(makeStringCallable(input), type, isResultConstant(inputEvaluators));
}
/**
* Builds a String Callable from a double input argument
*
* @param inputEvaluator
* the input
* @return the resulting callable<String>
*/
protected Callable<String> makeStringCallable(final ExpressionEvaluator inputEvaluator) {
final DoubleCallable func = inputEvaluator.getDoubleFunction();
try {
if (inputEvaluator.isConstant()) {
final String result = compute(func.call());
return new Callable<String>() {
@Override
public String call() throws Exception {
return result;
}
};
} else {
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(func.call());
}
};
}
} catch (ExpressionParsingException e) {
throw e;
} catch (Exception e) {
throw new ExpressionParsingException(e);
}
}
/**
* Computes the result for one input double value.
*
* @param value
* the double value to parse
*
* @return the result of the computation.
*/
protected String compute(double value) {
if (Double.isNaN(value)) {
return null;
}
return Tools.formatIntegerIfPossible(value);
}
@Override
protected ExpressionType computeType(ExpressionType... inputTypes) {
ExpressionType input = inputTypes[0];
if (input == ExpressionType.INTEGER || input == ExpressionType.DOUBLE) {
return ExpressionType.STRING;
} else {
throw new FunctionInputException("expression_parser.function_wrong_type", getFunctionName(), "numerical");
}
}
}