/**
* 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.text;
import java.util.concurrent.Callable;
import com.rapidminer.tools.Ontology;
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.Function;
import com.rapidminer.tools.expression.FunctionInputException;
import com.rapidminer.tools.expression.internal.SimpleExpressionEvaluator;
import com.rapidminer.tools.expression.internal.function.AbstractFunction;
/**
* A {@link Function} to cut a nominal value.
*
* @author Thilo Kamradt
*
*/
public class Cut extends AbstractFunction {
/**
* Creates a function to cut a nominal value.
*/
public Cut() {
super("text_transformation.cut", 3, Ontology.NOMINAL);
}
@Override
public ExpressionEvaluator compute(ExpressionEvaluator... inputEvaluators) {
if (inputEvaluators.length != 3) {
throw new FunctionInputException("expression_parser.function_wrong_input", getFunctionName(), 3,
inputEvaluators.length);
}
ExpressionType type = getResultType(inputEvaluators);
ExpressionEvaluator text = inputEvaluators[0];
ExpressionEvaluator startIndex = inputEvaluators[1];
ExpressionEvaluator length = inputEvaluators[2];
return new SimpleExpressionEvaluator(makeStringCallable(text, startIndex, length), type,
isResultConstant(inputEvaluators));
}
/**
* Builds a DoubleCallable from left and right using {@link #compute(String, String)}, where
* constant child results are evaluated.
*
* @param left
* the left input
* @param right
* the right input
* @return the resulting DoubleCallable
*/
protected Callable<String> makeStringCallable(ExpressionEvaluator text, ExpressionEvaluator startIndex,
ExpressionEvaluator length) {
final Callable<String> funcText = text.getStringFunction();
final DoubleCallable funcIndex = startIndex.getDoubleFunction();
final DoubleCallable funcLength = length.getDoubleFunction();
try {
final String valueText = text.isConstant() ? funcText.call() : "";
final double valueIndex = startIndex.isConstant() ? funcIndex.call() : Double.NaN;
final double valueLength = length.isConstant() ? funcLength.call() : Double.NaN;
// all three expressions are const
if (text.isConstant() && startIndex.isConstant() && length.isConstant()) {
final String result = compute(valueText, valueIndex, valueLength);
return new Callable<String>() {
@Override
public String call() throws Exception {
return result;
}
};
// two const expressions
} else if (!text.isConstant() && startIndex.isConstant() && length.isConstant()) {
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(funcText.call(), valueIndex, valueLength);
}
};
} else if (text.isConstant() && !startIndex.isConstant() && length.isConstant()) {
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(valueText, funcIndex.call(), valueLength);
}
};
} else if (text.isConstant() && startIndex.isConstant() && !length.isConstant()) {
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(valueText, valueIndex, funcLength.call());
}
};
// only one expression is const
} else if (text.isConstant() && !startIndex.isConstant() && !length.isConstant()) {
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(valueText, funcIndex.call(), funcLength.call());
}
};
} else if (!text.isConstant() && startIndex.isConstant() && !length.isConstant()) {
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(funcText.call(), valueIndex, funcLength.call());
}
};
} else if (!text.isConstant() && !startIndex.isConstant() && length.isConstant()) {
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(funcText.call(), funcIndex.call(), valueLength);
}
};
} else {
// no expression is const
return new Callable<String>() {
@Override
public String call() throws Exception {
return compute(funcText.call(), funcIndex.call(), funcLength.call());
}
};
}
} catch (ExpressionParsingException e) {
throw e;
} catch (Exception e) {
throw new ExpressionParsingException(e);
}
}
/**
* Computes the result.
*
* @param text
* @param index
* @param length
* @return the result of the computation.
*/
protected String compute(String text, double index, double length) {
if (Double.isNaN(index)) {
// this must be changed for compatibility with the old parser
index = 0;
}
if (Double.isNaN(length)) {
// this must be changed for compatibility with the old parser
length = 0;
}
if (text == null) {
return null;
} else if (index < 0 || length < 0) {
throw new FunctionInputException("expression_parser.function_non_negative", getFunctionName());
} else if (index + length > text.length()) {
throw new FunctionInputException("expression_parser.parameter_value_too_big", "start", "length",
getFunctionName(), text);
}
return text.substring((int) index, (int) index + (int) length);
}
@Override
protected ExpressionType computeType(ExpressionType... inputTypes) {
if (inputTypes[0] == ExpressionType.STRING
&& (inputTypes[1] == ExpressionType.INTEGER || inputTypes[1] == ExpressionType.DOUBLE)
&& (inputTypes[2] == ExpressionType.INTEGER || inputTypes[2] == ExpressionType.DOUBLE)) {
return ExpressionType.STRING;
} else {
throw new FunctionInputException("expression_parser.function_wrong_type", getFunctionName(),
"(nominal,integer,integer)");
}
}
}