/*******************************************************************************
* Copyright 2011 Google Inc. All Rights Reserved.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
* 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 uk.ac.cranfield.thesis.server.service;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import uk.ac.cranfield.thesis.client.service.ParserService;
import uk.ac.cranfield.thesis.shared.Equation;
import uk.ac.cranfield.thesis.shared.exception.IncorrectODEEquationException;
import com.google.gwt.regexp.shared.RegExp;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
@SuppressWarnings("serial")
public class ParserServiceImpl extends RemoteServiceServlet implements ParserService
{
@Override
public Equation parseEquation(String input) throws IncorrectODEEquationException
{
input = input.replace(" ", "");
String[] parts = input.split(",");
Equation equation = new Equation(parts[0]);
equation.setOrder(longestRun(parts[0], '\'', 1));
if (equation.getOrder() < parts.length - 1)
throw new IncorrectODEEquationException("lack of initial values");
List<String> init = new ArrayList<String>(parts.length - 1);
for (int i = 1; i < parts.length; i++)
init.add(parts[i]);
equation.setInitValues(parseInitialValues(init));
equation.setFunctionVariable(parseFunctionVariable(parts[0]));
equation.setIndependentVariable(parseIndependentVariable(parts[0], equation.getFunctionVariable()));
return equation;
}
private char parseFunctionVariable(String input) throws IncorrectODEEquationException
{
char result = 0;
for (char ch = 'a'; ch <= 'z'; ch++)
{
Pattern p = Pattern.compile(ch + " *'+");
Matcher m = p.matcher(input);
if (m.find())
{
if (result == 0)
result = ch;
else
throw new IncorrectODEEquationException(input);
}
}
return result;
}
private int longestRun(String s, char ch, int n)
{
int nm = n - 1;
if (RegExp.compile("(" + ch + "){" + n + ",}").test(s))
{
nm = longestRun(s, ch, n + 1);
}
return nm;
}
private char parseIndependentVariable(String input, char functionalVariable) throws IncorrectODEEquationException
{
char result = 0;
for (char ch = 'a'; ch <= 'z'; ch++)
{
Pattern p = Pattern.compile("^[^" + ch + "]*" + ch + "[^" + ch + "]*$");
Matcher m = p.matcher(input);
if (m.find() && ch != functionalVariable)
{
if (result == 0)
result = ch;
else
throw new IncorrectODEEquationException(input);
}
}
return result;
}
private List<Double> parseInitialValues(List<String> data) throws IncorrectODEEquationException
{
List<Double> result = new ArrayList<Double>(data.size());
for (int i = 0; i < data.size(); i++)
result.add(0.0);
for (String s : data)
{
String[] values = s.split("=");
if (values.length < 2)
throw new IncorrectODEEquationException("Wrong input of initial values");
int i = longestRun(values[0], '\'', 1);
result.set(i, Double.valueOf(values[1]));
}
return result;
}
}