/*
* Redberry: symbolic tensor computations.
*
* Copyright (c) 2010-2014:
* Stanislav Poslavsky <stvlpos@mail.ru>
* Bolotin Dmitriy <bolotin.dmitriy@gmail.com>
*
* This file is part of Redberry.
*
* Redberry is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Redberry 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Redberry. If not, see <http://www.gnu.org/licenses/>.
*/
package cc.redberry.core.parser;
import cc.redberry.core.indices.SimpleIndices;
/**
* Parser for simple tensors.
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
* @since 1.0
*/
public class ParserSimpleTensor implements TokenParser {
/**
* Singleton instance.
*/
public static final ParserSimpleTensor INSTANCE = new ParserSimpleTensor();
private ParserSimpleTensor() {
}
@Override
public ParseTokenSimpleTensor parseToken(String expression, Parser parser) {
expression = expression.replaceAll("\\{[\\s]*\\}", "");
int indicesBegin = expression.indexOf('_'), i = expression.indexOf('^');
if (indicesBegin < 0 && i >= 0)
indicesBegin = i;
if (indicesBegin >= 0 && i >= 0)
indicesBegin = Math.min(indicesBegin, i);
if (indicesBegin < 0)
indicesBegin = expression.length();
String name = expression.substring(0, indicesBegin);
if (name.isEmpty())
throw new ParserException("Simple tensor with empty name.");
SimpleIndices indices = ParserIndices.parseSimple(expression.substring(indicesBegin));
return new ParseTokenSimpleTensor(indices, name);
}
@Override
public int priority() {
return 0;
}
}