/*
* Redberry: symbolic tensor computations.
*
* Copyright (c) 2010-2012:
* 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.EmptyIndices;
import cc.redberry.core.indices.IndicesFactory;
import cc.redberry.core.indices.SimpleIndicesImpl;
import cc.redberry.core.indices.SimpleIndices;
import cc.redberry.core.tensor.SimpleTensor;
import cc.redberry.core.utils.IntArrayList;
/**
* This class performs main SimpleTensor parse algorithm. Constructor getting
* string expression and builds tensor name and tensor indices, which are ordered.
*
* @see SimpleIndicesImpl
* @see SimpleTensor
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
*/
public class ParserSimpleTensorStructure {
protected final String name;
protected final SimpleIndices indices;
protected boolean contentsDigits = false;
/**
* Constructs SimpleTensor name and indices.
*
* @param expression string as "T_{\alpha ab}^{\beta} etc."
*/
public ParserSimpleTensorStructure(String expression) {
IntArrayList indicesList = new IntArrayList();
boolean indexMode = false;
int indexState = 0;
StringBuilder nameBuilder = new StringBuilder();
StringBuilder indicesString = null;
int level = 0;
for (char c : expression.toCharArray()) {
if (c == '{') {
level++;
continue;
}
if (c == '}') {
level--;
continue;
}
if (c == '^') {
assert level == 0;
if (indexMode)
ParserIndices.parseIndices(indicesList, indicesString, indexState);
indexMode = true;
indexState = 1;
indicesString = new StringBuilder();
continue;
}
if (c == '_' && level == 0) {
if (indexMode)
ParserIndices.parseIndices(indicesList, indicesString, indexState);
indexMode = true;
indexState = 0;
indicesString = new StringBuilder();
continue;
}
if (!indexMode)
nameBuilder.append(c);
else
indicesString.append(c);
}
if (level != 0)
throw new BracketsError();
if (indexMode)
ParserIndices.parseIndices(indicesList, indicesString, indexState);
if (indicesList.size() == 0)
indices = EmptyIndices.INSTANCE;
else
indices = IndicesFactory.createSimple(indicesList.toArray());
name = nameBuilder.toString();
}
/**
*
* @return indices of SimpleTensor
*/
public SimpleIndices getIndices() {
return indices;
}
/**
*
* @return name of SimpleTensor
*/
public String getName() {
return name;
}
}