/*
* 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.Indices;
import cc.redberry.core.indices.SimpleIndices;
import cc.redberry.core.number.Complex;
import java.util.ArrayList;
import java.util.List;
/**
* Parser for tensor fields.
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
* @since 1.0
*/
public class ParserTensorField implements TokenParser {
/**
* Singleton instance.
*/
public static final ParserTensorField INSTANCE = new ParserTensorField();
private ParserTensorField() {
}
@Override
public int priority() {
return 7000;
}
public boolean canParse(String expression) {
char[] expressionChars = expression.toCharArray();
int level = 0;
boolean inBrackets = false;
for (char c : expressionChars) {
if ((c == '+' || c == '*' || c == '-' || c == '/') && !inBrackets)
return false;
if (c == '[') {
inBrackets = true;
level++;
}
if (c == ']')
level--;
if (level == 0)
inBrackets = false;
if (level < 0)
throw new BracketsError(expression);
}
return true;
}
@Override
public ParseToken parseToken(String expression, Parser parser) {
if (!expression.contains("["))
return null;
if (!canParse(expression))
return null;
String tensorPart = expression.substring(0, expression.indexOf('['));
ParseTokenSimpleTensor simpleTensorNode = ParserSimpleTensor.INSTANCE.parseToken(tensorPart, parser);
String argString = expression.substring(expression.indexOf("[") + 1, expression.length() - 1);
List<ParseToken> arguments = new ArrayList<>();
List<Indices> indices = new ArrayList<>();
int beginIndex = 0, level = 0;
char[] argsChars = argString.toCharArray();
ParseToken a;
SimpleIndices aIndices;
for (int i = 0; i < argsChars.length; ++i) {
char c = argsChars[i];
if ((c == ',' && level == 0) || i == argsChars.length - 1) {
String argument = argString.substring(beginIndex, i == argsChars.length - 1 ? i + 1 : i);
String[] split = argument.split(":");
if (split.length == 1) {
a = parser.parse(argument);
aIndices = null;
} else {
if (split.length != 2)
throw new ParserException(expression);
a = parser.parse(split[0]);
aIndices = ParserIndices.parseSimple(split[1]);
}
arguments.add(a);
indices.add(aIndices);
beginIndex = i + 1;
}
if (c == '[')
++level;
if (c == ']')
--level;
}
//todo fix CORE-106
//Sqrt[x]
if (simpleTensorNode.name.toLowerCase().equals("sqrt")
&& simpleTensorNode.indices.size() == 0
&& arguments.size() == 1
&& arguments.get(0).getIndices().getFree().size() == 0)
return new ParseToken(TokenType.Power, new ParseToken[]{arguments.get(0), new ParseTokenNumber(Complex.ONE_HALF)});
return new ParseTokenTensorField(
simpleTensorNode.indices,
simpleTensorNode.name,
arguments.toArray(new ParseToken[arguments.size()]),
indices.toArray(new SimpleIndices[indices.size()]));
}
}