/*
* Redberry: symbolic tensor computations.
*
* Copyright (c) 2010-2013:
* 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.context;
import cc.redberry.core.indices.*;
import cc.redberry.core.parser.ParseManager;
import cc.redberry.core.tensor.SimpleTensor;
import cc.redberry.core.tensor.Tensors;
import cc.redberry.core.utils.BitArray;
/**
* This class represents Redberry context. It stores all Redberry session data (in some sense it stores static data).
*
* <p>Management of current Redberry context is made through {@link ContextManager} class.
* Context of Redberry is attached to the current thread, so that any thread created from the outside of Redebrry
* will hold a unique instance of {@link Context} object. In such a way tensors created in one thread can not
* be used in the other thread because they are in some sense "attached" to the initial thread. However, if thread is
* created through the executor service which is obtained from {@link ContextManager#getExecutorService()}, it will
* share the same context as initial thread (such threads could hold concurrent computations regarding single context,
* the appropriate synchronization is assumed). In order to create a new session of Redberry with a particular context,
* an instance of this class should be set as a current context via {@link ContextManager#setCurrentContext(Context)}.</p>
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
* @see NameManager
* @see IndexConverterManager
* @see ParseManager
* @see OutputFormat
* @see ContextManager
* @see ContextSettings
* @since 1.0
*/
public final class Context {
/**
* NameManager has a sense of namespace
*/
private final NameManager nameManager;
/**
* Defaults output format can be changed during the session
*/
private OutputFormat defaultOutputFormat;
private final IndexConverterManager converterManager;
private final ParseManager parseManager;
/**
* Holds information about metric types.
* This is a "map" from (byte) type to (bit) isMetric
*/
private final BitArray metricTypes = new BitArray(128);
/**
* Creates context from the settings
*
* @param contextSettings settings
* @see ContextSettings
*/
public Context(ContextSettings contextSettings) {
this.parseManager = new ParseManager(contextSettings.getParser());
this.converterManager = contextSettings.getConverterManager();
nameManager = new NameManager(contextSettings.getNameManagerSeed(), contextSettings.getKronecker(), contextSettings.getMetricName());
defaultOutputFormat = contextSettings.getDefaultOutputFormat();
for (IndexType type : contextSettings.getMetricTypes())
metricTypes.set(type.getType());
}
/**
* This method resets all tensor names in the namespace.
*
* <p>Any tensor created before this method call becomes invalid, and
* must not be used! This method is mainly used in unit tests, so
* avoid invocations of this method in general computations.</p>
*/
public synchronized void resetTensorNames() {
nameManager.reset();
}
/**
* This method resets all tensor names in the namespace and sets a
* specified seed to the {@link NameManager}. If this method is invoked
* with constant seed before any interactions with Redberry, further
* behaviour of Redberry will be fully deterministic from run to run
* (order of summands and multipliers will be fixed, computation time
* will be pretty constant, hash codes will be the same).
*
* <p>Any tensor created before this method call becomes invalid, and
* must not be used! This method is mainly used in unit tests, so
* avoid invocations of this method in general computations.</p>
*/
public synchronized void resetTensorNames(long seed) {
nameManager.reset(seed);
}
/**
* Sets the default output format. After this step, all expressions
* will be printed according to the specified output format.
*
* @param defaultOutputFormat output format
*/
public void setDefaultOutputFormat(OutputFormat defaultOutputFormat) {
this.defaultOutputFormat = defaultOutputFormat;
}
/**
* Returns current default output format.
*
* @return current default output format
*/
public OutputFormat getDefaultOutputFormat() {
return defaultOutputFormat;
}
/**
* Returns index converter manager of current session.
*
* @return index converter manager of current session
*/
public IndexConverterManager getIndexConverterManager() {
return converterManager;
}
/**
* Returns the name manager (namespace) of current session.
*
* @return the name manager (namespace) of current session.
*/
public NameManager getNameManager() {
return nameManager;
}
/**
* Returns {@code NameDescriptor} corresponding to the specified {@code int} nameId.
*
* @param nameId integer name of tensor
* @return corresponding {@code NameDescriptor}
*/
public NameDescriptor getNameDescriptor(int nameId) {
return nameManager.getNameDescriptor(nameId);
}
/**
* Returns string representation of Kronecker delta name
*
* @return string representation of Kronecker delta name
*/
public String getKroneckerName() {
return nameManager.getKroneckerName();
}
/**
* Returns string representation of metric tensor name
*
* @return string representation of metric tensor name
*/
public String getMetricName() {
return nameManager.getMetricName();
}
/**
* Sets the default metric tensor name. After this step, metric tensor
* will be printed with the specified string name.
*
* @param name string representation of metric tensor name
*/
public void setMetricName(String name) {
nameManager.setMetricName(name);
}
/**
* Sets the default Kronecker tensor name. After this step, Kronecker tensor
* will be printed with the specified string name.
*
* @param name string representation of Kronecker tensor name
*/
public void setKroneckerName(String name) {
nameManager.setKroneckerName(name);
}
/**
* Returns {@code true} if specified tensor is a Kronecker tensor
*
* @param t tensor
* @return {@code true} if specified tensor is a Kronecker tensor
*/
public boolean isKronecker(SimpleTensor t) {
return nameManager.isKroneckerOrMetric(t.getName())
&& !IndicesUtils.haveEqualStates(t.getIndices().get(0), t.getIndices().get(1));
}
/**
* Returns {@code true} if specified tensor is a metric tensor
*
* @param t tensor
* @return {@code true} if specified tensor is a metric tensor
*/
public boolean isMetric(SimpleTensor t) {
return nameManager.isKroneckerOrMetric(t.getName())
&& IndicesUtils.haveEqualStates(t.getIndices().get(0), t.getIndices().get(1));
}
/**
* Returns {@code true} if specified tensor is a metric or a Kronecker tensor
*
* @param t tensor
* @return {@code true} if specified tensor is a metric or a Kronecker tensor
*/
public boolean isKroneckerOrMetric(SimpleTensor t) {
return nameManager.isKroneckerOrMetric(t.getName());
}
/**
* Returns parse manager of current session
*
* @return parse manager of current session
*/
public ParseManager getParseManager() {
return parseManager;
}
/**
* Returns true if metric is defined for the specified index type.
*
* @param type index type
* @return true if metric is defined for the specified index type
*/
public boolean isMetric(byte type) {
return metricTypes.get(type);
}
/**
* Returns Kronecker tensor with specified upper and lower indices.
*
* @param index1 first index
* @param index2 second index
* @return Kronecker tensor with specified upper and lower indices
* @throws IllegalArgumentException if indices have same states
* @throws IllegalArgumentException if indices have different types
*/
public SimpleTensor createKronecker(int index1, int index2) {
byte type;
if ((type = IndicesUtils.getType(index1)) != IndicesUtils.getType(index2) || IndicesUtils.getRawStateInt(index1) == IndicesUtils.getRawStateInt(index2))
throw new IllegalArgumentException("This is not kronecker indices!");
if (!isMetric(type) && IndicesUtils.getState(index2)) {
int t = index1;
index1 = index2;
index2 = t;
}
SimpleIndices indices = IndicesFactory.createSimple(null, index1, index2);
NameDescriptor nd = nameManager.mapNameDescriptor(nameManager.getKroneckerName(), new StructureOfIndices(indices));
int name = nd.getId();
return Tensors.simpleTensor(name, indices);
}
/**
* Returns metric tensor with specified indices.
*
* @param index1 first index
* @param index2 second index
* @return metric tensor with specified indices
* @throws IllegalArgumentException if indices have different states
* @throws IllegalArgumentException if indices have different types
* @throws IllegalArgumentException if indices have non metric types
*/
public SimpleTensor createMetric(int index1, int index2) {
byte type;
if ((type = IndicesUtils.getType(index1)) != IndicesUtils.getType(index2)
|| !IndicesUtils.haveEqualStates(index1, index2)
|| !metricTypes.get(type))
throw new IllegalArgumentException("Not metric indices.");
SimpleIndices indices = IndicesFactory.createSimple(null, index1, index2);
NameDescriptor nd = nameManager.mapNameDescriptor(nameManager.getMetricName(), new StructureOfIndices(indices));
int name = nd.getId();
return Tensors.simpleTensor(name, indices);
}
/**
* Returns metric tensor if specified indices have same states and
* Kronecker tensor if specified indices have different states.
*
* @param index1 first index
* @param index2 second index
* @return metric tensor if specified indices have same states and
* Kronecker tensor if specified indices have different states
* @throws IllegalArgumentException if indices have different types
* @throws IllegalArgumentException if indices have same states and non metric types
*/
public SimpleTensor createMetricOrKronecker(int index1, int index2) {
if (IndicesUtils.getRawStateInt(index1) == IndicesUtils.getRawStateInt(index2))
return createMetric(index1, index2);
return createKronecker(index1, index2);
}
/**
* Returns the current context of Redberry session.
*
* @return the current context of Redberry session.
*/
public static Context get() {
return ContextManager.getCurrentContext();
}
}