/*
* 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.indexmapping;
import cc.redberry.core.indices.IndicesUtils;
import cc.redberry.core.tensor.ApplyIndexMapping;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.core.transformations.Transformation;
import cc.redberry.core.utils.ArraysUtils;
import cc.redberry.core.utils.IntArray;
import gnu.trove.iterator.TIntObjectIterator;
import gnu.trove.map.hash.TIntObjectHashMap;
import java.util.Arrays;
/**
* This is the main class which represents the mapping from one tensor to another.
* <p>
* {@code Mapping} implements {@code Transformation} and perform transformation by simple invocation of
* {@link ApplyIndexMapping#applyIndexMappingAutomatically(cc.redberry.core.tensor.Tensor, Mapping)} ))} with
* {@code this} as a second argument.
* </p>
* <p>
* The underlying data structure is a
* simple pair of sorted arrays {@code fromNames} and {@code toData}, such that <i>i</i>-th mapping entry is
* {@code fromNames[i] -> toData[i]}. The array {@code fromNames} contains from indices names. The array {@code toData}
* contains names of to indices where the first bit indicates whether the state of from index should be inverted.
* </p>
*
* @author Dmitry Bolotin
* @author Stanislav Poslavsky
* @since 1.1.5
*/
public final class Mapping implements Transformation {
final int[] fromNames, toData;
final boolean sign;
/**
* Identity mapping
*/
public static final Mapping IDENTITY = new Mapping(new int[0], new int[0], false, false);
/**
* Creates mapping from given {@code from} and {@code to} arrays of indices.
*
* @param from indices from
* @param to indices to
*/
public Mapping(int[] from, int[] to) {
this(from, to, false);
}
/**
* Creates mapping from given {@code from} and {@code to} arrays of indices.
*
* @param from indices from
* @param to indices to
* @param sign the sign of mapping
*/
public Mapping(final int[] from, final int[] to, final boolean sign) {
if (from.length != to.length)
throw new IllegalArgumentException("From length != to length.");
fromNames = new int[from.length];
toData = new int[from.length];
for (int i = 0; i < from.length; ++i) {
fromNames[i] = IndicesUtils.getNameWithType(from[i]);
toData[i] = IndicesUtils.getRawStateInt(from[i]) ^ to[i];
}
ArraysUtils.quickSort(fromNames, toData);
this.sign = sign;
}
Mapping(IndexMappingBuffer buffer) {
TIntObjectHashMap<IndexMappingBufferRecord> map = buffer.getMap();
fromNames = new int[map.size()];
toData = new int[map.size()];
TIntObjectIterator<IndexMappingBufferRecord> iterator = map.iterator();
int i = 0;
IndexMappingBufferRecord record;
while (iterator.hasNext()) {
iterator.advance();
record = iterator.value();
fromNames[i] = iterator.key();
toData[i] = record.getRawDiffStateBit() | record.getIndexName();
++i;
}
ArraysUtils.quickSort(fromNames, toData);
sign = buffer.getSign();
}
private Mapping(int[] fromNames, int[] toData, boolean sign, boolean o) {
this.fromNames = fromNames;
this.toData = toData;
this.sign = sign;
}
@Override
public Tensor transform(Tensor t) {
return ApplyIndexMapping.applyIndexMappingAutomatically(t, this);
}
/**
* Returns {@code true} if this mapping does not contain any entries (however, it can have negative sign).
*
* @return {@code true} if this mapping does not contain any entries (however, it can have negative sign)
* @see #isIdentity()
*/
public boolean isEmpty() {return fromNames.length == 0;}
/**
* Returns {@code true} if this mapping does not contain any entries and have positive sign.
*
* @return {@code true} if this mapping does not contain any entries and have positive sign.
*/
public boolean isIdentity() {return fromNames.length == 0 && !sign;}
/**
* Returns the sign of this mapping
*
* @return sign of this mapping
*/
public boolean getSign() {return sign;}
/**
* Returns mapping, formed from this mapping by multiplying by specified sign.
*
* @param sign false - plus, true - minus one
* @return a new mapping, formed from this mapping by multiplying by specified sign
*/
public Mapping addSign(boolean sign) {
return new Mapping(fromNames, toData, sign ^ this.sign, true);
}
/**
* Returns the number of entries in this mapping.
*
* @return the number of entries in this mapping
*/
public int size() {return fromNames.length;}
/**
* Returns the names of from indices.
*
* @return names of from indices
*/
public IntArray getFromNames() {
return new IntArray(fromNames);
}
/**
* Returns the data array that represents to indices.
*
* @return data array that represents to indices.
*/
public IntArray getToData() {
return new IntArray(toData);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Mapping mapping = (Mapping) o;
if (sign != mapping.sign) return false;
if (!Arrays.equals(fromNames, mapping.fromNames)) return false;
if (!Arrays.equals(toData, mapping.toData)) return false;
return true;
}
@Override
public int hashCode() {
int result = Arrays.hashCode(fromNames);
result = 31 * result + Arrays.hashCode(toData);
result = 31 * result + (sign ? 1 : 0);
return result;
}
@Override
public String toString() {
int imax = fromNames.length - 1;
if (imax == -1) {
if (sign)
return "-{}";
else return "{}";
}
StringBuilder sb = new StringBuilder();
if (sign)
sb.append("-");
sb.append("{");
for (int i = 0; ; ++i) {
sb.append(IndicesUtils.toString(fromNames[i]));
sb.append("->");
sb.append(IndicesUtils.toString(toData[i]));
if (i == imax)
break;
sb.append(",");
}
sb.append("}");
return sb.toString();
}
}