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/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2023, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.solver.constraints.extension;
import org.chocosolver.solver.Settings;
import org.chocosolver.solver.constraints.Operator;
import org.chocosolver.solver.exception.SolverException;
import org.chocosolver.solver.variables.IntVar;
import java.util.Random;
import static org.chocosolver.util.tools.ArrayUtils.concat;
/**
* A Factory to ease generation of tuples.
* One may keep in mind that tuples generation directly depends on the product of domain cardinality, but also on the algorithm defines in the filter.
* and thus may be time consuming!
*
*
* @author Charles Prud'homme
* @since 24/04/2014
*/
public class TuplesFactory {
TuplesFactory() {
}
/**
* A method that generates all tuples from a set of variables and stores (and returns) the valid tuples wrt to the filter.
* One may keep in mind that tuples generation directly depends on the product of domain cardinality, but also on the algorithm defines in the filter.
*
* @param filter tuple validator
* @param feasible are tuples feasible (or infeasible)
* @param doms domains
* @return the valid tuples wrt to filter
* @see source
*/
public static Tuples generateTuples(TupleValidator filter, boolean feasible, int[]... doms) {
Tuples tuples = new Tuples(feasible);
int n = doms.length;
int[] t = new int[n];
int[] i = new int[n];
for (int j = 0; j < n; j++) {
t[j] = doms[j][0];
}
while (true) {
if (filter.valid(t)) tuples.add(t.clone());
int j;
for (j = 0; j < n; j++) {
i[j]++;
if (i[j] < doms[j].length) {
t[j] = doms[j][i[j]];
break;
}
i[j] = 0;
t[j] = doms[j][0];
}
if (j == n) break;
}
return tuples;
}
/**
* A method that generates all tuples from a set of variables and stores (and returns) the valid tuples wrt to the filter.
* One may keep in mind that tuples generation directly depends on the product of domain cardinality, but also on the algorithm defines in the filter.
*
* @param filter tuple validator
* @param feasible are tuples feasible (or infeasible)
* @param vars concerned variables
* @return the valid tuples wrt to filter
*/
public static Tuples generateTuples(TupleValidator filter, boolean feasible, IntVar... vars) {
Tuples tuples = new Tuples(feasible);
int n = vars.length;
int[] cvalue = new int[n];
int[] t = new int[n];
for (int j = 0; j < n; j++) {
t[j] = cvalue[j] = vars[j].getLB();
}
while (true) {
if (filter.valid(t)) tuples.add(t.clone());
int j;
for (j = 0; j < n; j++) {
int v = t[j] = cvalue[j] = vars[j].nextValue(cvalue[j]);
if (v < Integer.MAX_VALUE) {
break;
}
t[j] = cvalue[j] = vars[j].getLB();
}
if (j == n) break;
}
return tuples;
}
/**
* A method that randomly generates tuples from a set of variables.
*
* @param proba probability to keep a tuple in Tuples (0 < proba < 1)
* @param random an instance of pseudorandom numbers streamer
* @param vars concerned variables
* @return the set of retain tuples, which can be empty
* @implNote
* If proba <= 0, then the tuple list will be empty
*
*
* If proba > 1, then all combination will be retained
*
* All combinations of instantiations of vars are generated
* and for each of them, an instantiation is kept with probability p.
*
*/
public static Tuples randomTuples(final double proba, final Random random, IntVar... vars) {
return generateTuples(vs -> random.nextDouble() < proba, true,vars);
}
// BEWARE: PLEASE, keep signatures sorted by increasing arity and alphabetical order!!
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// BINARIES
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Generate valid tuples for absolute constraint: VAR1 = |VAR2|
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples absolute(IntVar VAR1, IntVar VAR2) {
return generateTuples(values -> values[0] == Math.abs(values[1]), true, VAR1, VAR2);
}
/**
* Generate valid tuples for VAR1 OP VAR2, where OP in {"=", "!=", ">","<",">=","<="}
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples arithm(IntVar VAR1, String OP, IntVar VAR2) {
final Operator op = Operator.get(OP);
return generateTuples(values -> {
switch (op) {
case LT:
return values[0] < values[1];
case GT:
return values[0] > values[1];
case LE:
return values[0] <= values[1];
case GE:
return values[0] >= values[1];
case NQ:
return values[0] != values[1];
case EQ:
return values[0] == values[1];
default:
throw new SolverException("Unexpected Tuple operator " + op
+ " (should be in {\"=\", \"!=\", \">\",\"<\",\">=\",\"<=\"})");
}
}, true, VAR1, VAR2);
}
/**
* Generate valid tuples for an element constraint : TABLE[INDEX-OFFSET] = VALUE
*
* @param VALUE an integer variable taking its value in TABLE
* @param TABLE an array of integer values
* @param INDEX an integer variable representing the value of VALUE in TABLE
* @param OFFSET offset matching INDEX.LB and TABLE[0] (Generally 0)
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples element(IntVar VALUE, int[] TABLE, IntVar INDEX, int OFFSET) {
Tuples t = new Tuples(true);
for (int v = INDEX.getLB(); v <= INDEX.getUB(); v = INDEX.nextValue(v)) {
if (v - OFFSET >= 0 && v - OFFSET < TABLE.length && VALUE.contains(TABLE[v - OFFSET])) {
t.add(TABLE[v - OFFSET], v);
}
}
return t;
}
/**
* Generate valid tuples for an element constraint : MATRIX[ROWINDEX-ROWOFFSET][COLINDEX-COLOFFSET] = VALUE
*
* @param VALUE an integer variable taking its value in MATRIX
* @param MATRIX an array of integer values
* @param ROWINDEX an integer variable representing the row of value of VALUE in MATRIX
* @param ROWOFFSET offset matching ROWINDEX.LB and MATRIX[0] (Generally 0)
* @param COLINDEX an integer variable representing the column of value of VALUE in MATRIX
* @param COLOFFSET offset matching COLINDEX.LB and MATRIX[][0] (Generally 0)
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples element(IntVar VALUE, int[][] MATRIX,
IntVar ROWINDEX, int ROWOFFSET,
IntVar COLINDEX, int COLOFFSET) {
Tuples t = new Tuples(true);
for (int i = 0; i < MATRIX.length; i++) {
for (int j = 0; j < MATRIX[i].length; j++) {
if (ROWINDEX.contains(i - ROWOFFSET)
&& COLINDEX.contains(j - COLOFFSET)
&& VALUE.contains(MATRIX[i][j])) {
t.add(i, j, MATRIX[i - -ROWOFFSET][j - COLOFFSET]);
}
}
}
return t;
}
/**
* Generate valid tuples for minimum constraint: VAR1 % m = VAR2
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples modulo(IntVar VAR1, int m, IntVar VAR2) {
return generateTuples(values -> values[1] == values[0] % m, true, VAR1, VAR2);
}
/**
* Generate valid tuples for absolute constraint: VAR1 = VAR2^POWER
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples power(IntVar VAR1, IntVar VAR2, final int POWER) {
return generateTuples(values -> values[0] == Math.pow(values[1], POWER), true, VAR1, VAR2);
}
/**
* Generate valid tuples for absolute constraint: VAR1 = VAR2^2
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples square(IntVar VAR1, IntVar VAR2) {
return generateTuples(values -> values[0] == Math.pow(values[1], 2), true, VAR1, VAR2);
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// TERNARIES
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Generate valid tuples for euclidean division constraint: DIVIDEND / DIVISOR = RESULT, rounding towards 0
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples eucl_div(IntVar DIVIDEND, IntVar DIVISOR, IntVar RESULT) {
return generateTuples(values -> values[0] / values[1] == values[2], true, DIVIDEND, DIVISOR, RESULT);
}
/**
* Generate valid tuples for minus constraint: MAX = max(VAR1,VAR2)
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples maximum(IntVar VAR1, IntVar VAR2, IntVar MAX) {
return generateTuples(values -> values[0] == Math.max(values[1], values[2]), true, MAX, VAR1, VAR2);
}
/**
* Generate valid tuples for minimum constraint: MIN = min(VAR1,VAR2)
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples minimum(IntVar VAR1, IntVar VAR2, IntVar MIN) {
return generateTuples(values -> values[0] == Math.min(values[1], values[2]), true, MIN, VAR1, VAR2);
}
/**
* Generate valid tuples for minimum constraint: VAR1 % VAR2 = RES
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples modulo(IntVar VAR1, IntVar VAR2, IntVar RES) {
return generateTuples(values -> values[1] != 0 && values[2] == values[0] % values[1], true, VAR1, VAR2, RES);
}
/**
* Generate valid tuples for minus constraint: VAR1 - VAR2 = RESULT
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples minus(IntVar VAR1, IntVar VAR2, IntVar RESULT) {
return generateTuples(values -> values[0] - values[1] == values[2], true, VAR1, VAR2, RESULT);
}
/**
* Generate valid tuples for plus constraint: VAR1 + VAR2 = RESULT
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples plus(IntVar VAR1, IntVar VAR2, IntVar RESULT) {
return generateTuples(values -> values[0] + values[1] == values[2], true, VAR1, VAR2, RESULT);
}
/**
* Generate valid tuples for times constraint: VAR1 * VAR2 = RESULT
*
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples times(IntVar VAR1, IntVar VAR2, IntVar RESULT) {
return generateTuples(values -> values[0] * values[1] == values[2], true, VAR1, VAR2, RESULT);
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// NARIES
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Generate valid tuples for allDifferent constraint
*
* @param VARS concerned variables
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples allDifferent(IntVar... VARS) {
return generateTuples(values -> {
for (int i = 0; i < values.length - 1; i++) {
for (int j = i + 1; j < values.length; j++) {
if (values[j] == values[i]) return false;
}
}
return true;
}, true, VARS);
}
/**
* Generate valid tuples for allEquals constraint
*
* @param VARS concerned variables
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples allEquals(IntVar... VARS) {
int min = Integer.MIN_VALUE;
int max = Integer.MAX_VALUE;
for (int i = 0; i < VARS.length; i++) {
min = Math.max(min, VARS[i].getLB());
max = Math.min(max, VARS[i].getUB());
}
Tuples tuples = new Tuples(true);
for (int k = min; k <= max; k++) {
int[] t = new int[VARS.length];
for (int i = 0; i < VARS.length; i++) {
t[i] = k;
}
tuples.add(t.clone());
}
return tuples;
/*return generateTuples(new TupleValidator() {
@Override
public boolean valid(int... values) {
for (int i = 0; i < values.length - 1; i++) {
if (values[i] != values[i + 1]) return false;
}
return true;
}
}, true, VARS);*/
}
/**
* Generate valid tuples for lexChainLess constraint
*
* @param VARS concerned variables
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples lex_chain_less(IntVar... VARS) {
return generateTuples(values -> {
for (int i = 0; i < values.length - 1; i++) {
if (values[i] < values[i + 1]) return false;
}
return true;
}, true, VARS);
}
/**
* Generate valid tuples for lexChainLessEq constraint
*
* @param VARS concerned variables
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples lex_chain_less_eq(IntVar... VARS) {
return generateTuples(values -> {
for (int i = 0; i < values.length - 1; i++) {
if (values[i] <= values[i + 1]) return false;
}
return true;
}, true, VARS);
}
/**
* Generate valid tuples for ∑i in |VARS|VARSi*COEFFSi OPERATOR SCALAR
*
* @param VARS concerned variables
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples scalar(IntVar[] VARS, final int[] COEFFS, IntVar SCALAR, final int SCALAR_COEFF) {
Tuples left = generateTuples(TupleValidator.TRUE, true, VARS);
Tuples tuples = new Tuples(true);
int n = VARS.length;
for (int[] tleft : left.tuples) {
int right = 0;
for (int i = 0; i < n; i++) {
right += tleft[i] * COEFFS[i];
}
if (right % SCALAR_COEFF == 0 && SCALAR.contains(right / SCALAR_COEFF)) {
int[] t = new int[n + 1];
System.arraycopy(tleft, 0, t, 0, n);
t[n] = right / SCALAR_COEFF;
tuples.add(t);
}
}
return tuples;
}
/**
* Generate valid tuples for ∑i in |VARS|VARSi*COEFFSi OPERATOR SCALAR + CSTE
*
* with OPERATOR in {"=", "!=", ">","<",">=","<="}
*
* @param VARS concerned variables
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples scalar(IntVar[] VARS, final int[] COEFFS, final String OPERATOR, IntVar SCALAR, final int SCALAR_COEFF, int CSTE) {
if ("=".equals(OPERATOR) && CSTE == 0) {
return scalar(VARS, COEFFS, SCALAR, SCALAR_COEFF);
}
final Operator op = Operator.get(OPERATOR);
return generateTuples(values -> {
int scalar = 0;
for (int i = 0; i < values.length - 1; i++) {
scalar += values[i] * COEFFS[i];
}
switch (op) {
case LT:
return scalar < values[values.length - 1] * SCALAR_COEFF + CSTE;
case GT:
return scalar > values[values.length - 1] * SCALAR_COEFF + CSTE;
case LE:
return scalar <= values[values.length - 1] * SCALAR_COEFF + CSTE;
case GE:
return scalar >= values[values.length - 1] * SCALAR_COEFF + CSTE;
case NQ:
return scalar != values[values.length - 1] * SCALAR_COEFF + CSTE;
case EQ:
return scalar == values[values.length - 1] * SCALAR_COEFF + CSTE;
default:
throw new SolverException("Unexpected Tuple operator " + op
+ " (should be in {\"=\", \"!=\", \">\",\"<\",\">=\",\"<=\"})");
}
}, true, concat(VARS, SCALAR));
}
/**
* Generate valid tuples for ∑i in |VARS|VARSi OPERATOR SUM + CSTE
*
* with OPERATOR in {"=", "!=", ">","<",">=","<="}
*
* @param VARS concerned variables
* @return a Tuples object, reserved for a table constraint
*/
public static Tuples sum(IntVar[] VARS, final String OPERATOR, IntVar SUM, int CSTE) {
final Operator op = Operator.get(OPERATOR);
return generateTuples(values -> {
int sum = 0;
for (int i = 0; i < values.length - 1; i++) {
sum += values[i];
}
switch (op) {
case LT:
return sum < values[values.length - 1] + CSTE;
case GT:
return sum > values[values.length - 1] + CSTE;
case LE:
return sum <= values[values.length - 1] + CSTE;
case GE:
return sum >= values[values.length - 1] + CSTE;
case NQ:
return sum != values[values.length - 1] + CSTE;
case EQ:
return sum == values[values.length - 1] + CSTE;
default:
throw new SolverException("Unexpected Tuple operator " + op
+ " (should be in {\"=\", \"!=\", \">\",\"<\",\">=\",\"<=\"})");
}
}, true, concat(VARS, SUM));
}
/**
* Check whether the intension constraint to extension constraint substitution is enabled and can be achieved
*
* @param VARS list of variables involved
* @return a boolean
*/
public static boolean canBeTupled(IntVar... VARS) {
Settings settings = VARS[0].getModel().getSettings();
if (!settings.enableTableSubstitution()) {
return false;
}
long doms = 1;
for (int i = 0; i < VARS.length && doms < settings.getMaxTupleSizeForSubstitution(); i++) {
if (!VARS[i].hasEnumeratedDomain()) {
return false;
}
doms *= VARS[i].getDomainSize();
}
return (doms < settings.getMaxTupleSizeForSubstitution());
}
}