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Open-source constraint solver.
/*
* 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.real;
import gnu.trove.map.hash.TIntIntHashMap;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.constraints.Constraint;
import org.chocosolver.solver.variables.BoolVar;
import org.chocosolver.solver.variables.Variable;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import static org.chocosolver.solver.constraints.ConstraintsName.REALCONSTRAINT;
/**
* A constraint on real variables, solved using IBEX.
*
* @author Charles Prud'homme, Jean-Guillaume Fages
* @since 18/07/12
*/
public class RealConstraint extends Constraint {
private static final Pattern p0 = Pattern.compile("\\{\\d*\\}");
private static final Pattern p1 = Pattern.compile("\\{_");
//***********************************************************************************
// CONSTRUCTORS
//***********************************************************************************
/**
* Make a new RealConstraint defined as a set of RealPropagators
*
* @param name name of the constraint
* @param propagators set of propagators defining the constraint
*/
private RealConstraint(String name, RealPropagator... propagators) {
super(name, propagators);
}
/**
* Make a new RealConstraint to model one or more continuous functions, separated with
* semi-colon ";"
A function is a string declared using the following format:
- the
* '{i}' tag defines a variable, where 'i' is an explicit index the array of variables
* vars,
- one or more operators :'+,-,*,/,=,<,>,<=,>=,exp( ),ln( ),max(
* ),min( ),abs( ),cos( ), sin( ),...'
A complete list is available in the documentation
* of IBEX.
*
*
*
* model.realIbexGenericConstraint("({0}*{1})+sin({0})=1.0;ln({0}+[-0.1,0.1])>=2.6", x,
* y).post();
*
*
*
* @param functions list of functions, separated by a semi-colon
* @param contractionRatio defines the domain contraction significance
* @param rvars a list of real variables
*/
public RealConstraint(String functions, double contractionRatio, Variable... rvars) {
this(REALCONSTRAINT, createPropagator(functions, contractionRatio, rvars));
}
public RealConstraint(String functions, Variable... rvars) {
this(functions, Ibex.RATIO, rvars);
}
//***********************************************************************************
// METHODS
//***********************************************************************************
/**
* Creates a RealPropagator to propagate one or more continuous functions, separated with
* semi-colon ";" Each function is set to a single propagator.
A function is a string
* declared using the following format:
- the '{i}' tag defines a variable, where 'i' is an
* explicit index the array of variables vars,
- one or more operators
* :'+,-,*,/,=,<,>,<=,>=,exp( ),ln( ),max( ),min( ),abs( ),cos( ), sin( ),...'
A complete
* list is available in the documentation of IBEX.
*
*
*
* model.realIbexGenericConstraint("({0}*{1})+sin({0})=1.0;ln({0}+[-0.1,0.1])>=2.6", x,
* y).post();
*
*
*
* @param functions list of functions, separated by a semi-colon
* @param contractionRatio defines the domain contraction significance
* @param rvars a list of real variables
* @return a RealPropagator to propagate the given functions over given variable domains
*/
private static RealPropagator[] createPropagator(String functions, double contractionRatio, Variable... rvars) {
// split functions to correctly maintain indices of contractors
String[] theFunctions = functions.split(";");
RealPropagator[] props = new RealPropagator[theFunctions.length];
List vars = new ArrayList<>();
TIntIntHashMap sidx = new TIntIntHashMap();
for (int i = 0; i < props.length; i++) {
String fct = theFunctions[i];
// determine the sub-scope of variables
Matcher m = p0.matcher(fct);
while (m.find()) {
String g = m.group();
int id = Integer.parseInt(g.substring(1, g.length() - 1));
if (!sidx.contains(id)) {
sidx.put(id, vars.size());
vars.add(rvars[id]);
}
}
// update the function
for (int k : sidx.keys()) {
fct = fct.replaceAll(
"\\{" + k + "\\}",
"{_" + sidx.get(k) + "}");
}
fct = p1.matcher(fct).replaceAll("{");
RealPropagator realPropagator = new RealPropagator(fct, vars.toArray(new Variable[0]));
realPropagator.setContractionRatio(contractionRatio);
props[i] = realPropagator;
sidx.clear();
vars.clear();
}
return props;
}
/**
* Reifies the constraint with a boolean variable
* If the reified boolean variable already exists, an additional (equality) constraint is automatically posted.
*
* @param bool the variable to reify with
*/
public void reifyWith(BoolVar bool) {
Model s = propagators[0].getModel();
getOpposite();
if (boolReif == null) {
this.post();
boolReif = bool;
if(propagators.length == 1) {
((RealPropagator) propagators[0]).reify(bool);
}else {
BoolVar[] bvars = bool.getModel().boolVarArray(propagators.length);
for (int i = 0; i < propagators.length; i++) {
((RealPropagator) propagators[i]).reify(bvars[i]);
}
bool.getModel().addClausesBoolAndArrayEqVar(bvars, bool);
}
} else if (bool != boolReif) {
s.arithm(bool, "=", boolReif).post();
}
}
}