internal TernaryConstraintExpression(ConstraintExpressionNode constraintExpressionModel, EncapsulatedVariableNode expressionNode, Arc leftArc, Arc rightArc)
{
ExpressionNode = constraintExpressionModel;
Node = expressionNode;
EncapsulatedVariable = expressionNode.Variable;
LeftArc = leftArc;
RightArc = rightArc;
}
private void ProcessSimpleConstraint(ConstraintExpressionNode constraintExpressionNode)
{
Constraint newConstraint;
var lhsExpr = GetExpressionFrom(constraintExpressionNode.InnerExpression.LeftExpression);
if (constraintExpressionNode.InnerExpression.RightExpression.IsExpression)
{
var rhsExpr = GetExpressionFrom(constraintExpressionNode.InnerExpression.RightExpression);
newConstraint = CreateConstraintBy(constraintExpressionNode.InnerExpression.Operator, lhsExpr, rhsExpr);
}
else if (constraintExpressionNode.InnerExpression.RightExpression.InnerExpression is BucketVariableReferenceExpressionNode)
{
var rhsExpr = GetExpressionFrom(constraintExpressionNode.InnerExpression.RightExpression);
newConstraint = CreateConstraintBy(constraintExpressionNode.InnerExpression.Operator, lhsExpr, rhsExpr);
}
else if (constraintExpressionNode.InnerExpression.RightExpression.IsVariable)
{
var rhsVariable = GetVariableFrom(constraintExpressionNode.InnerExpression.RightExpression);
newConstraint = CreateConstraintBy(constraintExpressionNode.InnerExpression.Operator, lhsExpr, rhsVariable);
}
else if (constraintExpressionNode.InnerExpression.RightExpression.InnerExpression is BucketVariableReferenceNode)
{
var rhsVariable = GetVariableFrom(constraintExpressionNode.InnerExpression.RightExpression);
newConstraint = CreateConstraintBy(constraintExpressionNode.InnerExpression.Operator, lhsExpr, rhsVariable);
}
else if (constraintExpressionNode.InnerExpression.RightExpression.InnerExpression is IntegerLiteralNode)
{
newConstraint = CreateConstraintBy(constraintExpressionNode.InnerExpression.Operator,
lhsExpr,
Convert.ToInt32(constraintExpressionNode.InnerExpression.RightExpression.GetLiteral()));
}
else if (constraintExpressionNode.InnerExpression.RightExpression.InnerExpression is ItemNameNode node)
{
var lhsVariableName = GetVariableNameFrom(constraintExpressionNode.InnerExpression.LeftExpression);
var lhsVariable = this.model.GetVariableByName(lhsVariableName);
var range = this.valueMapper.GetDomainValueFor(lhsVariable);
var modelValue = GetModelValueFrom(node);
var solverValue = range.MapTo(modelValue);
newConstraint = CreateConstraintBy(constraintExpressionNode.InnerExpression.Operator, lhsExpr, solverValue);
}
else if (constraintExpressionNode.InnerExpression.RightExpression.InnerExpression is CharacterLiteralNode literalNode)
{
var lhsVariableName = GetVariableNameFrom(constraintExpressionNode.InnerExpression.LeftExpression);
var lhsVariable = this.model.GetVariableByName(lhsVariableName);
var range = this.valueMapper.GetDomainValueFor(lhsVariable);
var modelValue = GetModelValueFrom(literalNode);
var solverValue = range.MapTo(modelValue);
newConstraint = CreateConstraintBy(constraintExpressionNode.InnerExpression.Operator, lhsExpr, solverValue);
}
else
{
throw new NotImplementedException("Unknown constraint expression.");
}
this.solver.Add(newConstraint);
}
private IReadOnlyCollection <Arc> BuildBinaryExpression(ConstraintExpressionNode expressionConstraintNode)
{
var left = CreateNodeFrom(expressionConstraintNode.InnerExpression.LeftExpression);
if (!expressionConstraintNode.InnerExpression.RightExpression.IsLiteral)
{
var right = CreateNodeFrom(expressionConstraintNode.InnerExpression.RightExpression);
return(new ReadOnlyCollection <Arc>(new[] { new Arc(left, right, CreateConnectorFrom(left, right, CreateConstraintFrom(expressionConstraintNode))) }));
}
return(new ReadOnlyCollection <Arc>(new[] { new Arc(left, left, CreateConnectorFrom(left, left, CreateConstraintFrom(expressionConstraintNode))) }));
}
/// <summary>
/// Build one or more arcs as necessary to represent the expression constraint.
/// </summary>
/// <param name="expressionConstraintNode">Expression constraint node.</param>
/// <returns>One or more arcs</returns>
internal IReadOnlyCollection <Arc> Build(ConstraintExpressionNode expressionConstraintNode)
{
switch (expressionConstraintNode.InnerExpression.Operator)
{
// Ternary operators
case OperatorType.Equals:
case OperatorType.NotEqual:
return(BuildTernaryExpression(expressionConstraintNode));
// Binary operators
default:
return(BuildBinaryExpression(expressionConstraintNode));
}
}
/// <summary>
/// Parse the raw constraint expression.
/// </summary>
/// <param name="rawExpression">Raw constraint expression.</param>
internal void ParseUnit(string rawExpression)
{
if (!string.IsNullOrWhiteSpace(rawExpression))
{
var interpreter = new ConstraintExpressionParser();
var parseResult = interpreter.Parse(rawExpression);
if (parseResult.Status == ParseStatus.Success)
{
Node = parseResult.Root;
}
}
else
{
Node = null;
}
}
/// <summary>
/// Build one or more arcs from the ternary constraint expression.
/// </summary>
/// <remarks>
/// There will be more than one arc because binarization of the expression requires introducing an
/// encapsulated variable between the two variables involved in the expression.
/// </remarks>
/// <param name="expressionConstraintNode">Expression constraint abstract syntax tree.</param>
/// <returns>One or more arcs.</returns>
private IReadOnlyCollection <Arc> BuildTernaryExpression(ConstraintExpressionNode expressionConstraintNode)
{
var arcAccumulator = new List <Arc>();
if (!expressionConstraintNode.InnerExpression.RightExpression.IsLiteral)
{
var left = CreateNodeFrom(expressionConstraintNode.InnerExpression.LeftExpression);
var right = CreateNodeFrom(expressionConstraintNode.InnerExpression.RightExpression);
var encapsulatedVariable = new EncapsulatedVariable("U");
var encapsulatedVariableNode = new EncapsulatedVariableNode(encapsulatedVariable);
var arc1 = new Arc(left, encapsulatedVariableNode, new EncapsulatedVariableConnector(left, encapsulatedVariableNode, new EncapsulatedSelector(1)));
arcAccumulator.Add(arc1);
var arc2 = new Arc(right, encapsulatedVariableNode, new EncapsulatedVariableConnector(encapsulatedVariableNode, right, new EncapsulatedSelector(2)));
arcAccumulator.Add(arc2);
var ternaryConstraintExpression = new TernaryConstraintExpression(expressionConstraintNode, encapsulatedVariableNode, arc1, arc2);
var encapsulatedVariableDomainValue = ComputeEncapsulatedDomain(ternaryConstraintExpression);
encapsulatedVariable.DomainValue = encapsulatedVariableDomainValue;
var expressionSolution = new TernaryConstraintExpressionSolution(ternaryConstraintExpression, encapsulatedVariableDomainValue);
_modelSolverMap.AddTernaryExpressionSolution(expressionSolution);
}
else
{
var left = CreateNodeFrom(expressionConstraintNode.InnerExpression.LeftExpression);
var encapsulatedVariable = new EncapsulatedVariable("U");
var encapsulatedVariableNode = new EncapsulatedVariableNode(encapsulatedVariable);
var arc1 = new Arc(left, encapsulatedVariableNode, new EncapsulatedVariableConnector(left, encapsulatedVariableNode, new EncapsulatedSelector(1)));
arcAccumulator.Add(arc1);
var ternaryConstraintExpression = new TernaryConstraintExpression(expressionConstraintNode, encapsulatedVariableNode, arc1, arc1);
var encapsulatedVariableDomainValue = ComputeEncapsulatedDomain(ternaryConstraintExpression);
encapsulatedVariable.DomainValue = encapsulatedVariableDomainValue;
var expressionSolution = new TernaryConstraintExpressionSolution(ternaryConstraintExpression, encapsulatedVariableDomainValue);
_modelSolverMap.AddTernaryExpressionSolution(expressionSolution);
}
return(new ReadOnlyCollection <Arc>(arcAccumulator));
}
private void ProcessConstraint(ConstraintExpressionNode constraintExpressionNode)
{
var newArcs = _arcBuilder.Build(constraintExpressionNode);
_constraintNetwork.AddArc(newArcs);
}
internal BinaryConstraintExpression(ConstraintExpressionNode expressionNode)
{
Node = expressionNode;
}
private BinaryConstraintExpression CreateConstraintFrom(ConstraintExpressionNode binaryExpressionNode)
{
return(new BinaryConstraintExpression(binaryExpressionNode));
}
public virtual object VisitConstraintExpression(ConstraintExpressionNode constraintExpression, object data)
{
stackMap.Push(constraintExpression);
if (constraintExpression.Expression != null)
{
constraintExpression.Expression.AcceptVisitor(this, data);
}
stackMap.Pop();
return null;
}
