/// <summary>
/// Creates a property reference.
/// </summary>
/// <param name="nHolder"> A holder of string representation of the name. </param>
/// <param name="varIndex"> An index in a result during evaluation. </param>
/// <param name="propID"> An ID of the accessed property. </param>
public VariablePropertyReference(VariableReferenceNameHolder nHolder, int varIndex, int propID) : base(nHolder, varIndex)
{
if (propID < 0)
{
throw new ArgumentException($"{this.GetType()}, property ID must be >= 0, propID == {propID}.");
}
this.PropertyID = propID;
}
/// <summary>
/// Creates a variable reference.
/// </summary>
/// <param name="nHolder"> A holder of string representation of the name. </param>
/// <param name="varIndex"> An index of an element in a result during evaluation.</param>
protected VariableReference(VariableReferenceNameHolder nHolder, int varIndex)
{
if (nHolder == null)
{
throw new ArgumentNullException($"{this.GetType()}, trying to assign null to a construtor.");
}
else if (varIndex < 0)
{
throw new ArgumentException($"{this.GetType()}, variable index must be >= 0, index == {varIndex}.");
}
this.NameHolder = nHolder;
this.VariableIndex = varIndex;
}
/// <summary>
/// If it consists only of a name, variable id reference is created.
/// Otherwise property reference will be created.
/// </summary>
public void Visit(VariableNode node)
{
this.nameHolder = new VariableReferenceNameHolder();
if (node.name == null)
{
throw new ArgumentException($"{this.GetType()}, expected name of a variable.");
}
else
{
node.name.Accept(this);
if (node.propName != null)
{
node.propName.Accept(this);
}
}
// Get the position of the variable in the result.
int varIndex = this.variableMap.GetVariablePosition(this.nameHolder.Name);
if (this.nameHolder.PropName == null)
{
this.expr = new VariableIDReference(this.nameHolder, varIndex);
}
else
{
// Get type of accessed property.
if (!this.labels.TryGetValue(this.nameHolder.PropName, out Tuple <int, Type> tuple))
{
throw new ArgumentException($"{this.GetType()}, property {this.nameHolder.PropName} does not exists in the graph.");
}
else
{
this.expr = VariableReferencePropertyFactory.Create(this.nameHolder, varIndex, tuple.Item2, tuple.Item1);
}
}
}
/// <summary>
/// Constructs an id reference.
/// </summary>
/// <param name="nHolder"> A holder of string representation of the name.</param>
/// <param name="varIndex"> An index in a result during evaluation.</param>
public VariableIDReference(VariableReferenceNameHolder nHolder, int varIndex) : base(nHolder, varIndex)
{
}
