/// <summary>
/// Constructor.
/// </summary>
/// <param name="parserContext"></param>
/// <param name="kind"></param>
/// <param name="castTypeName"></param>
/// <param name="expression"></param>
public CastExpression(IParserLocation parserContext, CoercionKind kind, string castTypeName, IExpression expression)
{
Location = parserContext;
Kind = kind;
CastTypeName = castTypeName;
Expression = expression;
}
/// <summary>
/// Creates a coercion rule
/// </summary>
/// <param name="kind"></param>
/// <param name="originalType"></param>
/// <param name="castingType"></param>
/// <param name="cast"></param>
public CoercionRule(CoercionKind kind, Type originalType, Type castingType, Func <object, object> cast)
{
Kind = kind;
OriginalType = originalType;
CastingType = castingType;
Cast = cast;
}
/// <summary>
/// Adds a new coercion rule. Trys to avoid cyclic implicit casts chains.
/// </summary>
/// <typeparam name="TOriginalType"></typeparam>
/// <typeparam name="TCastingType"></typeparam>
/// <param name="kind"></param>
/// <param name="cast"></param>
public void AddCoercionRule <TOriginalType, TCastingType>(CoercionKind kind, Func <TOriginalType, TCastingType> cast)
{
var original = typeof(TOriginalType);
var casting = typeof(TCastingType);
if (GetTypeByNative(original) == null)
{
throw new UnknownTypeException(original);
}
if (GetTypeByNative(casting) == null)
{
throw new UnknownTypeException(casting);
}
var rule = new CoercionRule(kind, original, casting, a => cast((TOriginalType)a));
if (allCoercionRules.TryGetEdge(original, casting, out TaggedEdge <Type, CoercionRule> existingEdge))
{
throw new InvalidOperationException("Such a rule does already exist!");
}
var edge = new TaggedEdge <System.Type, CoercionRule>(original, casting, rule);
if (kind == CoercionKind.Implicit)
{
implicitCoercionRules.AddVertex(original);
implicitCoercionRules.AddVertex(casting);
implicitCoercionRules.AddEdge(edge);
if (implicitCoercionRules.StronglyConnectedComponents(out IDictionary <Type, int> components) != implicitCoercionRules.Vertices.Count())
{
implicitCoercionRules.RemoveEdge(edge);
throw new InvalidOperationException("This action would create an implicit conversion cycle!");
}
}
allCoercionRules.AddVertex(original);
allCoercionRules.AddVertex(casting);
allCoercionRules.AddEdge(edge);
Debug.WriteLine($"- added coercion rule from '{original.Name}' to '{casting.Name}'");
}
/// <summary>
/// Adds a coercion rule.
/// </summary>
/// <typeparam name="TOriginalType"></typeparam>
/// <typeparam name="TCastingType"></typeparam>
/// <param name="kind"></param>
/// <param name="cast"></param>
public void AddCoercionRule <TOriginalType, TCastingType>(CoercionKind kind, Func <TOriginalType, TCastingType> cast)
{
typeSystem.AddCoercionRule(kind, cast);
}