public override object VisitAssignmentExpr([NotNull] ChessVCParser.AssignmentExprContext context)
{
string s = context.GetText();
var rhsNode = context.assignmentExpr();
if (rhsNode != null)
{
object lhs = Visit(context.conditionalExpr());
if (lhs == null || !(lhs is Reference))
{
throw new Exception("Attempt to assign to object without l-value");
}
object rhs = deref(Visit(rhsNode));
Type assignType = ((Reference)lhs).EffectiveType;
if (rhs.GetType() != assignType && !rhs.GetType().IsSubclassOf(assignType))
{
// First check - if we're assigning a string to a ChoiceVariable, we
// will automatically assign it to it's Value member. This makes cleaner
// code as we don't need to put ".Value" all over the place.
if (assignType == typeof(ChoiceVariable) && rhs is string)
{
return(((ChoiceVariable)(((Reference)lhs).GetValue())).Value = (string)rhs);
}
// We can't directly assign = however, we may be able to construct a new object
// if the type to be assigned contains a constructor with a single argument
// of the type supplied on the right-hand-side.
var constructors = assignType.GetConstructors();
foreach (ConstructorInfo ci in constructors)
{
var parameters = ci.GetParameters();
if (parameters.Length == 1)
{
if (rhs.GetType() == parameters[0].ParameterType ||
parameters[0].ParameterType.IsSubclassOf(assignType))
{
// types compatible - we can perform constructon
((Reference)lhs).SetValue(ci.Invoke(new object[] { rhs }));
return(lhs);
}
}
}
throw new Exception("Incompatable types for assignment");
}
((Reference)lhs).SetValue(rhs);
return(lhs);
}
return(base.VisitAssignmentExpr(context));
}
/// <summary>
/// Visit a parse tree produced by <see cref="ChessVCParser.assignmentExpr"/>.
/// <para>
/// The default implementation returns the result of calling <see cref="AbstractParseTreeVisitor{Result}.VisitChildren(IRuleNode)"/>
/// on <paramref name="context"/>.
/// </para>
/// </summary>
/// <param name="context">The parse tree.</param>
/// <return>The visitor result.</return>
public virtual Result VisitAssignmentExpr([NotNull] ChessVCParser.AssignmentExprContext context)
{
return(VisitChildren(context));
}
/// <summary>
/// Exit a parse tree produced by <see cref="ChessVCParser.assignmentExpr"/>.
/// <para>The default implementation does nothing.</para>
/// </summary>
/// <param name="context">The parse tree.</param>
public virtual void ExitAssignmentExpr([NotNull] ChessVCParser.AssignmentExprContext context)
{
}
