/// <summary>
/// Gets a "meta" operation on this userdata. If a descriptor does not support this functionality,
/// it should return "null" (not a nil).
/// See <see cref="IUserDataDescriptor.MetaIndex" /> for further details.
///
/// If a method exists marked with <see cref="MoonSharpUserDataMetamethodAttribute" /> for the specific
/// metamethod requested, that method is returned.
///
/// If the above fails, the following dispatching occur:
///
/// __add, __sub, __mul, __div, __mod and __unm are dispatched to C# operator overloads (if they exist)
/// __eq is dispatched to System.Object.Equals.
/// __lt and __le are dispatched IComparable.Compare, if the type implements IComparable or IComparable{object}
/// __len is dispatched to Length and Count properties, if those exist.
/// __iterator is handled if the object implements IEnumerable or IEnumerator.
/// __tonumber is dispatched to implicit or explicit conversion operators to standard numeric types.
/// __tobool is dispatched to an implicit or explicit conversion operator to bool. If that fails, operator true is used.
///
/// <param name="script">The script originating the request</param>
/// <param name="obj">The object (null if a static request is done)</param>
/// <param name="metaname">The name of the metamember.</param>
/// </summary>
/// <returns></returns>
public virtual DynValue MetaIndex(Script script, object obj, string metaname)
{
IMemberDescriptor desc = m_MetaMembers.GetOrDefault(metaname);
if (desc != null)
{
return(desc.GetValue(script, obj));
}
switch (metaname)
{
case "__add":
return(DispatchMetaOnMethod(script, obj, "op_Addition"));
case "__sub":
return(DispatchMetaOnMethod(script, obj, "op_Subtraction"));
case "__mul":
return(DispatchMetaOnMethod(script, obj, "op_Multiply"));
case "__div":
return(DispatchMetaOnMethod(script, obj, "op_Division"));
case "__mod":
return(DispatchMetaOnMethod(script, obj, "op_Modulus"));
case "__unm":
return(DispatchMetaOnMethod(script, obj, "op_UnaryNegation"));
case "__eq":
return(MultiDispatchEqual(script, obj));
case "__lt":
return(MultiDispatchLessThan(script, obj));
case "__le":
return(MultiDispatchLessThanOrEqual(script, obj));
case "__len":
return(TryDispatchLength(script, obj));
case "__tonumber":
return(TryDispatchToNumber(script, obj));
case "__tobool":
return(TryDispatchToBool(script, obj));
case "__iterator":
return(ClrToScriptConversions.EnumerationToDynValue(script, obj));
default:
return(null);
}
}
private DynValue DispatchMetaOnMethod(Script script, object obj, string methodName)
{
IMemberDescriptor desc = m_Members.GetOrDefault(methodName);
if (desc != null)
{
return(desc.GetValue(script, obj));
}
else
{
return(null);
}
}
/// <summary>
/// Executes the specified indexer method.
/// </summary>
/// <param name="ecToken">The execution control token used to cancel scripts if needed.</param>
/// <param name="mdesc">The method descriptor</param>
/// <param name="script">The script.</param>
/// <param name="obj">The object.</param>
/// <param name="index">The indexer parameter</param>
/// <param name="value">The dynvalue to set on a setter, or null.</param>
/// <exception cref="System.NotImplementedException"></exception>
protected virtual DynValue ExecuteIndexer(ExecutionControlToken ecToken, IMemberDescriptor mdesc, Script script,
object obj, DynValue index, DynValue value)
{
IList <DynValue> values;
if (index.Type == DataType.Tuple)
{
if (value == null)
{
values = index.Tuple;
}
else
{
values = new List <DynValue>(index.Tuple);
values.Add(value);
}
}
else
{
if (value == null)
{
values = new[] { index };
}
else
{
values = new[] { index, value };
}
}
var args = new CallbackArguments(values, false);
var execCtx = script.CreateDynamicExecutionContext(ecToken);
var v = mdesc.GetValue(script, obj);
if (v.Type != DataType.ClrFunction)
{
throw new ScriptRuntimeException("a clr callback was expected in member {0}, while a {1} was found",
mdesc.Name, v.Type);
}
return(v.Callback.ClrCallback(execCtx, args));
}
/// <summary>
/// Gets the getter of the member as a DynValue containing a callback
/// </summary>
/// <param name="desc">The descriptor instance.</param>
/// <param name="script">The script.</param>
/// <param name="obj">The object.</param>
/// <returns></returns>
public static DynValue GetGetterCallbackAsDynValue(this IMemberDescriptor desc, Script script, object obj)
{
return(DynValue.NewCallback((p1, p2) => desc.GetValue(script, obj)));
}
/// <summary>
/// Executes the specified indexer method.
/// </summary>
/// <param name="mdesc">The method descriptor</param>
/// <param name="script">The script.</param>
/// <param name="obj">The object.</param>
/// <param name="index">The indexer parameter</param>
/// <param name="value">The dynvalue to set on a setter, or null.</param>
/// <returns></returns>
/// <exception cref="System.NotImplementedException"></exception>
protected virtual DynValue ExecuteIndexer(IMemberDescriptor mdesc, Script script, object obj, DynValue index, DynValue value)
{
IList<DynValue> values;
if (index.Type == DataType.Tuple)
{
if (value == null)
{
values = index.Tuple;
}
else
{
values = new List<DynValue>(index.Tuple);
values.Add(value);
}
}
else
{
if (value == null)
{
values = new DynValue[] { index };
}
else
{
values = new DynValue[] { index, value };
}
}
CallbackArguments args = new CallbackArguments(values, false);
ScriptExecutionContext execCtx = script.CreateDynamicExecutionContext();
DynValue v = mdesc.GetValue(script, obj);
if (v.Type != DataType.ClrFunction)
throw new ScriptRuntimeException("a clr callback was expected in member {0}, while a {1} was found", mdesc.Name, v.Type);
return v.Callback.ClrCallback(execCtx, args);
}
