/// <summary> /// Defers the binding of the operation until later time when the runtime values of all dynamic operation arguments have been computed. /// </summary> /// <param name="args">An array of arguments of the dynamic operation.</param> /// <returns>The <see cref="DynamicMetaObject"/> representing the result of the binding.</returns> public DynamicMetaObject Defer(params DynamicMetaObject[] args) { return(MakeDeferred(BindingRestrictions.Combine(args), args)); }
/// <summary> /// Performs the runtime binding of the dynamic operation on a set of arguments. /// </summary> /// <param name="args">An array of arguments to the dynamic operation.</param> /// <param name="parameters">The array of <see cref="ParameterExpression"/> instances that represent the parameters of the call site in the binding process.</param> /// <param name="returnLabel">A LabelTarget used to return the result of the dynamic binding.</param> /// <returns> /// An Expression that performs tests on the dynamic operation arguments, and /// performs the dynamic operation if the tests are valid. If the tests fail on /// subsequent occurrences of the dynamic operation, Bind will be called again /// to produce a new <see cref="Expression"/> for the new argument types. /// </returns> public sealed override Expression Bind(object[] args, ReadOnlyCollection <ParameterExpression> parameters, LabelTarget returnLabel) { ContractUtils.RequiresNotNull(args, "args"); ContractUtils.RequiresNotNull(parameters, "parameters"); ContractUtils.RequiresNotNull(returnLabel, "returnLabel"); if (args.Length == 0) { throw Error.OutOfRange("args.Length", 1); } if (parameters.Count == 0) { throw Error.OutOfRange("parameters.Count", 1); } if (args.Length != parameters.Count) { throw new ArgumentOutOfRangeException("args"); } // Ensure that the binder's ReturnType matches CallSite's return // type. We do this so meta objects and language binders can // compose trees together without needing to insert converts. Type expectedResult; if (IsStandardBinder) { expectedResult = ReturnType; if (returnLabel.Type != typeof(void) && !TypeUtils.AreReferenceAssignable(returnLabel.Type, expectedResult)) { throw Error.BinderNotCompatibleWithCallSite(expectedResult, this, returnLabel.Type); } } else { // Even for non-standard binders, we have to at least make sure // it works with the CallSite's type to build the return. expectedResult = returnLabel.Type; } DynamicMetaObject target = DynamicMetaObject.Create(args[0], parameters[0]); DynamicMetaObject[] metaArgs = CreateArgumentMetaObjects(args, parameters); DynamicMetaObject binding = Bind(target, metaArgs); if (binding == null) { throw Error.BindingCannotBeNull(); } Expression body = binding.Expression; BindingRestrictions restrictions = binding.Restrictions; // Ensure the result matches the expected result type. if (expectedResult != typeof(void) && !TypeUtils.AreReferenceAssignable(expectedResult, body.Type)) { // // Blame the last person that handled the result: assume it's // the dynamic object (if any), otherwise blame the language. // if (target.Value is IDynamicMetaObjectProvider) { throw Error.DynamicObjectResultNotAssignable(body.Type, target.Value.GetType(), this, expectedResult); } else { throw Error.DynamicBinderResultNotAssignable(body.Type, this, expectedResult); } } // if the target is IDO, standard binders ask it to bind the rule so we may have a target-specific binding. // it makes sense to restrict on the target's type in such cases. // ideally IDO metaobjects should do this, but they often miss that type of "this" is significant. if (IsStandardBinder && args[0] as IDynamicMetaObjectProvider != null) { if (restrictions == BindingRestrictions.Empty) { throw Error.DynamicBindingNeedsRestrictions(target.Value.GetType(), this); } } restrictions = AddRemoteObjectRestrictions(restrictions, args, parameters); // Add the return if (body.NodeType != ExpressionType.Goto) { body = Expression.Return(returnLabel, body); } // Finally, add restrictions if (restrictions != BindingRestrictions.Empty) { body = Expression.IfThen(restrictions.ToExpression(), body); } return(body); }
/// <summary> /// Returns a Restrictions object which includes our current restrictions merged /// with a restriction limiting our type /// </summary> private BindingRestrictions GetRestrictions() { Debug.Assert(Restrictions == BindingRestrictions.Empty, "We don't merge, restrictions are always empty"); return(BindingRestrictions.GetTypeRestriction(this)); }