delegate.cs

C#编译器源代码。Micorsoft开放源代码

			int arg_count;

			if (args == null)
				arg_count = 0;
			else
				arg_count = args.Count;

			Expression ml = Expression.MemberLookup (
				ec, delegate_type, "Invoke", loc);

			MethodGroupExpr me = ml as MethodGroupExpr;
			if (me == null) {
				Report.Error (-100, loc, "Internal error: could not find Invoke method!" + delegate_type);
				return false;
			}
			
			MethodBase mb = me.Methods [0];
			ParameterData pd = TypeManager.GetParameterData (mb);

			int pd_count = pd.Count;

			bool params_method = (pd_count != 0) &&
				(pd.ParameterModifier (pd_count - 1) == Parameter.Modifier.PARAMS);

			bool is_params_applicable = false;
			bool is_applicable = Invocation.IsApplicable (ec, me, args, arg_count, ref mb);

			if (!is_applicable && params_method &&
			    Invocation.IsParamsMethodApplicable (ec, me, args, arg_count, ref mb))
				is_applicable = is_params_applicable = true;

			if (!is_applicable && !params_method && arg_count != pd_count) {
				Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
					TypeManager.CSharpName (delegate_type), arg_count);
				return false;
			}

			return Invocation.VerifyArgumentsCompat (
					ec, args, arg_count, mb, 
					is_params_applicable || (!is_applicable && params_method),
					delegate_type, false, loc);
		}
		
		/// <summary>
		///  Verifies whether the delegate in question is compatible with this one in
		///  order to determine if instantiation from the same is possible.
		/// </summary>
		public static bool VerifyDelegate (EmitContext ec, Type delegate_type, Type probe_type, Location loc)
		{
			Expression ml = Expression.MemberLookup (
				ec, delegate_type, "Invoke", loc);
			
			if (!(ml is MethodGroupExpr)) {
				Report.Error (-100, loc, "Internal error: could not find Invoke method!");
				return false;
			}
			
			MethodBase mb = ((MethodGroupExpr) ml).Methods [0];
			ParameterData pd = TypeManager.GetParameterData (mb);

			Expression probe_ml = Expression.MemberLookup (
				ec, delegate_type, "Invoke", loc);
			
			if (!(probe_ml is MethodGroupExpr)) {
				Report.Error (-100, loc, "Internal error: could not find Invoke method!");
				return false;
			}
			
			MethodBase probe_mb = ((MethodGroupExpr) probe_ml).Methods [0];
			ParameterData probe_pd = TypeManager.GetParameterData (probe_mb);
			
			if (((MethodInfo) mb).ReturnType != ((MethodInfo) probe_mb).ReturnType)
				return false;

			if (pd.Count != probe_pd.Count)
				return false;

			for (int i = pd.Count; i > 0; ) {
				i--;

				if (pd.ParameterType (i) != probe_pd.ParameterType (i) ||
				    pd.ParameterModifier (i) != probe_pd.ParameterModifier (i))
					return false;
			}
			
			return true;
		}
		
		public static string FullDelegateDesc (Type del_type, MethodBase mb, ParameterData pd)
		{
			StringBuilder sb = new StringBuilder ();
			sb.Append (TypeManager.CSharpName (((MethodInfo) mb).ReturnType));
			sb.Append (" ");
			sb.Append (TypeManager.CSharpName (del_type));
			sb.Append (pd.GetSignatureForError ());
			return sb.ToString ();			
		}
		
		// Hack around System.Reflection as found everywhere else
		public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
							MemberFilter filter, object criteria)
		{
			ArrayList members = new ArrayList ();

			if ((mt & MemberTypes.Method) != 0) {
				if (ConstructorBuilder != null)
				if (filter (ConstructorBuilder, criteria))
					members.Add (ConstructorBuilder);

				if (InvokeBuilder != null)
				if (filter (InvokeBuilder, criteria))
					members.Add (InvokeBuilder);

				if (BeginInvokeBuilder != null)
				if (filter (BeginInvokeBuilder, criteria))
					members.Add (BeginInvokeBuilder);

				if (EndInvokeBuilder != null)
				if (filter (EndInvokeBuilder, criteria))
					members.Add (EndInvokeBuilder);
			}

			return new MemberList (members);
		}

		public override MemberCache MemberCache {
			get {
				return null;
			}
		}

		public Expression InstanceExpression {
			get {
				return instance_expr;
			}
			set {
				instance_expr = value;
			}
		}

		public MethodBase TargetMethod {
			get {
				return delegate_method;
			}
			set {
				delegate_method = value;
			}
		}

		public Type TargetReturnType {
			get {
				return ret_type;
			}
		}

		public Type [] ParameterTypes {
			get {
				return param_types;
			}
		}

		public override AttributeTargets AttributeTargets {
			get {
				return AttributeTargets.Delegate;
			}
		}

		//
		//   Represents header string for documentation comment.
		//
		public override string DocCommentHeader {
			get { return "T:"; }
		}

	}

	//
	// Base class for `NewDelegate' and `ImplicitDelegateCreation'
	//
	public abstract class DelegateCreation : Expression {
		protected MethodBase constructor_method;
		protected MethodBase delegate_method;
		protected MethodGroupExpr method_group;
		protected Expression delegate_instance_expression;

		public DelegateCreation () {}

		public static void Error_NoMatchingMethodForDelegate (EmitContext ec, MethodGroupExpr mg, Type type, Location loc)
		{
			string method_desc;
			MethodInfo found_method = (MethodInfo)mg.Methods [0];
			
			if (mg.Methods.Length > 1)
				method_desc = found_method.Name;
			else
				method_desc = Invocation.FullMethodDesc (found_method);

			Expression invoke_method = Expression.MemberLookup (
				ec, type, "Invoke", MemberTypes.Method,
				Expression.AllBindingFlags, loc);
			MethodInfo method = ((MethodGroupExpr) invoke_method).Methods [0] as MethodInfo;

			ParameterData param = TypeManager.GetParameterData (method);
			string delegate_desc = Delegate.FullDelegateDesc (type, method, param);

			if (method.ReturnType != found_method.ReturnType) {
				Report.Error (407, loc, "`{0}' has the wrong return type to match the delegate `{1}'", method_desc, delegate_desc);
			} else {
				Report.Error (123, loc, "Method `{0}' does not match delegate `{1}'", method_desc, delegate_desc);
			}
		}
		
		public override void Emit (EmitContext ec)
		{
			if (delegate_instance_expression == null || delegate_method.IsStatic)
				ec.ig.Emit (OpCodes.Ldnull);
			else
				delegate_instance_expression.Emit (ec);
			
			if (delegate_method.IsVirtual && !method_group.IsBase) {
				ec.ig.Emit (OpCodes.Dup);
				ec.ig.Emit (OpCodes.Ldvirtftn, (MethodInfo) delegate_method);
			} else
				ec.ig.Emit (OpCodes.Ldftn, (MethodInfo) delegate_method);
			ec.ig.Emit (OpCodes.Newobj, (ConstructorInfo) constructor_method);
		}

		protected bool ResolveConstructorMethod (EmitContext ec)
		{
			Expression ml = Expression.MemberLookup (
				ec, type, ".ctor", loc);

			if (!(ml is MethodGroupExpr)) {
				Report.Error (-100, loc, "Internal error: Could not find delegate constructor!");
				return false;
			}

			constructor_method = ((MethodGroupExpr) ml).Methods [0];
			return true;
		}

		protected Expression ResolveMethodGroupExpr (EmitContext ec, MethodGroupExpr mg,
							     bool check_only)
		{
			foreach (MethodInfo mi in mg.Methods){
				delegate_method  = Delegate.VerifyMethod (ec, type, mi, loc);
				
				if (delegate_method != null)
					break;
			}
			
			if (delegate_method == null) {
				if (!check_only)
					Error_NoMatchingMethodForDelegate (ec, mg, type, loc);
				return null;
			}
			
			//
			// Check safe/unsafe of the delegate
			//
			if (!ec.InUnsafe){
				ParameterData param = TypeManager.GetParameterData (delegate_method);
				int count = param.Count;
				
				for (int i = 0; i < count; i++){
					if (param.ParameterType (i).IsPointer){
						Expression.UnsafeError (loc);
						return null;
					}
				}
			}
			
			//TODO: implement caching when performance will be low
			IMethodData md = TypeManager.GetMethod (delegate_method);
			if (md == null) {
				if (System.Attribute.GetCustomAttribute (delegate_method, TypeManager.conditional_attribute_type) != null) {
					Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute", TypeManager.CSharpSignature (delegate_method));
				}
			} else {
				md.SetMemberIsUsed ();
				if (md.OptAttributes != null && md.OptAttributes.Search (TypeManager.conditional_attribute_type, ec) != null) {
					Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute", TypeManager.CSharpSignature (delegate_method));
				}
			}
			
			if (mg.InstanceExpression != null)
				delegate_instance_expression = mg.InstanceExpression.Resolve (ec);
			else if (ec.IsStatic) {
				if (!delegate_method.IsStatic) {
					Report.Error (120, loc, "`{0}': An object reference is required for the nonstatic field, method or property",
						      TypeManager.CSharpSignature (delegate_method));
					return null;
				}
				delegate_instance_expression = null;
			} else
				delegate_instance_expression = ec.GetThis (loc);
			
			if (delegate_instance_expression != null && delegate_instance_expression.Type.IsValueType)
				delegate_instance_expression = new BoxedCast (
					delegate_instance_expression, TypeManager.object_type);
			
			method_group = mg;
			eclass = ExprClass.Value;
			return this;
		}
	}

	//
	// Created from the conversion code
	//
	public class ImplicitDelegateCreation : DelegateCreation {

		ImplicitDelegateCreation (Type t, Location l)
		{
			type = t;
			loc = l;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			return this;
		}

		static public Expression Create (EmitContext ec, MethodGroupExpr mge,
						 Type target_type, bool check_only, Location loc)
		{
			ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, loc);
			if (d.ResolveConstructorMethod (ec))
				return d.ResolveMethodGroupExpr (ec, mge, check_only);
			else
				return null;
		}
	}

	//
	// A delegate-creation-expression, invoked from the `New' class 
	//
	public class NewDelegate : DelegateCreation {
		public ArrayList Arguments;

		//
		// This constructor is invoked from the `New' expression
		//
		public NewDelegate (Type type, ArrayList Arguments, Location loc)
		{
			this.type = type;
			this.Arguments = Arguments;
			this.loc  = loc; 
		}

		public override Expression DoResolve (EmitContext ec)
		{
			if (Arguments == null || Arguments.Count != 1) {
				Report.Error (149, loc,
					      "Method name expected");
				return null;
			}

			if (!ResolveConstructorMethod (ec))
				return null;

			Argument a = (Argument) Arguments [0];

			if (!a.ResolveMethodGroup (ec, loc))
				return null;
			
			Expression e = a.Expr;

			if (e is AnonymousMethod && RootContext.Version != LanguageVersion.ISO_1)
				return ((AnonymousMethod) e).Compatible (ec, type, false);

			MethodGroupExpr mg = e as MethodGroupExpr;
			if (mg != null)
				return ResolveMethodGroupExpr (ec, mg, false);

			Type e_type = e.Type;

			if (!TypeManager.IsDelegateType (e_type)) {
				Report.Error (149, loc, "Method name expected");
				return null;
			}

			method_group = Expression.MemberLookup (
				ec, type, "Invoke", MemberTypes.Method,
				Expression.AllBindingFlags, loc) as MethodGroupExpr;

			if (method_group == null) {
				Report.Error (-200, loc, "Internal error ! Could not find Invoke method!");
				return null;
			}

			// This is what MS' compiler reports. We could always choose
			// to be more verbose and actually give delegate-level specifics			
			if (!Delegate.VerifyDelegate (ec, type, e_type, loc)) {
				Report.Error (29, loc, "Cannot implicitly convert type '" + e_type + "' " +
					      "to type '" + type + "'");
				return null;
			}
				
			delegate_instance_expression = e;
			delegate_method = method_group.Methods [0];
			
			eclass = ExprClass.Value;
			return this;
		}
	}

	public class DelegateInvocation : ExpressionStatement {

		public Expression InstanceExpr;
		public ArrayList  Arguments;

		MethodBase method;
		
		public DelegateInvocation (Expression instance_expr, ArrayList args, Location loc)
		{
			this.InstanceExpr = instance_expr;
			this.Arguments = args;
			this.loc = loc;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			if (InstanceExpr is EventExpr) {
				
				EventInfo ei = ((EventExpr) InstanceExpr).EventInfo;
				
				Expression ml = MemberLookup (
					ec, ec.ContainerType, ei.Name,
					MemberTypes.Event, AllBindingFlags | BindingFlags.DeclaredOnly, loc);

				if (ml == null) {
				        //
					// If this is the case, then the Event does not belong 
					// to this Type and so, according to the spec
					// cannot be accessed directly
					//
					// Note that target will not appear as an EventExpr
					// in the case it is being referenced within the same type container;
					// it will appear as a FieldExpr in that case.
					//
					
					Assign.error70 (ei, loc);
					return null;
				}
			}
			
			
			Type del_type = InstanceExpr.Type;
			if (del_type == null)
				return null;
			
			if (Arguments != null){
				foreach (Argument a in Arguments){
					if (!a.Resolve (ec, loc))
						return null;
				}
			}
			
			if (!Delegate.VerifyApplicability (ec, del_type, Arguments, loc))
				return null;

			Expression lookup = Expression.MemberLookup (ec, del_type, "Invoke", loc);
			if (!(lookup is MethodGroupExpr)) {
				Report.Error (-100, loc, "Internal error: could not find Invoke method!");
				return null;
			}
			
			method = ((MethodGroupExpr) lookup).Methods [0];
			type = ((MethodInfo) method).ReturnType;
			eclass = ExprClass.Value;
			
			return this;
		}

		public override void Emit (EmitContext ec)
		{
			//
			// Invocation on delegates call the virtual Invoke member
			// so we are always `instance' calls
			//
			Invocation.EmitCall (ec, false, false, InstanceExpr, method, Arguments, loc);
		}

		public override void EmitStatement (EmitContext ec)
		{
			Emit (ec);
			// 
			// Pop the return value if there is one
			//
			if (method is MethodInfo){
				if (((MethodInfo) method).ReturnType != TypeManager.void_type)
					ec.ig.Emit (OpCodes.Pop);
			}
		}

	}
}