C# BlockContext.EndFlowBranching方法代碼示例

		public override bool Resolve (BlockContext ec)
		{
			bool ok = true;

			expr = expr.Resolve (ec);
			if (expr == null)
				ok = false;

			//
			// Inform whether we are infinite or not
			//
			if (expr is Constant){
				bool value = !((Constant) expr).IsDefaultValue;

				if (value == false){
					if (!Statement.ResolveUnreachable (ec, true))
						return false;
					empty = true;
					return true;
				} else
					infinite = true;
			}

			ec.StartFlowBranching (FlowBranching.BranchingType.Loop, loc);
			if (!infinite)
				ec.CurrentBranching.CreateSibling ();

			ec.StartFlowBranching (FlowBranching.BranchingType.Embedded, loc);
			if (!Statement.Resolve (ec))
				ok = false;
			ec.EndFlowBranching ();

			// There's no direct control flow from the end of the embedded statement to the end of the loop
			ec.CurrentBranching.CurrentUsageVector.Goto ();

			ec.EndFlowBranching ();

			return ok;
		}

		public override bool Resolve (BlockContext ec)
		{
			Block prev_block = ec.CurrentBlock;
			bool ok = true;

			int errors = ec.Report.Errors;

			ec.CurrentBlock = this;
			ec.StartFlowBranching (this);

			Report.Debug (4, "RESOLVE BLOCK", StartLocation, ec.CurrentBranching);

			//
			// Compiler generated scope statements
			//
			if (scope_initializers != null) {
				foreach (Statement s in scope_initializers)
					s.Resolve (ec);
			}

			//
			// This flag is used to notate nested statements as unreachable from the beginning of this block.
			// For the purposes of this resolution, it doesn't matter that the whole block is unreachable 
			// from the beginning of the function.  The outer Resolve() that detected the unreachability is
			// responsible for handling the situation.
			//
			int statement_count = statements.Count;
			for (int ix = 0; ix < statement_count; ix++){
				Statement s = (Statement) statements [ix];
				if (s == null)
					continue; 
				
				// Check possible empty statement (CS0642)
				if (ix + 1 < statement_count && ec.Report.WarningLevel >= 3 &&
					statements [ix + 1] is ExplicitBlock)
					CheckPossibleMistakenEmptyStatement (ec, s);

				//
				// Warn if we detect unreachable code.
				//
				if (unreachable) {
					if (s is EmptyStatement)
						continue;

					if (!unreachable_shown && !(s is LabeledStatement)) {
						ec.Report.Warning (162, 2, s.loc, "Unreachable code detected");
						unreachable_shown = true;
					}

					Block c_block = s as Block;
					if (c_block != null)
						c_block.unreachable = c_block.unreachable_shown = true;
				}

				//
				// Note that we're not using ResolveUnreachable() for unreachable
				// statements here.  ResolveUnreachable() creates a temporary
				// flow branching and kills it afterwards.  This leads to problems
				// if you have two unreachable statements where the first one
				// assigns a variable and the second one tries to access it.
				//

				if (!s.Resolve (ec)) {
					ok = false;
					if (ec.IsInProbingMode)
						break;

					statements [ix] = EmptyStatement.Value;
					continue;
				}

				if (unreachable && !(s is LabeledStatement) && !(s is Block))
					statements [ix] = EmptyStatement.Value;

				unreachable = ec.CurrentBranching.CurrentUsageVector.IsUnreachable;
				if (unreachable && s is LabeledStatement)
					throw new InternalErrorException ("should not happen");
			}

			Report.Debug (4, "RESOLVE BLOCK DONE", StartLocation,
				      ec.CurrentBranching, statement_count);

			while (ec.CurrentBranching is FlowBranchingLabeled)
				ec.EndFlowBranching ();

			bool flow_unreachable = ec.EndFlowBranching ();

			ec.CurrentBlock = prev_block;

			if (flow_unreachable)
				flags |= Flags.HasRet;

			// If we're a non-static `struct' constructor which doesn't have an
			// initializer, then we must initialize all of the struct's fields.
			if (this == Toplevel && !Toplevel.IsThisAssigned (ec) && !flow_unreachable)
				ok = false;

			if ((labels != null) && (ec.Report.WarningLevel >= 2)) {
				foreach (LabeledStatement label in labels.Values)
					if (!label.HasBeenReferenced)
//.........這裏部分代碼省略.........

//.........這裏部分代碼省略.........
				// but the production on the grammar is more concise.
				//
				// So we have to enforce these rules here.
				//
				// We do not resolve before doing the case 1 test,
				// because the grammar is explicit in that the token &
				// is present, so we need to test for this particular case.
				//

				if (e is Cast){
					ec.Report.Error (254, loc, "The right hand side of a fixed statement assignment may not be a cast expression");
					return false;
				}

				using (ec.Set (ResolveContext.Options.FixedInitializerScope)) {
					e = e.Resolve (ec);
				}

				if (e == null)
					return false;

				//
				// Case 2: Array
				//
				if (e.Type.IsArray){
					TypeSpec array_type = TypeManager.GetElementType (e.Type);
					
					//
					// Provided that array_type is unmanaged,
					//
					if (!TypeManager.VerifyUnmanaged (ec.Compiler, array_type, loc))
						return false;

					//
					// and T* is implicitly convertible to the
					// pointer type given in the fixed statement.
					//
					ArrayPtr array_ptr = new ArrayPtr (e, array_type, loc);
					
					Expression converted = Convert.ImplicitConversionRequired (
						ec, array_ptr, vi.VariableType, loc);
					if (converted == null)
						return false;
					
					//
					// fixed (T* e_ptr = (e == null || e.Length == 0) ? null : converted [0])
					//
					converted = new Conditional (new BooleanExpression (new Binary (Binary.Operator.LogicalOr,
						new Binary (Binary.Operator.Equality, e, new NullLiteral (loc), loc),
						new Binary (Binary.Operator.Equality, new MemberAccess (e, "Length"), new IntConstant (0, loc), loc), loc)),
							new NullPointer (loc),
							converted, loc);

					converted = converted.Resolve (ec);					

					data [i] = new ExpressionEmitter (converted, vi);
					i++;

					continue;
				}

				//
				// Case 3: string
				//
				if (e.Type == TypeManager.string_type){
					data [i] = new StringEmitter (e, vi, loc).Resolve (ec);
					i++;
					continue;
				}

				// Case 4: fixed buffer
				if (e is FixedBufferPtr) {
					data [i++] = new ExpressionEmitter (e, vi);
					continue;
				}

				//
				// Case 1: & object.
				//
				Unary u = e as Unary;
				if (u != null && u.Oper == Unary.Operator.AddressOf) {
					IVariableReference vr = u.Expr as IVariableReference;
					if (vr == null || !vr.IsFixed) {
						data [i] = new ExpressionEmitter (e, vi);
					}
				}

				if (data [i++] == null)
					ec.Report.Error (213, vi.Location, "You cannot use the fixed statement to take the address of an already fixed expression");

				e = Convert.ImplicitConversionRequired (ec, e, expr_type, loc);
			}

			ec.StartFlowBranching (FlowBranching.BranchingType.Conditional, loc);
			bool ok = statement.Resolve (ec);
			bool flow_unreachable = ec.EndFlowBranching ();
			has_ret = flow_unreachable;

			return ok;
		}

		public override bool Resolve (BlockContext ec)
		{
			expr = expr.Resolve (ec);
			if (expr == null)
				return false;

			if (!TypeManager.IsReferenceType (expr.Type)){
				ec.Report.Error (185, loc,
					"`{0}' is not a reference type as required by the lock statement",
					expr.Type.GetSignatureForError ());
			}

			if (expr.Type.IsGenericParameter) {
				expr = Convert.ImplicitTypeParameterConversion (expr, TypeManager.object_type);
			}

			VariableReference lv = expr as VariableReference;
			bool locked;
			if (lv != null) {
				locked = lv.IsLockedByStatement;
				lv.IsLockedByStatement = true;
			} else {
				lv = null;
				locked = false;
			}

			ec.StartFlowBranching (this);
			Statement.Resolve (ec);
			ec.EndFlowBranching ();

			if (lv != null) {
				lv.IsLockedByStatement = locked;
			}

			base.Resolve (ec);

			//
			// Have to keep original lock value around to unlock same location
			// in the case the original has changed or is null
			//
			expr_copy = TemporaryVariableReference.Create (TypeManager.object_type, ec.CurrentBlock.Parent, loc);
			expr_copy.Resolve (ec);

			//
			// Ensure Monitor methods are available
			//
			if (ResolvePredefinedMethods (ec) > 1) {
				lock_taken = TemporaryVariableReference.Create (TypeManager.bool_type, ec.CurrentBlock.Parent, loc);
				lock_taken.Resolve (ec);
			}

			return true;
		}

		protected override Expression DoResolve (ResolveContext ec)
		{
			IteratorHost = (IteratorStorey) block.TopBlock.AnonymousMethodStorey;

			BlockContext ctx = new BlockContext (ec, block, ReturnType);
			ctx.CurrentAnonymousMethod = this;

			ctx.StartFlowBranching (this, ec.CurrentBranching);
			Block.Resolve (ctx);
			ctx.EndFlowBranching ();

			var move_next = new IteratorMethod (IteratorHost, new TypeExpression (TypeManager.bool_type, loc),
				Modifiers.PUBLIC, new MemberName ("MoveNext", Location));
			move_next.Block.AddStatement (new MoveNextMethodStatement (this));
			IteratorHost.AddMethod (move_next);

			eclass = ExprClass.Value;
			return this;
		}

 public override bool Resolve(BlockContext ec)
 {
     ec.StartFlowBranching (iterator);
     bool ok = original_block.Resolve (ec);
     ec.EndFlowBranching ();
     return ok;
 }