expression.cs

C#编译器源代码。Micorsoft开放源代码

				// A plus in front of something is just a no-op, so return the child.
				//
				return Expr;

			case Operator.UnaryNegation:
				//
				// Deals with -literals
				// int     operator- (int x)
				// long    operator- (long x)
				// float   operator- (float f)
				// double  operator- (double d)
				// decimal operator- (decimal d)
				//
				Expression expr = null;

				//
				// transform - - expr into expr
				//
				if (Expr is Unary){
					Unary unary = (Unary) Expr;
					
					if (unary.Oper == Operator.UnaryNegation)
						return unary.Expr;
				}

				//
				// perform numeric promotions to int,
				// long, double.
				//
				//
				// The following is inneficient, because we call
				// ImplicitConversion too many times.
				//
				// It is also not clear if we should convert to Float
				// or Double initially.
				//
				if (expr_type == TypeManager.uint32_type){
					//
					// FIXME: handle exception to this rule that
					// permits the int value -2147483648 (-2^31) to
					// bt wrote as a decimal interger literal
					//
					type = TypeManager.int64_type;
					Expr = Convert.ImplicitConversion (ec, Expr, type, loc);
					return this;
				}

				if (expr_type == TypeManager.uint64_type){
					//
					// FIXME: Handle exception of `long value'
					// -92233720368547758087 (-2^63) to be wrote as
					// decimal integer literal.
					//
					Error23 (expr_type);
					return null;
				}

				if (expr_type == TypeManager.float_type){
					type = expr_type;
					return this;
				}
				
				expr = Convert.ImplicitConversion (ec, Expr, TypeManager.int32_type, loc);
				if (expr != null){
					Expr = expr;
					type = expr.Type;
					return this;
				} 

				expr = Convert.ImplicitConversion (ec, Expr, TypeManager.int64_type, loc);
				if (expr != null){
					Expr = expr;
					type = expr.Type;
					return this;
				}

				expr = Convert.ImplicitConversion (ec, Expr, TypeManager.double_type, loc);
				if (expr != null){
					Expr = expr;
					type = expr.Type;
					return this;
				}
				
				Error23 (expr_type);
				return null;
			}

			Error (187, "No such operator '" + OperName (Oper) + "' defined for type '" +
			       TypeManager.CSharpName (expr_type) + "'");
			return null;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			if (Oper == Operator.AddressOf) {
				Expr = Expr.DoResolveLValue (ec, new EmptyExpression ());

				if (Expr == null || Expr.eclass != ExprClass.Variable){
					Error (211, "Cannot take the address of the given expression");
					return null;
				}
			}
			else
				Expr = Expr.Resolve (ec);
			
			if (Expr == null)
				return null;

			eclass = ExprClass.Value;
			return ResolveOperator (ec);
		}

		public override Expression DoResolveLValue (EmitContext ec, Expression right)
		{
			if (Oper == Operator.Indirection)
				return DoResolve (ec);

			return null;
		}

		public override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			
			switch (Oper) {
			case Operator.UnaryPlus:
				throw new Exception ("This should be caught by Resolve");
				
			case Operator.UnaryNegation:
				if (ec.CheckState) {
					ig.Emit (OpCodes.Ldc_I4_0);
					if (type == TypeManager.int64_type)
						ig.Emit (OpCodes.Conv_U8);
					Expr.Emit (ec);
					ig.Emit (OpCodes.Sub_Ovf);
				} else {
					Expr.Emit (ec);
					ig.Emit (OpCodes.Neg);
				}
				
				break;
				
			case Operator.LogicalNot:
				Expr.Emit (ec);
				ig.Emit (OpCodes.Ldc_I4_0);
				ig.Emit (OpCodes.Ceq);
				break;
				
			case Operator.OnesComplement:
				Expr.Emit (ec);
				ig.Emit (OpCodes.Not);
				break;
				
			case Operator.AddressOf:
				((IMemoryLocation)Expr).AddressOf (ec, AddressOp.LoadStore);
				break;
				
			default:
				throw new Exception ("This should not happen: Operator = "
						     + Oper.ToString ());
			}
		}

		public override void EmitBranchable (EmitContext ec, Label target, bool onTrue)
		{
			if (Oper == Operator.LogicalNot)
				Expr.EmitBranchable (ec, target, !onTrue);
			else
				base.EmitBranchable (ec, target, onTrue);
		}

		public override string ToString ()
		{
			return "Unary (" + Oper + ", " + Expr + ")";
		}
		
	}

	//
	// Unary operators are turned into Indirection expressions
	// after semantic analysis (this is so we can take the address
	// of an indirection).
	//
	public class Indirection : Expression, IMemoryLocation, IAssignMethod, IVariable {
		Expression expr;
		LocalTemporary temporary;
		bool prepared;
		
		public Indirection (Expression expr, Location l)
		{
			this.expr = expr;
			type = TypeManager.HasElementType (expr.Type) ? TypeManager.GetElementType (expr.Type) : expr.Type;
			eclass = ExprClass.Variable;
			loc = l;
		}
		
		public override void Emit (EmitContext ec)
		{
			if (!prepared)
				expr.Emit (ec);
			
			LoadFromPtr (ec.ig, Type);
		}

		public void Emit (EmitContext ec, bool leave_copy)
		{
			Emit (ec);
			if (leave_copy) {
				ec.ig.Emit (OpCodes.Dup);
				temporary = new LocalTemporary (ec, expr.Type);
				temporary.Store (ec);
			}
		}
		
		public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
		{
			prepared = prepare_for_load;
			
			expr.Emit (ec);

			if (prepare_for_load)
				ec.ig.Emit (OpCodes.Dup);
			
			source.Emit (ec);
			if (leave_copy) {
				ec.ig.Emit (OpCodes.Dup);
				temporary = new LocalTemporary (ec, expr.Type);
				temporary.Store (ec);
			}
			
			StoreFromPtr (ec.ig, type);
			
			if (temporary != null)
				temporary.Emit (ec);
		}
		
		public void AddressOf (EmitContext ec, AddressOp Mode)
		{
			expr.Emit (ec);
		}

		public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
		{
			return DoResolve (ec);
		}

		public override Expression DoResolve (EmitContext ec)
		{
			//
			// Born fully resolved
			//
			return this;
		}
		
		public override string ToString ()
		{
			return "*(" + expr + ")";
		}

		#region IVariable Members

		public VariableInfo VariableInfo {
			get {
				return null;
			}
		}

		public bool VerifyFixed ()
		{
			// A pointer-indirection is always fixed.
			return true;
		}

		#endregion
	}
	
	/// <summary>
	///   Unary Mutator expressions (pre and post ++ and --)
	/// </summary>
	///
	/// <remarks>
	///   UnaryMutator implements ++ and -- expressions.   It derives from
	///   ExpressionStatement becuase the pre/post increment/decrement
	///   operators can be used in a statement context.
	///
	/// FIXME: Idea, we could split this up in two classes, one simpler
	/// for the common case, and one with the extra fields for more complex
	/// classes (indexers require temporary access;  overloaded require method)
	///
	/// </remarks>
	public class UnaryMutator : ExpressionStatement {
		[Flags]
		public enum Mode : byte {
			IsIncrement    = 0,
			IsDecrement    = 1,
			IsPre          = 0,
			IsPost         = 2,
			
			PreIncrement   = 0,
			PreDecrement   = IsDecrement,
			PostIncrement  = IsPost,
			PostDecrement  = IsPost | IsDecrement
		}
		
		Mode mode;
		bool is_expr = false;
		bool recurse = false;
		
		Expression expr;

		//
		// This is expensive for the simplest case.
		//
		StaticCallExpr method;
			
		public UnaryMutator (Mode m, Expression e, Location l)
		{
			mode = m;
			loc = l;
			expr = e;
		}

		static string OperName (Mode mode)
		{
			return (mode == Mode.PreIncrement || mode == Mode.PostIncrement) ?
				"++" : "--";
		}
		
		/// <summary>
		///   Returns whether an object of type `t' can be incremented
		///   or decremented with add/sub (ie, basically whether we can
		///   use pre-post incr-decr operations on it, but it is not a
		///   System.Decimal, which we require operator overloading to catch)
		/// </summary>
		static bool IsIncrementableNumber (Type t)
		{
			return (t == TypeManager.sbyte_type) ||
				(t == TypeManager.byte_type) ||
				(t == TypeManager.short_type) ||
				(t == TypeManager.ushort_type) ||
				(t == TypeManager.int32_type) ||
				(t == TypeManager.uint32_type) ||
				(t == TypeManager.int64_type) ||
				(t == TypeManager.uint64_type) ||
				(t == TypeManager.char_type) ||
				(t.IsSubclassOf (TypeManager.enum_type)) ||
				(t == TypeManager.float_type) ||
				(t == TypeManager.double_type) ||
				(t.IsPointer && t != TypeManager.void_ptr_type);
		}

		Expression ResolveOperator (EmitContext ec)
		{
			Type expr_type = expr.Type;

			//
			// Step 1: Perform Operator Overload location
			//
			Expression mg;
			string op_name;
			
			if (mode == Mode.PreIncrement || mode == Mode.PostIncrement)
				op_name = "op_Increment";
			else 
				op_name = "op_Decrement";

			mg = MemberLookup (ec, expr_type, op_name, MemberTypes.Method, AllBindingFlags, loc);

			if (mg != null) {
				method = StaticCallExpr.MakeSimpleCall (
					ec, (MethodGroupExpr) mg, expr, loc);

				type = method.Type;
			} else if (!IsIncrementableNumber (expr_type)) {
				Error (187, "No such operator '" + OperName (mode) + "' defined for type '" +
				       TypeManager.CSharpName (expr_type) + "'");
				   return null;
			}

			//
			// The operand of the prefix/postfix increment decrement operators
			// should be an expression that is classified as a variable,
			// a property access or an indexer access
			//
			type = expr_type;
			if (expr.eclass == ExprClass.Variable){
				LocalVariableReference var = expr as LocalVariableReference;
				if ((var != null) && var.IsReadOnly) {
					Error (1604, "cannot assign to `" + var.Name + "' because it is readonly");
					return null;
				}
			} else if (expr.eclass == ExprClass.IndexerAccess || expr.eclass == ExprClass.PropertyAccess){
				expr = expr.ResolveLValue (ec, this, Location);
				if (expr == null)
					return null;
			} else {
				expr.Error_UnexpectedKind (ec, "variable, indexer or property access", loc);
				return null;
			}

			return this;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			expr = expr.Resolve (ec);
			
			if (expr == null)
				return null;

			eclass = ExprClass.Value;
			return ResolveOperator (ec);
		}

		static int PtrTypeSize (Type t)
		{
			return GetTypeSize (TypeManager.GetElementType (t));
		}

		//
		// Loads the proper "1" into the stack based on the type, then it emits the
		// opcode for the operation requested
		//
		void LoadOneAndEmitOp (EmitContext ec, Type t)
		{
			//
			// Measure if getting the typecode and using that is more/less efficient
			// that comparing types.  t.GetTypeCode() is an internal call.
			//
			ILGenerator ig = ec.ig;
						     
			if (t == TypeManager.uint64_type || t == TypeManager.int64_type)
				LongConstant.EmitLong (ig, 1);
			else if (t == TypeManager.double_type)
				ig.Emit (OpCodes.Ldc_R8, 1.0);
			else if (t == TypeManager.float_type)
				ig.Emit (OpCodes.Ldc_R4, 1.0F);
			else if (t.IsPointer){
				int n = PtrTypeSize (t);
				
				if (n == 0)
					ig.Emit (OpCodes.Sizeof, t);
				else
					IntConstant.EmitInt (ig, n);
			} else 
				ig.Emit (OpCodes.Ldc_I4_1);

			//
			// Now emit the operation
			//
			if (ec.CheckState){
				if (t == TypeManager.int32_type ||
				    t == TypeManager.int64_type){
					if ((mode & Mode.IsDecrement) != 0)
						ig.Emit (OpCodes.Sub_Ovf);
					else
						ig.Emit (OpCodes.Add_Ovf);
				} else if (t == TypeManager.uint32_type ||
					   t == TypeManager.uint64_type){
					if ((mode & Mode.IsDecrement) != 0)
						ig.Emit (OpCodes.Sub_Ovf_Un);
					else
						ig.Emit (OpCodes.Add_Ovf_Un);
				} else {
					if ((mode & Mode.IsDecrement) != 0)
						ig.Emit (OpCodes.Sub_Ovf);
					else
						ig.Emit (OpCodes.Add_Ovf);
				}
			} else {
				if ((mode & Mode.IsDecrement) != 0)
					ig.Emit (OpCodes.Sub);
				else
					ig.Emit (OpCodes.Add);
			}

			if (t == TypeManager.sbyte_type){
				if (ec.CheckState)
					ig.Emit (OpCodes.Conv_Ovf_I1);
				else
					ig.Emit (OpCodes.Conv_I1);
			} else if (t == TypeManager.byte_type){
				if (ec.CheckState)
					ig.Emit (OpCodes.Conv_Ovf_U1);
				else
					ig.Emit (OpCodes.Conv_U1);