parameter.cs

C#编译器源代码。Micorsoft开放源代码

	/// </summary>
	public class Parameters {
		public Parameter [] FixedParameters;
		public readonly Parameter ArrayParameter;
		public readonly bool HasArglist;
		string signature;
		Type [] types;
		
		static Parameters empty_parameters;
		
		public Parameters (Parameter [] fixed_parameters, Parameter array_parameter)
		{
			FixedParameters = fixed_parameters;
			ArrayParameter  = array_parameter;
		}

		public Parameters (Parameter [] fixed_parameters, bool has_arglist)
		{
			FixedParameters = fixed_parameters;
			HasArglist = has_arglist;
		}

		/// <summary>
		///   This is used to reuse a set of empty parameters, because they
		///   are common
		/// </summary>
		public static Parameters EmptyReadOnlyParameters {
			get {
				if (empty_parameters == null)
					empty_parameters = new Parameters (null, null);
			
				return empty_parameters;
			}
		}
		
		public bool Empty {
			get {
				return (FixedParameters == null) && (ArrayParameter == null);
			}
		}

		public void ComputeSignature (EmitContext ec)
		{
			signature = "";
			if (FixedParameters != null){
				for (int i = 0; i < FixedParameters.Length; i++){
					Parameter par = FixedParameters [i];
					
					signature += par.GetSignature (ec);
				}
			}
			//
			// Note: as per the spec, the `params' arguments (ArrayParameter)
			// are not used in the signature computation for a method
			//
		}

		void Error_DuplicateParameterName (string name, Location loc)
		{
			Report.Error (
				100, loc, "The parameter name `" + name + "' is a duplicate");
		}
		
		public bool VerifyArgs ()
		{
			int count;
			int i, j;

			if (FixedParameters == null)
				return true;
			
			count = FixedParameters.Length;
			string array_par_name = ArrayParameter != null ? ArrayParameter.Name : null;

			for (i = 0; i < count; i++){
				string base_name = FixedParameters [i].Name;
				for (j = i + 1; j < count; j++){
					if (base_name != FixedParameters [j].Name)
						continue;
					Error_DuplicateParameterName (base_name,
						FixedParameters [i].Location);
					return false;
				}

				if (base_name == array_par_name){
					Error_DuplicateParameterName (base_name,
						FixedParameters [i].Location);
					return false;
				}
			}
			return true;
		}
		
		/// <summary>
		///    Returns the signature of the Parameters evaluated in
		///    the @ec EmitContext
		/// </summary>
		public string GetSignature (EmitContext ec)
		{
			if (signature == null){
				VerifyArgs ();
				ComputeSignature (ec);
			}
			
			return signature;
		}
		
		/// <summary>
		///    Returns the paramenter information based on the name
		/// </summary>
		public Parameter GetParameterByName (string name, out int idx)
		{
			idx = 0;
			int i = 0;

			if (FixedParameters != null){
				foreach (Parameter par in FixedParameters){
					if (par.Name == name){
						idx = i;
						return par;
					}
					i++;
				}
			}

			if (ArrayParameter != null){
				if (name == ArrayParameter.Name){
					idx = i;
					return ArrayParameter;
				}
			}
			
			return null;
		}

		public Parameter GetParameterByName (string name)
		{
			int idx;

			return GetParameterByName (name, out idx);
		}
		
		bool ComputeParameterTypes (EmitContext ec)
		{
			int extra = (ArrayParameter != null) ? 1 : 0;
			int i = 0;
			int pc;

			if (FixedParameters == null)
				pc = extra;
			else
				pc = extra + FixedParameters.Length;

			types = new Type [pc];
			
			if (!VerifyArgs ()){
				FixedParameters = null;
				return false;
			}

			bool failed = false;
			if (FixedParameters != null){
				foreach (Parameter p in FixedParameters){
					Type t = null;
					
					if (p.Resolve (ec))
						t = p.ExternalType ();
					else
						failed = true;

					types [i] = t;
					i++;
				}
			}
			
			if (extra > 0){
				if (ArrayParameter.Resolve (ec))
					types [i] = ArrayParameter.ExternalType ();
				else 
					failed = true;
			}

			if (failed){
				types = null;
				return false;
			}

			return true;
		}
		
		/// <summary>
		///   Returns the argument types as an array
		/// </summary>
		static Type [] no_types = new Type [0];
		
		public Type [] GetParameterInfo (EmitContext ec)
		{
			if (types != null)
				return types;
			
			if (FixedParameters == null && ArrayParameter == null)
				return no_types;

			if (ComputeParameterTypes (ec) == false){
				types = null;
				return null;
			}

			return types;
		}

		/// <summary>
		///   Returns the type of a given parameter, and stores in the `is_out'
		///   boolean whether this is an out or ref parameter.
		///
		///   Note that the returned type will not contain any dereference in this
		///   case (ie, you get "int" for a ref int instead of "int&"
		/// </summary>
		public Type GetParameterInfo (EmitContext ec, int idx, out Parameter.Modifier mod)
		{
			mod = Parameter.Modifier.NONE;
			
			if (!VerifyArgs ()){
				FixedParameters = null;
				return null;
			}

			if (FixedParameters == null && ArrayParameter == null)
				return null;
			
			if (types == null)
				if (ComputeParameterTypes (ec) == false)
					return null;

			//
			// If this is a request for the variable lenght arg.
			//
			int array_idx = (FixedParameters != null ? FixedParameters.Length : 0);
			if (idx == array_idx)
				return types [idx];

			//
			// Otherwise, it is a fixed parameter
			//
			Parameter p = FixedParameters [idx];
			mod = p.ModFlags;

			if ((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) != 0)
				mod |= Parameter.Modifier.ISBYREF;

			return p.ParameterType;
		}

		public CallingConventions GetCallingConvention ()
		{
			if (HasArglist)
				return CallingConventions.VarArgs;
			else
				return CallingConventions.Standard;
		}

		//
		// The method's attributes are passed in because we need to extract
		// the "return:" attribute from there to apply on the return type
		//
		public void LabelParameters (EmitContext ec, MethodBase builder)
		{
			//
			// Define each type attribute (in/out/ref) and
			// the argument names.
			//
			int i = 0;
			
			MethodBuilder mb = builder as MethodBuilder;
			ConstructorBuilder cb = builder as ConstructorBuilder;

			if (FixedParameters != null) {
				for (i = 0; i < FixedParameters.Length; i++) {
					FixedParameters [i].DefineParameter (ec, mb, cb, i + 1);
				}
			}

			if (ArrayParameter != null){
				ParameterBuilder pb;
				Parameter array_param = ArrayParameter;

				if (mb == null)
					pb = cb.DefineParameter (
						i + 1, array_param.Attributes,
						array_param.Name);
				else
					pb = mb.DefineParameter (
						i + 1, array_param.Attributes,
						array_param.Name);
					
				CustomAttributeBuilder a = new CustomAttributeBuilder (
					TypeManager.cons_param_array_attribute, new object [0]);
				
				pb.SetCustomAttribute (a);
			}
		}

		public string GetSignatureForError ()
		{
			StringBuilder sb = new StringBuilder ("(");
			if (FixedParameters != null) {
				for (int i = 0; i < FixedParameters.Length; ++i) {
					sb.Append (FixedParameters[i].GetSignatureForError ());
					if (i < FixedParameters.Length - 1)
						sb.Append (", ");
				}
			}
			if (ArrayParameter != null) {
				if (sb.Length > 0)
					sb.Append (", ");
				sb.Append (ArrayParameter.GetSignatureForError ());
			}
			if (HasArglist) {
				if (sb.Length > 0)
					sb.Append (", ");
				sb.Append ("__arglist");
			}
			sb.Append (')');
			return sb.ToString ();

		}
	}
}