2 // const.cs: Constant declarations.
5 // Miguel de Icaza (miguel@ximian.com)
7 // (C) 2001 Ximian, Inc.
12 // This is needed because the following situation arises:
14 // The FieldBuilder is declared with the real type for an enumeration
16 // When we attempt to set the value for the constant, the FieldBuilder.SetConstant
17 // function aborts because it requires its argument to be of the same type
20 namespace Mono.CSharp {
23 using System.Reflection;
24 using System.Reflection.Emit;
25 using System.Collections;
27 public class Const : FieldBase {
28 public Expression Expr;
31 bool resolved = false;
32 object ConstantValue = null;
35 bool in_transit = false;
37 public const int AllowedModifiers =
44 public Const (Expression constant_type, string name, Expression expr, int mod_flags,
45 Attributes attrs, Location loc)
46 : base (constant_type, mod_flags, AllowedModifiers, name, null, attrs, loc)
51 public FieldAttributes FieldAttr {
53 return FieldAttributes.Literal | FieldAttributes.Static |
54 Modifiers.FieldAttr (ModFlags) ;
59 void dump_tree (Type t)
61 Console.WriteLine ("Dumping hierarchy");
63 Console.WriteLine (" " + t.FullName + " " +
64 (t.GetType ().IsEnum ? "yes" : "no"));
71 /// Defines the constant in the @parent
73 public override bool Define (TypeContainer parent)
75 type = parent.ResolveType (Type, false, Location);
80 const_ec = new EmitContext (parent, Location, null, type, ModFlags);
84 ttype = TypeManager.GetElementType (ttype);
86 if (!TypeManager.IsBuiltinType (ttype) &&
87 (!ttype.IsSubclassOf (TypeManager.enum_type))) {
90 "Constant type is not valid (only system types are allowed)");
94 Type ptype = parent.TypeBuilder.BaseType;
97 MemberList list = TypeContainer.FindMembers (
98 ptype, MemberTypes.Field, BindingFlags.Public,
99 System.Type.FilterName, Name);
102 if ((ModFlags & Modifiers.NEW) != 0)
103 WarningNotHiding (parent);
105 } else if ((ModFlags & Modifiers.NEW) != 0)
106 WarningNotHiding (parent);
108 FieldBuilder = parent.TypeBuilder.DefineField (Name, type, FieldAttr);
110 TypeManager.RegisterConstant (FieldBuilder, this);
116 // Changes the type of the constant expression `expr' to the Type `type'
117 // Returns null on failure.
119 public static Constant ChangeType (Location loc, Constant expr, Type type)
121 if (type == TypeManager.object_type)
126 // from the null type to any reference-type.
127 if (expr is NullLiteral && !type.IsValueType && !TypeManager.IsEnumType (type))
128 return NullLiteral.Null;
130 if (!Convert.ImplicitStandardConversionExists (expr, type)){
131 Convert.Error_CannotImplicitConversion (loc, expr.Type, type);
135 object constant_value = TypeManager.ChangeType (expr.GetValue (), type, out fail);
137 Convert.Error_CannotImplicitConversion (loc, expr.Type, type);
140 // We should always catch the error before this is ever
141 // reached, by calling Convert.ImplicitStandardConversionExists
143 throw new Exception (
144 String.Format ("LookupConstantValue: This should never be reached {0} {1}", expr.Type, type));
148 if (type == TypeManager.int32_type)
149 retval = new IntConstant ((int) constant_value);
150 else if (type == TypeManager.uint32_type)
151 retval = new UIntConstant ((uint) constant_value);
152 else if (type == TypeManager.int64_type)
153 retval = new LongConstant ((long) constant_value);
154 else if (type == TypeManager.uint64_type)
155 retval = new ULongConstant ((ulong) constant_value);
156 else if (type == TypeManager.float_type)
157 retval = new FloatConstant ((float) constant_value);
158 else if (type == TypeManager.double_type)
159 retval = new DoubleConstant ((double) constant_value);
160 else if (type == TypeManager.string_type)
161 retval = new StringConstant ((string) constant_value);
162 else if (type == TypeManager.short_type)
163 retval = new ShortConstant ((short) constant_value);
164 else if (type == TypeManager.ushort_type)
165 retval = new UShortConstant ((ushort) constant_value);
166 else if (type == TypeManager.sbyte_type)
167 retval = new SByteConstant ((sbyte) constant_value);
168 else if (type == TypeManager.byte_type)
169 retval = new ByteConstant ((byte) constant_value);
170 else if (type == TypeManager.char_type)
171 retval = new CharConstant ((char) constant_value);
172 else if (type == TypeManager.bool_type)
173 retval = new BoolConstant ((bool) constant_value);
175 throw new Exception ("LookupConstantValue: Unhandled constant type: " + type);
181 /// Looks up the value of a constant field. Defines it if it hasn't
182 /// already been. Similar to LookupEnumValue in spirit.
184 public bool LookupConstantValue (out object value)
187 value = ConstantValue;
192 Report.Error (110, Location,
193 "The evaluation of the constant value for `" +
194 Name + "' involves a circular definition.");
200 int errors = Report.Errors;
203 // We might have cleared Expr ourselves in a recursive definition
210 Expr = Expr.Resolve (const_ec);
215 if (errors == Report.Errors)
216 Report.Error (150, Location, "A constant value is expected");
221 Expression real_expr = Expr;
223 Constant ce = Expr as Constant;
225 UnCheckedExpr un_expr = Expr as UnCheckedExpr;
226 CheckedExpr ch_expr = Expr as CheckedExpr;
227 EmptyCast ec_expr = Expr as EmptyCast;
229 if ((un_expr != null) && (un_expr.Expr is Constant))
231 else if ((ch_expr != null) && (ch_expr.Expr is Constant))
233 else if ((ec_expr != null) && (ec_expr.Child is Constant))
234 Expr = ec_expr.Child;
235 else if (Expr is ArrayCreation) {
236 ArrayCreation ac = (ArrayCreation) Expr;
238 Expr = ac.TurnIntoConstant ();
240 Report.Error (150, Location, "A constant value is expected");
245 if (errors == Report.Errors)
246 Report.Error (150, Location, "A constant value is expected");
251 ce = Expr as Constant;
254 if (type != real_expr.Type) {
255 ce = ChangeType (Location, ce, type);
262 ConstantValue = ce.GetValue ();
266 // This sadly does not work for our user-defined enumerations types ;-(
269 ConstantValue = System.Enum.ToObject (
270 type, ConstantValue);
271 } catch (ArgumentException){
274 ".NET SDK 1.0 does not permit to create the constant "+
275 " field from a user-defined enumeration");
279 FieldBuilder.SetConstant (ConstantValue);
281 if (!TypeManager.RegisterFieldValue (FieldBuilder, ConstantValue))
282 throw new Exception ("Cannot register const value");
284 value = ConstantValue;
291 /// Emits the field value by evaluating the expression
293 public override void Emit (TypeContainer parent)
296 LookupConstantValue (out value);
298 if (OptAttributes != null) {
299 OptAttributes.Emit (const_ec, this);