2 // const.cs: Constant declarations.
5 // Miguel de Icaza (miguel@ximian.com)
6 // Marek Safar (marek.safar@seznam.cz)
8 // (C) 2001 Ximian, Inc.
12 namespace Mono.CSharp {
15 using System.Reflection;
16 using System.Reflection.Emit;
17 using System.Collections;
19 public interface IConstant
21 void CheckObsoleteness (Location loc);
23 Constant Value { get; }
26 public class Const : FieldMember, IConstant {
31 public const int AllowedModifiers =
38 public Const (TypeContainer parent, Expression constant_type, string name,
39 Expression expr, int mod_flags, Attributes attrs, Location loc)
40 : base (parent, constant_type, mod_flags, AllowedModifiers,
41 new MemberName (name, loc), expr, attrs)
44 ModFlags |= Modifiers.STATIC;
47 protected override bool CheckBase ()
49 // Constant.Define can be called when the parent type hasn't yet been populated
50 // and it's base types need not have been populated. So, we defer this check
51 // to the second time Define () is called on this member.
52 if (Parent.BaseCache == null)
54 return base.CheckBase ();
58 /// Defines the constant in the @parent
60 public override bool Define ()
62 // Make Define () idempotent, but ensure that the error check happens.
63 if (FieldBuilder != null)
64 return base.CheckBase ();
69 Type ttype = MemberType;
71 ttype = TypeManager.GetElementType (ttype);
73 FieldAttributes field_attr = FieldAttributes.Static | Modifiers.FieldAttr (ModFlags);
74 // Decimals cannot be emitted into the constant blob. So, convert to 'readonly'.
75 if (ttype == TypeManager.decimal_type) {
76 field_attr |= FieldAttributes.InitOnly;
77 Parent.RegisterFieldForInitialization (this);
80 field_attr |= FieldAttributes.Literal;
83 FieldBuilder = Parent.TypeBuilder.DefineField (Name, MemberType, field_attr);
85 TypeManager.RegisterConstant (FieldBuilder, this);
91 /// Emits the field value by evaluating the expression
93 public override void Emit ()
98 if (value.Type == TypeManager.decimal_type) {
99 Decimal d = ((DecimalConstant)value).Value;
100 int[] bits = Decimal.GetBits (d);
101 object[] args = new object[] { (byte)(bits [3] >> 16), (byte)(bits [3] >> 31), (uint)bits [2], (uint)bits [1], (uint)bits [0] };
102 CustomAttributeBuilder cab = new CustomAttributeBuilder (TypeManager.decimal_constant_attribute_ctor, args);
103 FieldBuilder.SetCustomAttribute (cab);
106 FieldBuilder.SetConstant (value.GetTypedValue ());
112 public static void Error_ExpressionMustBeConstant (Location loc, string e_name)
114 Report.Error (133, loc, "The expression being assigned to `{0}' must be constant", e_name);
117 public static void Error_CyclicDeclaration (MemberCore mc)
119 Report.Error (110, mc.Location, "The evaluation of the constant value for `{0}' involves a circular definition",
120 mc.GetSignatureForError ());
123 #region IConstant Members
125 public bool ResolveValue ()
132 Error_CyclicDeclaration (this);
133 // Suppress cyclic errors
134 value = New.Constantify (MemberType);
139 EmitContext ec = new EmitContext (Parent, Location, null, MemberType, ModFlags);
140 value = Expr.ResolveAsConstant (ec, this);
146 value = value.ToType (MemberType, Location);
150 if (!MemberType.IsValueType && MemberType != TypeManager.string_type && !value.IsDefaultValue) {
151 Report.Error (134, Location, "`{0}': A const of reference other than string can only be initialized with null",
152 GetSignatureForError ());
159 public Constant Value {
168 public class ExternalConstant: IConstant
173 public ExternalConstant (FieldInfo fi)
178 private ExternalConstant (FieldInfo fi, Constant value):
185 // Decimal constants cannot be encoded in the constant blob, and thus are marked
186 // as IsInitOnly ('readonly' in C# parlance). We get its value from the
187 // DecimalConstantAttribute metadata.
189 public static IConstant CreateDecimal (FieldInfo fi)
191 if (fi is FieldBuilder)
194 object[] attrs = fi.GetCustomAttributes (TypeManager.decimal_constant_attribute_type, false);
195 if (attrs.Length != 1)
198 IConstant ic = new ExternalConstant (fi,
199 new DecimalConstant (((System.Runtime.CompilerServices.DecimalConstantAttribute) attrs [0]).Value, Location.Null));
204 #region IConstant Members
206 public void CheckObsoleteness (Location loc)
208 ObsoleteAttribute oa = AttributeTester.GetMemberObsoleteAttribute (fi);
213 AttributeTester.Report_ObsoleteMessage (oa, TypeManager.GetFullNameSignature (fi), loc);
216 public bool ResolveValue ()
221 if (fi.DeclaringType.IsEnum) {
222 value = Expression.Constantify (fi.GetValue (fi), TypeManager.EnumToUnderlying (fi.FieldType));
223 value = new EnumConstant (value, fi.DeclaringType);
227 value = Expression.Constantify (fi.GetValue (fi), fi.FieldType);
231 public Constant Value {