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 : MemberBase {
28 public Expression ConstantType;
29 public Expression Expr;
30 public FieldBuilder FieldBuilder;
33 object ConstantValue = null;
36 bool in_transit = false;
38 public const int AllowedModifiers =
45 public Const (Expression constant_type, string name, Expression expr, int mod_flags,
46 Attributes attrs, Location loc)
47 : base (constant_type, mod_flags, AllowedModifiers, Modifiers.PRIVATE, name, attrs, loc)
49 ConstantType = constant_type;
54 public FieldAttributes FieldAttr {
56 return FieldAttributes.Literal | FieldAttributes.Static |
57 Modifiers.FieldAttr (ModFlags) ;
62 void dump_tree (Type t)
64 Console.WriteLine ("Dumping hierarchy");
66 Console.WriteLine (" " + t.FullName + " " +
67 (t.GetType ().IsEnum ? "yes" : "no"));
74 /// Defines the constant in the @parent
76 public override bool Define (TypeContainer parent)
78 type = parent.ResolveType (ConstantType, false, Location);
83 const_ec = new EmitContext (parent, Location, null, type, ModFlags);
85 if (!TypeManager.IsBuiltinType (type) &&
86 (!type.IsSubclassOf (TypeManager.enum_type))) {
89 "Constant type is not valid (only system types are allowed)");
93 Type ptype = parent.TypeBuilder.BaseType;
96 MemberList list = TypeContainer.FindMembers (
97 ptype, MemberTypes.Field, BindingFlags.Public,
98 System.Type.FilterName, Name);
101 if ((ModFlags & Modifiers.NEW) != 0)
102 WarningNotHiding (parent);
104 } else if ((ModFlags & Modifiers.NEW) != 0)
105 WarningNotHiding (parent);
107 FieldBuilder = parent.TypeBuilder.DefineField (Name, type, FieldAttr);
109 TypeManager.RegisterConstant (FieldBuilder, this);
115 // Changes the type of the constant expression `expr' to the Type `type'
116 // Returns null on failure.
118 public static Constant ChangeType (Location loc, Constant expr, Type type)
122 // from the null type to any reference-type.
123 if (expr is NullLiteral && !type.IsValueType && !TypeManager.IsEnumType (type))
124 return NullLiteral.Null;
126 if (!Convert.ImplicitStandardConversionExists (expr, type)){
127 Convert.Error_CannotImplicitConversion (loc, expr.Type, type);
131 object constant_value = TypeManager.ChangeType (expr.GetValue (), type, out fail);
133 Convert.Error_CannotImplicitConversion (loc, expr.Type, type);
136 // We should always catch the error before this is ever
137 // reached, by calling Convert.ImplicitStandardConversionExists
139 throw new Exception (
140 String.Format ("LookupConstantValue: This should never be reached {0} {1}", expr.Type, type));
144 if (type == TypeManager.int32_type)
145 retval = new IntConstant ((int) constant_value);
146 else if (type == TypeManager.uint32_type)
147 retval = new UIntConstant ((uint) constant_value);
148 else if (type == TypeManager.int64_type)
149 retval = new LongConstant ((long) constant_value);
150 else if (type == TypeManager.uint64_type)
151 retval = new ULongConstant ((ulong) constant_value);
152 else if (type == TypeManager.float_type)
153 retval = new FloatConstant ((float) constant_value);
154 else if (type == TypeManager.double_type)
155 retval = new DoubleConstant ((double) constant_value);
156 else if (type == TypeManager.string_type)
157 retval = new StringConstant ((string) constant_value);
158 else if (type == TypeManager.short_type)
159 retval = new ShortConstant ((short) constant_value);
160 else if (type == TypeManager.ushort_type)
161 retval = new UShortConstant ((ushort) constant_value);
162 else if (type == TypeManager.sbyte_type)
163 retval = new SByteConstant ((sbyte) constant_value);
164 else if (type == TypeManager.byte_type)
165 retval = new ByteConstant ((byte) constant_value);
166 else if (type == TypeManager.char_type)
167 retval = new CharConstant ((char) constant_value);
168 else if (type == TypeManager.bool_type)
169 retval = new BoolConstant ((bool) constant_value);
171 throw new Exception ("LookupConstantValue: Unhandled constant type: " + type);
177 /// Looks up the value of a constant field. Defines it if it hasn't
178 /// already been. Similar to LookupEnumValue in spirit.
180 public object LookupConstantValue ()
182 if (ConstantValue != null)
183 return ConstantValue;
186 Report.Error (110, Location,
187 "The evaluation of the constant value for `" +
188 Name + "' involves a circular definition.");
193 int errors = Report.Errors;
196 // We might have cleared Expr ourselves in a recursive definition
201 Expr = Expr.Resolve (const_ec);
206 if (errors == Report.Errors)
207 Report.Error (150, Location, "A constant value is expected");
211 Constant ce = Expr as Constant;
213 UnCheckedExpr un_expr = Expr as UnCheckedExpr;
214 CheckedExpr ch_expr = Expr as CheckedExpr;
216 if ((un_expr != null) && (un_expr.Expr is Constant))
218 else if ((ch_expr != null) && (ch_expr.Expr is Constant))
221 if (errors == Report.Errors)
222 Report.Error (150, Location, "A constant value is expected");
227 if (type != ce.Type) {
228 ce = ChangeType (Location, ce, type);
233 ConstantValue = ce.GetValue ();
237 // This sadly does not work for our user-defined enumerations types ;-(
240 ConstantValue = System.Enum.ToObject (
241 type, ConstantValue);
242 } catch (ArgumentException){
245 ".NET SDK 1.0 does not permit to create the constant "+
246 " field from a user-defined enumeration");
250 FieldBuilder.SetConstant (ConstantValue);
252 if (!TypeManager.RegisterFieldValue (FieldBuilder, ConstantValue))
255 return ConstantValue;
260 /// Emits the field value by evaluating the expression
262 public void EmitConstant (TypeContainer parent)
264 LookupConstantValue ();