mcs/literal.cs

   1 //
   2 // literal.cs: Literal representation for the IL tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // Copyright 2001 Ximian, Inc.
   9 //
  10 //
  11 // Notice that during parsing we create objects of type Literal, but the
  12 // types are not loaded (thats why the Resolve method has to assign the
  13 // type at that point).
  14 //
  15 // Literals differ from the constants in that we know we encountered them
  16 // as a literal in the source code (and some extra rules apply there) and
  17 // they have to be resolved (since during parsing we have not loaded the
  18 // types yet) while constants are created only after types have been loaded
  19 // and are fully resolved when born.
  20 //
  21
  22 using System;
  23 using System.Reflection;
  24 using System.Reflection.Emit;
  25
  26 namespace Mono.CSharp {
  27
  28         //
  29         // The null literal
  30         //
  31         // Note: C# specification null-literal is NullLiteral of NullType type
  32         //
  33         public class NullLiteral : NullConstant
  34         {
  35                 //
  36                 // Default type of null is an object
  37                 //
  38                 public NullLiteral (Location loc)
  39                         : base (typeof (NullLiteral), loc)
  40                 {
  41                 }
  42
  43                 public override Expression CreateExpressionTree (ResolveContext ec)
  44                 {
  45                         // Optimized version, also avoids referencing literal internal type
  46                         Arguments args = new Arguments (1);
  47                         args.Add (new Argument (this));
  48                         return CreateExpressionFactoryCall (ec, "Constant", args);
  49                 }
  50
  51                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, Type t, bool expl)
  52                 {
  53                         if (TypeManager.IsGenericParameter (t)) {
  54                                 ec.Report.Error(403, loc,
  55                                         "Cannot convert null to the type parameter `{0}' because it could be a value " +
  56                                         "type. Consider using `default ({0})' instead", t.Name);
  57                                 return;
  58                         }
  59
  60                         if (TypeManager.IsValueType (t)) {
  61                                 ec.Report.Error(37, loc, "Cannot convert null to `{0}' because it is a value type",
  62                                         TypeManager.CSharpName(t));
  63                                 return;
  64                         }
  65
  66                         base.Error_ValueCannotBeConverted (ec, loc, t, expl);
  67                 }
  68
  69                 public override Constant ConvertImplicitly (ResolveContext rc, Type targetType)
  70                 {
  71                         //
  72                         // Null literal is of object type
  73                         //
  74                         if (targetType == TypeManager.object_type)
  75                                 return this;
  76
  77                         return base.ConvertImplicitly (rc, targetType);
  78                 }
  79
  80                 public override bool IsLiteral {
  81                         get { return true; }
  82                 }
  83
  84                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
  85                 {
  86                         return System.Linq.Expressions.Expression.Constant (null);
  87                 }
  88         }
  89
  90         //
  91         // A null literal in a pointer context
  92         //
  93         class NullPointer : NullLiteral {
  94                 public NullPointer (Location loc):
  95                         base (loc)
  96                 {
  97                         type = TypeManager.object_type;
  98                 }
  99
 100                 public override void Emit (EmitContext ec)
 101                 {
 102                         ILGenerator ig = ec.ig;
 103
 104                         //
 105                         // Emits null pointer
 106                         //
 107                         ig.Emit (OpCodes.Ldc_I4_0);
 108                         ig.Emit (OpCodes.Conv_U);
 109                 }
 110         }
 111
 112         public class BoolLiteral : BoolConstant {
 113                 public BoolLiteral (bool val, Location loc) : base (val, loc)
 114                 {
 115                 }
 116
 117                 public override bool IsLiteral {
 118                         get { return true; }
 119                 }
 120         }
 121
 122         public class CharLiteral : CharConstant {
 123                 public CharLiteral (char c, Location loc) : base (c, loc)
 124                 {
 125                 }
 126
 127                 public override bool IsLiteral {
 128                         get { return true; }
 129                 }
 130         }
 131
 132         public class IntLiteral : IntConstant {
 133                 public IntLiteral (int l, Location loc) : base (l, loc)
 134                 {
 135                 }
 136
 137                 public override Constant ConvertImplicitly (ResolveContext rc, Type type)
 138                 {
 139                         //
 140                         // The 0 literal can be converted to an enum value
 141                         //
 142                         if (Value == 0 && TypeManager.IsEnumType (type)) {
 143                                 Constant c = ConvertImplicitly (rc, TypeManager.GetEnumUnderlyingType (type));
 144                                 if (c == null)
 145                                         return null;
 146
 147                                 return new EnumConstant (c, type).Resolve (rc);
 148                         }
 149
 150                         return base.ConvertImplicitly (rc, type);
 151                 }
 152
 153                 public override bool IsLiteral {
 154                         get { return true; }
 155                 }
 156         }
 157
 158         public class UIntLiteral : UIntConstant {
 159                 public UIntLiteral (uint l, Location loc) : base (l, loc)
 160                 {
 161                 }
 162
 163                 public override bool IsLiteral {
 164                         get { return true; }
 165                 }
 166         }
 167
 168         public class LongLiteral : LongConstant {
 169                 public LongLiteral (long l, Location loc) : base (l, loc)
 170                 {
 171                 }
 172
 173                 public override bool IsLiteral {
 174                         get { return true; }
 175                 }
 176         }
 177
 178         public class ULongLiteral : ULongConstant {
 179                 public ULongLiteral (ulong l, Location loc) : base (l, loc)
 180                 {
 181                 }
 182
 183                 public override bool IsLiteral {
 184                         get { return true; }
 185                 }
 186         }
 187
 188         public class FloatLiteral : FloatConstant {
 189
 190                 public FloatLiteral (float f, Location loc) : base (f, loc)
 191                 {
 192                 }
 193
 194                 public override bool IsLiteral {
 195                         get { return true; }
 196                 }
 197
 198         }
 199
 200         public class DoubleLiteral : DoubleConstant {
 201                 public DoubleLiteral (double d, Location loc) : base (d, loc)
 202                 {
 203                 }
 204
 205                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, Type target, bool expl)
 206                 {
 207                         if (target == TypeManager.float_type) {
 208                                 Error_664 (ec, loc, "float", "f");
 209                                 return;
 210                         }
 211
 212                         if (target == TypeManager.decimal_type) {
 213                                 Error_664 (ec, loc, "decimal", "m");
 214                                 return;
 215                         }
 216
 217                         base.Error_ValueCannotBeConverted (ec, loc, target, expl);
 218                 }
 219
 220                 static void Error_664 (ResolveContext ec, Location loc, string type, string suffix)
 221                 {
 222                         ec.Report.Error (664, loc,
 223                                 "Literal of type double cannot be implicitly converted to type `{0}'. Add suffix `{1}' to create a literal of this type",
 224                                 type, suffix);
 225                 }
 226
 227                 public override bool IsLiteral {
 228                         get { return true; }
 229                 }
 230
 231         }
 232
 233         public class DecimalLiteral : DecimalConstant {
 234                 public DecimalLiteral (decimal d, Location loc) : base (d, loc)
 235                 {
 236                 }
 237
 238                 public override bool IsLiteral {
 239                         get { return true; }
 240                 }
 241         }
 242
 243         public class StringLiteral : StringConstant {
 244                 public StringLiteral (string s, Location loc) : base (s, loc)
 245                 {
 246                 }
 247
 248                 public override bool IsLiteral {
 249                         get { return true; }
 250                 }
 251
 252         }
 253 }