gmcs/literal.cs

   1 //
   2 // literal.cs: Literal representation for the IL tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2001 Ximian, Inc.
   8 //
   9 //
  10 // Notice that during parsing we create objects of type Literal, but the
  11 // types are not loaded (thats why the Resolve method has to assign the
  12 // type at that point).
  13 //
  14 // Literals differ from the constants in that we know we encountered them
  15 // as a literal in the source code (and some extra rules apply there) and
  16 // they have to be resolved (since during parsing we have not loaded the
  17 // types yet) while constants are created only after types have been loaded
  18 // and are fully resolved when born.
  19 //
  20
  21 using System;
  22 using System.Reflection;
  23 using System.Reflection.Emit;
  24
  25 //
  26 // I put System.Null just so we do not have to special case it on
  27 // TypeManager.CSharpName
  28 //
  29 namespace System {
  30         //
  31         // Represents the Null Type, just used as a placeholder for the type in NullLiteral
  32         //
  33         public class Null {
  34         }
  35 }
  36
  37 namespace Mono.CSharp {
  38
  39         //
  40         // The NullType just exists to compare type equality, and for
  41         // expressions that might have the `null type'
  42         //
  43         public class NullType {
  44         }
  45
  46         //
  47         // The null Literal constant
  48         //
  49         public class NullLiteral : Constant {
  50                 public NullLiteral (Location loc):
  51                         base (loc)
  52                 {
  53                         eclass = ExprClass.Value;
  54                 }
  55
  56                 override public string AsString ()
  57                 {
  58                         return "null";
  59                 }
  60
  61                 public override object GetValue ()
  62                 {
  63                         return null;
  64                 }
  65
  66                 public override Expression DoResolve (EmitContext ec)
  67                 {
  68                         type = TypeManager.null_type;
  69                         return this;
  70                 }
  71
  72                 public override void Emit (EmitContext ec)
  73                 {
  74                         ec.ig.Emit (OpCodes.Ldnull);
  75                 }
  76
  77                 public override Constant Increment ()
  78                 {
  79                         throw new NotSupportedException ();
  80                 }
  81
  82                 public override bool IsDefaultValue {
  83                         get {
  84                                 return true;
  85                         }
  86                 }
  87
  88                 public override bool IsNegative {
  89                         get {
  90                                 return false;
  91                         }
  92                 }
  93
  94                 public override bool IsZeroInteger {
  95                         get { return true; }
  96                 }
  97
  98                 public override string GetSignatureForError()
  99                 {
 100                         return "null";
 101                 }
 102
 103                 public override void Error_ValueCannotBeConverted (Location loc, Type t, bool expl)
 104                 {
 105                         Report.Error (37, loc, "Cannot convert null to `{0}' because it is a value type",
 106                                 TypeManager.CSharpName (t));
 107                 }
 108
 109                 public override Constant ToType (Type type, Location loc)
 110                 {
 111                         if (!type.IsValueType && !TypeManager.IsEnumType (type))
 112                                 return this;
 113
 114                         return base.ToType (type, loc);
 115                 }
 116
 117                 public override Constant Reduce(bool inCheckedContext, Type target_type)
 118                 {
 119                         if (!TypeManager.IsValueType (target_type))
 120                                 return new NullCast (this, target_type);
 121
 122                         return null;
 123                 }
 124         }
 125
 126         //
 127         // A null literal in a pointer context
 128         //
 129         public class NullPointer : NullLiteral {
 130                 public static readonly NullLiteral Null;
 131
 132                 static NullPointer ()
 133                 {
 134                         Null = new NullPointer ();
 135                 }
 136
 137                 private NullPointer ():
 138                         base (Location.Null)
 139                 {
 140                         type = TypeManager.object_type;
 141                 }
 142
 143                 public override void Emit (EmitContext ec)
 144                 {
 145                         ILGenerator ig = ec.ig;
 146
 147                         ig.Emit (OpCodes.Ldc_I4_0);
 148                         ig.Emit (OpCodes.Conv_U);
 149                 }
 150         }
 151
 152         public class BoolLiteral : BoolConstant {
 153                 public BoolLiteral (bool val, Location loc) : base (val, loc)
 154                 {
 155                 }
 156
 157                 public override Expression DoResolve (EmitContext ec)
 158                 {
 159                         type = TypeManager.bool_type;
 160                         return this;
 161                 }
 162         }
 163
 164         public class CharLiteral : CharConstant {
 165                 public CharLiteral (char c, Location loc) : base (c, loc)
 166                 {
 167                 }
 168
 169                 public override Expression DoResolve (EmitContext ec)
 170                 {
 171                         type = TypeManager.char_type;
 172                         return this;
 173                 }
 174         }
 175
 176         public class IntLiteral : IntConstant {
 177                 public IntLiteral (int l, Location loc) : base (l, loc)
 178                 {
 179                 }
 180
 181                 public override Expression DoResolve (EmitContext ec)
 182                 {
 183                         type = TypeManager.int32_type;
 184                         return this;
 185                 }
 186         }
 187
 188         public class UIntLiteral : UIntConstant {
 189                 public UIntLiteral (uint l, Location loc) : base (l, loc)
 190                 {
 191                 }
 192
 193                 public override Expression DoResolve (EmitContext ec)
 194                 {
 195                         type = TypeManager.uint32_type;
 196                         return this;
 197                 }
 198         }
 199
 200         public class LongLiteral : LongConstant {
 201                 public LongLiteral (long l, Location loc) : base (l, loc)
 202                 {
 203                 }
 204
 205                 public override Expression DoResolve (EmitContext ec)
 206                 {
 207                         type = TypeManager.int64_type;
 208
 209                         return this;
 210                 }
 211         }
 212
 213         public class ULongLiteral : ULongConstant {
 214                 public ULongLiteral (ulong l, Location loc) : base (l, loc)
 215                 {
 216                 }
 217
 218                 public override Expression DoResolve (EmitContext ec)
 219                 {
 220                         type = TypeManager.uint64_type;
 221                         return this;
 222                 }
 223         }
 224
 225         public class FloatLiteral : FloatConstant {
 226
 227                 public FloatLiteral (float f, Location loc) : base (f, loc)
 228                 {
 229                 }
 230
 231                 public override Expression DoResolve (EmitContext ec)
 232                 {
 233                         type = TypeManager.float_type;
 234                         return this;
 235                 }
 236         }
 237
 238         public class DoubleLiteral : DoubleConstant {
 239                 public DoubleLiteral (double d, Location loc) : base (d, loc)
 240                 {
 241                 }
 242
 243                 public override Expression DoResolve (EmitContext ec)
 244                 {
 245                         type = TypeManager.double_type;
 246
 247                         return this;
 248                 }
 249
 250                 public override void Error_ValueCannotBeConverted (Location loc, Type target, bool expl)
 251                 {
 252                         if (target == TypeManager.float_type) {
 253                                 Error_664 (loc, "float", "f");
 254                                 return;
 255                         }
 256
 257                         if (target == TypeManager.decimal_type) {
 258                                 Error_664 (loc, "decimal", "m");
 259                                 return;
 260                         }
 261
 262                         base.Error_ValueCannotBeConverted (loc, target, expl);
 263                 }
 264
 265                 static void Error_664 (Location loc, string type, string suffix)
 266                 {
 267                         Report.Error (664, loc,
 268                                 "Literal of type double cannot be implicitly converted to type `{0}'. Add suffix `{1}' to create a literal of this type",
 269                                 type, suffix);
 270                 }
 271         }
 272
 273         public class DecimalLiteral : DecimalConstant {
 274                 public DecimalLiteral (decimal d, Location loc) : base (d, loc)
 275                 {
 276                 }
 277
 278                 public override Expression DoResolve (EmitContext ec)
 279                 {
 280                         type = TypeManager.decimal_type;
 281                         return this;
 282                 }
 283         }
 284
 285         public class StringLiteral : StringConstant {
 286                 public StringLiteral (string s, Location loc) : base (s, loc)
 287                 {
 288                 }
 289
 290                 public override Expression DoResolve (EmitContext ec)
 291                 {
 292                         type = TypeManager.string_type;
 293
 294                         return this;
 295                 }
 296         }
 297 }