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 #if NET_4_0
  85                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
  86                 {
  87                         return System.Linq.Expressions.Expression.Constant (null);
  88                 }
  89 #endif
  90         }
  91
  92         //
  93         // A null literal in a pointer context
  94         //
  95         class NullPointer : NullLiteral {
  96                 public NullPointer (Location loc):
  97                         base (loc)
  98                 {
  99                         type = TypeManager.object_type;
 100                 }
 101
 102                 public override void Emit (EmitContext ec)
 103                 {
 104                         ILGenerator ig = ec.ig;
 105
 106                         //
 107                         // Emits null pointer
 108                         //
 109                         ig.Emit (OpCodes.Ldc_I4_0);
 110                         ig.Emit (OpCodes.Conv_U);
 111                 }
 112         }
 113
 114         public class BoolLiteral : BoolConstant {
 115                 public BoolLiteral (bool val, Location loc) : base (val, loc)
 116                 {
 117                 }
 118
 119                 public override bool IsLiteral {
 120                         get { return true; }
 121                 }
 122         }
 123
 124         public class CharLiteral : CharConstant {
 125                 public CharLiteral (char c, Location loc) : base (c, loc)
 126                 {
 127                 }
 128
 129                 public override bool IsLiteral {
 130                         get { return true; }
 131                 }
 132         }
 133
 134         public class IntLiteral : IntConstant {
 135                 public IntLiteral (int l, Location loc) : base (l, loc)
 136                 {
 137                 }
 138
 139                 public override Constant ConvertImplicitly (ResolveContext rc, Type type)
 140                 {
 141                         //
 142                         // The 0 literal can be converted to an enum value
 143                         //
 144                         if (Value == 0 && TypeManager.IsEnumType (type)) {
 145                                 Constant c = ConvertImplicitly (rc, TypeManager.GetEnumUnderlyingType (type));
 146                                 if (c == null)
 147                                         return null;
 148
 149                                 return new EnumConstant (c, type).Resolve (rc);
 150                         }
 151
 152                         return base.ConvertImplicitly (rc, type);
 153                 }
 154
 155                 public override bool IsLiteral {
 156                         get { return true; }
 157                 }
 158         }
 159
 160         public class UIntLiteral : UIntConstant {
 161                 public UIntLiteral (uint l, Location loc) : base (l, loc)
 162                 {
 163                 }
 164
 165                 public override bool IsLiteral {
 166                         get { return true; }
 167                 }
 168         }
 169
 170         public class LongLiteral : LongConstant {
 171                 public LongLiteral (long l, Location loc) : base (l, loc)
 172                 {
 173                 }
 174
 175                 public override bool IsLiteral {
 176                         get { return true; }
 177                 }
 178         }
 179
 180         public class ULongLiteral : ULongConstant {
 181                 public ULongLiteral (ulong l, Location loc) : base (l, loc)
 182                 {
 183                 }
 184
 185                 public override bool IsLiteral {
 186                         get { return true; }
 187                 }
 188         }
 189
 190         public class FloatLiteral : FloatConstant {
 191
 192                 public FloatLiteral (float f, Location loc) : base (f, loc)
 193                 {
 194                 }
 195
 196                 public override bool IsLiteral {
 197                         get { return true; }
 198                 }
 199
 200         }
 201
 202         public class DoubleLiteral : DoubleConstant {
 203                 public DoubleLiteral (double d, Location loc) : base (d, loc)
 204                 {
 205                 }
 206
 207                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, Type target, bool expl)
 208                 {
 209                         if (target == TypeManager.float_type) {
 210                                 Error_664 (ec, loc, "float", "f");
 211                                 return;
 212                         }
 213
 214                         if (target == TypeManager.decimal_type) {
 215                                 Error_664 (ec, loc, "decimal", "m");
 216                                 return;
 217                         }
 218
 219                         base.Error_ValueCannotBeConverted (ec, loc, target, expl);
 220                 }
 221
 222                 static void Error_664 (ResolveContext ec, Location loc, string type, string suffix)
 223                 {
 224                         ec.Report.Error (664, loc,
 225                                 "Literal of type double cannot be implicitly converted to type `{0}'. Add suffix `{1}' to create a literal of this type",
 226                                 type, suffix);
 227                 }
 228
 229                 public override bool IsLiteral {
 230                         get { return true; }
 231                 }
 232
 233         }
 234
 235         public class DecimalLiteral : DecimalConstant {
 236                 public DecimalLiteral (decimal d, Location loc) : base (d, loc)
 237                 {
 238                 }
 239
 240                 public override bool IsLiteral {
 241                         get { return true; }
 242                 }
 243         }
 244
 245         public class StringLiteral : StringConstant {
 246                 public StringLiteral (string s, Location loc) : base (s, loc)
 247                 {
 248                 }
 249
 250                 public override bool IsLiteral {
 251                         get { return true; }
 252                 }
 253
 254         }
 255 }