source: trunk/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/mcs/constant.cs @ 16240

//
// constant.cs: Constants.
//
// Author:
//   Miguel de Icaza (miguel@ximian.com)
//   Marek Safar (marek.safar@gmail.com)
//
// Copyright 2001-2003 Ximian, Inc.
// Copyright 2003-2008 Novell, Inc.
// Copyright 2011-2013 Xamarin Inc
//

using System;
using System.Globalization;

#if STATIC
using IKVM.Reflection.Emit;
#else
using System.Reflection.Emit;
#endif

namespace Mono.CSharp {

  /// <summary>
  ///   Base class for constants and literals.
  /// </summary>
  public abstract class Constant : Expression
  {
    static readonly NumberFormatInfo nfi = CultureInfo.InvariantCulture.NumberFormat;

    protected Constant (Location loc)
    {
      this.loc = loc;
    }

    override public string ToString ()
    {
      return this.GetType ().Name + " (" + GetValueAsLiteral () + ")";
    }

    /// <summary>
    ///  This is used to obtain the actual value of the literal
    ///  cast into an object.
    /// </summary>
    public abstract object GetValue ();

    public abstract long GetValueAsLong ();

    public abstract string GetValueAsLiteral ();

#if !STATIC
    //
    // Returns an object value which is typed to contant type
    //
    public virtual object GetTypedValue ()
    {
      return GetValue ();
    }
#endif

    public override void Error_ValueCannotBeConverted (ResolveContext ec, TypeSpec target, bool expl)
    {
      if (!expl && IsLiteral && 
        BuiltinTypeSpec.IsPrimitiveTypeOrDecimal (target) &&
        BuiltinTypeSpec.IsPrimitiveTypeOrDecimal (type)) {
        ec.Report.Error (31, loc, "Constant value `{0}' cannot be converted to a `{1}'",
          GetValueAsLiteral (), target.GetSignatureForError ());
      } else {
        base.Error_ValueCannotBeConverted (ec, target, expl);
      }
    }

    public Constant ImplicitConversionRequired (ResolveContext ec, TypeSpec type)
    {
      Constant c = ConvertImplicitly (type);
      if (c == null)
        Error_ValueCannotBeConverted (ec, type, false);

      return c;
    }

    public override bool ContainsEmitWithAwait ()
    {
      return false;
    }

    public virtual Constant ConvertImplicitly (TypeSpec type)
    {
      if (this.type == type)
        return this;

      if (!Convert.ImplicitNumericConversionExists (this.type, type))
        return null;

      bool fail;      
      object constant_value = ChangeType (GetValue (), type, out fail);
      if (fail){
        //
        // We should always catch the error before this is ever
        // reached, by calling Convert.ImplicitStandardConversionExists
        //
        throw new InternalErrorException ("Missing constant conversion between `{0}' and `{1}'",
         Type.GetSignatureForError (), type.GetSignatureForError ());
      }

      return CreateConstantFromValue (type, constant_value, loc);
    }

    //
    //  Returns a constant instance based on Type
    //
    public static Constant CreateConstantFromValue (TypeSpec t, object v, Location loc)
    {
      switch (t.BuiltinType) {
      case BuiltinTypeSpec.Type.Int:
        return new IntConstant (t, (int) v, loc);
      case BuiltinTypeSpec.Type.String:
        return new StringConstant (t, (string) v, loc);
      case BuiltinTypeSpec.Type.UInt:
        return new UIntConstant (t, (uint) v, loc);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (t, (long) v, loc);
      case BuiltinTypeSpec.Type.ULong:
        return new ULongConstant (t, (ulong) v, loc);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (t, (float) v, loc);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (t, (double) v, loc);
      case BuiltinTypeSpec.Type.Short:
        return new ShortConstant (t, (short) v, loc);
      case BuiltinTypeSpec.Type.UShort:
        return new UShortConstant (t, (ushort) v, loc);
      case BuiltinTypeSpec.Type.SByte:
        return new SByteConstant (t, (sbyte) v, loc);
      case BuiltinTypeSpec.Type.Byte:
        return new ByteConstant (t, (byte) v, loc);
      case BuiltinTypeSpec.Type.Char:
        return new CharConstant (t, (char) v, loc);
      case BuiltinTypeSpec.Type.Bool:
        return new BoolConstant (t, (bool) v, loc);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (t, (decimal) v, loc);
      }

      if (t.IsEnum) {
        var real_type = EnumSpec.GetUnderlyingType (t);
        return new EnumConstant (CreateConstantFromValue (real_type, v, loc), t);
      }

      if (v == null) {
        if (t.IsNullableType)
          return Nullable.LiftedNull.Create (t, loc);

        if (TypeSpec.IsReferenceType (t))
          return new NullConstant (t, loc);
      }

#if STATIC
      throw new InternalErrorException ("Constant value `{0}' has unexpected underlying type `{1}'", v, t.GetSignatureForError ());
#else
      return null;
#endif
    }

    //
    // Returns a constant instance based on value and type. This is probing version of
    // CreateConstantFromValue
    //
    public static Constant ExtractConstantFromValue (TypeSpec t, object v, Location loc)
    {
      switch (t.BuiltinType) {
      case BuiltinTypeSpec.Type.Int:
        if (v is int)
          return new IntConstant (t, (int) v, loc);
        break;
      case BuiltinTypeSpec.Type.String:
        if (v is string)
          return new StringConstant (t, (string) v, loc);
        break;
      case BuiltinTypeSpec.Type.UInt:
        if (v is uint)
          return new UIntConstant (t, (uint) v, loc);
        break;
      case BuiltinTypeSpec.Type.Long:
        if (v is long)
          return new LongConstant (t, (long) v, loc);
        break;
      case BuiltinTypeSpec.Type.ULong:
        if (v is ulong)
          return new ULongConstant (t, (ulong) v, loc);
        break;
      case BuiltinTypeSpec.Type.Float:
        if (v is float)
          return new FloatConstant (t, (float) v, loc);
        break;
      case BuiltinTypeSpec.Type.Double:
        if (v is double)
          return new DoubleConstant (t, (double) v, loc);
        break;
      case BuiltinTypeSpec.Type.Short:
        if (v is short)
          return new ShortConstant (t, (short) v, loc);
        break;
      case BuiltinTypeSpec.Type.UShort:
        if (v is ushort)
          return new UShortConstant (t, (ushort) v, loc);
        break;
      case BuiltinTypeSpec.Type.SByte:
        if (v is sbyte)
          return new SByteConstant (t, (sbyte) v, loc);
        break;
      case BuiltinTypeSpec.Type.Byte:
        if (v is byte)
          return new ByteConstant (t, (byte) v, loc);
        break;
      case BuiltinTypeSpec.Type.Char:
        if (v is char)
          return new CharConstant (t, (char) v, loc);
        break;
      case BuiltinTypeSpec.Type.Bool:
        if (v is bool)
          return new BoolConstant (t, (bool) v, loc);
        break;
      case BuiltinTypeSpec.Type.Decimal:
        if (v is decimal)
          return new DecimalConstant (t, (decimal) v, loc);
        break;
      }

      if (t.IsEnum) {
        var real_type = EnumSpec.GetUnderlyingType (t);
        return new EnumConstant (CreateConstantFromValue (real_type, v, loc), t);
      }

      if (v == null) {
        if (t.IsNullableType)
          return Nullable.LiftedNull.Create (t, loc);

        if (TypeSpec.IsReferenceType (t))
          return new NullConstant (t, loc);
      }

      return null;
    }


    public override Expression CreateExpressionTree (ResolveContext ec)
    {
      Arguments args = new Arguments (2);
      args.Add (new Argument (this));
      args.Add (new Argument (new TypeOf (type, loc)));

      return CreateExpressionFactoryCall (ec, "Constant", args);
    }

    /// <summary>
    /// Maybe ConvertTo name is better. It tries to convert `this' constant to target_type.
    /// It throws OverflowException 
    /// </summary>
    // DON'T CALL THIS METHOD DIRECTLY AS IT DOES NOT HANDLE ENUMS
    public abstract Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type);

    // This is a custom version of Convert.ChangeType() which works
    // with the TypeBuilder defined types when compiling corlib.
    static object ChangeType (object value, TypeSpec targetType, out bool error)
    {
      IConvertible convert_value = value as IConvertible;

      if (convert_value == null) {
        error = true;
        return null;
      }

      //
      // We cannot rely on build-in type conversions as they are
      // more limited than what C# supports.
      // See char -> float/decimal/double conversion
      //
      error = false;
      try {
        switch (targetType.BuiltinType) {
        case BuiltinTypeSpec.Type.Bool:
          return convert_value.ToBoolean (nfi);
        case BuiltinTypeSpec.Type.Byte:
          return convert_value.ToByte (nfi);
        case BuiltinTypeSpec.Type.Char:
          return convert_value.ToChar (nfi);
        case BuiltinTypeSpec.Type.Short:
          return convert_value.ToInt16 (nfi);
        case BuiltinTypeSpec.Type.Int:
          return convert_value.ToInt32 (nfi);
        case BuiltinTypeSpec.Type.Long:
          return convert_value.ToInt64 (nfi);
        case BuiltinTypeSpec.Type.SByte:
          return convert_value.ToSByte (nfi);
        case BuiltinTypeSpec.Type.Decimal:
          if (convert_value.GetType () == typeof (char))
            return (decimal) convert_value.ToInt32 (nfi);
          return convert_value.ToDecimal (nfi);
        case BuiltinTypeSpec.Type.Double:
          if (convert_value.GetType () == typeof (char))
            return (double) convert_value.ToInt32 (nfi);
          return convert_value.ToDouble (nfi);
        case BuiltinTypeSpec.Type.Float:
          if (convert_value.GetType () == typeof (char))
            return (float) convert_value.ToInt32 (nfi);
          return convert_value.ToSingle (nfi);
        case BuiltinTypeSpec.Type.String:
          return convert_value.ToString (nfi);
        case BuiltinTypeSpec.Type.UShort:
          return convert_value.ToUInt16 (nfi);
        case BuiltinTypeSpec.Type.UInt:
          return convert_value.ToUInt32 (nfi);
        case BuiltinTypeSpec.Type.ULong:
          return convert_value.ToUInt64 (nfi);
        case BuiltinTypeSpec.Type.Object:
          return value;
        }
      } catch {
      }

      error = true;
      return null;
    }

    protected override Expression DoResolve (ResolveContext rc)
    {
      return this;
    }

    //
    // Attempts to do a compile-time folding of a constant cast and handles
    // error reporting for constant overlows only, on normal conversion
    // errors returns null
    // 
    public Constant Reduce (ResolveContext ec, TypeSpec target_type)
    {
      try {
        return TryReduceConstant (ec, target_type);
      } catch (OverflowException) {
        if (ec.ConstantCheckState && Type.BuiltinType != BuiltinTypeSpec.Type.Decimal) {
          ec.Report.Error (221, loc,
            "Constant value `{0}' cannot be converted to a `{1}' (use `unchecked' syntax to override)",
            GetValueAsLiteral (), target_type.GetSignatureForError ());
        } else {
          Error_ValueCannotBeConverted (ec, target_type, false);
        }

        return New.Constantify (target_type, loc);
      }
    }

    public Constant TryReduce (ResolveContext rc, TypeSpec targetType)
    {
      try {
        return TryReduceConstant (rc, targetType);
      } catch (OverflowException) {
        return null;
      }
    }

    Constant TryReduceConstant (ResolveContext ec, TypeSpec target_type)
    {
      if (Type == target_type) {
        //
        // Reducing literal value produces a new constant. Syntactically 10 is not same as (int)10 
        //
        if (IsLiteral)
          return CreateConstantFromValue (target_type, GetValue (), loc);

        return this;
      }

      Constant c;
      if (target_type.IsEnum) {
        c = TryReduceConstant (ec, EnumSpec.GetUnderlyingType (target_type));
        if (c == null)
          return null;

        return new EnumConstant (c, target_type);
      }

      return ConvertExplicitly (ec.ConstantCheckState, target_type);
    }

    /// <summary>
    /// Need to pass type as the constant can require a boxing
    /// and in such case no optimization is possible
    /// </summary>
    public bool IsDefaultInitializer (TypeSpec type)
    {
      if (type == Type)
        return IsDefaultValue;

      return this is NullLiteral;
    }

    public abstract bool IsDefaultValue {
      get;
    }

    public abstract bool IsNegative {
      get;
    }

    //
    // When constant is declared as literal
    //
    public virtual bool IsLiteral {
      get { return false; }
    }
    
    public virtual bool IsOneInteger {
      get { return false; }
    }

    public override bool IsSideEffectFree {
      get {
        return true;
      }
    }

    //
    // Returns true iff 1) the stack type of this is one of Object, 
    // int32, int64 and 2) this == 0 or this == null.
    //
    public virtual bool IsZeroInteger {
      get { return false; }
    }

    public override void EmitSideEffect (EmitContext ec)
    {
      // do nothing
    }

    public sealed override Expression Clone (CloneContext clonectx)
    {
      // No cloning is not needed for constants
      return this;
    }

    protected override void CloneTo (CloneContext clonectx, Expression target)
    {
      throw new NotSupportedException ("should not be reached");
    }

    public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
    {
#if STATIC
      return base.MakeExpression (ctx);
#else
      return System.Linq.Expressions.Expression.Constant (GetTypedValue (), type.GetMetaInfo ());
#endif
    }

    public new bool Resolve (ResolveContext rc)
    {
      // It exists only as hint not to call Resolve on constants
      return true;
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }

  }

  public abstract class IntegralConstant : Constant
  {
    protected IntegralConstant (TypeSpec type, Location loc)
      : base (loc)
    {
      this.type = type;
      eclass = ExprClass.Value;
    }

    public override void Error_ValueCannotBeConverted (ResolveContext ec, TypeSpec target, bool expl)
    {
      try {
        ConvertExplicitly (true, target);
        base.Error_ValueCannotBeConverted (ec, target, expl);
      }
      catch
      {
        ec.Report.Error (31, loc, "Constant value `{0}' cannot be converted to a `{1}'",
          GetValue ().ToString (), target.GetSignatureForError ());
      }
    }

    public override string GetValueAsLiteral ()
    {
      return GetValue ().ToString ();
    }
    
    public abstract Constant Increment ();
  }
  
  public class BoolConstant : Constant {
    public readonly bool Value;

    public BoolConstant (BuiltinTypes types, bool val, Location loc)
      : this (types.Bool, val, loc)
    {
    }
    
    public BoolConstant (TypeSpec type, bool val, Location loc)
      : base (loc)
    {
      eclass = ExprClass.Value;
      this.type = type;

      Value = val;
    }

    public override object GetValue ()
    {
      return (object) Value;
    }

    public override string GetValueAsLiteral ()
    {
      return Value ? "true" : "false";
    }

    public override long GetValueAsLong ()
    {
      return Value ? 1 : 0;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }
    
    public override void Emit (EmitContext ec)
    {
      if (Value)
        ec.EmitInt (1);
      else
        ec.EmitInt (0);
    }

    public override bool IsDefaultValue {
      get {
        return !Value;
      }
    }

    public override bool IsNegative {
      get {
        return false;
      }
    }
  
    public override bool IsZeroInteger {
      get { return Value == false; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      return null;
    }

  }

  public class ByteConstant : IntegralConstant
  {
    public readonly byte Value;

    public ByteConstant (BuiltinTypes types, byte v, Location loc)
      : this (types.Byte, v, loc)
    {
    }

    public ByteConstant (TypeSpec type, byte v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitInt (Value);
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }

    public override Constant Increment ()
    {
      return new ByteConstant (type, checked ((byte)(Value + 1)), loc);
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   

    public override bool IsNegative {
      get {
        return false;
      }
    }

    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context){
          if (Value > SByte.MaxValue)
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

  }

  public class CharConstant : Constant {
    public readonly char Value;

    public CharConstant (BuiltinTypes types, char v, Location loc)
      : this (types.Char, v, loc)
    {
    }

    public CharConstant (TypeSpec type, char v, Location loc)
      : base (loc)
    {
      this.type = type;
      eclass = ExprClass.Value;

      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode ((ushort) Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitInt (Value);
    }

    static string descape (char c)
    {
      switch (c){
      case '\a':
        return "\\a"; 
      case '\b':
        return "\\b"; 
      case '\n':
        return "\\n"; 
      case '\t':
        return "\\t"; 
      case '\v':
        return "\\v"; 
      case '\r':
        return "\\r"; 
      case '\\':
        return "\\\\";
      case '\f':
        return "\\f"; 
      case '\0':
        return "\\0"; 
      case '"':
        return "\\\""; 
      case '\'':
        return "\\\'"; 
      }
      return c.ToString ();
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }

    public override string GetValueAsLiteral ()
    {
      return "\"" + descape (Value) + "\"";
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return false;
      }
    }

    public override bool IsZeroInteger {
      get { return Value == '\0'; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value < Byte.MinValue || Value > Byte.MaxValue)
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value > SByte.MaxValue)
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);

      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context) {
          if (Value > Int16.MaxValue)
            throw new OverflowException ();
        }
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

  }

  public class SByteConstant : IntegralConstant
  {
    public readonly sbyte Value;

    public SByteConstant (BuiltinTypes types, sbyte v, Location loc)
      : this (types.SByte, v, loc)
    {
    }

    public SByteConstant (TypeSpec type, sbyte v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitInt (Value);
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }

    public override Constant Increment ()
    {
        return new SByteConstant (type, checked((sbyte)(Value + 1)), loc);
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return Value < 0;
      }
    }
    
    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   
    
    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

  }

  public class ShortConstant : IntegralConstant {
    public readonly short Value;

    public ShortConstant (BuiltinTypes types, short v, Location loc)
      : this (types.Short, v, loc)
    {
    }

    public ShortConstant (TypeSpec type, short v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitInt (Value);
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }

    public override Constant Increment ()
    {
      return new ShortConstant (type, checked((short)(Value + 1)), loc);
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }
    
    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override bool IsNegative {
      get {
        return Value < 0;
      }
    }
    
    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value < Byte.MinValue || Value > Byte.MaxValue)
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value < SByte.MinValue || Value > SByte.MaxValue)
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();

        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context) {
          if (Value < Char.MinValue)
            throw new OverflowException ();
        }
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

  }

  public class UShortConstant : IntegralConstant
  {
    public readonly ushort Value;

    public UShortConstant (BuiltinTypes types, ushort v, Location loc)
      : this (types.UShort, v, loc)
    {
    }

    public UShortConstant (TypeSpec type, ushort v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitInt (Value);
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }
  
    public override Constant Increment ()
    {
      return new UShortConstant (type, checked((ushort)(Value + 1)), loc);
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return false;
      }
    }
    
    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   
  
    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value > Byte.MaxValue)
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value > SByte.MaxValue)
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context) {
          if (Value > Int16.MaxValue)
            throw new OverflowException ();
        }
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context) {
          if (Value > Char.MaxValue)
            throw new OverflowException ();
        }
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }
  }

  public class IntConstant : IntegralConstant
  {
    public readonly int Value;

    public IntConstant (BuiltinTypes types, int v, Location loc)
      : this (types.Int, v, loc)
    {
    }

    public IntConstant (TypeSpec type, int v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitInt (Value);
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }

    public override Constant Increment ()
    {
      return new IntConstant (type, checked(Value + 1), loc);
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }
    
    public override bool IsNegative {
      get {
        return Value < 0;
      }
    }
    
    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   

    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value < Byte.MinValue || Value > Byte.MaxValue)
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value < SByte.MinValue || Value > SByte.MaxValue)
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context) {
          if (Value < Int16.MinValue || Value > Int16.MaxValue)
            throw new OverflowException ();
        }
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context) {
          if (Value < UInt16.MinValue || Value > UInt16.MaxValue)
            throw new OverflowException ();
        }
        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        if (in_checked_context) {
          if (Value < UInt32.MinValue)
            throw new OverflowException ();
        }
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context) {
          if (Value < Char.MinValue || Value > Char.MaxValue)
            throw new OverflowException ();
        }
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

    public override Constant ConvertImplicitly (TypeSpec type)
    {
      if (this.type == type)
        return this;

      Constant c = TryImplicitIntConversion (type);
      if (c != null)
        return c; //.Resolve (rc);

      return base.ConvertImplicitly (type);
    }

    /// <summary>
    ///   Attempts to perform an implicit constant conversion of the IntConstant
    ///   into a different data type using casts (See Implicit Constant
    ///   Expression Conversions)
    /// </summary>
    Constant TryImplicitIntConversion (TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.SByte:
        if (Value >= SByte.MinValue && Value <= SByte.MaxValue)
          return new SByteConstant (target_type, (sbyte) Value, loc);
        break;
      case BuiltinTypeSpec.Type.Byte:
        if (Value >= Byte.MinValue && Value <= Byte.MaxValue)
          return new ByteConstant (target_type, (byte) Value, loc);
        break;
      case BuiltinTypeSpec.Type.Short:
        if (Value >= Int16.MinValue && Value <= Int16.MaxValue)
          return new ShortConstant (target_type, (short) Value, loc);
        break;
      case BuiltinTypeSpec.Type.UShort:
        if (Value >= UInt16.MinValue && Value <= UInt16.MaxValue)
          return new UShortConstant (target_type, (ushort) Value, loc);
        break;
      case BuiltinTypeSpec.Type.UInt:
        if (Value >= 0)
          return new UIntConstant (target_type, (uint) Value, loc);
        break;
      case BuiltinTypeSpec.Type.ULong:
        //
        // we can optimize this case: a positive int32
        // always fits on a uint64.  But we need an opcode
        // to do it.
        //
        if (Value >= 0)
          return new ULongConstant (target_type, (ulong) Value, loc);
        break;
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, loc);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, loc);
      }

      return null;
    }
  }

  public class UIntConstant : IntegralConstant {
    public readonly uint Value;

    public UIntConstant (BuiltinTypes types, uint v, Location loc)
      : this (types.UInt, v, loc)
    {
    }

    public UIntConstant (TypeSpec type, uint v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitInt (unchecked ((int) Value));
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }

    public override Constant Increment ()
    {
      return new UIntConstant (type, checked(Value + 1), loc);
    }
  
    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return false;
      }
    }
    
    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   

    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value < 0 || Value > byte.MaxValue)
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value > SByte.MaxValue)
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context) {
          if (Value > Int16.MaxValue)
            throw new OverflowException ();
        }
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context) {
          if (Value < UInt16.MinValue || Value > UInt16.MaxValue)
            throw new OverflowException ();
        }
        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        if (in_checked_context) {
          if (Value > Int32.MaxValue)
            throw new OverflowException ();
        }
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context) {
          if (Value < Char.MinValue || Value > Char.MaxValue)
            throw new OverflowException ();
        }
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

  }

  public class LongConstant : IntegralConstant {
    public readonly long Value;

    public LongConstant (BuiltinTypes types, long v, Location loc)
      : this (types.Long, v, loc)
    {
    }

    public LongConstant (TypeSpec type, long v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitLong (Value);
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return Value;
    }

    public override Constant Increment ()
    {
      return new LongConstant (type, checked(Value + 1), loc);
    }
    
    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return Value < 0;
      }
    }
    
    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   

    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value < Byte.MinValue || Value > Byte.MaxValue)
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value < SByte.MinValue || Value > SByte.MaxValue)
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context) {
          if (Value < Int16.MinValue || Value > Int16.MaxValue)
            throw new OverflowException ();
        }
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context) {
          if (Value < UInt16.MinValue || Value > UInt16.MaxValue)
            throw new OverflowException ();
        }
        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        if (in_checked_context) {
          if (Value < Int32.MinValue || Value > Int32.MaxValue)
            throw new OverflowException ();
        }
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        if (in_checked_context) {
          if (Value < UInt32.MinValue || Value > UInt32.MaxValue)
            throw new OverflowException ();
        }
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        if (in_checked_context && Value < 0)
          throw new OverflowException ();
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context) {
          if (Value < Char.MinValue || Value > Char.MaxValue)
            throw new OverflowException ();
        }
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

    public override Constant ConvertImplicitly (TypeSpec type)
    {
      if (Value >= 0 && type.BuiltinType == BuiltinTypeSpec.Type.ULong) {
        return new ULongConstant (type, (ulong) Value, loc);
      }

      return base.ConvertImplicitly (type);
    }
  }

  public class ULongConstant : IntegralConstant {
    public readonly ulong Value;

    public ULongConstant (BuiltinTypes types, ulong v, Location loc)
      : this (types.ULong, v, loc)
    {
    }

    public ULongConstant (TypeSpec type, ulong v, Location loc)
      : base (type, loc)
    {
      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitLong (unchecked ((long) Value));
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override long GetValueAsLong ()
    {
      return (long) Value;
    }

    public override Constant Increment ()
    {
      return new ULongConstant (type, checked(Value + 1), loc);
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return false;
      }
    }
    
    public override bool IsOneInteger {
      get {
        return Value == 1;
      }
    }   

    public override bool IsZeroInteger {
      get { return Value == 0; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context && Value > Byte.MaxValue)
          throw new OverflowException ();
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context && Value > ((ulong) SByte.MaxValue))
          throw new OverflowException ();
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context && Value > ((ulong) Int16.MaxValue))
          throw new OverflowException ();
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context && Value > UInt16.MaxValue)
          throw new OverflowException ();
        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        if (in_checked_context && Value > UInt32.MaxValue)
          throw new OverflowException ();
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        if (in_checked_context && Value > UInt32.MaxValue)
          throw new OverflowException ();
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        if (in_checked_context && Value > Int64.MaxValue)
          throw new OverflowException ();
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context && Value > Char.MaxValue)
          throw new OverflowException ();
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

  }

  public class FloatConstant : Constant {
    //
    // Store constant value as double because float constant operations
    // need to work on double value to match JIT
    //
    public readonly double DoubleValue;

    public FloatConstant (BuiltinTypes types, double v, Location loc)
      : this (types.Float, v, loc)
    {
    }

    public FloatConstant (TypeSpec type, double v, Location loc)
      : base (loc)
    {
      this.type = type;
      eclass = ExprClass.Value;

      DoubleValue = v;
    }

    public override Constant ConvertImplicitly (TypeSpec type)
    {
      if (type.BuiltinType == BuiltinTypeSpec.Type.Double)
        return new DoubleConstant (type, DoubleValue, loc);

      return base.ConvertImplicitly (type);
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.Emit (OpCodes.Ldc_R4, Value);
    }

    public float Value {
      get {
        return (float) DoubleValue;
      }
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override string GetValueAsLiteral ()
    {
      return Value.ToString ();
    }

    public override long GetValueAsLong ()
    {
      throw new NotSupportedException ();
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return Value < 0;
      }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value < byte.MinValue || Value > byte.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) DoubleValue, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value < sbyte.MinValue || Value > sbyte.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) DoubleValue, Location);
      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context) {
          if (Value < short.MinValue || Value > short.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new ShortConstant (target_type, (short) DoubleValue, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context) {
          if (Value < ushort.MinValue || Value > ushort.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new UShortConstant (target_type, (ushort) DoubleValue, Location);
      case BuiltinTypeSpec.Type.Int:
        if (in_checked_context) {
          if (Value < int.MinValue || Value > int.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new IntConstant (target_type, (int) DoubleValue, Location);
      case BuiltinTypeSpec.Type.UInt:
        if (in_checked_context) {
          if (Value < uint.MinValue || Value > uint.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new UIntConstant (target_type, (uint) DoubleValue, Location);
      case BuiltinTypeSpec.Type.Long:
        if (in_checked_context) {
          if (Value < long.MinValue || Value > long.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new LongConstant (target_type, (long) DoubleValue, Location);
      case BuiltinTypeSpec.Type.ULong:
        if (in_checked_context) {
          if (Value < ulong.MinValue || Value > ulong.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new ULongConstant (target_type, (ulong) DoubleValue, Location);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, DoubleValue, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context) {
          if (Value < (float) char.MinValue || Value > (float) char.MaxValue || float.IsNaN (Value))
            throw new OverflowException ();
        }
        return new CharConstant (target_type, (char) DoubleValue, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) DoubleValue, Location);
      }

      return null;
    }

  }

  public class DoubleConstant : Constant
  {
    public readonly double Value;

    public DoubleConstant (BuiltinTypes types, double v, Location loc)
      : this (types.Double, v, loc)
    {
    }

    public DoubleConstant (TypeSpec type, double v, Location loc)
      : base (loc)
    {
      this.type = type;
      eclass = ExprClass.Value;

      Value = v;
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      enc.Encode (Value);
    }

    public override void Emit (EmitContext ec)
    {
      ec.Emit (OpCodes.Ldc_R8, Value);
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override string GetValueAsLiteral ()
    {
      return Value.ToString ();
    }

    public override long GetValueAsLong ()
    {
      throw new NotSupportedException ();
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return Value < 0;
      }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.Byte:
        if (in_checked_context) {
          if (Value < Byte.MinValue || Value > Byte.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new ByteConstant (target_type, (byte) Value, Location);
      case BuiltinTypeSpec.Type.SByte:
        if (in_checked_context) {
          if (Value < SByte.MinValue || Value > SByte.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new SByteConstant (target_type, (sbyte) Value, Location);
      case BuiltinTypeSpec.Type.Short:
        if (in_checked_context) {
          if (Value < short.MinValue || Value > short.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new ShortConstant (target_type, (short) Value, Location);
      case BuiltinTypeSpec.Type.UShort:
        if (in_checked_context) {
          if (Value < ushort.MinValue || Value > ushort.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new UShortConstant (target_type, (ushort) Value, Location);
      case BuiltinTypeSpec.Type.Int:
        if (in_checked_context) {
          if (Value < int.MinValue || Value > int.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new IntConstant (target_type, (int) Value, Location);
      case BuiltinTypeSpec.Type.UInt:
        if (in_checked_context) {
          if (Value < uint.MinValue || Value > uint.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new UIntConstant (target_type, (uint) Value, Location);
      case BuiltinTypeSpec.Type.Long:
        if (in_checked_context) {
          if (Value < long.MinValue || Value > long.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new LongConstant (target_type, (long) Value, Location);
      case BuiltinTypeSpec.Type.ULong:
        if (in_checked_context) {
          if (Value < ulong.MinValue || Value > ulong.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new ULongConstant (target_type, (ulong) Value, Location);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, Location);
      case BuiltinTypeSpec.Type.Char:
        if (in_checked_context) {
          if (Value < (double) char.MinValue || Value > (double) char.MaxValue || double.IsNaN (Value))
            throw new OverflowException ();
        }
        return new CharConstant (target_type, (char) Value, Location);
      case BuiltinTypeSpec.Type.Decimal:
        return new DecimalConstant (target_type, (decimal) Value, Location);
      }

      return null;
    }

  }

  public class DecimalConstant : Constant {
    public readonly decimal Value;

    public DecimalConstant (BuiltinTypes types, decimal d, Location loc)
      : this (types.Decimal, d, loc)
    {
    }

    public DecimalConstant (TypeSpec type, decimal d, Location loc)
      : base (loc)
    {
      this.type = type;
      eclass = ExprClass.Value;

      Value = d;
    }

    public override void Emit (EmitContext ec)
    {
      MethodSpec m;

      int [] words = decimal.GetBits (Value);
      int power = (words [3] >> 16) & 0xff;

      if (power == 0) {
        if (Value <= int.MaxValue && Value >= int.MinValue) {
          m = ec.Module.PredefinedMembers.DecimalCtorInt.Resolve (loc);
          if (m == null) {
            return;
          }

          ec.EmitInt ((int) Value);
          ec.Emit (OpCodes.Newobj, m);
          return;
        }

        if (Value <= long.MaxValue && Value >= long.MinValue) {
          m = ec.Module.PredefinedMembers.DecimalCtorLong.Resolve (loc);
          if (m == null) {
            return;
          }

          ec.EmitLong ((long) Value);
          ec.Emit (OpCodes.Newobj, m);
          return;
        }
      }

      ec.EmitInt (words [0]);
      ec.EmitInt (words [1]);
      ec.EmitInt (words [2]);

      // sign
      ec.EmitInt (words [3] >> 31);

      // power
      ec.EmitInt (power);

      m = ec.Module.PredefinedMembers.DecimalCtor.Resolve (loc);
      if (m != null) {
        ec.Emit (OpCodes.Newobj, m);
      }
    }

    public override bool IsDefaultValue {
      get {
        return Value == 0;
      }
    }

    public override bool IsNegative {
      get {
        return Value < 0;
      }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      switch (target_type.BuiltinType) {
      case BuiltinTypeSpec.Type.SByte:
        return new SByteConstant (target_type, (sbyte) Value, loc);
      case BuiltinTypeSpec.Type.Byte:
        return new ByteConstant (target_type, (byte) Value, loc);
      case BuiltinTypeSpec.Type.Short:
        return new ShortConstant (target_type, (short) Value, loc);
      case BuiltinTypeSpec.Type.UShort:
        return new UShortConstant (target_type, (ushort) Value, loc);
      case BuiltinTypeSpec.Type.Int:
        return new IntConstant (target_type, (int) Value, loc);
      case BuiltinTypeSpec.Type.UInt:
        return new UIntConstant (target_type, (uint) Value, loc);
      case BuiltinTypeSpec.Type.Long:
        return new LongConstant (target_type, (long) Value, loc);
      case BuiltinTypeSpec.Type.ULong:
        return new ULongConstant (target_type, (ulong) Value, loc);
      case BuiltinTypeSpec.Type.Char:
        return new CharConstant (target_type, (char) Value, loc);
      case BuiltinTypeSpec.Type.Float:
        return new FloatConstant (target_type, (float) Value, loc);
      case BuiltinTypeSpec.Type.Double:
        return new DoubleConstant (target_type, (double) Value, loc);
      }

      return null;
    }

    public override object GetValue ()
    {
      return Value;
    }

    public override string GetValueAsLiteral ()
    {
      return Value.ToString () + "M";
    }

    public override long GetValueAsLong ()
    {
      throw new NotSupportedException ();
    }
  }

  public class StringConstant : Constant {
    public StringConstant (BuiltinTypes types, string s, Location loc)
      : this (types.String, s, loc)
    {
    }

    public StringConstant (TypeSpec type, string s, Location loc)
      : base (loc)
    {
      this.type = type;
      eclass = ExprClass.Value;

      Value = s;
    }

    protected StringConstant (Location loc)
      : base (loc)
    {
    }

    public string Value { get; protected set; }

    public override object GetValue ()
    {
      return Value;
    }

    public override string GetValueAsLiteral ()
    {
      // FIXME: Escape the string.
      return "\"" + Value + "\"";
    }

    public override long GetValueAsLong ()
    {
      throw new NotSupportedException ();
    }
    
    public override void Emit (EmitContext ec)
    {
      if (Value == null) {
        ec.EmitNull ();
        return;
      }

      //
      // Use string.Empty for both literals and constants even if
      // it's not allowed at language level
      //
      if (Value.Length == 0 && ec.Module.Compiler.Settings.Optimize) {
        var string_type = ec.BuiltinTypes.String;
        if (ec.CurrentType != string_type) {
          var m = ec.Module.PredefinedMembers.StringEmpty.Get ();
          if (m != null) {
            ec.Emit (OpCodes.Ldsfld, m);
            return;
          }
        }
      }

      ec.Emit (OpCodes.Ldstr, Value);
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      // cast to object
      if (type != targetType)
        enc.Encode (type);

      enc.Encode (Value);
    }

    public override bool IsDefaultValue {
      get {
        return Value == null;
      }
    }

    public override bool IsNegative {
      get {
        return false;
      }
    }

    public override bool IsNull {
      get {
        return IsDefaultValue;
      }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      return null;
    }

    public override Constant ConvertImplicitly (TypeSpec type)
    {
      if (IsDefaultValue && type.BuiltinType == BuiltinTypeSpec.Type.Object)
        return new NullConstant (type, loc);

      return base.ConvertImplicitly (type);
    }
  }

  class NameOf : StringConstant
  {
    readonly SimpleName name;

    public NameOf (SimpleName name)
      : base (name.Location)
    {
      this.name = name;
    }

    protected override Expression DoResolve (ResolveContext rc)
    {
      throw new NotSupportedException ();
    }

    bool ResolveArgumentExpression (ResolveContext rc, Expression expr)
    {
      var sn = expr as SimpleName;
      if (sn != null) {
        Value = sn.Name;

        if (rc.Module.Compiler.Settings.Version < LanguageVersion.V_6)
          rc.Report.FeatureIsNotAvailable (rc.Module.Compiler, Location, "nameof operator");

        if (sn.HasTypeArguments) {
          // TODO: csc compatible but unhelpful error message
          rc.Report.Error (1001, loc, "Identifier expected");
          return true;
        }

        sn.LookupNameExpression (rc, MemberLookupRestrictions.IgnoreArity | MemberLookupRestrictions.IgnoreAmbiguity);
        return true;
      }

      var ma = expr as MemberAccess;
      if (ma != null) {
        FullNamedExpression fne = ma.LeftExpression as ATypeNameExpression;
        if (fne == null) {
          var qam = ma as QualifiedAliasMember;
          if (qam == null)
            return false;

          fne = qam.CreateExpressionFromAlias (rc);
          if (fne == null)
            return true;
        }

        Value = ma.Name;

        if (rc.Module.Compiler.Settings.Version < LanguageVersion.V_6)
          rc.Report.FeatureIsNotAvailable (rc.Module.Compiler, Location, "nameof operator");

        if (ma.HasTypeArguments) {
          // TODO: csc compatible but unhelpful error message
          rc.Report.Error (1001, loc, "Identifier expected");
          return true;
        }
          
        var left = fne.ResolveAsTypeOrNamespace (rc, true);
        if (left == null)
          return true;

        var ns = left as NamespaceExpression;
        if (ns != null) {
          FullNamedExpression retval = ns.LookupTypeOrNamespace (rc, ma.Name, 0, LookupMode.NameOf, loc);
          if (retval == null)
            ns.Error_NamespaceDoesNotExist (rc, ma.Name, 0);

          return true;
        }

        if (left.Type.IsGenericOrParentIsGeneric && left.Type.GetDefinition () != left.Type) {
          rc.Report.Error (8071, loc, "Type arguments are not allowed in the nameof operator");
        }

        var mexpr = MemberLookup (rc, false, left.Type, ma.Name, 0, MemberLookupRestrictions.IgnoreArity | MemberLookupRestrictions.IgnoreAmbiguity, loc);
        if (mexpr == null) {
          ma.Error_IdentifierNotFound (rc, left.Type);
          return true;
        }

        return true;
      }

      return false;
    }

    public Expression ResolveOverload (ResolveContext rc, Arguments args)
    {
      if (args == null || args.Count != 1) {
        name.Error_NameDoesNotExist (rc);
        return null;
      }

      var arg = args [0];
      var res = ResolveArgumentExpression (rc, arg.Expr);
      if (!res) {
        name.Error_NameDoesNotExist (rc);
        return null;
      }

      type = rc.BuiltinTypes.String;
      eclass = ExprClass.Value;
      return this;
    }
  }

  //
  // Null constant can have its own type, think of `default (Foo)'
  //
  public class NullConstant : Constant
  {
    public NullConstant (TypeSpec type, Location loc)
      : base (loc)
    {
      eclass = ExprClass.Value;
      this.type = type;
    }

    public override Expression CreateExpressionTree (ResolveContext ec)
    {
      if (type == InternalType.NullLiteral || type.BuiltinType == BuiltinTypeSpec.Type.Object) {
        // Optimized version, also avoids referencing literal internal type
        Arguments args = new Arguments (1);
        args.Add (new Argument (this));
        return CreateExpressionFactoryCall (ec, "Constant", args);
      }

      return base.CreateExpressionTree (ec);
    }

    public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType, TypeSpec parameterType)
    {
      switch (targetType.BuiltinType) {
      case BuiltinTypeSpec.Type.Object:
        // Type it as string cast
        enc.Encode (rc.Module.Compiler.BuiltinTypes.String);
        goto case BuiltinTypeSpec.Type.String;
      case BuiltinTypeSpec.Type.String:
      case BuiltinTypeSpec.Type.Type:
        enc.Encode (byte.MaxValue);
        return;
      default:
        var ac = targetType as ArrayContainer;
        if (ac != null && ac.Rank == 1 && !ac.Element.IsArray) {
          enc.Encode (uint.MaxValue);
          return;
        }

        break;
      }

      base.EncodeAttributeValue (rc, enc, targetType, parameterType);
    }

    public override void Emit (EmitContext ec)
    {
      ec.EmitNull ();

      // Only to make verifier happy
      if (type.IsGenericParameter)
        ec.Emit (OpCodes.Unbox_Any, type);
    }

    public override string ExprClassName {
      get {
        return GetSignatureForError ();
      }
    }

    public override Constant ConvertExplicitly (bool inCheckedContext, TypeSpec targetType)
    {
      if (targetType.IsPointer) {
        if (IsLiteral || this is NullPointer)
          return new NullPointer (targetType, loc);

        return null;
      }

      // Exlude internal compiler types
      if (targetType.Kind == MemberKind.InternalCompilerType && targetType.BuiltinType != BuiltinTypeSpec.Type.Dynamic)
        return null;

      if (!IsLiteral && !Convert.ImplicitStandardConversionExists (this, targetType))
        return null;

      if (TypeSpec.IsReferenceType (targetType))
        return new NullConstant (targetType, loc);

      if (targetType.IsNullableType)
        return Nullable.LiftedNull.Create (targetType, loc);

      return null;
    }

    public override Constant ConvertImplicitly (TypeSpec targetType)
    {
      return ConvertExplicitly (false, targetType);
    }

    public override string GetSignatureForError ()
    {
      return "null";
    }

    public override object GetValue ()
    {
      return null;
    }

    public override string GetValueAsLiteral ()
    {
      return GetSignatureForError ();
    }

    public override long GetValueAsLong ()
    {
      throw new NotSupportedException ();
    }

    public override bool IsDefaultValue {
      get { return true; }
    }

    public override bool IsNegative {
      get { return false; }
    }

    public override bool IsNull {
      get { return true; }
    }

    public override bool IsZeroInteger {
      get { return true; }
    }
  }


  //
  // A null constant in a pointer context
  //
  class NullPointer : NullConstant
  {
    public NullPointer (TypeSpec type, Location loc)
      : base (type, loc)
    {
    }

    public override Expression CreateExpressionTree (ResolveContext ec)
    {
      Error_PointerInsideExpressionTree (ec);
      return base.CreateExpressionTree (ec);
    }

    public override void Emit (EmitContext ec)
    {
      //
      // Emits null pointer
      //
      ec.EmitInt (0);
      ec.Emit (OpCodes.Conv_U);
    }
  }

  /// <summary>
  ///   The value is constant, but when emitted has a side effect.  This is
  ///   used by BitwiseAnd to ensure that the second expression is invoked
  ///   regardless of the value of the left side.  
  /// </summary>
  public class SideEffectConstant : Constant
  {
    public readonly Constant value;
    Expression side_effect;
    
    public SideEffectConstant (Constant value, Expression side_effect, Location loc)
      : base (loc)
    {
      this.value = value;
      type = value.Type;
      eclass = ExprClass.Value;

      while (side_effect is SideEffectConstant)
        side_effect = ((SideEffectConstant) side_effect).side_effect;
      this.side_effect = side_effect;
    }

    public override bool IsSideEffectFree {
      get {
        return false;
      }
    }

    public override bool ContainsEmitWithAwait ()
    {
      return side_effect.ContainsEmitWithAwait ();
    }

    public override object GetValue ()
    {
      return value.GetValue ();
    }

    public override string GetValueAsLiteral ()
    {
      return value.GetValueAsLiteral ();
    }

    public override long GetValueAsLong ()
    {
      return value.GetValueAsLong ();
    }

    public override void Emit (EmitContext ec)
    {
      side_effect.EmitSideEffect (ec);
      value.Emit (ec);
    }

    public override void EmitSideEffect (EmitContext ec)
    {
      side_effect.EmitSideEffect (ec);
      value.EmitSideEffect (ec);
    }

    public override void FlowAnalysis (FlowAnalysisContext fc)
    {
      side_effect.FlowAnalysis (fc);
    }

    public override bool IsDefaultValue {
      get { return value.IsDefaultValue; }
    }

    public override bool IsNegative {
      get { return value.IsNegative; }
    }

    public override bool IsZeroInteger {
      get { return value.IsZeroInteger; }
    }

    public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
    {
      Constant new_value = value.ConvertExplicitly (in_checked_context, target_type);
      if (new_value == null)
        return null;

      var c = new SideEffectConstant (new_value, side_effect, new_value.Location);
      c.type = target_type;
      c.eclass = eclass;
      return c;
    }
  }
}