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//
// const.cs: Constant declarations.
//
// Author:
// Miguel de Icaza (miguel@ximian.com)
//
// (C) 2001 Ximian, Inc.
//
//
//
// This is needed because the following situation arises:
//
// The FieldBuilder is declared with the real type for an enumeration
//
// When we attempt to set the value for the constant, the FieldBuilder.SetConstant
// function aborts because it requires its argument to be of the same type
//
namespace Mono.CSharp {
using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Collections;
public class Const : MemberCore {
public readonly string ConstantType;
public Expression Expr;
public Attributes OptAttributes;
public FieldBuilder FieldBuilder;
object ConstantValue = null;
Type type;
public const int AllowedModifiers =
Modifiers.NEW |
Modifiers.PUBLIC |
Modifiers.PROTECTED |
Modifiers.INTERNAL |
Modifiers.PRIVATE;
public Const (string constant_type, string name, Expression expr, int mod_flags,
Attributes attrs, Location loc)
: base (name, loc)
{
ConstantType = constant_type;
Name = name;
Expr = expr;
ModFlags = Modifiers.Check (AllowedModifiers, mod_flags, Modifiers.PRIVATE, loc);
OptAttributes = attrs;
}
public FieldAttributes FieldAttr {
get {
return FieldAttributes.Literal | FieldAttributes.Static |
Modifiers.FieldAttr (ModFlags) ;
}
}
#if DEBUG
void dump_tree (Type t)
{
Console.WriteLine ("Dumping hierarchy");
while (t != null){
Console.WriteLine (" " + t.FullName + " " +
(t.GetType ().IsEnum ? "yes" : "no"));
t = t.BaseType;
}
}
#endif
/// <summary>
/// Defines the constant in the @parent
/// </summary>
public override bool Define (TypeContainer parent)
{
type = RootContext.LookupType (parent, ConstantType, true, Location);
if (type == null)
return false;
if (!TypeManager.IsBuiltinType (type) &&
(!type.IsSubclassOf (TypeManager.enum_type))) {
Report.Error (
-3, Location,
"Constant type is not valid (only system types are allowed)");
return false;
}
Type ptype = parent.TypeBuilder.BaseType;
if (ptype != null) {
MemberInfo [] mi = TypeContainer.FindMembers (
ptype, MemberTypes.Field, BindingFlags.Public,
Type.FilterName, Name);
if (mi == null || mi.Length == 0)
if ((ModFlags & Modifiers.NEW) != 0)
WarningNotHiding (parent);
} else if ((ModFlags & Modifiers.NEW) != 0)
WarningNotHiding (parent);
FieldBuilder = parent.TypeBuilder.DefineField (Name, type, FieldAttr);
TypeManager.RegisterConstant (FieldBuilder, this);
return true;
}
/// <summary>
/// Looks up the value of a constant field. Defines it if it hasn't
/// already been. Similar to LookupEnumValue in spirit.
/// </summary>
public object LookupConstantValue (EmitContext ec)
{
if (ConstantValue != null)
return ConstantValue;
Expr = Expr.Resolve (ec);
if (Expr == null) {
Report.Error (150, Location, "A constant value is expected");
return null;
}
if (!(Expr is Constant)) {
Report.Error (150, Location, "A constant value is expected");
return null;
}
ConstantValue = ((Constant) Expr).GetValue ();
if (type != Expr.Type) {
try {
ConstantValue = TypeManager.ChangeType (ConstantValue, type);
} catch {
Expression.Error_CannotConvertImplicit (Location, Expr.Type, type);
return null;
}
if (type == TypeManager.int32_type)
Expr = new IntConstant ((int) ConstantValue);
else if (type == TypeManager.uint32_type)
Expr = new UIntConstant ((uint) ConstantValue);
else if (type == TypeManager.int64_type)
Expr = new LongConstant ((long) ConstantValue);
else if (type == TypeManager.uint64_type)
Expr = new ULongConstant ((ulong) ConstantValue);
else if (type == TypeManager.float_type)
Expr = new FloatConstant ((float) ConstantValue);
else if (type == TypeManager.double_type)
Expr = new DoubleConstant ((double) ConstantValue);
else if (type == TypeManager.string_type)
Expr = new StringConstant ((string) ConstantValue);
else if (type == TypeManager.short_type)
Expr = new ShortConstant ((short) ConstantValue);
else if (type == TypeManager.ushort_type)
Expr = new UShortConstant ((ushort) ConstantValue);
else if (type == TypeManager.sbyte_type)
Expr = new SByteConstant ((sbyte) ConstantValue);
else if (type == TypeManager.byte_type)
Expr = new ByteConstant ((byte) ConstantValue);
else if (type == TypeManager.char_type)
Expr = new CharConstant ((char) ConstantValue);
else if (type == TypeManager.bool_type)
Expr = new BoolConstant ((bool) ConstantValue);
}
if (type.IsEnum){
//
// This sadly does not work for our user-defined enumerations types ;-(
//
try {
ConstantValue = System.Enum.ToObject (
type, ConstantValue);
} catch (ArgumentException){
Report.Error (
-16, Location,
".NET SDK 1.0 does not permit to create the constant "+
" field from a user-defined enumeration");
}
}
FieldBuilder.SetConstant (ConstantValue);
if (!TypeManager.RegisterFieldValue (FieldBuilder, ConstantValue))
return null;
return ConstantValue;
}
/// <summary>
/// Emits the field value by evaluating the expression
/// </summary>
public void EmitConstant (TypeContainer parent)
{
EmitContext ec = new EmitContext (parent, Location, null, type, ModFlags);
LookupConstantValue (ec);
return;
}
}
}
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