/
convert.cs
1821 lines (1574 loc) · 61.2 KB
/
convert.cs
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//
// conversion.cs: various routines for implementing conversions.
//
// Authors:
// Miguel de Icaza (miguel@ximian.com)
// Ravi Pratap (ravi@ximian.com)
//
// (C) 2001, 2002, 2003 Ximian, Inc.
//
namespace Mono.CSharp {
using System;
using System.Collections;
using System.Diagnostics;
using System.Reflection;
using System.Reflection.Emit;
//
// A container class for all the conversion operations
//
public class Convert {
//
// This is used to prettify the code: a null argument is allowed
// for ImplicitStandardConversion as long as it is known that
// no anonymous method will play a role.
//
// FIXME: renamed from `const' to `static' to allow bootstraping from older
// versions of the compiler that could not cope with this construct.
//
public static EmitContext ConstantEC = null;
static EmptyExpression MyEmptyExpr;
static public Expression ImplicitReferenceConversion (Expression expr, Type target_type)
{
Type expr_type = expr.Type;
if (expr_type == null && expr.eclass == ExprClass.MethodGroup){
// if we are a method group, emit a warning
expr.Emit (null);
}
if (expr_type == TypeManager.void_type)
return null;
//
// notice that it is possible to write "ValueType v = 1", the ValueType here
// is an abstract class, and not really a value type, so we apply the same rules.
//
if (target_type == TypeManager.object_type) {
//
// A pointer type cannot be converted to object
//
if (expr_type.IsPointer)
return null;
if (expr_type.IsValueType)
return new BoxedCast (expr, target_type);
if (expr_type.IsClass || expr_type.IsInterface || expr_type == TypeManager.enum_type){
if (expr_type == TypeManager.anonymous_method_type)
return null;
return new EmptyCast (expr, target_type);
}
return null;
} else if (target_type == TypeManager.value_type) {
if (expr_type.IsValueType)
return new BoxedCast (expr, target_type);
if (expr_type == TypeManager.null_type)
return new NullCast ((Constant)expr, target_type);
return null;
} else if (expr_type.IsSubclassOf (target_type)) {
//
// Special case: enumeration to System.Enum.
// System.Enum is not a value type, it is a class, so we need
// a boxing conversion
//
if (expr_type.IsEnum)
return new BoxedCast (expr, target_type);
return new EmptyCast (expr, target_type);
}
// This code is kind of mirrored inside ImplicitStandardConversionExists
// with the small distinction that we only probe there
//
// Always ensure that the code here and there is in sync
// from the null type to any reference-type.
if (expr_type == TypeManager.null_type){
if (target_type.IsPointer)
return new EmptyCast (NullPointer.Null, target_type);
if (!target_type.IsValueType) {
if (expr is Constant)
return new NullCast ((Constant)expr, target_type);
// I found only one case when it happens -- Foo () ? null : null;
Report.Warning (-100, 1, expr.Location, "The result of the expression is always `null'");
return new NullCast (new NullLiteral (expr.Location), target_type);
}
}
// from any class-type S to any interface-type T.
if (target_type.IsInterface) {
if (target_type != TypeManager.iconvertible_type &&
expr_type.IsValueType && (expr is Constant) &&
!(expr is IntLiteral || expr is BoolLiteral ||
expr is FloatLiteral || expr is DoubleLiteral ||
expr is LongLiteral || expr is CharLiteral ||
expr is StringLiteral || expr is DecimalLiteral ||
expr is UIntLiteral || expr is ULongLiteral)) {
return null;
}
if (TypeManager.ImplementsInterface (expr_type, target_type)){
if (expr_type.IsClass)
return new EmptyCast (expr, target_type);
else if (expr_type.IsValueType)
return new BoxedCast (expr, target_type);
else
return new EmptyCast (expr, target_type);
}
}
// from any interface type S to interface-type T.
if (expr_type.IsInterface && target_type.IsInterface) {
if (TypeManager.ImplementsInterface (expr_type, target_type))
return new EmptyCast (expr, target_type);
else
return null;
}
// from an array-type S to an array-type of type T
if (expr_type.IsArray && target_type.IsArray) {
if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
Type expr_element_type = TypeManager.GetElementType (expr_type);
if (MyEmptyExpr == null)
MyEmptyExpr = new EmptyExpression ();
MyEmptyExpr.SetType (expr_element_type);
Type target_element_type = TypeManager.GetElementType (target_type);
if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
if (ImplicitStandardConversionExists (ConstantEC, MyEmptyExpr,
target_element_type))
return new EmptyCast (expr, target_type);
}
}
// from an array-type to System.Array
if (expr_type.IsArray && target_type == TypeManager.array_type)
return new EmptyCast (expr, target_type);
// from any delegate type to System.Delegate
if ((expr_type == TypeManager.delegate_type ||
expr_type.IsSubclassOf (TypeManager.delegate_type)) &&
target_type == TypeManager.delegate_type)
return new EmptyCast (expr, target_type);
// from any array-type or delegate type into System.ICloneable.
if (expr_type.IsArray ||
expr_type == TypeManager.delegate_type ||
expr_type.IsSubclassOf (TypeManager.delegate_type))
if (target_type == TypeManager.icloneable_type)
return new EmptyCast (expr, target_type);
return null;
}
//
// Tests whether an implicit reference conversion exists between expr_type
// and target_type
//
static bool ImplicitReferenceConversionExists (Expression expr, Type target_type)
{
if (target_type.IsValueType)
return false;
Type expr_type = expr.Type;
//
// This is the boxed case.
//
if (target_type == TypeManager.object_type) {
if (expr_type.IsClass || expr_type.IsValueType ||
expr_type.IsInterface || expr_type == TypeManager.enum_type)
if (target_type != TypeManager.anonymous_method_type)
return true;
return false;
} else if (expr_type.IsSubclassOf (target_type))
return true;
// Please remember that all code below actually comes
// from ImplicitReferenceConversion so make sure code remains in sync
// from any class-type S to any interface-type T.
if (target_type.IsInterface) {
if (target_type != TypeManager.iconvertible_type &&
expr_type.IsValueType && (expr is Constant) &&
!(expr is IntLiteral || expr is BoolLiteral ||
expr is FloatLiteral || expr is DoubleLiteral ||
expr is LongLiteral || expr is CharLiteral ||
expr is StringLiteral || expr is DecimalLiteral ||
expr is UIntLiteral || expr is ULongLiteral)) {
return false;
}
if (TypeManager.ImplementsInterface (expr_type, target_type))
return true;
}
// from any interface type S to interface-type T.
if (expr_type.IsInterface && target_type.IsInterface)
if (TypeManager.ImplementsInterface (expr_type, target_type))
return true;
// from an array-type S to an array-type of type T
if (expr_type.IsArray && target_type.IsArray) {
if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
Type expr_element_type = expr_type.GetElementType ();
if (MyEmptyExpr == null)
MyEmptyExpr = new EmptyExpression ();
MyEmptyExpr.SetType (expr_element_type);
Type target_element_type = TypeManager.GetElementType (target_type);
if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
if (ImplicitStandardConversionExists (ConstantEC, MyEmptyExpr,
target_element_type))
return true;
}
}
// from an array-type to System.Array
if (expr_type.IsArray && (target_type == TypeManager.array_type))
return true;
// from any delegate type to System.Delegate
if ((expr_type == TypeManager.delegate_type ||
expr_type.IsSubclassOf (TypeManager.delegate_type)) &&
target_type == TypeManager.delegate_type)
if (target_type.IsAssignableFrom (expr_type))
return true;
// from any array-type or delegate type into System.ICloneable.
if (expr_type.IsArray ||
expr_type == TypeManager.delegate_type ||
expr_type.IsSubclassOf (TypeManager.delegate_type))
if (target_type == TypeManager.icloneable_type)
return true;
// from the null type to any reference-type.
if (expr_type == TypeManager.null_type){
if (target_type.IsPointer)
return true;
if (!target_type.IsValueType)
return true;
}
return false;
}
/// <summary>
/// Implicit Numeric Conversions.
///
/// expr is the expression to convert, returns a new expression of type
/// target_type or null if an implicit conversion is not possible.
/// </summary>
static public Expression ImplicitNumericConversion (EmitContext ec, Expression expr,
Type target_type)
{
Type expr_type = expr.Type;
//
// Attempt to do the implicit constant expression conversions
if (expr is Constant){
if (expr is IntConstant){
Expression e;
e = TryImplicitIntConversion (target_type, (IntConstant) expr);
if (e != null)
return e;
} else if (expr is LongConstant && target_type == TypeManager.uint64_type){
//
// Try the implicit constant expression conversion
// from long to ulong, instead of a nice routine,
// we just inline it
//
long v = ((LongConstant) expr).Value;
if (v >= 0)
return new ULongConstant ((ulong) v, expr.Location);
}
}
Type real_target_type = target_type;
if (expr_type == TypeManager.sbyte_type){
//
// From sbyte to short, int, long, float, double, decimal
//
if (real_target_type == TypeManager.int32_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
if (real_target_type == TypeManager.int64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
if (real_target_type == TypeManager.short_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.byte_type){
//
// From byte to short, ushort, int, uint, long, ulong, float, double, decimal
//
if ((real_target_type == TypeManager.short_type) ||
(real_target_type == TypeManager.ushort_type) ||
(real_target_type == TypeManager.int32_type) ||
(real_target_type == TypeManager.uint32_type))
return new EmptyCast (expr, target_type);
if (real_target_type == TypeManager.uint64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
if (real_target_type == TypeManager.int64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.short_type){
//
// From short to int, long, float, double, decimal
//
if (real_target_type == TypeManager.int32_type)
return new EmptyCast (expr, target_type);
if (real_target_type == TypeManager.int64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.ushort_type){
//
// From ushort to int, uint, long, ulong, float, double, decimal
//
if (real_target_type == TypeManager.uint32_type)
return new EmptyCast (expr, target_type);
if (real_target_type == TypeManager.uint64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
if (real_target_type == TypeManager.int32_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
if (real_target_type == TypeManager.int64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.int32_type){
//
// From int to long, float, double, decimal
//
if (real_target_type == TypeManager.int64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.uint32_type){
//
// From uint to long, ulong, float, double, decimal
//
if (real_target_type == TypeManager.int64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
if (real_target_type == TypeManager.uint64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
OpCodes.Conv_R8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
OpCodes.Conv_R4);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.int64_type){
//
// From long/ulong to float, double
//
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.uint64_type){
//
// From ulong to float, double
//
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
OpCodes.Conv_R8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
OpCodes.Conv_R4);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.char_type){
//
// From char to ushort, int, uint, long, ulong, float, double, decimal
//
if ((real_target_type == TypeManager.ushort_type) ||
(real_target_type == TypeManager.int32_type) ||
(real_target_type == TypeManager.uint32_type))
return new EmptyCast (expr, target_type);
if (real_target_type == TypeManager.uint64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
if (real_target_type == TypeManager.int64_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
if (real_target_type == TypeManager.float_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
if (real_target_type == TypeManager.decimal_type)
return new CastToDecimal (expr);
} else if (expr_type == TypeManager.float_type){
//
// float to double
//
if (real_target_type == TypeManager.double_type)
return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
}
return null;
}
/// <summary>
/// Same as ImplicitStandardConversionExists except that it also looks at
/// implicit user defined conversions - needed for overload resolution
/// </summary>
public static bool ImplicitConversionExists (EmitContext ec, Expression expr, Type target_type)
{
if (ImplicitStandardConversionExists (ec, expr, target_type))
return true;
Expression dummy = ImplicitUserConversion (ec, expr, target_type, Location.Null);
if (dummy != null)
return true;
return false;
}
public static bool ImplicitUserConversionExists (EmitContext ec, Type source, Type target)
{
return ImplicitUserConversion (ec, new EmptyExpression (source), target, Location.Null) != null;
}
/// <summary>
/// Determines if a standard implicit conversion exists from
/// expr_type to target_type
///
/// ec should point to a real EmitContext if expr.Type is TypeManager.anonymous_method_type.
/// </summary>
public static bool ImplicitStandardConversionExists (EmitContext ec, Expression expr, Type target_type)
{
Type expr_type = expr.Type;
if (expr_type == TypeManager.void_type)
return false;
if (expr_type == target_type)
return true;
// First numeric conversions
if (expr_type == TypeManager.sbyte_type){
//
// From sbyte to short, int, long, float, double, decimal
//
if ((target_type == TypeManager.int32_type) ||
(target_type == TypeManager.int64_type) ||
(target_type == TypeManager.double_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.short_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if (expr_type == TypeManager.byte_type){
//
// From byte to short, ushort, int, uint, long, ulong, float, double, decimal
//
if ((target_type == TypeManager.short_type) ||
(target_type == TypeManager.ushort_type) ||
(target_type == TypeManager.int32_type) ||
(target_type == TypeManager.uint32_type) ||
(target_type == TypeManager.uint64_type) ||
(target_type == TypeManager.int64_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.double_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if (expr_type == TypeManager.short_type){
//
// From short to int, long, double, float, decimal
//
if ((target_type == TypeManager.int32_type) ||
(target_type == TypeManager.int64_type) ||
(target_type == TypeManager.double_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if (expr_type == TypeManager.ushort_type){
//
// From ushort to int, uint, long, ulong, double, float, decimal
//
if ((target_type == TypeManager.uint32_type) ||
(target_type == TypeManager.uint64_type) ||
(target_type == TypeManager.int32_type) ||
(target_type == TypeManager.int64_type) ||
(target_type == TypeManager.double_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if (expr_type == TypeManager.int32_type){
//
// From int to long, double, float, decimal
//
if ((target_type == TypeManager.int64_type) ||
(target_type == TypeManager.double_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if (expr_type == TypeManager.uint32_type){
//
// From uint to long, ulong, double, float, decimal
//
if ((target_type == TypeManager.int64_type) ||
(target_type == TypeManager.uint64_type) ||
(target_type == TypeManager.double_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if ((expr_type == TypeManager.uint64_type) ||
(expr_type == TypeManager.int64_type)) {
//
// From long/ulong to double, float, decimal
//
if ((target_type == TypeManager.double_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if (expr_type == TypeManager.char_type){
//
// From char to ushort, int, uint, ulong, long, float, double, decimal
//
if ((target_type == TypeManager.ushort_type) ||
(target_type == TypeManager.int32_type) ||
(target_type == TypeManager.uint32_type) ||
(target_type == TypeManager.uint64_type) ||
(target_type == TypeManager.int64_type) ||
(target_type == TypeManager.float_type) ||
(target_type == TypeManager.double_type) ||
(target_type == TypeManager.decimal_type))
return true;
} else if (expr_type == TypeManager.float_type){
//
// float to double
//
if (target_type == TypeManager.double_type)
return true;
}
if (expr.eclass == ExprClass.MethodGroup){
if (TypeManager.IsDelegateType (target_type) && RootContext.Version != LanguageVersion.ISO_1){
MethodGroupExpr mg = expr as MethodGroupExpr;
if (mg != null){
//
// This should not happen frequently, so we can create an object
// to test compatibility
//
Expression c = ImplicitDelegateCreation.Create (
ec, mg, target_type, true, Location.Null);
return c != null;
}
}
}
if (ImplicitReferenceConversionExists (expr, target_type))
return true;
//
// Implicit Constant Expression Conversions
//
if (expr is IntConstant){
int value = ((IntConstant) expr).Value;
if (target_type == TypeManager.sbyte_type){
if (value >= SByte.MinValue && value <= SByte.MaxValue)
return true;
} else if (target_type == TypeManager.byte_type){
if (value >= 0 && value <= Byte.MaxValue)
return true;
} else if (target_type == TypeManager.short_type){
if (value >= Int16.MinValue && value <= Int16.MaxValue)
return true;
} else if (target_type == TypeManager.ushort_type){
if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
return true;
} else if (target_type == TypeManager.uint32_type){
if (value >= 0)
return true;
} else if (target_type == TypeManager.uint64_type){
//
// 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 true;
}
if (value == 0 && expr is IntLiteral && TypeManager.IsEnumType (target_type))
return true;
}
if (expr is LongConstant && target_type == TypeManager.uint64_type){
//
// Try the implicit constant expression conversion
// from long to ulong, instead of a nice routine,
// we just inline it
//
long v = ((LongConstant) expr).Value;
if (v >= 0)
return true;
}
if ((target_type == TypeManager.enum_type ||
target_type.IsSubclassOf (TypeManager.enum_type)) &&
expr is IntLiteral){
IntLiteral i = (IntLiteral) expr;
if (i.Value == 0)
return true;
}
//
// If `expr_type' implements `target_type' (which is an iface)
// see TryImplicitIntConversion
//
if (target_type.IsInterface && target_type.IsAssignableFrom (expr_type))
return true;
if (target_type == TypeManager.void_ptr_type && expr_type.IsPointer)
return true;
if (expr_type == TypeManager.anonymous_method_type){
if (!TypeManager.IsDelegateType (target_type))
return false;
AnonymousMethod am = (AnonymousMethod) expr;
Expression conv = am.Compatible (ec, target_type, true);
if (conv != null)
return true;
}
return false;
}
/// <summary>
/// Finds "most encompassed type" according to the spec (13.4.2)
/// amongst the methods in the MethodGroupExpr
/// </summary>
static Type FindMostEncompassedType (EmitContext ec, ArrayList types)
{
Type best = null;
if (types.Count == 0)
return null;
if (types.Count == 1)
return (Type) types [0];
EmptyExpression expr = EmptyExpression.Grab ();
foreach (Type t in types) {
if (best == null) {
best = t;
continue;
}
expr.SetType (t);
if (ImplicitStandardConversionExists (ec, expr, best))
best = t;
}
expr.SetType (best);
foreach (Type t in types) {
if (best == t)
continue;
if (!ImplicitStandardConversionExists (ec, expr, t)) {
best = null;
break;
}
}
EmptyExpression.Release (expr);
return best;
}
/// <summary>
/// Finds "most encompassing type" according to the spec (13.4.2)
/// amongst the types in the given set
/// </summary>
static Type FindMostEncompassingType (EmitContext ec, ArrayList types)
{
Type best = null;
if (types.Count == 0)
return null;
if (types.Count == 1)
return (Type) types [0];
EmptyExpression expr = EmptyExpression.Grab ();
foreach (Type t in types) {
if (best == null) {
best = t;
continue;
}
expr.SetType (best);
if (ImplicitStandardConversionExists (ec, expr, t))
best = t;
}
foreach (Type t in types) {
if (best == t)
continue;
expr.SetType (t);
if (!ImplicitStandardConversionExists (ec, expr, best)) {
best = null;
break;
}
}
EmptyExpression.Release (expr);
return best;
}
/// <summary>
/// Finds the most specific source Sx according to the rules of the spec (13.4.4)
/// by making use of FindMostEncomp* methods. Applies the correct rules separately
/// for explicit and implicit conversion operators.
/// </summary>
static public Type FindMostSpecificSource (EmitContext ec, IList list,
Expression source, bool apply_explicit_conv_rules)
{
ArrayList src_types_set = new ArrayList ();
//
// If any operator converts from S then Sx = S
//
Type source_type = source.Type;
foreach (MethodBase mb in list){
ParameterData pd = TypeManager.GetParameterData (mb);
Type param_type = pd.ParameterType (0);
if (param_type == source_type)
return param_type;
src_types_set.Add (param_type);
}
//
// Explicit Conv rules
//
if (apply_explicit_conv_rules) {
ArrayList candidate_set = new ArrayList ();
foreach (Type param_type in src_types_set){
if (ImplicitStandardConversionExists (ec, source, param_type))
candidate_set.Add (param_type);
}
if (candidate_set.Count != 0)
return FindMostEncompassedType (ec, candidate_set);
}
//
// Final case
//
if (apply_explicit_conv_rules)
return FindMostEncompassingType (ec, src_types_set);
else
return FindMostEncompassedType (ec, src_types_set);
}
/// <summary>
/// Finds the most specific target Tx according to section 13.4.4
/// </summary>
static public Type FindMostSpecificTarget (EmitContext ec, IList list,
Type target, bool apply_explicit_conv_rules)
{
ArrayList tgt_types_set = new ArrayList ();
//
// If any operator converts to T then Tx = T
//
foreach (MethodInfo mi in list){
Type ret_type = mi.ReturnType;
if (ret_type == target)
return ret_type;
tgt_types_set.Add (ret_type);
}
//
// Explicit conv rules
//
if (apply_explicit_conv_rules) {
ArrayList candidate_set = new ArrayList ();
EmptyExpression expr = EmptyExpression.Grab ();
foreach (Type ret_type in tgt_types_set){
expr.SetType (ret_type);
if (ImplicitStandardConversionExists (ec, expr, target))
candidate_set.Add (ret_type);
}
EmptyExpression.Release (expr);
if (candidate_set.Count != 0)
return FindMostEncompassingType (ec, candidate_set);
}
//
// Okay, final case !
//
if (apply_explicit_conv_rules)
return FindMostEncompassedType (ec, tgt_types_set);
else
return FindMostEncompassingType (ec, tgt_types_set);
}
/// <summary>
/// User-defined Implicit conversions
/// </summary>
static public Expression ImplicitUserConversion (EmitContext ec, Expression source,
Type target, Location loc)
{
return UserDefinedConversion (ec, source, target, loc, false);
}
/// <summary>
/// User-defined Explicit conversions
/// </summary>
static public Expression ExplicitUserConversion (EmitContext ec, Expression source,
Type target, Location loc)
{
return UserDefinedConversion (ec, source, target, loc, true);
}
static void AddConversionOperators (EmitContext ec, ArrayList list,
Expression source, Type target_type,
bool look_for_explicit,
MethodGroupExpr mg)
{
if (mg == null)
return;
Type source_type = source.Type;
EmptyExpression expr = EmptyExpression.Grab ();
foreach (MethodInfo m in mg.Methods) {
ParameterData pd = TypeManager.GetParameterData (m);
Type return_type = m.ReturnType;
Type arg_type = pd.ParameterType (0);
if (source_type != arg_type) {
if (!ImplicitStandardConversionExists (ec, source, arg_type)) {
if (!look_for_explicit)
continue;
expr.SetType (arg_type);
if (!ImplicitStandardConversionExists (ec, expr, source_type))
continue;
}
}
if (target_type != return_type) {
expr.SetType (return_type);
if (!ImplicitStandardConversionExists (ec, expr, target_type)) {
if (!look_for_explicit)
continue;
expr.SetType (target_type);
if (!ImplicitStandardConversionExists (ec, expr, return_type))
continue;
}
}
list.Add (m);
}
EmptyExpression.Release (expr);
}
/// <summary>
/// Compute the user-defined conversion operator from source_type to target_type.
/// `look_for_explicit' controls whether we should also include the list of explicit operators
/// </summary>
static MethodInfo GetConversionOperator (EmitContext ec, Expression source, Type target_type, bool look_for_explicit)
{
ArrayList ops = new ArrayList (4);
Type source_type = source.Type;
if (source_type != TypeManager.decimal_type) {
AddConversionOperators (ec, ops, source, target_type, look_for_explicit,
Expression.MethodLookup (ec, source_type, "op_Implicit", Location.Null) as MethodGroupExpr);
if (look_for_explicit) {
AddConversionOperators (ec, ops, source, target_type, look_for_explicit,
Expression.MethodLookup (
ec, source_type, "op_Explicit", Location.Null) as MethodGroupExpr);
}
}
if (target_type != TypeManager.decimal_type) {
AddConversionOperators (ec, ops, source, target_type, look_for_explicit,
Expression.MethodLookup (ec, target_type, "op_Implicit", Location.Null) as MethodGroupExpr);
if (look_for_explicit) {
AddConversionOperators (ec, ops, source, target_type, look_for_explicit,
Expression.MethodLookup (
ec, target_type, "op_Explicit", Location.Null) as MethodGroupExpr);
}
}
if (ops.Count == 0)
return null;
Type most_specific_source = FindMostSpecificSource (ec, ops, source, look_for_explicit);
if (most_specific_source == null)
return null;
Type most_specific_target = FindMostSpecificTarget (ec, ops, target_type, look_for_explicit);
if (most_specific_target == null)
return null;
MethodInfo method = null;
foreach (MethodInfo m in ops) {
if (m.ReturnType != most_specific_target)
continue;
if (TypeManager.GetParameterData (m).ParameterType (0) != most_specific_source)
continue;
// Ambiguous: more than one conversion operator satisfies the signature.
if (method != null)
return null;
method = m;
}
return method;
}
static DoubleHash explicit_conv = new DoubleHash (100);
static DoubleHash implicit_conv = new DoubleHash (100);
/// <summary>
/// User-defined conversions