|
public GetAts ( |
||
| errorContext | ||
| return | ||
// Value
public Expr BindValue(Expr exprSrc)
{
Debug.Assert(exprSrc != null && exprSrc.Type is NullableType);
// For new T?(x), the answer is x.
if (IsNullableConstructor(exprSrc, out ExprCall call))
{
var args = call.OptionalArguments;
Debug.Assert(args != null && !(args is ExprList));
return(args);
}
NullableType nubSrc = (NullableType)exprSrc.Type;
CType typeBase = nubSrc.GetUnderlyingType();
AggregateType ats = nubSrc.GetAts();
PropertySymbol prop = GetSymbolLoader().getBSymmgr().propNubValue;
if (prop == null)
{
prop = GetSymbolLoader().getPredefinedMembers().GetProperty(PREDEFPROP.PP_G_OPTIONAL_VALUE);
Debug.Assert(prop != null);
GetSymbolLoader().getBSymmgr().propNubValue = prop;
}
PropWithType pwt = new PropWithType(prop, ats);
MethPropWithInst mpwi = new MethPropWithInst(prop, ats);
ExprMemberGroup pMemGroup = GetExprFactory().CreateMemGroup(exprSrc, mpwi);
return(GetExprFactory().CreateProperty(typeBase, null, null, pMemGroup, pwt, null));
}
// Create an expr for new T?(exprSrc) where T is exprSrc.type.
private static ExprCall BindNubNew(Expr exprSrc)
{
Debug.Assert(exprSrc != null);
NullableType pNubSourceType = TypeManager.GetNullable(exprSrc.Type);
AggregateType pSourceType = pNubSourceType.GetAts();
MethodSymbol meth = PredefinedMembers.GetMethod(PREDEFMETH.PM_G_OPTIONAL_CTOR);
MethWithInst methwithinst = new MethWithInst(meth, pSourceType, TypeArray.Empty);
ExprMemberGroup memgroup = ExprFactory.CreateMemGroup(null, methwithinst);
return(ExprFactory.CreateCall(EXPRFLAG.EXF_NEWOBJCALL | EXPRFLAG.EXF_CANTBENULL, pNubSourceType, exprSrc, memgroup, methwithinst));
}
private bool bindImplicitConversionFromNullable(NullableType nubSrc)
{
// We can convert T? using a boxing conversion, we can convert it to ValueType, and
// we can convert it to any interface implemented by T.
//
// 13.1.5 Boxing Conversions
//
// A nullable-type has a boxing conversion to the same set of types to which the nullable-type's
// underlying type has boxing conversions. A boxing conversion applied to a value of a nullable-type
// proceeds as follows:
//
// * If the HasValue property of the nullable value evaluates to false, then the result of the
// boxing conversion is the null reference of the appropriate type.
//
// Otherwise, the result is obtained by boxing the result of evaluating the Value property on
// the nullable value.
AggregateType atsNub = nubSrc.GetAts(GetErrorContext());
if (atsNub == null)
{
return(false);
}
if (atsNub == typeDest)
{
// REVIEW : Should this ASSERT?
if (needsExprDest)
{
exprDest = exprSrc;
}
return(true);
}
if (GetSymbolLoader().HasBaseConversion(nubSrc.GetUnderlyingType(), typeDest) && !CConversions.FUnwrappingConv(nubSrc, typeDest))
{
if (needsExprDest)
{
binder.bindSimpleCast(exprSrc, exprTypeDest, out exprDest, EXPRFLAG.EXF_BOX);
if (!typeDest.isPredefType(PredefinedType.PT_OBJECT))
{
// DevDiv Bugs 125348: The base type of a nullable is always a non-nullable value type,
// therefore so is typeDest unless typeDest is PT_OBJECT. In this case the conversion
// needs to be unboxed. We only need this if we actually will use the result.
binder.bindSimpleCast(exprDest, exprTypeDest, out exprDest, EXPRFLAG.EXF_FORCE_UNBOX);
}
}
return(true);
}
return(0 == (flags & CONVERTTYPE.NOUDC) && binder.bindUserDefinedConversion(exprSrc, nubSrc, typeDest, needsExprDest, out exprDest, true));
}
private bool bindImplicitConversionFromNullable(NullableType nubSrc)
{
// We can convert T? using a boxing conversion, we can convert it to ValueType, and
// we can convert it to any interface implemented by T.
//
// 13.1.5 Boxing Conversions
//
// A nullable-type has a boxing conversion to the same set of types to which the nullable-type's
// underlying type has boxing conversions. A boxing conversion applied to a value of a nullable-type
// proceeds as follows:
//
// * If the HasValue property of the nullable value evaluates to false, then the result of the
// boxing conversion is the null reference of the appropriate type.
//
// Otherwise, the result is obtained by boxing the result of evaluating the Value property on
// the nullable value.
AggregateType atsNub = nubSrc.GetAts();
if (atsNub == _typeDest)
{
if (_needsExprDest)
{
_exprDest = _exprSrc;
}
return true;
}
if (SymbolLoader.HasBaseConversion(nubSrc.UnderlyingType, _typeDest) && !CConversions.FUnwrappingConv(nubSrc, _typeDest))
{
if (_needsExprDest)
{
_binder.bindSimpleCast(_exprSrc, _typeDest, out _exprDest, EXPRFLAG.EXF_BOX);
if (!_typeDest.IsPredefType(PredefinedType.PT_OBJECT))
{
// The base type of a nullable is always a non-nullable value type,
// therefore so is typeDest unless typeDest is PT_OBJECT. In this case the conversion
// needs to be unboxed. We only need this if we actually will use the result.
_binder.bindSimpleCast(_exprDest, _typeDest, out _exprDest, EXPRFLAG.EXF_FORCE_UNBOX);
}
}
return true;
}
return 0 == (_flags & CONVERTTYPE.NOUDC) && _binder.bindUserDefinedConversion(_exprSrc, nubSrc, _typeDest, _needsExprDest, out _exprDest, true);
}
public ExprCall BindNew(Expr pExprSrc)
{
Debug.Assert(pExprSrc != null);
NullableType pNubSourceType = GetSymbolLoader().GetTypeManager().GetNullable(pExprSrc.Type);
AggregateType pSourceType = pNubSourceType.GetAts();
MethodSymbol meth = GetSymbolLoader().getBSymmgr().methNubCtor;
if (meth == null)
{
meth = GetSymbolLoader().getPredefinedMembers().GetMethod(PREDEFMETH.PM_G_OPTIONAL_CTOR);
Debug.Assert(meth != null);
GetSymbolLoader().getBSymmgr().methNubCtor = meth;
}
MethWithInst methwithinst = new MethWithInst(meth, pSourceType, BSYMMGR.EmptyTypeArray());
ExprMemberGroup memgroup = GetExprFactory().CreateMemGroup(null, methwithinst);
return(GetExprFactory().CreateCall(EXPRFLAG.EXF_NEWOBJCALL | EXPRFLAG.EXF_CANTBENULL, pNubSourceType, pExprSrc, memgroup, methwithinst));
}
public EXPRCALL BindNew(EXPR pExprSrc)
{
Debug.Assert(pExprSrc != null);
NullableType pNubSourceType = GetSymbolLoader().GetTypeManager().GetNullable(pExprSrc.type);
AggregateType pSourceType = pNubSourceType.GetAts(GetErrorContext());
if (pSourceType == null)
{
MethWithInst mwi = new MethWithInst(null, null);
EXPRMEMGRP pMemGroup = GetExprFactory().CreateMemGroup(pExprSrc, mwi);
EXPRCALL rval = GetExprFactory().CreateCall(0, pNubSourceType, null, pMemGroup, null);
rval.SetError();
return(rval);
}
// UNDONE: move this to transform pass
MethodSymbol meth = GetSymbolLoader().getBSymmgr().methNubCtor;
if (meth == null)
{
meth = GetSymbolLoader().getPredefinedMembers().GetMethod(PREDEFMETH.PM_G_OPTIONAL_CTOR);
GetSymbolLoader().getBSymmgr().methNubCtor = meth;
}
MethWithInst methwithinst = new MethWithInst(meth, pSourceType, BSYMMGR.EmptyTypeArray());
EXPRMEMGRP memgroup = GetExprFactory().CreateMemGroup(null, methwithinst);
EXPRCALL pExprRes = GetExprFactory().CreateCall(EXPRFLAG.EXF_NEWOBJCALL | EXPRFLAG.EXF_CANTBENULL, pNubSourceType, pExprSrc, memgroup, methwithinst);
if (meth == null)
{
pExprRes.SetError();
}
return(pExprRes);
}
/***************************************************************************************************
* Called by BindImplicitConversion when the destination type is Nullable<T>. The following
* conversions are handled by this method:
*
* For S in { object, ValueType, interfaces implemented by underlying type} there is an explicit
* unboxing conversion S => T?
* System.Enum => T? there is an unboxing conversion if T is an enum type
* null => T? implemented as default(T?)
*
* Implicit T?* => T?+ implemented by either wrapping or calling GetValueOrDefault the
* appropriate number of times.
* If imp/exp S => T then imp/exp S => T?+ implemented by converting to T then wrapping the
* appropriate number of times.
* If imp/exp S => T then imp/exp S?+ => T?+ implemented by calling GetValueOrDefault (m-1) times
* then calling HasValue, producing a null if it returns false, otherwise calling Value,
* converting to T then wrapping the appropriate number of times.
*
* The 3 rules above can be summarized with the following recursive rules:
*
* If imp/exp S => T? then imp/exp S? => T? implemented as
* qs.HasValue ? (T?)(qs.Value) : default(T?)
* If imp/exp S => T then imp/exp S => T? implemented as new T?((T)s)
*
* This method also handles calling bindUserDefinedConverion. This method does NOT handle
* the following conversions:
*
* Implicit boxing conversion from S? to { object, ValueType, Enum, ifaces implemented by S }. (Handled by BindImplicitConversion.)
* If imp/exp S => T then explicit S?+ => T implemented by calling Value the appropriate number
* of times. (Handled by BindExplicitConversion.)
*
* The recursive equivalent is:
*
* If imp/exp S => T and T is not nullable then explicit S? => T implemented as qs.Value
*
* Some nullable conversion are NOT standard conversions. In particular, if S => T is implicit
* then S? => T is not standard. Similarly if S => T is not implicit then S => T? is not standard.
***************************************************************************************************/
private bool BindNubConversion(NullableType nubDst)
{
// This code assumes that STANDARD and ISEXPLICIT are never both set.
// bindUserDefinedConversion should ensure this!
Debug.Assert(0 != (~_flags & (CONVERTTYPE.STANDARD | CONVERTTYPE.ISEXPLICIT)));
Debug.Assert(_exprSrc == null || _exprSrc.Type == _typeSrc);
Debug.Assert(!_needsExprDest || _exprSrc != null);
Debug.Assert(_typeSrc != nubDst); // BindImplicitConversion should have taken care of this already.
AggregateType atsDst = nubDst.GetAts();
// Check for the unboxing conversion. This takes precedence over the wrapping conversions.
if (GetSymbolLoader().HasBaseConversion(nubDst.GetUnderlyingType(), _typeSrc) && !CConversions.FWrappingConv(_typeSrc, nubDst))
{
// These should be different! Fix the caller if typeSrc is an AggregateType of Nullable.
Debug.Assert(atsDst != _typeSrc);
// typeSrc is a base type of the destination nullable type so there is an explicit
// unboxing conversion.
if (0 == (_flags & CONVERTTYPE.ISEXPLICIT))
{
return(false);
}
if (_needsExprDest)
{
_binder.bindSimpleCast(_exprSrc, _typeDest, out _exprDest, EXPRFLAG.EXF_UNBOX);
}
return(true);
}
bool dstWasNullable;
bool srcWasNullable;
CType typeDstBase = nubDst.StripNubs(out dstWasNullable);
CType typeSrcBase = _typeSrc.StripNubs(out srcWasNullable);
ConversionFunc pfn = (_flags & CONVERTTYPE.ISEXPLICIT) != 0 ?
(ConversionFunc)_binder.BindExplicitConversion :
(ConversionFunc)_binder.BindImplicitConversion;
if (!srcWasNullable)
{
Debug.Assert(_typeSrc == typeSrcBase);
// The null type can be implicitly converted to T? as the default value.
if (_typeSrc is NullType)
{
// If we have the constant null, generate it as a default value of T?. If we have
// some crazy expression which has been determined to be always null, like (null??null)
// keep it in its expression form and transform it in the nullable rewrite pass.
if (_needsExprDest)
{
if (_exprSrc.isCONSTANT_OK())
{
_exprDest = GetExprFactory().CreateZeroInit(nubDst);
}
else
{
_exprDest = GetExprFactory().CreateCast(_typeDest, _exprSrc);
}
}
return(true);
}
Expr exprTmp = _exprSrc;
// If there is an implicit/explicit S => T then there is an implicit/explicit S => T?
if (_typeSrc == typeDstBase || pfn(_exprSrc, _typeSrc, typeDstBase, _needsExprDest, out exprTmp, _flags | CONVERTTYPE.NOUDC))
{
if (_needsExprDest)
{
ExprUserDefinedConversion exprUDC = exprTmp as ExprUserDefinedConversion;
if (exprUDC != null)
{
exprTmp = exprUDC.UserDefinedCall;
}
if (dstWasNullable)
{
ExprCall call = _binder.BindNubNew(exprTmp);
exprTmp = call;
call.NullableCallLiftKind = NullableCallLiftKind.NullableConversionConstructor;
}
if (exprUDC != null)
{
exprUDC.UserDefinedCall = exprTmp;
exprTmp = exprUDC;
}
Debug.Assert(exprTmp.Type == nubDst);
_exprDest = exprTmp;
}
return(true);
}
// No builtin conversion. Maybe there is a user defined conversion....
return(0 == (_flags & CONVERTTYPE.NOUDC) && _binder.bindUserDefinedConversion(_exprSrc, _typeSrc, nubDst, _needsExprDest, out _exprDest, 0 == (_flags & CONVERTTYPE.ISEXPLICIT)));
}
// Both are Nullable so there is only a conversion if there is a conversion between the base types.
// That is, if there is an implicit/explicit S => T then there is an implicit/explicit S?+ => T?+.
if (typeSrcBase != typeDstBase && !pfn(null, typeSrcBase, typeDstBase, false, out _exprDest, _flags | CONVERTTYPE.NOUDC))
{
// No builtin conversion. Maybe there is a user defined conversion....
return(0 == (_flags & CONVERTTYPE.NOUDC) && _binder.bindUserDefinedConversion(_exprSrc, _typeSrc, nubDst, _needsExprDest, out _exprDest, 0 == (_flags & CONVERTTYPE.ISEXPLICIT)));
}
if (_needsExprDest)
{
MethWithInst mwi = new MethWithInst(null, null);
ExprMemberGroup pMemGroup = GetExprFactory().CreateMemGroup(null, mwi);
ExprCall exprDst = GetExprFactory().CreateCall(0, nubDst, _exprSrc, pMemGroup, null);
// Here we want to first check whether or not the conversions work on the base types.
Expr arg1 = _binder.mustCast(_exprSrc, typeSrcBase);
bool convertible = (_flags & CONVERTTYPE.ISEXPLICIT) != 0
? _binder.BindExplicitConversion(
arg1, arg1.Type, typeDstBase, out arg1, _flags | CONVERTTYPE.NOUDC)
: _binder.BindImplicitConversion(
arg1, arg1.Type, typeDstBase, out arg1, _flags | CONVERTTYPE.NOUDC);
if (!convertible)
{
Debug.Fail("bind(Im|Ex)plicitConversion failed unexpectedly");
return(false);
}
exprDst.CastOfNonLiftedResultToLiftedType = _binder.mustCast(arg1, nubDst, 0);
exprDst.NullableCallLiftKind = NullableCallLiftKind.NullableConversion;
exprDst.PConversions = exprDst.CastOfNonLiftedResultToLiftedType;
_exprDest = exprDst;
}
return(true);
}
/***************************************************************************************************
* Called by BindImplicitConversion when the destination type is Nullable<T>. The following
* conversions are handled by this method:
*
* For S in { object, ValueType, interfaces implemented by underlying type} there is an explicit
* unboxing conversion S => T?
* System.Enum => T? there is an unboxing conversion if T is an enum type
* null => T? implemented as default(T?)
*
* Implicit T?* => T?+ implemented by either wrapping or calling GetValueOrDefault the
* appropriate number of times.
* If imp/exp S => T then imp/exp S => T?+ implemented by converting to T then wrapping the
* appropriate number of times.
* If imp/exp S => T then imp/exp S?+ => T?+ implemented by calling GetValueOrDefault (m-1) times
* then calling HasValue, producing a null if it returns false, otherwise calling Value,
* converting to T then wrapping the appropriate number of times.
*
* The 3 rules above can be summarized with the following recursive rules:
*
* If imp/exp S => T? then imp/exp S? => T? implemented as
* qs.HasValue ? (T?)(qs.Value) : default(T?)
* If imp/exp S => T then imp/exp S => T? implemented as new T?((T)s)
*
* This method also handles calling bindUserDefinedConverion. This method does NOT handle
* the following conversions:
*
* Implicit boxing conversion from S? to { object, ValueType, Enum, ifaces implemented by S }. (Handled by BindImplicitConversion.)
* If imp/exp S => T then explicit S?+ => T implemented by calling Value the appropriate number
* of times. (Handled by BindExplicitConversion.)
*
* The recursive equivalent is:
*
* If imp/exp S => T and T is not nullable then explicit S? => T implemented as qs.Value
*
* Some nullable conversion are NOT standard conversions. In particular, if S => T is implicit
* then S? => T is not standard. Similarly if S => T is not implicit then S => T? is not standard.
***************************************************************************************************/
private bool BindNubConversion(NullableType nubDst)
{
// This code assumes that STANDARD and ISEXPLICIT are never both set.
// bindUserDefinedConversion should ensure this!
Debug.Assert(0 != (~flags & (CONVERTTYPE.STANDARD | CONVERTTYPE.ISEXPLICIT)));
Debug.Assert(exprSrc == null || exprSrc.type == typeSrc);
Debug.Assert(!needsExprDest || exprSrc != null);
Debug.Assert(typeSrc != nubDst); // BindImplicitConversion should have taken care of this already.
AggregateType atsDst = nubDst.GetAts(GetErrorContext());
if (atsDst == null)
{
return(false);
}
// Check for the unboxing conversion. This takes precedence over the wrapping conversions.
if (GetSymbolLoader().HasBaseConversion(nubDst.GetUnderlyingType(), typeSrc) && !CConversions.FWrappingConv(typeSrc, nubDst))
{
// These should be different! Fix the caller if typeSrc is an AggregateType of Nullable.
Debug.Assert(atsDst != typeSrc);
// typeSrc is a base type of the destination nullable type so there is an explicit
// unboxing conversion.
if (0 == (flags & CONVERTTYPE.ISEXPLICIT))
{
return(false);
}
if (needsExprDest)
{
binder.bindSimpleCast(exprSrc, exprTypeDest, out exprDest, EXPRFLAG.EXF_UNBOX);
}
return(true);
}
int cnubDst;
int cnubSrc;
CType typeDstBase = nubDst.StripNubs(out cnubDst);
EXPRCLASS exprTypeDstBase = GetExprFactory().MakeClass(typeDstBase);
CType typeSrcBase = typeSrc.StripNubs(out cnubSrc);
ConversionFunc pfn = (flags & CONVERTTYPE.ISEXPLICIT) != 0 ?
(ConversionFunc)binder.BindExplicitConversion :
(ConversionFunc)binder.BindImplicitConversion;
if (cnubSrc == 0)
{
Debug.Assert(typeSrc == typeSrcBase);
// The null type can be implicitly converted to T? as the default value.
if (typeSrc.IsNullType())
{
// If we have the constant null, generate it as a default value of T?. If we have
// some crazy expression which has been determined to be always null, like (null??null)
// keep it in its expression form and transform it in the nullable rewrite pass.
if (needsExprDest)
{
if (exprSrc.isCONSTANT_OK())
{
exprDest = GetExprFactory().CreateZeroInit(nubDst);
}
else
{
exprDest = GetExprFactory().CreateCast(0x00, typeDest, exprSrc);
}
}
return(true);
}
EXPR exprTmp = exprSrc;
// If there is an implicit/explicit S => T then there is an implicit/explicit S => T?
if (typeSrc == typeDstBase || pfn(exprSrc, typeSrc, exprTypeDstBase, nubDst, needsExprDest, out exprTmp, flags | CONVERTTYPE.NOUDC))
{
if (needsExprDest)
{
// UNDONE: This is a premature realization of the nullable conversion as
// UNDONE: a constructor. Rather than flagging this, can we simply emit it
// UNDONE: as a cast node and have the operator rewrite pass turn it into
// UNDONE: a constructor call?
EXPRUSERDEFINEDCONVERSION exprUDC = exprTmp.kind == ExpressionKind.EK_USERDEFINEDCONVERSION ? exprTmp.asUSERDEFINEDCONVERSION() : null;
if (exprUDC != null)
{
exprTmp = exprUDC.UserDefinedCall;
}
// This logic is left over from the days when T?? was legal. However there are error/LAF cases that necessitates the loop.
// typeSrc is not nullable so just wrap the required number of times. For legal code (cnubDst <= 0).
for (int i = 0; i < cnubDst; i++)
{
exprTmp = binder.BindNubNew(exprTmp);
exprTmp.asCALL().nubLiftKind = NullableCallLiftKind.NullableConversionConstructor;
}
if (exprUDC != null)
{
exprUDC.UserDefinedCall = exprTmp;
exprUDC.setType((CType)exprTmp.type);
exprTmp = exprUDC;
}
Debug.Assert(exprTmp.type == nubDst);
exprDest = exprTmp;
}
return(true);
}
// No builtin conversion. Maybe there is a user defined conversion....
return(0 == (flags & CONVERTTYPE.NOUDC) && binder.bindUserDefinedConversion(exprSrc, typeSrc, nubDst, needsExprDest, out exprDest, 0 == (flags & CONVERTTYPE.ISEXPLICIT)));
}
// Both are Nullable so there is only a conversion if there is a conversion between the base types.
// That is, if there is an implicit/explicit S => T then there is an implicit/explicit S?+ => T?+.
if (typeSrcBase != typeDstBase && !pfn(null, typeSrcBase, exprTypeDstBase, nubDst, false, out exprDest, flags | CONVERTTYPE.NOUDC))
{
// No builtin conversion. Maybe there is a user defined conversion....
return(0 == (flags & CONVERTTYPE.NOUDC) && binder.bindUserDefinedConversion(exprSrc, typeSrc, nubDst, needsExprDest, out exprDest, 0 == (flags & CONVERTTYPE.ISEXPLICIT)));
}
if (needsExprDest)
{
MethWithInst mwi = new MethWithInst(null, null);
EXPRMEMGRP pMemGroup = GetExprFactory().CreateMemGroup(null, mwi);
EXPRCALL exprDst = GetExprFactory().CreateCall(0, nubDst, exprSrc, pMemGroup, null);
// Here we want to first check whether or not the conversions work on the base types.
EXPR arg1 = binder.mustCast(exprSrc, typeSrcBase);
EXPRCLASS arg2 = GetExprFactory().MakeClass(typeDstBase);
bool convertible;
if (0 != (flags & CONVERTTYPE.ISEXPLICIT))
{
convertible = binder.BindExplicitConversion(arg1, arg1.type, arg2, typeDstBase, out arg1, flags | CONVERTTYPE.NOUDC);
}
else
{
convertible = binder.BindImplicitConversion(arg1, arg1.type, arg2, typeDstBase, out arg1, flags | CONVERTTYPE.NOUDC);
}
if (!convertible)
{
VSFAIL("bind(Im|Ex)plicitConversion failed unexpectedly");
return(false);
}
exprDst.castOfNonLiftedResultToLiftedType = binder.mustCast(arg1, nubDst, 0);
exprDst.nubLiftKind = NullableCallLiftKind.NullableConversion;
exprDst.pConversions = exprDst.castOfNonLiftedResultToLiftedType;
exprDest = exprDst;
}
return(true);
}
private bool bindImplicitConversionFromNullable(NullableType nubSrc)
{
// We can convert T? using a boxing conversion, we can convert it to ValueType, and
// we can convert it to any interface implemented by T.
//
// 13.1.5 Boxing Conversions
//
// A nullable-type has a boxing conversion to the same set of types to which the nullable-type's
// underlying type has boxing conversions. A boxing conversion applied to a value of a nullable-type
// proceeds as follows:
//
// * If the HasValue property of the nullable value evaluates to false, then the result of the
// boxing conversion is the null reference of the appropriate type.
//
// Otherwise, the result is obtained by boxing the result of evaluating the Value property on
// the nullable value.
AggregateType atsNub = nubSrc.GetAts(GetErrorContext());
if (atsNub == null)
{
return false;
}
if (atsNub == _typeDest)
{
if (_needsExprDest)
{
_exprDest = _exprSrc;
}
return true;
}
if (GetSymbolLoader().HasBaseConversion(nubSrc.GetUnderlyingType(), _typeDest) && !CConversions.FUnwrappingConv(nubSrc, _typeDest))
{
if (_needsExprDest)
{
_binder.bindSimpleCast(_exprSrc, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_BOX);
if (!_typeDest.isPredefType(PredefinedType.PT_OBJECT))
{
// The base type of a nullable is always a non-nullable value type,
// therefore so is typeDest unless typeDest is PT_OBJECT. In this case the conversion
// needs to be unboxed. We only need this if we actually will use the result.
_binder.bindSimpleCast(_exprDest, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_FORCE_UNBOX);
}
}
return true;
}
return 0 == (_flags & CONVERTTYPE.NOUDC) && _binder.bindUserDefinedConversion(_exprSrc, nubSrc, _typeDest, _needsExprDest, out _exprDest, true);
}
/***************************************************************************************************
Called by BindImplicitConversion when the destination type is Nullable<T>. The following
conversions are handled by this method:
* For S in { object, ValueType, interfaces implemented by underlying type} there is an explicit
unboxing conversion S => T?
* System.Enum => T? there is an unboxing conversion if T is an enum type
* null => T? implemented as default(T?)
* Implicit T?* => T?+ implemented by either wrapping or calling GetValueOrDefault the
appropriate number of times.
* If imp/exp S => T then imp/exp S => T?+ implemented by converting to T then wrapping the
appropriate number of times.
* If imp/exp S => T then imp/exp S?+ => T?+ implemented by calling GetValueOrDefault (m-1) times
then calling HasValue, producing a null if it returns false, otherwise calling Value,
converting to T then wrapping the appropriate number of times.
The 3 rules above can be summarized with the following recursive rules:
* If imp/exp S => T? then imp/exp S? => T? implemented as
qs.HasValue ? (T?)(qs.Value) : default(T?)
* If imp/exp S => T then imp/exp S => T? implemented as new T?((T)s)
This method also handles calling bindUserDefinedConverion. This method does NOT handle
the following conversions:
* Implicit boxing conversion from S? to { object, ValueType, Enum, ifaces implemented by S }. (Handled by BindImplicitConversion.)
* If imp/exp S => T then explicit S?+ => T implemented by calling Value the appropriate number
of times. (Handled by BindExplicitConversion.)
The recursive equivalent is:
* If imp/exp S => T and T is not nullable then explicit S? => T implemented as qs.Value
Some nullable conversion are NOT standard conversions. In particular, if S => T is implicit
then S? => T is not standard. Similarly if S => T is not implicit then S => T? is not standard.
***************************************************************************************************/
private bool BindNubConversion(NullableType nubDst)
{
// This code assumes that STANDARD and ISEXPLICIT are never both set.
// bindUserDefinedConversion should ensure this!
Debug.Assert(0 != (~_flags & (CONVERTTYPE.STANDARD | CONVERTTYPE.ISEXPLICIT)));
Debug.Assert(_exprSrc == null || _exprSrc.type == _typeSrc);
Debug.Assert(!_needsExprDest || _exprSrc != null);
Debug.Assert(_typeSrc != nubDst); // BindImplicitConversion should have taken care of this already.
AggregateType atsDst = nubDst.GetAts(GetErrorContext());
if (atsDst == null)
return false;
// Check for the unboxing conversion. This takes precedence over the wrapping conversions.
if (GetSymbolLoader().HasBaseConversion(nubDst.GetUnderlyingType(), _typeSrc) && !CConversions.FWrappingConv(_typeSrc, nubDst))
{
// These should be different! Fix the caller if typeSrc is an AggregateType of Nullable.
Debug.Assert(atsDst != _typeSrc);
// typeSrc is a base type of the destination nullable type so there is an explicit
// unboxing conversion.
if (0 == (_flags & CONVERTTYPE.ISEXPLICIT))
{
return false;
}
if (_needsExprDest)
{
_binder.bindSimpleCast(_exprSrc, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_UNBOX);
}
return true;
}
int cnubDst;
int cnubSrc;
CType typeDstBase = nubDst.StripNubs(out cnubDst);
EXPRCLASS exprTypeDstBase = GetExprFactory().MakeClass(typeDstBase);
CType typeSrcBase = _typeSrc.StripNubs(out cnubSrc);
ConversionFunc pfn = (_flags & CONVERTTYPE.ISEXPLICIT) != 0 ?
(ConversionFunc)_binder.BindExplicitConversion :
(ConversionFunc)_binder.BindImplicitConversion;
if (cnubSrc == 0)
{
Debug.Assert(_typeSrc == typeSrcBase);
// The null type can be implicitly converted to T? as the default value.
if (_typeSrc.IsNullType())
{
// If we have the constant null, generate it as a default value of T?. If we have
// some crazy expression which has been determined to be always null, like (null??null)
// keep it in its expression form and transform it in the nullable rewrite pass.
if (_needsExprDest)
{
if (_exprSrc.isCONSTANT_OK())
{
_exprDest = GetExprFactory().CreateZeroInit(nubDst);
}
else
{
_exprDest = GetExprFactory().CreateCast(0x00, _typeDest, _exprSrc);
}
}
return true;
}
EXPR exprTmp = _exprSrc;
// If there is an implicit/explicit S => T then there is an implicit/explicit S => T?
if (_typeSrc == typeDstBase || pfn(_exprSrc, _typeSrc, exprTypeDstBase, nubDst, _needsExprDest, out exprTmp, _flags | CONVERTTYPE.NOUDC))
{
if (_needsExprDest)
{
EXPRUSERDEFINEDCONVERSION exprUDC = exprTmp.kind == ExpressionKind.EK_USERDEFINEDCONVERSION ? exprTmp.asUSERDEFINEDCONVERSION() : null;
if (exprUDC != null)
{
exprTmp = exprUDC.UserDefinedCall;
}
// This logic is left over from the days when T?? was legal. However there are error/LAF cases that necessitates the loop.
// typeSrc is not nullable so just wrap the required number of times. For legal code (cnubDst <= 0).
for (int i = 0; i < cnubDst; i++)
{
exprTmp = _binder.BindNubNew(exprTmp);
exprTmp.asCALL().nubLiftKind = NullableCallLiftKind.NullableConversionConstructor;
}
if (exprUDC != null)
{
exprUDC.UserDefinedCall = exprTmp;
exprUDC.setType((CType)exprTmp.type);
exprTmp = exprUDC;
}
Debug.Assert(exprTmp.type == nubDst);
_exprDest = exprTmp;
}
return true;
}
// No builtin conversion. Maybe there is a user defined conversion....
return 0 == (_flags & CONVERTTYPE.NOUDC) && _binder.bindUserDefinedConversion(_exprSrc, _typeSrc, nubDst, _needsExprDest, out _exprDest, 0 == (_flags & CONVERTTYPE.ISEXPLICIT));
}
// Both are Nullable so there is only a conversion if there is a conversion between the base types.
// That is, if there is an implicit/explicit S => T then there is an implicit/explicit S?+ => T?+.
if (typeSrcBase != typeDstBase && !pfn(null, typeSrcBase, exprTypeDstBase, nubDst, false, out _exprDest, _flags | CONVERTTYPE.NOUDC))
{
// No builtin conversion. Maybe there is a user defined conversion....
return 0 == (_flags & CONVERTTYPE.NOUDC) && _binder.bindUserDefinedConversion(_exprSrc, _typeSrc, nubDst, _needsExprDest, out _exprDest, 0 == (_flags & CONVERTTYPE.ISEXPLICIT));
}
if (_needsExprDest)
{
MethWithInst mwi = new MethWithInst(null, null);
EXPRMEMGRP pMemGroup = GetExprFactory().CreateMemGroup(null, mwi);
EXPRCALL exprDst = GetExprFactory().CreateCall(0, nubDst, _exprSrc, pMemGroup, null);
// Here we want to first check whether or not the conversions work on the base types.
EXPR arg1 = _binder.mustCast(_exprSrc, typeSrcBase);
EXPRCLASS arg2 = GetExprFactory().MakeClass(typeDstBase);
bool convertible;
if (0 != (_flags & CONVERTTYPE.ISEXPLICIT))
{
convertible = _binder.BindExplicitConversion(arg1, arg1.type, arg2, typeDstBase, out arg1, _flags | CONVERTTYPE.NOUDC);
}
else
{
convertible = _binder.BindImplicitConversion(arg1, arg1.type, arg2, typeDstBase, out arg1, _flags | CONVERTTYPE.NOUDC);
}
if (!convertible)
{
VSFAIL("bind(Im|Ex)plicitConversion failed unexpectedly");
return false;
}
exprDst.castOfNonLiftedResultToLiftedType = _binder.mustCast(arg1, nubDst, 0);
exprDst.nubLiftKind = NullableCallLiftKind.NullableConversion;
exprDst.pConversions = exprDst.castOfNonLiftedResultToLiftedType;
_exprDest = exprDst;
}
return true;
}