/// <summary>
/// Matches Roslyn C# switch on nullable.
/// </summary>
bool MatchRoslynSwitchOnNullable(InstructionCollection <ILInstruction> instructions, int i, out SwitchInstruction newSwitch)
{
newSwitch = null;
// match first block:
// stloc tmp(ldloc switchValueVar)
// if (logic.not(call get_HasValue(ldloca tmp))) br nullCaseBlock
// br switchBlock
if (i < 1)
{
return(false);
}
if (!instructions[i - 1].MatchStLoc(out var tmp, out var switchValue) ||
!instructions[i].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
if (tmp.StoreCount != 1 || tmp.AddressCount != 2 || tmp.LoadCount != 0)
{
return(false);
}
if (!instructions[i + 1].MatchBranch(out var switchBlock) || !trueInst.MatchBranch(out var nullCaseBlock))
{
return(false);
}
if (!condition.MatchLogicNot(out var getHasValue) || !NullableLiftingTransform.MatchHasValueCall(getHasValue, out ILVariable target1) || target1 != tmp)
{
return(false);
}
// match second block: switchBlock
// stloc switchVar(call GetValueOrDefault(ldloca tmp))
// switch (ldloc switchVar) {
// case [0..1): br caseBlock1
// ... more cases ...
// case [long.MinValue..0),[1..5),[6..10),[11..long.MaxValue]: br defaultBlock
// }
if (switchBlock.Instructions.Count != 2 || switchBlock.IncomingEdgeCount != 1)
{
return(false);
}
if (!switchBlock.Instructions[0].MatchStLoc(out var switchVar, out var getValueOrDefault))
{
return(false);
}
if (!switchVar.IsSingleDefinition || switchVar.LoadCount != 1)
{
return(false);
}
if (!NullableLiftingTransform.MatchGetValueOrDefault(getValueOrDefault, tmp))
{
return(false);
}
if (!(switchBlock.Instructions[1] is SwitchInstruction switchInst))
{
return(false);
}
newSwitch = BuildLiftedSwitch(nullCaseBlock, switchInst, switchValue);
return(true);
}
bool MatchDisposeCheck(ILVariable objVar, ILInstruction checkInst, bool isReference, bool usingNull, out int numObjVarLoadsInCheck)
{
numObjVarLoadsInCheck = 2;
CallVirt callVirt;
if (objVar.Type.IsKnownType(KnownTypeCode.NullableOfT))
{
if (!checkInst.MatchIfInstruction(out var condition, out var disposeInst))
{
return(false);
}
if (!NullableLiftingTransform.MatchHasValueCall(condition, objVar))
{
return(false);
}
if (!(disposeInst is Block disposeBlock) || disposeBlock.Instructions.Count != 1)
{
return(false);
}
if (!(disposeBlock.Instructions[0] is CallVirt cv))
{
return(false);
}
callVirt = cv;
if (callVirt.Method.FullName != "System.IDisposable.Dispose")
{
return(false);
}
if (callVirt.Method.Parameters.Count > 0)
{
return(false);
}
if (callVirt.Arguments.Count != 1)
{
return(false);
}
var firstArg = cv.Arguments.FirstOrDefault();
if (!(firstArg.MatchUnboxAny(out var innerArg1, out var unboxType) && unboxType.IsKnownType(KnownTypeCode.IDisposable)))
{
if (!firstArg.MatchAddressOf(out var innerArg2))
{
return(false);
}
return(NullableLiftingTransform.MatchGetValueOrDefault(innerArg2, objVar));
}
else
{
if (!(innerArg1.MatchBox(out firstArg, out var boxType) && boxType.IsKnownType(KnownTypeCode.NullableOfT) &&
NullableType.GetUnderlyingType(boxType).Equals(NullableType.GetUnderlyingType(objVar.Type))))
{
return(false);
}
return(firstArg.MatchLdLoc(objVar));
}
}
/// <summary>
/// Determines whether a variable should be inlined in non-aggressive mode, even though it is not a generated variable.
/// </summary>
/// <param name="next">The next top-level expression</param>
/// <param name="v">The variable being eliminated by inlining.</param>
/// <param name="inlinedExpression">The expression being inlined</param>
static bool NonAggressiveInlineInto(ILInstruction next, FindResult findResult, ILInstruction inlinedExpression, ILVariable v)
{
if (findResult.Type == FindResultType.NamedArgument)
{
var originalStore = (StLoc)inlinedExpression.Parent;
return(!originalStore.ILStackWasEmpty);
}
Debug.Assert(findResult.Type == FindResultType.Found);
var loadInst = findResult.LoadInst;
Debug.Assert(loadInst.IsDescendantOf(next));
// decide based on the source expression being inlined
switch (inlinedExpression.OpCode)
{
case OpCode.DefaultValue:
case OpCode.StObj:
case OpCode.NumericCompoundAssign:
case OpCode.UserDefinedCompoundAssign:
case OpCode.Await:
case OpCode.SwitchInstruction:
return(true);
case OpCode.LdLoc:
if (v.StateMachineField == null && ((LdLoc)inlinedExpression).Variable.StateMachineField != null)
{
// Roslyn likes to put the result of fetching a state machine field into a temporary variable,
// so inline more aggressively in such cases.
return(true);
}
break;
}
if (inlinedExpression.ResultType == StackType.Ref)
{
// VB likes to use ref locals for compound assignment
// (the C# compiler uses ref stack slots instead).
// We want to avoid unnecessary ref locals, so we'll always inline them if possible.
return(true);
}
var parent = loadInst.Parent;
if (NullableLiftingTransform.MatchNullableCtor(parent, out _, out _))
{
// inline into nullable ctor call in lifted operator
parent = parent.Parent;
}
if (parent is ILiftableInstruction liftable && liftable.IsLifted)
{
return(true); // inline into lifted operators
}
// decide based on the new parent into which we are inlining:
switch (parent.OpCode)
{
case OpCode.NullCoalescingInstruction:
if (NullableType.IsNullable(v.Type))
{
return(true); // inline nullables into ?? operator
}
break;
case OpCode.NullableUnwrap:
return(true); // inline into ?. operator
case OpCode.UserDefinedLogicOperator:
case OpCode.DynamicLogicOperatorInstruction:
return(true); // inline into (left slot of) user-defined && or || operator
case OpCode.DynamicGetMemberInstruction:
case OpCode.DynamicGetIndexInstruction:
if (parent.Parent.OpCode == OpCode.DynamicCompoundAssign)
{
return(true); // inline into dynamic compound assignments
}
break;
case OpCode.DynamicCompoundAssign:
return(true);
case OpCode.GetPinnableReference:
case OpCode.LocAllocSpan:
return(true); // inline size-expressions into localloc.span
case OpCode.Call:
case OpCode.CallVirt:
// Aggressive inline into property/indexer getter calls for compound assignment calls
// (The compiler generates locals for these because it doesn't want to evalute the args twice for getter+setter)
if (parent.SlotInfo == CompoundAssignmentInstruction.TargetSlot)
{
return(true);
}
if (((CallInstruction)parent).Method is SyntheticRangeIndexAccessor)
{
return(true);
}
break;
case OpCode.CallIndirect when loadInst.SlotInfo == CallIndirect.FunctionPointerSlot:
return(true);
case OpCode.LdElema:
if (((LdElema)parent).WithSystemIndex)
{
return(true);
}
break;
case OpCode.Leave:
case OpCode.YieldReturn:
return(true);
case OpCode.SwitchInstruction:
//case OpCode.BinaryNumericInstruction when parent.SlotInfo == SwitchInstruction.ValueSlot:
case OpCode.StringToInt when parent.SlotInfo == SwitchInstruction.ValueSlot:
return(true);
case OpCode.MatchInstruction when((MatchInstruction)parent).IsDeconstructTuple:
return(true);
}
// decide based on the top-level target instruction into which we are inlining:
switch (next.OpCode)
{
case OpCode.IfInstruction:
while (parent.MatchLogicNot(out _))
{
parent = parent.Parent;
}
return(parent == next);
default:
return(false);
}
}
/// <summary>
/// Determines whether a variable should be inlined in non-aggressive mode, even though it is not a generated variable.
/// </summary>
/// <param name="next">The next top-level expression</param>
/// <param name="loadInst">The load within 'next'</param>
/// <param name="inlinedExpression">The expression being inlined</param>
static bool NonAggressiveInlineInto(ILInstruction next, ILInstruction loadInst, ILInstruction inlinedExpression, ILVariable v)
{
Debug.Assert(loadInst.IsDescendantOf(next));
// decide based on the source expression being inlined
switch (inlinedExpression.OpCode)
{
case OpCode.DefaultValue:
case OpCode.StObj:
case OpCode.NumericCompoundAssign:
case OpCode.UserDefinedCompoundAssign:
case OpCode.Await:
return(true);
case OpCode.LdLoc:
if (v.StateMachineField == null && ((LdLoc)inlinedExpression).Variable.StateMachineField != null)
{
// Roslyn likes to put the result of fetching a state machine field into a temporary variable,
// so inline more aggressively in such cases.
return(true);
}
break;
}
var parent = loadInst.Parent;
if (NullableLiftingTransform.MatchNullableCtor(parent, out _, out _))
{
// inline into nullable ctor call in lifted operator
parent = parent.Parent;
}
if (parent is ILiftableInstruction liftable && liftable.IsLifted)
{
return(true); // inline into lifted operators
}
switch (parent.OpCode)
{
case OpCode.NullCoalescingInstruction:
if (NullableType.IsNullable(v.Type))
{
return(true); // inline nullables into ?? operator
}
break;
case OpCode.NullableUnwrap:
return(true); // inline into ?. operator
case OpCode.UserDefinedLogicOperator:
case OpCode.DynamicLogicOperatorInstruction:
return(true); // inline into (left slot of) user-defined && or || operator
case OpCode.DynamicGetMemberInstruction:
case OpCode.DynamicGetIndexInstruction:
case OpCode.LdObj:
if (parent.Parent.OpCode == OpCode.DynamicCompoundAssign)
{
return(true); // inline into dynamic compound assignments
}
break;
}
// decide based on the target into which we are inlining
switch (next.OpCode)
{
case OpCode.Leave:
case OpCode.YieldReturn:
return(parent == next);
case OpCode.IfInstruction:
while (parent.MatchLogicNot(out _))
{
parent = parent.Parent;
}
return(parent == next);
case OpCode.BlockContainer:
if (((BlockContainer)next).EntryPoint.Instructions[0] is SwitchInstruction switchInst)
{
next = switchInst;
goto case OpCode.SwitchInstruction;
}
else
{
return(false);
}
case OpCode.SwitchInstruction:
return(parent == next || (parent.MatchBinaryNumericInstruction(BinaryNumericOperator.Sub) && parent.Parent == next));
default:
return(false);
}
}
bool MatchDisposeBlock(BlockContainer container, ILVariable objVar, bool usingNull)
{
var entryPoint = container.EntryPoint;
if (entryPoint.Instructions.Count < 2 || entryPoint.Instructions.Count > 3 || entryPoint.IncomingEdgeCount != 1)
{
return(false);
}
int leaveIndex = entryPoint.Instructions.Count == 2 ? 1 : 2;
int checkIndex = entryPoint.Instructions.Count == 2 ? 0 : 1;
int castIndex = entryPoint.Instructions.Count == 3 ? 0 : -1;
bool isReference = objVar.Type.IsReferenceType != false;
if (castIndex > -1)
{
if (!entryPoint.Instructions[castIndex].MatchStLoc(out var tempVar, out var isinst))
{
return(false);
}
if (!isinst.MatchIsInst(out var load, out var disposableType) || !load.MatchLdLoc(objVar) || !disposableType.IsKnownType(KnownTypeCode.IDisposable))
{
return(false);
}
if (tempVar.StoreCount != 1 || tempVar.LoadCount != 2)
{
return(false);
}
objVar = tempVar;
isReference = true;
}
if (!entryPoint.Instructions[leaveIndex].MatchLeave(container, out var returnValue) || !returnValue.MatchNop())
{
return(false);
}
CallVirt callVirt;
if (objVar.Type.IsKnownType(KnownTypeCode.NullableOfT))
{
if (!entryPoint.Instructions[checkIndex].MatchIfInstruction(out var condition, out var disposeInst))
{
return(false);
}
if (!NullableLiftingTransform.MatchHasValueCall(condition, objVar))
{
return(false);
}
if (!(disposeInst is Block disposeBlock) || disposeBlock.Instructions.Count != 1)
{
return(false);
}
if (!(disposeBlock.Instructions[0] is CallVirt cv))
{
return(false);
}
callVirt = cv;
if (callVirt.Method.FullName != "System.IDisposable.Dispose")
{
return(false);
}
if (callVirt.Method.Parameters.Count > 0)
{
return(false);
}
if (callVirt.Arguments.Count != 1)
{
return(false);
}
var firstArg = cv.Arguments.FirstOrDefault();
if (!(firstArg.MatchUnboxAny(out var innerArg1, out var unboxType) && unboxType.IsKnownType(KnownTypeCode.IDisposable)))
{
if (!firstArg.MatchAddressOf(out var innerArg2))
{
return(false);
}
return(NullableLiftingTransform.MatchGetValueOrDefault(innerArg2, objVar));
}
else
{
if (!(innerArg1.MatchBox(out firstArg, out var boxType) && boxType.IsKnownType(KnownTypeCode.NullableOfT) &&
NullableType.GetUnderlyingType(boxType).Equals(NullableType.GetUnderlyingType(objVar.Type))))
{
return(false);
}
return(firstArg.MatchLdLoc(objVar));
}
}
/// <summary>
/// stloc v(value)
/// if (logic.not(call get_HasValue(ldloca v))) throw(...)
/// ... Call(arg1, arg2, call GetValueOrDefault(ldloca v), arg4) ...
/// =>
/// ... Call(arg1, arg2, if.notnull(value, throw(...)), arg4) ...
/// </summary>
bool TransformThrowExpressionValueTypes(Block block, int pos, StatementTransformContext context)
{
if (pos + 2 >= block.Instructions.Count)
{
return(false);
}
if (!(block.Instructions[pos] is StLoc stloc))
{
return(false);
}
ILVariable v = stloc.Variable;
if (!(v.StoreCount == 1 && v.LoadCount == 0 && v.AddressCount == 2))
{
return(false);
}
if (!block.Instructions[pos + 1].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
if (!(Block.Unwrap(trueInst) is Throw throwInst))
{
return(false);
}
if (!condition.MatchLogicNot(out var arg))
{
return(false);
}
if (!(arg is CallInstruction call && NullableLiftingTransform.MatchHasValueCall(call, v)))
{
return(false);
}
var throwInstParent = throwInst.Parent;
var throwInstChildIndex = throwInst.ChildIndex;
var nullCoalescingWithThrow = new NullCoalescingInstruction(
NullCoalescingKind.NullableWithValueFallback,
stloc.Value,
throwInst);
var resultType = NullableType.GetUnderlyingType(call.Method.DeclaringType).GetStackType();
nullCoalescingWithThrow.UnderlyingResultType = resultType;
var result = ILInlining.FindLoadInNext(block.Instructions[pos + 2], v, nullCoalescingWithThrow, InliningOptions.None);
if (result.Type == ILInlining.FindResultType.Found &&
NullableLiftingTransform.MatchGetValueOrDefault(result.LoadInst.Parent, v))
{
context.Step("NullCoalescingTransform (value types + throw expression)", stloc);
throwInst.resultType = resultType;
result.LoadInst.Parent.ReplaceWith(nullCoalescingWithThrow);
block.Instructions.RemoveRange(pos, 2); // remove store(s) and if instruction
return(true);
}
else
{
// reset the primary position (see remarks on ILInstruction.Parent)
stloc.Value = stloc.Value;
var children = throwInstParent.Children;
children[throwInstChildIndex] = throwInst;
return(false);
}
}
/// <summary>
/// Matches Roslyn C# switch on nullable.
/// </summary>
bool MatchRoslynSwitchOnNullable(InstructionCollection <ILInstruction> instructions, int i, out SwitchInstruction newSwitch)
{
newSwitch = null;
// match first block:
// stloc tmp(ldloc switchValueVar)
// if (logic.not(call get_HasValue(ldloca tmp))) br nullCaseBlock
// br switchBlock
if (i < 1)
{
return(false);
}
if (!instructions[i - 1].MatchStLoc(out var tmp, out var switchValue) ||
!instructions[i].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
if (tmp.StoreCount != 1 || tmp.AddressCount != 2 || tmp.LoadCount != 0)
{
return(false);
}
if (!instructions[i + 1].MatchBranch(out var switchBlock) || !trueInst.MatchBranch(out var nullCaseBlock))
{
return(false);
}
if (!condition.MatchLogicNot(out var getHasValue) || !NullableLiftingTransform.MatchHasValueCall(getHasValue, out ILVariable target1) || target1 != tmp)
{
return(false);
}
// match second block: switchBlock
// note: I have seen cases where switchVar is inlined into the switch.
// stloc switchVar(call GetValueOrDefault(ldloca tmp))
// switch (ldloc switchVar) {
// case [0..1): br caseBlock1
// ... more cases ...
// case [long.MinValue..0),[1..5),[6..10),[11..long.MaxValue]: br defaultBlock
// }
if (switchBlock.IncomingEdgeCount != 1)
{
return(false);
}
SwitchInstruction switchInst;
switch (switchBlock.Instructions.Count)
{
case 2: {
// this is the normal case described by the pattern above
if (!switchBlock.Instructions[0].MatchStLoc(out var switchVar, out var getValueOrDefault))
{
return(false);
}
if (!switchVar.IsSingleDefinition || switchVar.LoadCount != 1)
{
return(false);
}
if (!NullableLiftingTransform.MatchGetValueOrDefault(getValueOrDefault, tmp))
{
return(false);
}
if (!(switchBlock.Instructions[1] is SwitchInstruction si))
{
return(false);
}
switchInst = si;
break;
}
case 1: {
// this is the special case where `call GetValueOrDefault(ldloca tmp)` is inlined into the switch.
if (!(switchBlock.Instructions[0] is SwitchInstruction si))
{
return(false);
}
if (!NullableLiftingTransform.MatchGetValueOrDefault(si.Value, tmp))
{
return(false);
}
switchInst = si;
break;
}
default: {
return(false);
}
}
newSwitch = BuildLiftedSwitch(nullCaseBlock, switchInst, switchValue);
return(true);
}
/// <summary>
/// Matches Roslyn C# switch on nullable.
/// </summary>
bool MatchRoslynSwitchOnNullable(InstructionCollection <ILInstruction> instructions, int i, out SwitchInstruction newSwitch)
{
newSwitch = null;
// match first block:
// if (logic.not(call get_HasValue(target))) br nullCaseBlock
// br switchBlock
if (!instructions[i].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
if (!instructions[i + 1].MatchBranch(out var switchBlock) || !trueInst.MatchBranch(out var nullCaseBlock))
{
return(false);
}
if (!condition.MatchLogicNot(out var getHasValue) || !NullableLiftingTransform.MatchHasValueCall(getHasValue, out ILInstruction target) || !SemanticHelper.IsPure(target.Flags))
{
return(false);
}
// match second block: switchBlock
// note: I have seen cases where switchVar is inlined into the switch.
// stloc switchVar(call GetValueOrDefault(ldloca tmp))
// switch (ldloc switchVar) {
// case [0..1): br caseBlock1
// ... more cases ...
// case [long.MinValue..0),[1..5),[6..10),[11..long.MaxValue]: br defaultBlock
// }
if (switchBlock.IncomingEdgeCount != 1)
{
return(false);
}
SwitchInstruction switchInst;
switch (switchBlock.Instructions.Count)
{
case 2:
{
// this is the normal case described by the pattern above
if (!switchBlock.Instructions[0].MatchStLoc(out var switchVar, out var getValueOrDefault))
{
return(false);
}
if (!switchVar.IsSingleDefinition || switchVar.LoadCount != 1)
{
return(false);
}
if (!(NullableLiftingTransform.MatchGetValueOrDefault(getValueOrDefault, out ILInstruction target2) && target2.Match(target).Success))
{
return(false);
}
if (!(switchBlock.Instructions[1] is SwitchInstruction si))
{
return(false);
}
switchInst = si;
break;
}
case 1:
{
// this is the special case where `call GetValueOrDefault(ldloca tmp)` is inlined into the switch.
if (!(switchBlock.Instructions[0] is SwitchInstruction si))
{
return(false);
}
if (!(NullableLiftingTransform.MatchGetValueOrDefault(si.Value, out ILInstruction target2) && target2.Match(target).Success))
{
return(false);
}
switchInst = si;
break;
}
default:
{
return(false);
}
}
ILInstruction switchValue;
if (target.MatchLdLoca(out var v))
{
switchValue = new LdLoc(v).WithILRange(target);
}
else
{
switchValue = new LdObj(target, ((CallInstruction)getHasValue).Method.DeclaringType);
}
newSwitch = BuildLiftedSwitch(nullCaseBlock, switchInst, switchValue);
return(true);
}
/// <summary>
/// Determines whether a variable should be inlined in non-aggressive mode, even though it is not a generated variable.
/// </summary>
/// <param name="next">The next top-level expression</param>
/// <param name="v">The variable being eliminated by inlining.</param>
/// <param name="inlinedExpression">The expression being inlined</param>
static bool NonAggressiveInlineInto(ILInstruction next, FindResult findResult, ILInstruction inlinedExpression, ILVariable v)
{
if (findResult.Type == FindResultType.NamedArgument)
{
var originalStore = (StLoc)inlinedExpression.Parent;
return(!originalStore.ILStackWasEmpty);
}
Debug.Assert(findResult.Type == FindResultType.Found);
var loadInst = findResult.LoadInst;
Debug.Assert(loadInst.IsDescendantOf(next));
// decide based on the source expression being inlined
switch (inlinedExpression.OpCode)
{
case OpCode.DefaultValue:
case OpCode.StObj:
case OpCode.NumericCompoundAssign:
case OpCode.UserDefinedCompoundAssign:
case OpCode.Await:
return(true);
case OpCode.LdLoc:
if (v.StateMachineField == null && ((LdLoc)inlinedExpression).Variable.StateMachineField != null)
{
// Roslyn likes to put the result of fetching a state machine field into a temporary variable,
// so inline more aggressively in such cases.
return(true);
}
break;
}
var parent = loadInst.Parent;
if (NullableLiftingTransform.MatchNullableCtor(parent, out _, out _))
{
// inline into nullable ctor call in lifted operator
parent = parent.Parent;
}
if (parent is ILiftableInstruction liftable && liftable.IsLifted)
{
return(true); // inline into lifted operators
}
// decide based on the new parent into which we are inlining:
switch (parent.OpCode)
{
case OpCode.NullCoalescingInstruction:
if (NullableType.IsNullable(v.Type))
{
return(true); // inline nullables into ?? operator
}
break;
case OpCode.NullableUnwrap:
return(true); // inline into ?. operator
case OpCode.UserDefinedLogicOperator:
case OpCode.DynamicLogicOperatorInstruction:
return(true); // inline into (left slot of) user-defined && or || operator
case OpCode.DynamicGetMemberInstruction:
case OpCode.DynamicGetIndexInstruction:
if (parent.Parent.OpCode == OpCode.DynamicCompoundAssign)
{
return(true); // inline into dynamic compound assignments
}
break;
case OpCode.DynamicCompoundAssign:
return(true);
case OpCode.ArrayToPointer:
case OpCode.LocAllocSpan:
return(true); // inline size-expressions into localloc.span
case OpCode.Call:
case OpCode.CallVirt:
// Aggressive inline into property/indexer getter calls for compound assignment calls
// (The compiler generates locals for these because it doesn't want to evalute the args twice for getter+setter)
if (parent.SlotInfo == CompoundAssignmentInstruction.TargetSlot)
{
return(true);
}
break;
}
// decide based on the top-level target instruction into which we are inlining:
switch (next.OpCode)
{
case OpCode.Leave:
case OpCode.YieldReturn:
return(parent == next);
case OpCode.IfInstruction:
while (parent.MatchLogicNot(out _))
{
parent = parent.Parent;
}
return(parent == next);
case OpCode.BlockContainer:
if (((BlockContainer)next).EntryPoint.Instructions[0] is SwitchInstruction switchInst)
{
next = switchInst;
goto case OpCode.SwitchInstruction;
}
else
{
return(false);
}
case OpCode.SwitchInstruction:
if (parent == next)
{
return(true);
}
if (parent.MatchBinaryNumericInstruction(BinaryNumericOperator.Sub) && parent.Parent == next)
{
return(true);
}
if (parent is StringToInt stringToInt && stringToInt.Parent == next)
{
return(true);
}
return(false);
default:
return(false);
}
}