/// <summary>
/// Produces a chain of equality (or inequality) checks combined logically with AND (or OR)
/// </summary>
private BoundExpression RewriteNonNullableNestedTupleOperators(TupleBinaryOperatorInfo.Multiple operators,
BoundExpression left, BoundExpression right, TypeSymbol type,
ArrayBuilder <LocalSymbol> temps, ArrayBuilder <BoundExpression> effects, BinaryOperatorKind operatorKind)
{
ImmutableArray <TupleBinaryOperatorInfo> nestedOperators = operators.Operators;
BoundExpression currentResult = null;
for (int i = 0; i < nestedOperators.Length; i++)
{
BoundExpression leftElement = GetTuplePart(left, i);
BoundExpression rightElement = GetTuplePart(right, i);
BoundExpression nextLogicalOperand = RewriteTupleOperator(nestedOperators[i], leftElement, rightElement, type, temps, operatorKind);
if (currentResult is null)
{
currentResult = nextLogicalOperand;
}
else
{
var logicalOperator = operatorKind == BinaryOperatorKind.Equal ? BinaryOperatorKind.LogicalBoolAnd : BinaryOperatorKind.LogicalBoolOr;
currentResult = _factory.Binary(logicalOperator, type, currentResult, nextLogicalOperand);
}
}
return(currentResult);
}
/// <summary>
/// If the left and right are tuples of matching cardinality, we'll try to bind the operator element-wise.
/// When that succeeds, the element-wise conversions are collected. We keep them for semantic model.
/// The element-wise binary operators are collected and stored as a tree for lowering.
/// </summary>
private BoundTupleBinaryOperator BindTupleBinaryOperator(BinaryExpressionSyntax node, BinaryOperatorKind kind,
BoundExpression left, BoundExpression right, DiagnosticBag diagnostics)
{
TupleBinaryOperatorInfo.Multiple operators = BindTupleBinaryOperatorNestedInfo(node, kind, left, right, diagnostics);
// The converted types are only used for the semantic model, so we don't need the conversion diagnostics
DiagnosticBag discardDiagnostics = DiagnosticBag.GetInstance();
BoundExpression convertedLeft = ApplyConvertedTypes(left, operators, isRight: false, discardDiagnostics);
BoundExpression convertedRight = ApplyConvertedTypes(right, operators, isRight: true, discardDiagnostics);
discardDiagnostics.Free();
TypeSymbol resultType = GetSpecialType(SpecialType.System_Boolean, diagnostics, node);
return(new BoundTupleBinaryOperator(node, left, right, convertedLeft, convertedRight, kind, operators, resultType));
}
private BoundExpression RewriteTupleNestedOperators(TupleBinaryOperatorInfo.Multiple operators, BoundExpression left, BoundExpression right,
TypeSymbol boolType, ArrayBuilder <LocalSymbol> temps, BinaryOperatorKind operatorKind)
{
left = Binder.GiveTupleTypeToDefaultLiteralIfNeeded(left, right.Type);
right = Binder.GiveTupleTypeToDefaultLiteralIfNeeded(right, left.Type);
// If either left or right is nullable, produce:
//
// // outer sequence
// leftHasValue = left.HasValue; (or true if !leftNullable)
// leftHasValue == right.HasValue (or true if !rightNullable)
// ? leftHasValue ? ... inner sequence ... : true/false
// : false/true
//
// where inner sequence is:
// leftValue = left.GetValueOrDefault(); (or left if !leftNullable)
// rightValue = right.GetValueOrDefault(); (or right if !rightNullable)
// ... logical expression using leftValue and rightValue ...
//
// and true/false and false/true depend on operatorKind (== vs. !=)
//
// But if neither is nullable, then just produce the inner sequence.
//
// Note: all the temps are created in a single bucket (rather than different scopes of applicability) for simplicity
var outerEffects = ArrayBuilder <BoundExpression> .GetInstance();
var innerEffects = ArrayBuilder <BoundExpression> .GetInstance();
BoundExpression leftHasValue, leftValue;
bool isLeftNullable;
MakeNullableParts(left, temps, innerEffects, outerEffects, saveHasValue: true, out leftHasValue, out leftValue, out isLeftNullable);
BoundExpression rightHasValue, rightValue;
bool isRightNullable;
// no need for local for right.HasValue since used once
MakeNullableParts(right, temps, innerEffects, outerEffects, saveHasValue: false, out rightHasValue, out rightValue, out isRightNullable);
// Produces:
// ... logical expression using leftValue and rightValue ...
BoundExpression logicalExpression = RewriteNonNullableNestedTupleOperators(operators, leftValue, rightValue, boolType, temps, innerEffects, operatorKind);
// Produces:
// leftValue = left.GetValueOrDefault(); (or left if !leftNullable)
// rightValue = right.GetValueOrDefault(); (or right if !rightNullable)
// ... logical expression using leftValue and rightValue ...
BoundExpression innerSequence = MakeSequenceOrResultValue(locals: ImmutableArray <LocalSymbol> .Empty, innerEffects.ToImmutableAndFree(), logicalExpression);
if (!isLeftNullable && !isRightNullable)
{
// The outer sequence degenerates when we know that both `leftHasValue` and `rightHasValue` are true
return(innerSequence);
}
bool boolValue = operatorKind == BinaryOperatorKind.Equal; // true/false
if (rightHasValue.ConstantValue == ConstantValue.False)
{
// The outer sequence degenerates when we known that `rightHasValue` is false
// Produce: !leftHasValue (or leftHasValue for inequality comparison)
return(MakeSequenceOrResultValue(ImmutableArray <LocalSymbol> .Empty, outerEffects.ToImmutableAndFree(),
returnValue: boolValue?_factory.Not(leftHasValue) : leftHasValue));
}
if (leftHasValue.ConstantValue == ConstantValue.False)
{
// The outer sequence degenerates when we known that `leftHasValue` is false
// Produce: !rightHasValue (or rightHasValue for inequality comparison)
return(MakeSequenceOrResultValue(ImmutableArray <LocalSymbol> .Empty, outerEffects.ToImmutableAndFree(),
returnValue: boolValue?_factory.Not(rightHasValue) : rightHasValue));
}
// outer sequence:
// leftHasValue == rightHasValue
// ? leftHasValue ? ... inner sequence ... : true/false
// : false/true
BoundExpression outerSequence =
MakeSequenceOrResultValue(ImmutableArray <LocalSymbol> .Empty, outerEffects.ToImmutableAndFree(),
_factory.Conditional(
_factory.Binary(BinaryOperatorKind.Equal, boolType, leftHasValue, rightHasValue),
_factory.Conditional(leftHasValue, innerSequence, MakeBooleanConstant(right.Syntax, boolValue), boolType),
MakeBooleanConstant(right.Syntax, !boolValue),
boolType));
return(outerSequence);
}