private HqlTreeNode TranslateEqualityComparison(BinaryExpression expression)
{
var lhs = VisitExpression(expression.Left).ToArithmeticExpression();
var rhs = VisitExpression(expression.Right).ToArithmeticExpression();
// Check for nulls on left or right.
if (VisitorUtil.IsNullConstant(expression.Right))
{
rhs = null;
}
if (VisitorUtil.IsNullConstant(expression.Left))
{
lhs = null;
}
if (lhs == null && rhs == null)
{
return(_hqlTreeBuilder.True());
}
if (lhs == null)
{
return(_hqlTreeBuilder.IsNull(rhs));
}
if (rhs == null)
{
return(_hqlTreeBuilder.IsNull((lhs)));
}
var lhsNullable = IsNullable(lhs);
var rhsNullable = IsNullable(rhs);
var equality = _hqlTreeBuilder.Equality(lhs, rhs);
if (!lhsNullable || !rhsNullable)
{
return(equality);
}
var lhs2 = VisitExpression(expression.Left).ToArithmeticExpression();
var rhs2 = VisitExpression(expression.Right).ToArithmeticExpression();
return(_hqlTreeBuilder.BooleanOr(
equality,
_hqlTreeBuilder.BooleanAnd(
_hqlTreeBuilder.IsNull(lhs2),
_hqlTreeBuilder.IsNull(rhs2))));
}
private static bool IsConstructionToNullComparison(Expression expression)
{
var testExpression = expression as BinaryExpression;
if (testExpression != null)
{
if ((IsConstruction(testExpression.Left) && VisitorUtil.IsNullConstant(testExpression.Right)) ||
(IsConstruction(testExpression.Right) && VisitorUtil.IsNullConstant(testExpression.Left)))
{
return(true);
}
}
return(false);
}
private void FindNotNullMember(BinaryExpression binaryExpression, List <MemberExpression> notNullMembers)
{
_equalityNotNullMembers[binaryExpression] = notNullMembers;
if (binaryExpression.NodeType != ExpressionType.NotEqual)
{
return;
}
MemberExpression memberExpression;
if (VisitorUtil.IsNullConstant(binaryExpression.Right) && TryGetMemberAccess(binaryExpression.Left, out memberExpression))
{
notNullMembers.Add(memberExpression);
}
else if (VisitorUtil.IsNullConstant(binaryExpression.Left) && TryGetMemberAccess(binaryExpression.Right, out memberExpression))
{
notNullMembers.Add(memberExpression);
}
}
private HqlTreeNode TranslateEqualityComparison(BinaryExpression expression, HqlExpression lhs, HqlExpression rhs, Func <HqlExpression, HqlTreeNode> applyNullComparison, Func <HqlExpression, HqlExpression, HqlTreeNode> applyRegularComparison)
{
// Check for nulls on left or right.
if (VisitorUtil.IsNullConstant(expression.Right))
{
rhs = null;
}
if (VisitorUtil.IsNullConstant(expression.Left))
{
lhs = null;
}
// Need to check for boolean equality
if (lhs is HqlBooleanExpression || rhs is HqlBooleanExpression)
{
if (lhs != null)
{
lhs = GetExpressionForBooleanEquality(expression.Left, lhs);
}
if (rhs != null)
{
rhs = GetExpressionForBooleanEquality(expression.Right, rhs);
}
}
if (lhs == null)
{
return(applyNullComparison(rhs));
}
if (rhs == null)
{
return(applyNullComparison(lhs));
}
return(applyRegularComparison(lhs, rhs));
}
protected override Expression VisitBinaryExpression(BinaryExpression expression)
{
var result = base.VisitBinaryExpression(expression);
if (expression.NodeType == ExpressionType.AndAlso)
{
HandleBinaryOperation((a, b) => a.AndAlso(b));
}
else if (expression.NodeType == ExpressionType.OrElse)
{
HandleBinaryOperation((a, b) => a.OrElse(b));
}
else if (expression.NodeType == ExpressionType.NotEqual && VisitorUtil.IsNullConstant(expression.Right))
{
// Discard result from right null. Left is visited first, so it's below right on the stack.
_values.Pop();
HandleUnaryOperation(pvs => pvs.IsNotNull());
}
else if (expression.NodeType == ExpressionType.NotEqual && VisitorUtil.IsNullConstant(expression.Left))
{
// Discard result from left null.
var right = _values.Pop();
_values.Pop(); // Discard left.
_values.Push(right);
HandleUnaryOperation(pvs => pvs.IsNotNull());
}
else if (expression.NodeType == ExpressionType.Equal && VisitorUtil.IsNullConstant(expression.Right))
{
// Discard result from right null. Left is visited first, so it's below right on the stack.
_values.Pop();
HandleUnaryOperation(pvs => pvs.IsNull());
}
else if (expression.NodeType == ExpressionType.Equal && VisitorUtil.IsNullConstant(expression.Left))
{
// Discard result from left null.
var right = _values.Pop();
_values.Pop(); // Discard left.
_values.Push(right);
HandleUnaryOperation(pvs => pvs.IsNull());
}
else if (expression.NodeType == ExpressionType.Coalesce)
{
HandleBinaryOperation((a, b) => a.Coalesce(b));
}
else if (expression.NodeType == ExpressionType.Add || expression.NodeType == ExpressionType.AddChecked)
{
HandleBinaryOperation((a, b) => a.Add(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.Divide)
{
HandleBinaryOperation((a, b) => a.Divide(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.Modulo)
{
HandleBinaryOperation((a, b) => a.Modulo(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.Multiply || expression.NodeType == ExpressionType.MultiplyChecked)
{
HandleBinaryOperation((a, b) => a.Multiply(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.Power)
{
HandleBinaryOperation((a, b) => a.Power(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.Subtract || expression.NodeType == ExpressionType.SubtractChecked)
{
HandleBinaryOperation((a, b) => a.Subtract(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.And)
{
HandleBinaryOperation((a, b) => a.And(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.Or)
{
HandleBinaryOperation((a, b) => a.Or(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.ExclusiveOr)
{
HandleBinaryOperation((a, b) => a.ExclusiveOr(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.LeftShift)
{
HandleBinaryOperation((a, b) => a.LeftShift(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.RightShift)
{
HandleBinaryOperation((a, b) => a.RightShift(b, expression.Type));
}
else if (expression.NodeType == ExpressionType.Equal)
{
HandleBinaryOperation((a, b) => a.Equal(b));
}
else if (expression.NodeType == ExpressionType.NotEqual)
{
HandleBinaryOperation((a, b) => a.NotEqual(b));
}
else if (expression.NodeType == ExpressionType.GreaterThanOrEqual)
{
HandleBinaryOperation((a, b) => a.GreaterThanOrEqual(b));
}
else if (expression.NodeType == ExpressionType.GreaterThan)
{
HandleBinaryOperation((a, b) => a.GreaterThan(b));
}
else if (expression.NodeType == ExpressionType.LessThan)
{
HandleBinaryOperation((a, b) => a.LessThan(b));
}
else if (expression.NodeType == ExpressionType.LessThanOrEqual)
{
HandleBinaryOperation((a, b) => a.LessThanOrEqual(b));
}
return(result);
}
private HqlTreeNode TranslateInequalityComparison(BinaryExpression expression)
{
var lhs = VisitExpression(expression.Left).ToArithmeticExpression();
var rhs = VisitExpression(expression.Right).ToArithmeticExpression();
// Check for nulls on left or right.
if (VisitorUtil.IsNullConstant(expression.Right))
{
rhs = null;
}
if (VisitorUtil.IsNullConstant(expression.Left))
{
lhs = null;
}
if (lhs == null && rhs == null)
{
return(_hqlTreeBuilder.False());
}
if (lhs == null)
{
return(_hqlTreeBuilder.IsNotNull(rhs));
}
if (rhs == null)
{
return(_hqlTreeBuilder.IsNotNull(lhs));
}
var lhsNullable = IsNullable(lhs);
var rhsNullable = IsNullable(rhs);
var inequality = _hqlTreeBuilder.Inequality(lhs, rhs);
if (!lhsNullable && !rhsNullable)
{
return(inequality);
}
var lhs2 = VisitExpression(expression.Left).ToArithmeticExpression();
var rhs2 = VisitExpression(expression.Right).ToArithmeticExpression();
HqlBooleanExpression booleanExpression;
if (lhsNullable && rhsNullable)
{
booleanExpression = _hqlTreeBuilder.Inequality(
_hqlTreeBuilder.IsNull(lhs2).ToArithmeticExpression(),
_hqlTreeBuilder.IsNull(rhs2).ToArithmeticExpression());
}
else if (lhsNullable)
{
booleanExpression = _hqlTreeBuilder.IsNull(lhs2);
}
else
{
booleanExpression = _hqlTreeBuilder.IsNull(rhs2);
}
return(_hqlTreeBuilder.BooleanOr(inequality, booleanExpression));
}
public bool IsNullable(Expression expression, BinaryExpression equalityExpression)
{
switch (expression.NodeType)
{
case ExpressionType.Convert:
case ExpressionType.ConvertChecked:
case ExpressionType.TypeAs:
// a cast will not return null if the operand is not null (as long as TypeAs is not translated to
// try_convert in SQL).
return(IsNullable(((UnaryExpression)expression).Operand, equalityExpression));
case ExpressionType.Not:
case ExpressionType.And:
case ExpressionType.Or:
case ExpressionType.ExclusiveOr:
case ExpressionType.LeftShift:
case ExpressionType.RightShift:
case ExpressionType.AndAlso:
case ExpressionType.OrElse:
case ExpressionType.Equal:
case ExpressionType.NotEqual:
case ExpressionType.GreaterThanOrEqual:
case ExpressionType.GreaterThan:
case ExpressionType.LessThan:
case ExpressionType.LessThanOrEqual:
return(false);
case ExpressionType.Add:
case ExpressionType.AddChecked:
case ExpressionType.Divide:
case ExpressionType.Modulo:
case ExpressionType.Multiply:
case ExpressionType.MultiplyChecked:
case ExpressionType.Power:
case ExpressionType.Subtract:
case ExpressionType.SubtractChecked:
var binaryExpression = (BinaryExpression)expression;
return(IsNullable(binaryExpression.Left, equalityExpression) || IsNullable(binaryExpression.Right, equalityExpression));
case ExpressionType.ArrayIndex:
return(true); // for indexed lists we cannot determine whether the item will be null or not
case ExpressionType.Coalesce:
return(IsNullable(((BinaryExpression)expression).Right, equalityExpression));
case ExpressionType.Conditional:
var conditionalExpression = (ConditionalExpression)expression;
return(IsNullable(conditionalExpression.IfTrue, equalityExpression) ||
IsNullable(conditionalExpression.IfFalse, equalityExpression));
case ExpressionType.Call:
var methodInfo = ((MethodCallExpression)expression).Method;
return(!_functionRegistry.TryGetGenerator(methodInfo, out var method) || method.AllowsNullableReturnType(methodInfo));
case ExpressionType.MemberAccess:
return(IsNullable((MemberExpression)expression, equalityExpression));
case ExpressionType.Extension:
return(IsNullableExtension(expression, equalityExpression));
case ExpressionType.TypeIs: // an equal or in operator will be generated and those cannot return null
case ExpressionType.NewArrayInit:
return(false);
case ExpressionType.Constant:
return(VisitorUtil.IsNullConstant(expression));
case ExpressionType.Parameter:
return(!expression.Type.IsValueType);
default:
return(true);
}
}