private SqlExpression TryTranslateCompareExpression(BinaryExpression expression)
{
bool isGoodExpression =
expression.Left.NodeType == ExpressionType.Call && expression.Right.NodeType == ExpressionType.Constant ||
expression.Right.NodeType == ExpressionType.Call && expression.Left.NodeType == ExpressionType.Constant;
if (!isGoodExpression)
{
return(null);
}
MethodCallExpression callExpression;
ConstantExpression constantExpression;
bool swapped;
if (expression.Left.NodeType == ExpressionType.Call)
{
callExpression = (MethodCallExpression)expression.Left;
constantExpression = (ConstantExpression)expression.Right;
swapped = false;
}
else
{
callExpression = (MethodCallExpression)expression.Right;
constantExpression = (ConstantExpression)expression.Left;
swapped = true;
}
var method = (MethodInfo)callExpression.Method.GetInterfaceMember() ?? callExpression.Method;
var methodType = method.DeclaringType;
// There no methods in IComparable except CompareTo so checking only DeclatingType.
bool isCompareTo = methodType == typeof(IComparable) ||
methodType.IsGenericType && methodType.GetGenericTypeDefinition() == typeof(IComparable <>);
bool isVbStringCompare = method.DeclaringType.FullName == "Microsoft.VisualBasic.CompilerServices.Operators" &&
method.Name == "CompareString" &&
method.GetParameters().Length == 3 &&
method.IsStatic;
bool isCompare = method.Name == "Compare" && method.GetParameters().Length == 2 && method.IsStatic;
if (!isCompareTo && !isCompare && !isVbStringCompare)
{
return(null);
}
if (constantExpression.Value == null)
{
return(null);
}
if (!(constantExpression.Value is int))
{
return(null);
}
var constant = (int)constantExpression.Value;
SqlExpression leftComparand = null;
SqlExpression rightComparand = null;
if (isCompareTo)
{
leftComparand = Visit(callExpression.Object);
rightComparand = Visit(callExpression.Arguments[0]);
}
if (isCompare || isVbStringCompare)
{
leftComparand = Visit(callExpression.Arguments[0]);
rightComparand = Visit(callExpression.Arguments[1]);
}
if (swapped)
{
var tmp = leftComparand;
leftComparand = rightComparand;
rightComparand = tmp;
}
if (constant > 0)
{
switch (expression.NodeType)
{
case ExpressionType.Equal:
case ExpressionType.GreaterThan:
case ExpressionType.GreaterThanOrEqual:
return(SqlDml.GreaterThan(leftComparand, rightComparand));
case ExpressionType.NotEqual:
case ExpressionType.LessThanOrEqual:
case ExpressionType.LessThan:
return(SqlDml.LessThanOrEquals(leftComparand, rightComparand));
default:
return(null);
}
}
if (constant < 0)
{
switch (expression.NodeType)
{
case ExpressionType.NotEqual:
case ExpressionType.GreaterThan:
case ExpressionType.GreaterThanOrEqual:
return(SqlDml.GreaterThanOrEquals(leftComparand, rightComparand));
case ExpressionType.Equal:
case ExpressionType.LessThanOrEqual:
case ExpressionType.LessThan:
return(SqlDml.LessThan(leftComparand, rightComparand));
default:
return(null);
}
}
switch (expression.NodeType)
{
case ExpressionType.GreaterThan:
return(SqlDml.GreaterThan(leftComparand, rightComparand));
case ExpressionType.GreaterThanOrEqual:
return(SqlDml.GreaterThanOrEquals(leftComparand, rightComparand));
case ExpressionType.Equal:
return(SqlDml.Equals(leftComparand, rightComparand));
case ExpressionType.NotEqual:
return(SqlDml.NotEquals(leftComparand, rightComparand));
case ExpressionType.LessThanOrEqual:
return(SqlDml.LessThanOrEquals(leftComparand, rightComparand));
case ExpressionType.LessThan:
return(SqlDml.LessThan(leftComparand, rightComparand));
default:
return(null);
}
}
public static SqlBinary operator >(SqlExpression left, SqlExpression right)
{
return(SqlDml.GreaterThan(left, right));
}
protected override SqlExpression VisitBinary(BinaryExpression expression)
{
// handle x.CompareTo(y) > 0 and similar comparisons
SqlExpression result = TryTranslateCompareExpression(expression);
if (!result.IsNullReference())
{
return(result);
}
SqlExpression left;
SqlExpression right;
bool isEqualityCheck =
expression.NodeType == ExpressionType.Equal ||
expression.NodeType == ExpressionType.NotEqual;
bool isBooleanFixRequired = fixBooleanExpressions &&
(isEqualityCheck || expression.NodeType == ExpressionType.Coalesce) &&
(IsBooleanExpression(expression.Left) || IsBooleanExpression(expression.Right));
if (IsCharToIntConvert(expression.Left) && IsCharToIntConvert(expression.Right))
{
// chars are compared as integers, but we store them as strings and should compare them like strings.
left = Visit(GetOperand(expression.Left), isEqualityCheck);
right = Visit(GetOperand(expression.Right), isEqualityCheck);
}
else if (IsCharToIntConvert(expression.Left) && IsIntConstant(expression.Right))
{
// another case of char comparison
left = Visit(GetOperand(expression.Left), isEqualityCheck);
right = ConvertIntConstantToSingleCharString(expression.Right);
}
else if (IsIntConstant(expression.Left) && IsCharToIntConvert(expression.Right))
{
// another case of char comparison
left = ConvertIntConstantToSingleCharString(expression.Left);
right = Visit(GetOperand(expression.Right), isEqualityCheck);
}
else
{
// regular case
left = Visit(expression.Left, isEqualityCheck);
right = Visit(expression.Right, isEqualityCheck);
}
if (isBooleanFixRequired)
{
// boolean expressions should be compared as integers.
// additional check is required because some type information might be lost.
// we assume they already have correct format in that case.
if (IsBooleanExpression(expression.Left))
{
left = booleanExpressionConverter.BooleanToInt(left);
}
if (IsBooleanExpression(expression.Right))
{
right = booleanExpressionConverter.BooleanToInt(right);
}
}
//handle SQLite DateTime comparsion
if (dateTimeEmulation &&
left.NodeType != SqlNodeType.Null &&
right.NodeType != SqlNodeType.Null &&
IsComparisonExpression(expression) &&
(IsDateTimeExpression(expression.Left) || IsDateTimeExpression(expression.Right)))
{
left = SqlDml.Cast(left, SqlType.DateTime);
right = SqlDml.Cast(right, SqlType.DateTime);
}
//handle SQLite DateTimeOffset comparsion
if (dateTimeOffsetEmulation &&
left.NodeType != SqlNodeType.Null &&
right.NodeType != SqlNodeType.Null &&
IsComparisonExpression(expression) &&
(IsDateTimeOffsetExpression(expression.Left) || IsDateTimeOffsetExpression(expression.Right)))
{
left = SqlDml.Cast(left, SqlType.DateTimeOffset);
right = SqlDml.Cast(right, SqlType.DateTimeOffset);
}
// handle special cases
result = TryTranslateBinaryExpressionSpecialCases(expression, left, right);
if (!result.IsNullReference())
{
return(result);
}
// handle overloaded operators
if (expression.Method != null)
{
return(CompileMember(expression.Method, null, left, right));
}
//handle wrapped enums
SqlContainer container = left as SqlContainer;
if (container != null)
{
left = TryUnwrapEnum(container);
}
container = right as SqlContainer;
if (container != null)
{
right = TryUnwrapEnum(container);
}
switch (expression.NodeType)
{
case ExpressionType.Add:
case ExpressionType.AddChecked:
return(SqlDml.Add(left, right));
case ExpressionType.And:
return(IsBooleanExpression(expression.Left)
? SqlDml.And(left, right)
: SqlDml.BitAnd(left, right));
case ExpressionType.AndAlso:
return(SqlDml.And(left, right));
case ExpressionType.Coalesce:
SqlExpression coalesce = SqlDml.Coalesce(left, right);
if (isBooleanFixRequired)
{
coalesce = booleanExpressionConverter.IntToBoolean(coalesce);
}
return(coalesce);
case ExpressionType.Divide:
return(SqlDml.Divide(left, right));
case ExpressionType.Equal:
return(SqlDml.Equals(left, right));
case ExpressionType.ExclusiveOr:
return(SqlDml.BitXor(left, right));
case ExpressionType.GreaterThan:
return(SqlDml.GreaterThan(left, right));
case ExpressionType.GreaterThanOrEqual:
return(SqlDml.GreaterThanOrEquals(left, right));
case ExpressionType.LessThan:
return(SqlDml.LessThan(left, right));
case ExpressionType.LessThanOrEqual:
return(SqlDml.LessThanOrEquals(left, right));
case ExpressionType.Modulo:
return(SqlDml.Modulo(left, right));
case ExpressionType.Multiply:
case ExpressionType.MultiplyChecked:
return(SqlDml.Multiply(left, right));
case ExpressionType.NotEqual:
return(SqlDml.NotEquals(left, right));
case ExpressionType.Or:
return(IsBooleanExpression(expression.Left)
? SqlDml.Or(left, right)
: SqlDml.BitOr(left, right));
case ExpressionType.OrElse:
return(SqlDml.Or(left, right));
case ExpressionType.Subtract:
case ExpressionType.SubtractChecked:
return(SqlDml.Subtract(left, right));
default:
throw new ArgumentOutOfRangeException("expression");
}
}
public static SqlExpression StringGreaterThan(
[Type(typeof(string))] SqlExpression _this,
[Type(typeof(string))] SqlExpression value)
{
return(SqlDml.GreaterThan(_this, value));
}