public static Expressions.BooleanComparisonType ConvertNot(Expressions.BooleanComparisonType booleanComparisonType, bool isNot)
{
if (!isNot)
{
return(booleanComparisonType);
}
else
{
//Convert rules according to DeMorgans law
switch (booleanComparisonType)
{
case Expressions.BooleanComparisonType.Equals:
return(Expressions.BooleanComparisonType.NotEqualTo);
case Expressions.BooleanComparisonType.NotEqualTo:
return(Expressions.BooleanComparisonType.Equals);
case Expressions.BooleanComparisonType.GreaterThan:
return(Expressions.BooleanComparisonType.LessThanOrEqualTo);
case Expressions.BooleanComparisonType.GreaterThanOrEqualTo:
return(Expressions.BooleanComparisonType.LessThan);
case Expressions.BooleanComparisonType.LessThan:
return(Expressions.BooleanComparisonType.GreaterThanOrEqualTo);
case Expressions.BooleanComparisonType.LessThanOrEqualTo:
return(Expressions.BooleanComparisonType.GreaterThan);
default:
throw new NotImplementedException();
}
}
}
private void VisitBooleanComparisonExpression(BinaryExpression binaryExpression)
{
//Check if it is a string compareTo
if (FilterUtils.CheckIfStringCompareTo(binaryExpression, _inNot, out var stringComparison))
{
_stack.Push(stringComparison);
return;
}
var left = VisitPop <Expressions.ScalarExpression>(binaryExpression.Left);
var right = VisitPop <Expressions.ScalarExpression>(binaryExpression.Right);
Expressions.BooleanComparisonType booleanComparisonType = FilterUtils.ConvertNot(FilterUtils.ParseBooleanComparisonType(binaryExpression.NodeType), _inNot);
_stack.Push(new Expressions.BooleanComparisonExpression()
{
Type = booleanComparisonType,
Left = left,
Right = right
});
}
public static bool CheckIfStringCompareTo(BinaryExpression binaryExpression, bool isNot, out Expressions.BooleanComparisonExpression stringComparison)
{
stringComparison = null;
//check that it follows: o.prop.CompareTo("text") > < >= <= != == 0 1 -1
if (binaryExpression.Left.NodeType == ExpressionType.Call &&
binaryExpression.Left is MethodCallExpression methodCallExpression &&
methodCallExpression.Method.Name == "CompareTo" &&
methodCallExpression.Object is MemberExpression memberExpression &&
methodCallExpression.Object.Type.Equals(typeof(string)) &&
binaryExpression.Right.NodeType == ExpressionType.Constant &&
binaryExpression.Right is ConstantExpression constantExpression &&
methodCallExpression.Arguments.Count == 1 &&
methodCallExpression.Arguments[0] is ConstantExpression argumentExpression)
{
Expressions.BooleanComparisonType booleanComparisonType = FilterUtils.ParseBooleanComparisonType(binaryExpression.NodeType);
var compareValue = (long)Convert.ChangeType(constantExpression.Value, typeof(long));
var convertedComparison = ConvertNot(ConvertBooleanComparisonType(booleanComparisonType, compareValue), isNot);
var columnReference = new Expressions.ColumnReference()
{
Identifiers = new List <string>()
{
memberExpression.Member.Name
}
};
stringComparison = new Expressions.BooleanComparisonExpression()
{
Left = columnReference,
Right = new StringLiteral()
{
Value = (string)argumentExpression.Value
},
Type = convertedComparison
};
return(true);
}
return(false);
}
/// <summary>
/// Converts the current boolean comparison type based on the comparison value.
/// </summary>
/// <param name="type"></param>
/// <param name="val"></param>
/// <returns></returns>
private static Expressions.BooleanComparisonType ConvertBooleanComparisonType(Expressions.BooleanComparisonType type, long val)
{
if (val == 0)
{
return(type);
}
if (val == -1)
{
switch (type)
{
//compareTo == -1 is v1 < v2
case Expressions.BooleanComparisonType.Equals:
return(Expressions.BooleanComparisonType.LessThan);
//compareTo != -1 is v1 >= v2
case Expressions.BooleanComparisonType.NotEqualTo:
return(Expressions.BooleanComparisonType.GreaterThanOrEqualTo);
//compareTo > -1 is v1 >= v2
case Expressions.BooleanComparisonType.GreaterThan:
return(Expressions.BooleanComparisonType.GreaterThanOrEqualTo);
//compareTo >= -1 is always true since it hits -1 0 1
case Expressions.BooleanComparisonType.GreaterThanOrEqualTo:
//always true?
//TODO
throw new Exception("Found a string compareTo that is always true");
//compareTo < -1 is always false, it never hits -1 0 1
case Expressions.BooleanComparisonType.LessThan:
//always false, throw exception?
throw new Exception("Found a string compareTo that is always false");
//compareTo <= -1 hits -1, is v1 < v2
case Expressions.BooleanComparisonType.LessThanOrEqualTo:
return(Expressions.BooleanComparisonType.LessThan);
}
}
else if (val == 1)
{
switch (type)
{
//compareTo == 1 is v1 > v2
case Expressions.BooleanComparisonType.Equals:
return(Expressions.BooleanComparisonType.GreaterThan);
//compareTo != 1 is v1 <= v2
case Expressions.BooleanComparisonType.NotEqualTo:
return(Expressions.BooleanComparisonType.LessThanOrEqualTo);
//compareTo > 1 is is always false
case Expressions.BooleanComparisonType.GreaterThan:
throw new Exception("Found a string compareTo that is always false");
break;
//compareTo >= 1 is v1 > v2
case Expressions.BooleanComparisonType.GreaterThanOrEqualTo:
return(Expressions.BooleanComparisonType.GreaterThan);
//compareTo < 1 is v1 <= v2
case Expressions.BooleanComparisonType.LessThan:
return(Expressions.BooleanComparisonType.LessThanOrEqualTo);
//compareTo <= 1 is always true
case Expressions.BooleanComparisonType.LessThanOrEqualTo:
//always true
//TODO
throw new Exception("Found a string compareTo that is always true");
}
}
//TODO: fix exception
throw new Exception("Only use values 0, 1, -1 when comparing strings in compareTo.");
}