public override void VisitWhereClause(WhereClause whereClause, QueryModel queryModel, int index)
{
if (whereClause.Predicate is BinaryExpression expression)
{
VisitBinaryExpression(expression, RootExpression);
}
else
{
if (whereClause.Predicate is SubQueryExpression subQuery)
{
ExplainAndExpression andExpression;
if (!RootExpression.MultipleWhereClauses)
{
andExpression = new ExplainAndExpression();
RootExpression.Elements.Add(andExpression);
}
else // multiple where clauses are joined by AND
{
andExpression = RootExpression.Elements[0];
}
var leaf = new LeafExpression();
andExpression.Elements.Add(leaf);
VisitContainsExpression(subQuery, leaf);
}
else if (whereClause.Predicate is MethodCallExpression call)
{
ExplainAndExpression andExpression;
if (!RootExpression.MultipleWhereClauses)
{
andExpression = new ExplainAndExpression();
RootExpression.Elements.Add(andExpression);
}
else // multiple where clauses are joined by AND
{
andExpression = RootExpression.Elements[0];
}
var leaf = CallToLeafExpression(call);
andExpression.Elements.Add(leaf);
}
else if (whereClause.Predicate.NodeType != ExpressionType.Constant)
{
throw new NotSupportedException("query too complex");
}
}
RootExpression.MultipleWhereClauses = true;
base.VisitWhereClause(whereClause, queryModel, index);
}
private void VisitAndExpression(BinaryExpression binaryExpression, ExplainAndExpression andExpression)
{
if (IsLeafExpression(binaryExpression.Left))
{
andExpression.Elements.Add(VisitLeafExpression((BinaryExpression)binaryExpression.Left));
}
else if (binaryExpression.Left.NodeType == ExpressionType.AndAlso)
{
VisitAndExpression((BinaryExpression)binaryExpression.Left, andExpression);
}
else if (binaryExpression.Left.NodeType == ExpressionType.Extension)
{
if (binaryExpression.Left is SubQueryExpression subQuery)
{
var leaf = new LeafExpression();
andExpression.Elements.Add(leaf);
VisitContainsExpression(subQuery, leaf);
}
}
else if (binaryExpression.Left is MethodCallExpression callExpression)
{
andExpression.Elements.Add(CallToLeafExpression(callExpression));
}
else
{
throw new NotSupportedException("ExplainExpression too complex");
}
if (IsLeafExpression(binaryExpression.Right))
{
andExpression.Elements.Add(VisitLeafExpression((BinaryExpression)binaryExpression.Right));
}
else if (binaryExpression.Right.NodeType == ExpressionType.Extension)
{
if (binaryExpression.Right is SubQueryExpression subQuery)
{
var leaf = new LeafExpression();
andExpression.Elements.Add(leaf);
VisitContainsExpression(subQuery, leaf);
}
}
else if (binaryExpression.Right is MethodCallExpression callExpression)
{
andExpression.Elements.Add(CallToLeafExpression(callExpression));
}
else
{
throw new NotSupportedException("ExplainExpression too complex");
}
}
private static LeafExpression CallToLeafExpression(MethodCallExpression call)
{
StringBuilder sb = new StringBuilder();
sb.Append(call.Method.Name);
sb.Append("(");
foreach (var argument in call.Arguments)
{
if (argument is ConstantExpression constant)
{
sb.Append(constant.Value);
}
}
sb.Append(")");
var leaf = new LeafExpression {
MethodCall = sb.ToString()
};
return(leaf);
}
//TODO add unit test for OR expression with Contains
/// <summary>
/// OR expression can be present only at root level
/// </summary>
/// <param name="binaryExpression"></param>
/// <param name="rootExpression"></param>
private void VisitOrExpression(BinaryExpression binaryExpression, ExplainOrExpression rootExpression)
{
// visit left part
if (IsLeafExpression(binaryExpression.Left))
{
var andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
andExpression.Elements.Add(VisitLeafExpression((BinaryExpression)binaryExpression.Left));
}
else if (binaryExpression.Left.NodeType == ExpressionType.AndAlso)
{
var andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
VisitAndExpression((BinaryExpression)binaryExpression.Left, andExpression);
}
else if (binaryExpression.Left.NodeType == ExpressionType.Extension)
{
if (binaryExpression.Left is SubQueryExpression subQuery)
{
ExplainAndExpression andExpression;
if (!rootExpression.MultipleWhereClauses)
{
andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
}
else // multiple where clauses are joined by AND
{
andExpression = rootExpression.Elements[0];
}
var leaf = new LeafExpression();
andExpression.Elements.Add(leaf);
VisitContainsExpression(subQuery, leaf);
}
}
else if (binaryExpression.Left.NodeType == ExpressionType.OrElse)
{
VisitOrExpression((BinaryExpression)binaryExpression.Left, rootExpression);
}
else if (binaryExpression.Left.NodeType == ExpressionType.AndAlso)
{
var andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
VisitAndExpression((BinaryExpression)binaryExpression.Left, andExpression);
}
else if (binaryExpression.Left is MethodCallExpression call)
{
ExplainAndExpression andExpression;
if (!RootExpression.MultipleWhereClauses)
{
andExpression = new ExplainAndExpression();
RootExpression.Elements.Add(andExpression);
}
else // multiple where clauses are joined by AND
{
andExpression = RootExpression.Elements[0];
}
var leaf = CallToLeafExpression(call);
andExpression.Elements.Add(leaf);
}
else
{
throw new NotSupportedException("ExplainExpression too complex");
}
// visit right part
if (IsLeafExpression(binaryExpression.Right))
{
var andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
andExpression.Elements.Add(VisitLeafExpression((BinaryExpression)binaryExpression.Right));
}
else if (binaryExpression.Right.NodeType == ExpressionType.Extension)
{
if (binaryExpression.Right is SubQueryExpression subQuery)
{
var andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
if (rootExpression.MultipleWhereClauses)
{
throw new NotSupportedException(
"Multiple where clauses can be used only with simple expressions");
}
var leaf = new LeafExpression();
andExpression.Elements.Add(leaf);
VisitContainsExpression(subQuery, leaf);
}
}
else if (binaryExpression.Right.NodeType == ExpressionType.OrElse)
{
VisitOrExpression((BinaryExpression)binaryExpression.Right, rootExpression);
}
else if (binaryExpression.Right.NodeType == ExpressionType.AndAlso)
{
var andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
VisitAndExpression((BinaryExpression)binaryExpression.Right, andExpression);
}
else if (binaryExpression.Right is MethodCallExpression call)
{
ExplainAndExpression andExpression;
if (!RootExpression.MultipleWhereClauses)
{
andExpression = new ExplainAndExpression();
RootExpression.Elements.Add(andExpression);
}
else // multiple where clauses are joined by AND
{
andExpression = RootExpression.Elements[0];
}
var leaf = CallToLeafExpression(call);
andExpression.Elements.Add(leaf);
}
else
{
throw new NotSupportedException("ExplainExpression too complex");
}
}
private void VisitContainsExpression(SubQueryExpression subQuery, LeafExpression leaf)
{
if (subQuery.QueryModel.ResultOperators.Count != 1)
{
throw new NotSupportedException("Only Contains extension is supported");
}
var contains = subQuery.QueryModel.ResultOperators[0] as ContainsResultOperator;
// process collection.Contains(x=>x.Member)
if (contains?.Item is MemberExpression item)
{
var select = subQuery.QueryModel?.SelectClause.Selector as QuerySourceReferenceExpression;
leaf.MemberName = item.Member.Name;
if (select?.ReferencedQuerySource is MainFromClause from)
{
var expression = from.FromExpression as ConstantExpression;
if (expression?.Value is IEnumerable values)
{
leaf.Operator = QueryOperator.In;
foreach (var value in values)
{
leaf.InValues.Add(value);
}
return;
}
}
}
// process x=>x.VectorMember.Contains(value)
else
{
var value = contains?.Item;
if (value != null)
{
var select = subQuery.QueryModel?.SelectClause.Selector as QuerySourceReferenceExpression;
var from = select?.ReferencedQuerySource as MainFromClause;
if (from?.FromExpression is MemberExpression expression)
{
// the member must not be a scalar type. A string is a vector of chars but still considered a scalar in this context
var isVector = typeof(IEnumerable).IsAssignableFrom(expression.Type) &&
!typeof(string).IsAssignableFrom(expression.Type);
if (!isVector)
{
throw new NotSupportedException("Trying to use Contains extension on a scalar member");
}
if (value is ConstantExpression valueExpession)
{
leaf.Operator = QueryOperator.In;
leaf.InValues.Add(valueExpession.Value);
return;
}
}
}
}
throw new NotSupportedException("Only Contains extension is supported");
}