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 void VisitBinaryExpression(BinaryExpression binaryExpression, ExplainOrExpression rootExpression)
{
// manage AND expressions
if (binaryExpression.NodeType == ExpressionType.AndAlso)
{
var andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
VisitAndExpression(binaryExpression, andExpression);
}
// manage OR expressions
else if (binaryExpression.NodeType == ExpressionType.OrElse)
{
VisitOrExpression(binaryExpression, rootExpression);
}
// manage simple expressions like a > 10
else if (IsLeafExpression(binaryExpression))
{
ExplainAndExpression andExpression;
if (!rootExpression.MultipleWhereClauses)
{
andExpression = new ExplainAndExpression();
rootExpression.Elements.Add(andExpression);
}
else // if multiple where clauses consider them as expressions linked by AND
{
andExpression = rootExpression.Elements[0];
}
andExpression.Elements.Add(VisitLeafExpression(binaryExpression));
}
else
{
throw new NotSupportedException("ExplainExpression too complex");
}
}
//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");
}
}