private static VfpExpression GetProjection(VfpFilterExpression filterExpression, string filterVariableName, VfpExpression projectionExpression)
{
var newInstanceExpression = projectionExpression as VfpNewInstanceExpression;
if (newInstanceExpression == null)
{
return(projectionExpression);
}
var newInstanceVariableNames = VariableReferenceGatherer.Gather(newInstanceExpression)
.Select(x => x.VariableName)
.Distinct()
.ToArray();
if (newInstanceVariableNames.Length != 1)
{
return(projectionExpression);
}
if (filterVariableName != newInstanceVariableNames.First())
{
return(projectionExpression);
}
return(VariableReferenceReplacer.Replace(filterExpression.Input.Variable, newInstanceExpression));
}
private static VfpExpression GetScanProperty(VfpVariableReferenceExpression variable, VfpExpression property)
{
var expression = VariableReferenceReplacer.Replace(variable, property);
var scanProperty = expression as VfpPropertyExpression;
if (scanProperty == null)
{
return(expression);
}
var variables = VariableReferenceGatherer.Gather(expression);
if (!variables.Any())
{
return(expression);
}
var scanVariable = variables.First();
return(scanVariable.Property(scanProperty.ResultType, scanProperty.Property));
}
public override VfpExpression Visit(VfpFilterExpression expression)
{
expression = (VfpFilterExpression)base.Visit(expression);
var innerFilter = expression.Input.Expression as VfpFilterExpression;
if (innerFilter == null)
{
return(expression);
}
var variables = VariableReferenceGatherer.Gather(innerFilter.Predicate);
if (!variables.Any() || variables.Select(x => x.VariableName).Distinct().Count() > 1)
{
return(expression);
}
var predicate = VariableReferenceReplacer.Replace(variables.First(), expression.Predicate);
return(innerFilter.Input.Filter(predicate.And(innerFilter.Predicate)));
}