protected override VfpExpressionBinding VisitVfpExpressionBinding(VfpExpressionBinding binding)
{
binding = base.VisitVfpExpressionBinding(binding);
var filterExpression = binding.Expression as VfpFilterExpression;
if (filterExpression == null)
{
return(binding);
}
var project = filterExpression.Input.Expression as VfpProjectExpression;
if (project == null)
{
return(binding);
}
var scan = project.Input.Expression as VfpScanExpression;
if (scan == null)
{
return(binding);
}
var newInstance = project.Projection as VfpNewInstanceExpression;
if (newInstance == null)
{
return(binding);
}
var properties = newInstance.Arguments.OfType <VfpPropertyExpression>().ToList().AsReadOnly();
if (!properties.Any())
{
return(binding);
}
if (!VfpPropertyExpressionChecker.CanRewrite(filterExpression.Predicate))
{
return(binding);
}
var newFilterPredicate = VfpPropertyExpressionRewriter.Rewrite(filterExpression.Predicate, properties);
var newFilterExpression = project.Input.Filter(newFilterPredicate);
var newFilterBinding = newFilterExpression.BindAs(binding.Variable.VariableName);
var newProjection = VfpVariableReferenceExpressionRewriter.Rewrite(project.Projection, binding.Variable);
var newProjectExpression = newFilterBinding.Project(newProjection);
var newBinding = newProjectExpression.BindAs(binding.Variable.VariableName);
return(newBinding);
}
public static VfpExpression Rewrite(VfpExpression expression, ReadOnlyCollection <VfpPropertyExpression> properties)
{
var rewriter = new VfpPropertyExpressionRewriter(properties);
return(rewriter.Visit(expression));
}