public virtual VfpExpression Visit(VfpProjectExpression expression)
{
var projection = expression.Projection.Accept(this);
var input = VisitVfpExpressionBinding(expression.Input);
return(new VfpProjectExpression(expression.ResultType, input, projection));
}
public override VfpExpression Visit(VfpProjectExpression expression)
{
Write(" SELECT ");
expression.Projection.Accept(this);
VisitVfpExpressionBinding(expression.Input);
return(expression);
}
public override VfpExpression Visit(VfpProjectExpression expression)
{
VfpProjectExpression innerProjectionExpression;
bool hasNotExpression;
if (GetInnerProjectionExpression(expression, out innerProjectionExpression, out hasNotExpression))
{
var innerNewInstanceExpression = innerProjectionExpression.Projection as VfpNewInstanceExpression;
if (innerNewInstanceExpression != null)
{
var innerConstExpression = innerNewInstanceExpression.Arguments[0] as VfpConstantExpression;
if (innerConstExpression != null)
{
var countExpression = new VfpConstantExpression(innerConstExpression.ResultType, "COUNT(*)");
innerNewInstanceExpression = new VfpNewInstanceExpression(innerNewInstanceExpression.ResultType, new VfpExpressionList(new List <VfpExpression> {
countExpression
}));
innerProjectionExpression = new VfpProjectExpression(innerProjectionExpression.ResultType, innerProjectionExpression.Input, innerNewInstanceExpression);
VfpExpression comparison = new VfpComparisonExpression(VfpExpressionKind.LessThan,
PrimitiveTypeKind.Boolean.ToTypeUsage(),
new VfpConstantExpression(
PrimitiveTypeKind.Int32.ToTypeUsage(), 0),
innerProjectionExpression);
if (!hasNotExpression)
{
comparison = new VfpNotExpression(comparison.ResultType, comparison);
}
innerNewInstanceExpression = new VfpNewInstanceExpression(innerNewInstanceExpression.ResultType, new VfpExpressionList(new List <VfpExpression> {
comparison
}));
innerProjectionExpression = new VfpProjectExpression(expression.ResultType, expression.Input, innerNewInstanceExpression);
return(innerProjectionExpression);
}
}
}
return(base.Visit(expression));
}
private static bool GetInnerProjectionExpression(VfpProjectExpression expression, out VfpProjectExpression innerProjectionExpression, out bool hasNotExpression)
{
innerProjectionExpression = null;
hasNotExpression = false;
if (!expression.Input.VariableName.StartsWith("SingleRowTable"))
{
return(false);
}
var newInstanceExpression = expression.Projection as VfpNewInstanceExpression;
if (newInstanceExpression == null)
{
return(false);
}
var notExpression = newInstanceExpression.Arguments[0] as VfpNotExpression;
VfpIsEmptyExpression isEmptyExpression = null;
if (notExpression == null)
{
isEmptyExpression = newInstanceExpression.Arguments[0] as VfpIsEmptyExpression;
}
else
{
isEmptyExpression = notExpression.Argument as VfpIsEmptyExpression;
hasNotExpression = true;
}
if (isEmptyExpression == null)
{
return(false);
}
innerProjectionExpression = isEmptyExpression.Argument as VfpProjectExpression;
return(innerProjectionExpression != null);
}
public override VfpExpression Visit(VfpProjectExpression expression)
{
var result = base.Visit(expression);
expression = result as VfpProjectExpression;
if (expression == null)
{
return(result);
}
var filterExpression = expression.Input.Expression as VfpFilterExpression;
if (IsZeroEqualsZero(filterExpression))
{
var projectionExpression = GetProjection(filterExpression, expression.Input.VariableName, expression.Projection);
return(filterExpression.Input.Project(projectionExpression));
}
return(result);
}
private static VfpLimitExpression GetVfpLimitExpression(VfpLimitExpression limitExpression, VfpProjectExpression projectExpression)
{
var keyMembers = GetKeyMembers(projectExpression);
if (!keyMembers.Any())
{
return(null);
}
var sortBinding = GetSortBinding(keyMembers, projectExpression.Input, projectExpression);
var newProject = sortBinding.Project(projectExpression.Projection);
return(new VfpLimitExpression(limitExpression.ResultType,
newProject,
limitExpression.Limit,
limitExpression.WithTies));
}
private static IEnumerable <EdmMember> GetKeyMembers(VfpProjectExpression expression)
{
return(expression == null ? new EdmMember[] { } : GetKeyMembers(expression.Input, expression));
}
