public virtual VfpExpression Visit(VfpComparisonExpression expression)
{
return(new VfpComparisonExpression(expression.ExpressionKind,
expression.ResultType,
expression.Left.Accept(this),
expression.Right.Accept(this)));
}
public override VfpExpression Visit(VfpComparisonExpression expression)
{
// Check the left expression to see if it contains a property expression.
// Don't need to rewrite the comparison expression of the left side already contains a property expression.
if (PropertyGatherer.Gather(expression.Left).Any())
{
return(expression);
}
// Check the right expression to see if it has a property expression.
if (!PropertyGatherer.Gather(expression.Right).Any())
{
return(expression);
}
return(reverseExpression(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 VfpComparisonExpression reverseExpression(VfpComparisonExpression expression)
{
switch (expression.ExpressionKind)
{
case VfpExpressionKind.GreaterThan:
return(expression.Right.LessThan(expression.Left));
case VfpExpressionKind.GreaterThanOrEquals:
return(expression.Right.LessThanOrEquals(expression.Left));
case VfpExpressionKind.LessThan:
return(expression.Right.GreaterThan(expression.Left));
case VfpExpressionKind.LessThanOrEquals:
return(expression.Right.GreaterThanOrEquals(expression.Left));
default:
return(expression);
}
}
public override VfpExpression Visit(VfpComparisonExpression expression)
{
return(Visit((VfpBinaryExpression)expression));
}
private static bool IsZeroEqualsZero(VfpComparisonExpression expression)
{
return(expression != null && expression.ExpressionKind == VfpExpressionKind.Equals && IsZero(expression.Left as VfpConstantExpression) && IsZero(expression.Right as VfpConstantExpression));
}
public override VfpExpression Visit(VfpComparisonExpression expression)
{
_expressions.Add(expression);
return(base.Visit(expression));
}
