private InvocationExpander(ParameterExpression parameter, Expression expansion, InvocationExpander previous)
{
EnitityUtility.CheckArgumentNotNull(parameter, "parameter");
EnitityUtility.CheckArgumentNotNull(expansion, "expansion");
EnitityUtility.CheckArgumentNotNull(previous, "previous");
_parameter = parameter;
_expansion = expansion;
_previous = previous;
}
protected override Expression VisitParameter(ParameterExpression p)
{
InvocationExpander expander = this;
while (null != expander)
{
if (expander._parameter == p)
{
return(base.Visit(expander._expansion));
}
expander = expander._previous;
}
return(base.VisitParameter(p));
}
public void CanExpandTwoVariablePredicate()
{
Expression <Func <int, int, bool> > p1 = (x, y) => x > y;
Expression <Func <int, int, bool> > p2 = (y, x) => x > y;
// (x, y) => x > y || invoke((y, x) => x > y, x, y);
p1 = Expression.Lambda <Func <int, int, bool> >(Expression.OrElse(p1.Body, Expression.Invoke(p2, p1.Parameters.ToArray())), p1.Parameters.ToArray());
p1.Nodes().OfType <ParameterExpression>().Count().Should().Be(10);
p1.Nodes().OfType <InvocationExpression>().Count().Should().Be(1);
// (x, y) => x > y || y > x;
p1 = InvocationExpander.Expand(p1);
p1.Nodes().OfType <ParameterExpression>().Count().Should().Be(6);
p1.Nodes().OfType <InvocationExpression>().Count().Should().Be(0);
//expected result
Expression <Func <int, int, bool> > pExp = (x, y) => x > y || y > x;
p1.ToString().Should().Be(pExp.ToString());
}
public void CanExpandSimplePredicate()
{
Expression <Predicate <int> > p1 = x => x > 2;
Expression <Predicate <int> > p2 = y => y < 3;
// x => x > 2 && invoke(y => y < 3, x);
p1 = Expression.Lambda <Predicate <int> >(Expression.AndAlso(p1.Body, Expression.Invoke(p2, p1.Parameters.ToArray())), p1.Parameters.ToArray());
p1.Nodes().OfType <ParameterExpression>().Count().Should().Be(5);
p1.Nodes().OfType <InvocationExpression>().Count().Should().Be(1);
// x => x > 2 && x < 3
p1 = InvocationExpander.Expand(p1);
p1.Nodes().OfType <ParameterExpression>().Count().Should().Be(3);
p1.Nodes().OfType <InvocationExpression>().Count().Should().Be(0);
//expected result
Expression <Predicate <int> > pExp = x => x > 2 && x < 3;
p1.ToString().Should().Be(pExp.ToString());
}
public static Expression <Func <T, bool> > ExpandInvocations <T>(this Expression <Func <T, bool> > expr)
{
return(InvocationExpander.Expand(expr));
}
/// <summary>
/// Expands all InvocationExpression instances within the given expression.
/// </summary>
/// <param name="expression">Expression to expand.</param>
/// <returns>Expanded expression.</returns>
public static Expression ExpandInvocations(this Expression expression)
{
return(InvocationExpander.Expand(expression));
}