public static Expression <Func <T, bool> > Or <T>(params Expression <Func <T, bool> >[] predicates)
{
Expression <Func <T, bool> > predicate = x => true;
if (predicates == null || predicates.Length == 0)
{
return(predicate);
}
for (int i = 0; i < predicates.Length; i++)
{
if (i == 0)
{
predicate = predicates[i];
continue;
}
ParameterExpression p = predicate.Parameters[0];
SubstExpressionVisitor visitor = new SubstExpressionVisitor();
visitor.subst[predicates[i].Parameters[0]] = p;
Expression body = Expression.Or(predicate.Body, visitor.Visit(predicates[i].Body));
predicate = Expression.Lambda <Func <T, bool> >(body, p);
}
return(predicate);
}
public static Expression <Func <T, bool> > Or <T>(this Expression <Func <T, bool> > a, Expression <Func <T, bool> > b)
{
ParameterExpression p = a.Parameters[0];
SubstExpressionVisitor visitor = new SubstExpressionVisitor {
Subst = { [b.Parameters[0]] = p }
};
Expression body = Expression.OrElse(a.Body, visitor.Visit(b.Body) ?? throw new InvalidOperationException());
return(Expression.Lambda <Func <T, bool> >(body, p));
}
public static Expression <Func <T, bool> > And <T>(this Expression <Func <T, bool> > a, Expression <Func <T, bool> > b)
{
ParameterExpression p = a.Parameters[0];
SubstExpressionVisitor visitor = new SubstExpressionVisitor();
visitor.subst[b.Parameters[0]] = p;
Expression body = Expression.AndAlso(a.Body, visitor.Visit(b.Body));
return(Expression.Lambda <Func <T, bool> >(body, p));
}
public static Expression <Func <T, bool> > Or <T>(this Expression <Func <T, bool> > first, Expression <Func <T, bool> > second)
{
ParameterExpression p = first.Parameters[0];
SubstExpressionVisitor visitor = new SubstExpressionVisitor();
visitor.subst[second.Parameters[0]] = p;
Expression body = Expression.OrElse(first.Body, visitor.Visit(second.Body));
return(Expression.Lambda <Func <T, bool> >(body, p));
}
public static Expression <Func <T, bool> > And <T>(this Expression <Func <T, bool> > a, Expression <Func <T, bool> > b)
{
var p = a.Parameters[0];
var visitor = new SubstExpressionVisitor();
visitor.Subst[b.Parameters[0]] = p;
Expression body = Expression.AndAlso(a.Body, visitor.Visit(b.Body) ?? throw new InvalidOperationException());
return(Expression.Lambda <Func <T, bool> >(body, p));
}
/// <summary>
/// Or operator between expressions
/// </summary>
/// <param name="exprLeft"></param>
/// <param name="exprRight"></param>
private static Expression <Func <T, bool> > Or <T>(this Expression <Func <T, bool> > exprLeft, Expression <Func <T, bool> > exprRight)
{
ParameterExpression p = exprLeft.Parameters[0];
var visitor = new SubstExpressionVisitor();
visitor._subst[exprRight.Parameters[0]] = p;
Expression body = Expression.OrElse(exprLeft.Body, visitor.Visit(exprRight.Body));
return(Expression.Lambda <Func <T, bool> >(body, p));
}
