/// <summary>
/// 或 expr1 or expr2
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="expr1"></param>
/// <param name="expr2"></param>
/// <returns></returns>
public static Expression <Func <T, bool> > Or <T>(this Expression <Func <T, bool> > expr1, Expression <Func <T, bool> > expr2)
{
ParameterExpression newParameter = Expression.Parameter(typeof(T), "c");
NewExpressionVisitor visitor = new NewExpressionVisitor(newParameter);
var left = visitor.Visit(expr1.Body);
var right = visitor.Visit(expr2.Body);
var body = Expression.Or(left, right);
return(Expression.Lambda <Func <T, bool> >(body, newParameter));
}
/// <summary>
/// 非 !expr
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="expr"></param>
/// <returns></returns>
public static Expression <Func <T, bool> > Not <T>(this Expression <Func <T, bool> > expr)
{
ParameterExpression newParameter = Expression.Parameter(typeof(T), "c");
NewExpressionVisitor visitor = new NewExpressionVisitor(newParameter);
var temp = visitor.Visit(expr.Body);
var body = Expression.Not(temp);
return(Expression.Lambda <Func <T, bool> >(body, newParameter));
}