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// Copyright (c) 2018 The predicates-rs Project Developers. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. use std::fmt; /// Trait for generically evaluating a type against a dynamically created /// predicate function. /// /// The exact meaning of `eval` depends on the situation, but will usually /// mean that the evaluated item is in some sort of pre-defined set. This is /// different from `Ord` and `Eq` in that an `item` will almost never be the /// same type as the implementing `Predicate` type. pub trait Predicate<Item: ?Sized>: fmt::Display { /// Execute this `Predicate` against `variable`, returning the resulting /// boolean. fn eval(&self, variable: &Item) -> bool; }