| // Copyright 2022 Google LLC |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| // Also licensed under MIT license, at your choice. |
| |
| /// Interface for a monoid. The default value must be the identity of |
| /// the monoid. |
| pub trait Monoid: Default { |
| /// The source value for constructing the monoid. |
| type SourceValue; |
| |
| /// Creates a monoid from a given value. |
| fn new(value: Self::SourceValue) -> Self; |
| |
| /// Combines two monoids. This operation must be associative. |
| fn combine(&self, other: &Self) -> Self; |
| } |