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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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
//
//   http://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.

//! Generic hashing support.
//!
//! This module provides a generic way to compute the [hash] of a value.
//! Hashes are most commonly used with [`HashMap`] and [`HashSet`].
//!
//! [hash]: https://en.wikipedia.org/wiki/Hash_function
//! [`HashMap`]: ../../std/collections/struct.HashMap.html
//! [`HashSet`]: ../../std/collections/struct.HashSet.html
//!
//! The simplest way to make a type hashable is to use `#[derive(Hash)]`:
//!
//! # Examples
//!
//! ```rust
//! use std::hash::{DefaultHasher, Hash, Hasher};
//!
//! #[derive(Hash)]
//! struct Person {
//!     id: u32,
//!     name: String,
//!     phone: u64,
//! }
//!
//! let person1 = Person {
//!     id: 5,
//!     name: "Janet".to_string(),
//!     phone: 555_666_7777,
//! };
//! let person2 = Person {
//!     id: 5,
//!     name: "Bob".to_string(),
//!     phone: 555_666_7777,
//! };
//!
//! assert!(calculate_hash(&person1) != calculate_hash(&person2));
//!
//! fn calculate_hash<T: Hash>(t: &T) -> u64 {
//!     let mut s = DefaultHasher::new();
//!     t.hash(&mut s);
//!     s.finish()
//! }
//! ```
//!
//! If you need more control over how a value is hashed, you need to implement
//! the [`Hash`] trait:
//!
//! ```rust
//! use std::hash::{DefaultHasher, Hash, Hasher};
//!
//! struct Person {
//!     id: u32,
//!     # #[allow(dead_code)]
//!     name: String,
//!     phone: u64,
//! }
//!
//! impl Hash for Person {
//!     fn hash<H: Hasher>(&self, state: &mut H) {
//!         self.id.hash(state);
//!         self.phone.hash(state);
//!     }
//! }
//!
//! let person1 = Person {
//!     id: 5,
//!     name: "Janet".to_string(),
//!     phone: 555_666_7777,
//! };
//! let person2 = Person {
//!     id: 5,
//!     name: "Bob".to_string(),
//!     phone: 555_666_7777,
//! };
//!
//! assert_eq!(calculate_hash(&person1), calculate_hash(&person2));
//!
//! fn calculate_hash<T: Hash>(t: &T) -> u64 {
//!     let mut s = DefaultHasher::new();
//!     t.hash(&mut s);
//!     s.finish()
//! }
//! ```

pub(crate) mod random;

pub use core::hash::*;

pub use self::random::{DefaultHasher, RandomState};