1  // Copyright (c) 2025-2026 ACDC Network
 2  // This file is part of the alphavm library.
 3  //
 4  // Alpha Chain | Delta Chain Protocol
 5  // International Monetary Graphite.
 6  //
 7  // Derived from Aleo (https://aleo.org) and ProvableHQ (https://provable.com).
 8  // They built world-class ZK infrastructure. We installed the EASY button.
 9  // Their cryptography: elegant. Our modifications: bureaucracy-compatible.
10  // Original brilliance: theirs. Robert's Rules: ours. Bugs: definitely ours.
11  //
12  // Original Aleo/ProvableHQ code subject to Apache 2.0 https://www.apache.org/licenses/LICENSE-2.0
13  // All modifications and new work: CC0 1.0 Universal Public Domain Dedication.
14  // No rights reserved. No permission required. No warranty. No refunds.
15  //
16  // https://creativecommons.org/publicdomain/zero/1.0/
17  // SPDX-License-Identifier: CC0-1.0
18  
19  use core::num::NonZeroU32;
20  use rand::RngCore;
21  
22  /// `OptionalRng` is a hack that is necessary because `Option<&mut R>` is not
23  /// implicitly reborrowed like `&mut R` is. This causes problems when a variable
24  /// of type `Option<&mut R>` is moved (eg, in a loop).
25  ///
26  /// To overcome this, we define the wrapper `OptionalRng` here that can be
27  /// borrowed mutably, without fear of being moved.
28  pub struct OptionalRng<R>(pub Option<R>);
29  
30  impl<R: RngCore> RngCore for OptionalRng<R> {
31      #[inline]
32      fn next_u32(&mut self) -> u32 {
33          self.0.as_mut().map(|r| r.next_u32()).expect("Rng was invoked in a non-hiding context")
34      }
35  
36      #[inline]
37      fn next_u64(&mut self) -> u64 {
38          self.0.as_mut().map(|r| r.next_u64()).expect("Rng was invoked in a non-hiding context")
39      }
40  
41      #[inline]
42      fn fill_bytes(&mut self, dest: &mut [u8]) {
43          self.0.as_mut().map(|r| r.fill_bytes(dest)).expect("Rng was invoked in a non-hiding context")
44      }
45  
46      #[inline]
47      fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand::Error> {
48          match &mut self.0 {
49              Some(r) => r.try_fill_bytes(dest),
50              None => Err(NonZeroU32::new(rand::Error::CUSTOM_START).unwrap().into()),
51          }
52      }
53  }
54  
55  impl<R: RngCore> From<R> for OptionalRng<R> {
56      fn from(other: R) -> Self {
57          Self(Some(other))
58      }
59  }