icydb_schema/
nat_big.rs

1//! Canonical arbitrary-precision unsigned-integer atom.
2
3use crate::{Decimal, NumericValue};
4use candid::{CandidType, Nat as WrappedNat};
5use derive_more::{Add, AddAssign, Sub, SubAssign};
6use num_bigint::BigUint;
7use serde::{Deserialize, Serialize};
8use std::{
9    fmt,
10    iter::{Product, Sum},
11    ops::{Div, DivAssign, Mul, MulAssign},
12    str::FromStr,
13};
14
15//
16// NatBig
17//
18
19#[derive(
20    Add,
21    AddAssign,
22    CandidType,
23    Clone,
24    Debug,
25    Default,
26    Eq,
27    PartialEq,
28    Hash,
29    Ord,
30    PartialOrd,
31    Serialize,
32    Deserialize,
33    Sub,
34    SubAssign,
35)]
36/// Arbitrary-precision unsigned integer used by schema and typed values.
37pub struct NatBig(WrappedNat);
38
39impl NatBig {
40    /// Return the magnitude's bit length without allocating an encoded copy.
41    #[must_use]
42    pub fn magnitude_bits(&self) -> u64 {
43        self.0.0.bits()
44    }
45
46    /// Return the exact unsigned LEB128 byte length without allocating or encoding.
47    #[must_use]
48    pub fn leb128_len(&self) -> u64 {
49        self.magnitude_bits().div_ceil(7).max(1)
50    }
51
52    /// Construct from the canonical Candid natural-number representation.
53    #[must_use]
54    pub const fn from_candid(value: WrappedNat) -> Self {
55        Self(value)
56    }
57
58    /// Construct from a `num_bigint` unsigned integer.
59    #[must_use]
60    pub fn from_biguint(value: BigUint) -> Self {
61        Self::from_candid(WrappedNat::from(value))
62    }
63
64    /// Return base-2^32 limbs for decimal key encoding.
65    ///
66    /// This allocates for the returned limb vector.
67    #[must_use]
68    pub fn u32_digits(&self) -> Vec<u32> {
69        self.0.0.to_u32_digits()
70    }
71
72    /// Convert to `u128` when the value is in range.
73    #[must_use]
74    pub fn to_u128(&self) -> Option<u128> {
75        let big = &self.0.0;
76
77        u128::try_from(big).ok()
78    }
79
80    /// Convert to `u64` when the value is in range.
81    #[must_use]
82    pub fn to_u64(&self) -> Option<u64> {
83        let big = &self.0.0;
84
85        u64::try_from(big).ok()
86    }
87
88    /// Serialize this arbitrary-precision natural for internal hash and sort-key framing.
89    #[must_use]
90    pub fn to_leb128(&self) -> Vec<u8> {
91        let mut out = Vec::new();
92        let encoded = self.0.encode(&mut out);
93        debug_assert!(
94            encoded.is_ok(),
95            "Vec-backed unsigned LEB128 encoding failed"
96        );
97
98        out
99    }
100
101    pub(crate) fn to_magnitude_bytes(&self) -> Vec<u8> {
102        self.0.0.to_bytes_be()
103    }
104
105    pub(crate) fn from_magnitude_bytes(magnitude: &[u8]) -> Self {
106        Self::from_biguint(BigUint::from_bytes_be(magnitude))
107    }
108
109    /// Saturating addition (unbounded; equivalent to normal addition).
110    #[must_use]
111    pub fn saturating_add(self, rhs: Self) -> Self {
112        Self(self.0 + rhs.0)
113    }
114
115    /// Saturating subtraction; clamps at zero on underflow.
116    #[must_use]
117    pub fn saturating_sub(self, rhs: Self) -> Self {
118        if rhs > self {
119            return Self::default();
120        }
121
122        Self(self.0 - rhs.0)
123    }
124}
125
126impl fmt::Display for NatBig {
127    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
128        self.0.fmt(f)
129    }
130}
131
132impl FromStr for NatBig {
133    type Err = <WrappedNat as FromStr>::Err;
134
135    fn from_str(s: &str) -> Result<Self, Self::Err> {
136        WrappedNat::from_str(s).map(Self::from_candid)
137    }
138}
139
140impl Div for NatBig {
141    type Output = Self;
142
143    fn div(self, other: Self) -> Self::Output {
144        Self(self.0 / other.0)
145    }
146}
147
148impl DivAssign for NatBig {
149    fn div_assign(&mut self, other: Self) {
150        self.0 /= other.0;
151    }
152}
153
154impl From<u64> for NatBig {
155    fn from(n: u64) -> Self {
156        Self::from_candid(WrappedNat::from(n))
157    }
158}
159
160impl From<u32> for NatBig {
161    fn from(n: u32) -> Self {
162        Self::from_candid(WrappedNat::from(n))
163    }
164}
165
166impl Mul for NatBig {
167    type Output = Self;
168
169    fn mul(self, other: Self) -> Self::Output {
170        Self(self.0 * other.0)
171    }
172}
173
174impl MulAssign for NatBig {
175    fn mul_assign(&mut self, other: Self) {
176        self.0 *= other.0;
177    }
178}
179
180impl NumericValue for NatBig {
181    fn try_to_decimal(&self) -> Option<Decimal> {
182        self.to_u128().and_then(Decimal::from_u128)
183    }
184
185    fn try_from_decimal(value: Decimal) -> Option<Self> {
186        value.to_u128().map(WrappedNat::from).map(Self::from_candid)
187    }
188}
189
190impl Product for NatBig {
191    fn product<I: Iterator<Item = Self>>(iter: I) -> Self {
192        iter.fold(Self::from(1_u32), |acc, value| acc * value)
193    }
194}
195
196impl Sum for NatBig {
197    fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
198        iter.fold(Self::default(), |acc, x| acc + x)
199    }
200}
201
202impl TryFrom<i32> for NatBig {
203    type Error = std::num::TryFromIntError;
204
205    fn try_from(n: i32) -> Result<Self, Self::Error> {
206        let v = Self::from_candid(WrappedNat::from(u32::try_from(n)?));
207        Ok(v)
208    }
209}
icydb_schema/nat_big.rs

icydb_schema/
nat_big.rs
