zebra_chain/block/
height.rs1use std::ops::{Add, Sub};
4use thiserror::Error;
5use zcash_primitives::consensus::BlockHeight;
6
7use crate::{serialization::SerializationError, BoxError};
8
9#[cfg(feature = "json-conversion")]
10pub mod json_conversion;
11
12#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
27#[cfg_attr(any(test, feature = "proptest-impl"), derive(Default))]
28pub struct Height(pub u32);
29
30#[derive(Error, Debug)]
31pub enum HeightError {
32 #[error("The resulting height would overflow Height::MAX.")]
33 Overflow,
34 #[error("The resulting height would underflow Height::MIN.")]
35 Underflow,
36}
37
38impl std::str::FromStr for Height {
39 type Err = SerializationError;
40 fn from_str(s: &str) -> Result<Self, Self::Err> {
41 match s.parse() {
42 Ok(h) if (Height(h) <= Height::MAX) => Ok(Height(h)),
43 Ok(_) => Err(SerializationError::Parse("Height exceeds maximum height")),
44 Err(_) => Err(SerializationError::Parse("Height(u32) integer parse error")),
45 }
46 }
47}
48
49impl Height {
50 pub const MIN: Height = Height(0);
58
59 pub const MAX: Height = Height(u32::MAX / 2);
68
69 pub const MAX_AS_U32: u32 = Self::MAX.0;
74
75 pub const MAX_EXPIRY_HEIGHT: Height = Height(499_999_999);
79
80 pub fn next(self) -> Result<Self, HeightError> {
86 (self + 1).ok_or(HeightError::Overflow)
87 }
88
89 pub fn previous(self) -> Result<Self, HeightError> {
95 (self - 1).ok_or(HeightError::Underflow)
96 }
97
98 pub fn is_min(self) -> bool {
100 self == Self::MIN
101 }
102
103 pub fn as_usize(self) -> usize {
105 self.0.try_into().expect("fits in usize")
106 }
107}
108
109impl From<Height> for BlockHeight {
110 fn from(height: Height) -> Self {
111 BlockHeight::from_u32(height.0)
112 }
113}
114
115impl TryFrom<BlockHeight> for Height {
116 type Error = &'static str;
117
118 fn try_from(height: BlockHeight) -> Result<Self, Self::Error> {
120 Self::try_from(u32::from(height))
121 }
122}
123
124pub type HeightDiff = i64;
129
130impl TryFrom<u32> for Height {
134 type Error = &'static str;
135
136 fn try_from(height: u32) -> Result<Self, Self::Error> {
138 assert_eq!(Height::MIN.0, 0);
142
143 if height <= Height::MAX.0 {
144 Ok(Height(height))
145 } else {
146 Err("heights must be less than or equal to Height::MAX")
147 }
148 }
149}
150
151pub trait TryIntoHeight {
153 type Error;
155
156 fn try_into_height(&self) -> Result<Height, Self::Error>;
158}
159
160impl TryIntoHeight for u64 {
161 type Error = BoxError;
162
163 fn try_into_height(&self) -> Result<Height, Self::Error> {
164 u32::try_from(*self)?.try_into().map_err(Into::into)
165 }
166}
167
168impl TryIntoHeight for usize {
169 type Error = BoxError;
170
171 fn try_into_height(&self) -> Result<Height, Self::Error> {
172 u32::try_from(*self)?.try_into().map_err(Into::into)
173 }
174}
175
176impl TryIntoHeight for str {
177 type Error = BoxError;
178
179 fn try_into_height(&self) -> Result<Height, Self::Error> {
180 self.parse().map_err(Into::into)
181 }
182}
183
184impl TryIntoHeight for String {
185 type Error = BoxError;
186
187 fn try_into_height(&self) -> Result<Height, Self::Error> {
188 self.as_str().try_into_height()
189 }
190}
191
192impl TryIntoHeight for i32 {
193 type Error = BoxError;
194
195 fn try_into_height(&self) -> Result<Height, Self::Error> {
196 u32::try_from(*self)?.try_into().map_err(Into::into)
197 }
198}
199
200impl Sub<Height> for Height {
203 type Output = HeightDiff;
204
205 fn sub(self, rhs: Height) -> Self::Output {
208 let lhs = HeightDiff::from(self.0);
210 let rhs = HeightDiff::from(rhs.0);
211
212 lhs - rhs
213 }
214}
215
216impl Sub<HeightDiff> for Height {
217 type Output = Option<Self>;
218
219 fn sub(self, rhs: HeightDiff) -> Option<Self> {
222 let lhs = HeightDiff::from(self.0);
224 let res = lhs - rhs;
225
226 let res = u32::try_from(res).ok()?;
228 Height::try_from(res).ok()
229 }
230}
231
232impl Add<HeightDiff> for Height {
233 type Output = Option<Height>;
234
235 fn add(self, rhs: HeightDiff) -> Option<Height> {
238 let lhs = i64::from(self.0);
240 let res = lhs + rhs;
241
242 let res = u32::try_from(res).ok()?;
244 Height::try_from(res).ok()
245 }
246}
247
248#[test]
249fn operator_tests() {
250 let _init_guard = zebra_test::init();
251
252 assert_eq!(Some(Height(2)), Height(1) + 1);
254 assert_eq!(None, Height::MAX + 1);
255
256 let height = Height(u32::pow(2, 31) - 2);
257 assert!(height < Height::MAX);
258
259 let max_height = (height + 1).expect("this addition should produce the max height");
260 assert!(height < max_height);
261 assert!(max_height <= Height::MAX);
262 assert_eq!(Height::MAX, max_height);
263 assert_eq!(None, max_height + 1);
264
265 assert_eq!(None, Height(Height::MAX_AS_U32 + 1) + 0);
267 assert_eq!(None, Height(i32::MAX as u32) + 1);
268 assert_eq!(None, Height(u32::MAX) + 0);
269
270 assert_eq!(Some(Height(1)), Height(2) + -1);
272 assert_eq!(Some(Height(0)), Height(1) + -1);
273 assert_eq!(None, Height(0) + -1);
274 assert_eq!(Some(Height(Height::MAX_AS_U32 - 1)), Height::MAX + -1);
275
276 assert_eq!(None, Height(Height::MAX_AS_U32 + 1) + 1);
279 assert_eq!(None, Height(i32::MAX as u32) + 1);
280 assert_eq!(None, Height(u32::MAX) + 1);
281
282 assert_eq!(Some(Height::MAX), Height(i32::MAX as u32 + 1) + -1);
284 assert_eq!(None, Height(u32::MAX) + -1);
285
286 assert_eq!(Some(Height(1)), Height(2) - 1);
287 assert_eq!(Some(Height(0)), Height(1) - 1);
288 assert_eq!(None, Height(0) - 1);
289 assert_eq!(Some(Height(Height::MAX_AS_U32 - 1)), Height::MAX - 1);
290
291 assert_eq!(Some(Height(2)), Height(1) - -1);
293 assert_eq!(Some(Height::MAX), Height(Height::MAX_AS_U32 - 1) - -1);
294 assert_eq!(None, Height::MAX - -1);
295
296 assert_eq!(Some(Height::MAX), Height(i32::MAX as u32 + 1) - 1);
299 assert_eq!(None, Height(u32::MAX) - 1);
300
301 assert_eq!(None, Height(Height::MAX_AS_U32 + 1) - -1);
303 assert_eq!(None, Height(i32::MAX as u32) - -1);
304 assert_eq!(None, Height(u32::MAX) - -1);
305
306 assert_eq!(1, (Height(2) - Height(1)));
307 assert_eq!(0, (Height(1) - Height(1)));
308 assert_eq!(-1, Height(0) - Height(1));
309 assert_eq!(-5, Height(2) - Height(7));
310 assert_eq!(Height::MAX.0 as HeightDiff, (Height::MAX - Height(0)));
311 assert_eq!(1, (Height::MAX - Height(Height::MAX_AS_U32 - 1)));
312 assert_eq!(-1, Height(Height::MAX_AS_U32 - 1) - Height::MAX);
313 assert_eq!(-(Height::MAX_AS_U32 as HeightDiff), Height(0) - Height::MAX);
314}