iridium_units/unit/
base.rs

1//! Base unit definitions.
2//!
3//! Base units are the fundamental building blocks of the unit system.
4//! They are `Copy` types defined as `const` values in [`crate::systems`].
5//!
6//! # Examples
7//!
8//! ```
9//! use iridium_units::prelude::*;
10//!
11//! // Predefined base units are const and Copy
12//! let distance = 42.195 * KM;
13//! let in_miles = distance.to(MILE).unwrap();
14//!
15//! // Create composite units with arithmetic
16//! let accel = 9.8 * &(M / S.pow(2));
17//!
18//! // Access unit metadata
19//! assert_eq!(M.symbol, "m");
20//! assert_eq!(M.name, "meter");
21//! assert_eq!(M.dimension(), Dimension::LENGTH);
22//! ```
23
24use crate::dimension::Dimension;
25use std::fmt;
26
27/// An irreducible base unit like meter, second, or kilogram.
28#[derive(Clone, Copy, PartialEq)]
29pub struct BaseUnit {
30    /// Primary name (e.g., "meter")
31    pub name: &'static str,
32    /// Short symbol (e.g., "m")
33    pub symbol: &'static str,
34    /// Alternative names/aliases
35    pub aliases: &'static [&'static str],
36    /// The dimension this unit represents
37    pub dimension: Dimension,
38    /// Scale relative to the canonical SI base unit (1.0 for SI base units)
39    pub scale: f64,
40    /// Additive offset for converting to SI: `SI = (value + offset) * scale`.
41    /// Zero for most units. Celsius has offset 273.15 (K = °C + 273.15).
42    pub offset: f64,
43}
44
45impl BaseUnit {
46    /// Create a new base unit.
47    pub const fn new(
48        name: &'static str,
49        symbol: &'static str,
50        aliases: &'static [&'static str],
51        dimension: Dimension,
52        scale: f64,
53    ) -> Self {
54        BaseUnit {
55            name,
56            symbol,
57            aliases,
58            dimension,
59            scale,
60            offset: 0.0,
61        }
62    }
63
64    /// Create a new base unit with an additive offset.
65    /// Offset units use affine conversion via their `scale` and `offset`.
66    pub const fn with_offset(
67        name: &'static str,
68        symbol: &'static str,
69        aliases: &'static [&'static str],
70        dimension: Dimension,
71        scale: f64,
72        offset: f64,
73    ) -> Self {
74        BaseUnit {
75            name,
76            symbol,
77            aliases,
78            dimension,
79            scale,
80            offset,
81        }
82    }
83}
84
85impl BaseUnit {
86    /// Get the dimension of this unit.
87    pub const fn dimension(&self) -> Dimension {
88        self.dimension
89    }
90
91    /// Raise this unit to a power, returning a [`Unit`](crate::Unit).
92    pub fn pow(&self, exp: impl Into<crate::dimension::Rational16>) -> crate::Unit {
93        crate::Unit::from(*self).pow(exp)
94    }
95}
96
97impl fmt::Debug for BaseUnit {
98    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
99        write!(f, "BaseUnit({})", self.symbol)
100    }
101}
102
103impl fmt::Display for BaseUnit {
104    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
105        write!(f, "{}", self.symbol)
106    }
107}
iridium_units/unit/base.rs

iridium_units/unit/
base.rs
