constraint_solver/
exp.rs

1/*
2MIT License
3
4Copyright (c) 2026 Raja Lehtihet & Wael El Oraiby
5
6Permission is hereby granted, free of charge, to any person obtaining a copy
7of this software and associated documentation files (the "Software"), to deal
8in the Software without restriction, including without limitation the rights
9to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10copies of the Software, and to permit persons to whom the Software is
11furnished to do so, subject to the following conditions:
12
13The above copyright notice and this permission notice shall be included in all
14copies or substantial portions of the Software.
15
16THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22SOFTWARE.
23*/
24
25use std::fmt;
26
27#[derive(Debug, Clone, PartialEq, Eq)]
28pub struct MissingVarError {
29    pub var_name: String,
30}
31
32impl fmt::Display for MissingVarError {
33    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
34        write!(f, "Missing variable '{}'", self.var_name)
35    }
36}
37
38impl std::error::Error for MissingVarError {}
39
40#[derive(Debug, Clone, PartialEq)]
41pub enum Exp {
42    Val(f64),
43    Var(String),
44    Add(Box<Exp>, Box<Exp>),
45    Sub(Box<Exp>, Box<Exp>),
46    Mul(Box<Exp>, Box<Exp>),
47    Div(Box<Exp>, Box<Exp>),
48    Power(Box<Exp>, f64),
49    Neg(Box<Exp>),
50    Sin(Box<Exp>),
51    Cos(Box<Exp>),
52    Ln(Box<Exp>),
53    Exp(Box<Exp>),
54}
55
56#[allow(clippy::self_named_constructors, clippy::should_implement_trait)]
57impl Exp {
58    pub fn var(name: impl Into<String>) -> Self {
59        Exp::Var(name.into())
60    }
61
62    pub fn val(v: f64) -> Self {
63        Exp::Val(v)
64    }
65
66    pub fn add(lhs: Exp, rhs: Exp) -> Self {
67        Exp::Add(Box::new(lhs), Box::new(rhs))
68    }
69
70    pub fn sub(lhs: Exp, rhs: Exp) -> Self {
71        Exp::Sub(Box::new(lhs), Box::new(rhs))
72    }
73
74    pub fn mul(lhs: Exp, rhs: Exp) -> Self {
75        Exp::Mul(Box::new(lhs), Box::new(rhs))
76    }
77
78    pub fn div(lhs: Exp, rhs: Exp) -> Self {
79        Exp::Div(Box::new(lhs), Box::new(rhs))
80    }
81
82    pub fn power(base: Exp, exp: f64) -> Self {
83        Exp::Power(Box::new(base), exp)
84    }
85
86    pub fn neg(exp: Exp) -> Self {
87        Exp::Neg(Box::new(exp))
88    }
89
90    pub fn sin(exp: Exp) -> Self {
91        Exp::Sin(Box::new(exp))
92    }
93
94    pub fn cos(exp: Exp) -> Self {
95        Exp::Cos(Box::new(exp))
96    }
97
98    pub fn ln(exp: Exp) -> Self {
99        Exp::Ln(Box::new(exp))
100    }
101
102    pub fn exp(exp: Exp) -> Self {
103        Exp::Exp(Box::new(exp))
104    }
105}
106
107impl fmt::Display for Exp {
108    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
109        match self {
110            Exp::Val(v) => write!(f, "{v}"),
111            Exp::Var(name) => write!(f, "{name}"),
112            Exp::Add(l, r) => write!(f, "({l} + {r})"),
113            Exp::Sub(l, r) => write!(f, "({l} - {r})"),
114            Exp::Mul(l, r) => write!(f, "({l} * {r})"),
115            Exp::Div(l, r) => write!(f, "({l} / {r})"),
116            Exp::Power(base, exp) => write!(f, "({base}^{exp})"),
117            Exp::Neg(e) => write!(f, "(-{e})"),
118            Exp::Sin(e) => write!(f, "sin({e})"),
119            Exp::Cos(e) => write!(f, "cos({e})"),
120            Exp::Ln(e) => write!(f, "ln({e})"),
121            Exp::Exp(e) => write!(f, "exp({e})"),
122        }
123    }
124}
125
126#[cfg(test)]
127mod tests {
128    use super::*;
129
130    #[test]
131    fn test_constructors_match_variants() {
132        assert_eq!(Exp::var("x"), Exp::Var("x".to_string()));
133        assert_eq!(Exp::val(2.5), Exp::Val(2.5));
134
135        let expr = Exp::add(Exp::val(1.0), Exp::val(2.0));
136        assert_eq!(
137            expr,
138            Exp::Add(Box::new(Exp::Val(1.0)), Box::new(Exp::Val(2.0)))
139        );
140    }
141
142    #[test]
143    fn test_display_formats_expression() {
144        let x = Exp::var("x");
145        let y = Exp::var("y");
146        let expr = Exp::sub(
147            Exp::add(
148                Exp::power(x.clone(), 2.0),
149                Exp::mul(Exp::val(3.0), y.clone()),
150            ),
151            Exp::val(1.0),
152        );
153
154        assert_eq!(format!("{expr}"), "(((x^2) + (3 * y)) - 1)");
155    }
156}
constraint_solver/exp.rs

constraint_solver/
exp.rs
