1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
use pest::{
iterators::{
Pair,
Pairs,
},
pratt_parser::PrattParser,
Parser,
};
use rand::Rng as _;
#[derive(pest_derive::Parser)]
#[grammar = "calc.pest"]
pub struct Calc;
#[derive(Copy, Clone, thiserror::Error, Debug, PartialEq, Eq, Hash)]
pub enum Error {
#[error("unable to parse input")]
Pest,
#[error("invalid number format")]
NumberFormat,
#[error("bad argument count")]
ArgCount,
}
lazy_static::lazy_static! {
static ref PRATT_PARSER: PrattParser<Rule> = {
use pest::pratt_parser::{
Assoc::*,
Op,
};
use Rule::*;
PrattParser::new()
.op(Op::infix(add, Left) | Op::infix(sub, Left) | Op::infix(modulo, Left))
.op(Op::infix(mul, Left) | Op::infix(div, Left))
.op(Op::infix(dice, Left))
.op(Op::infix(pow, Right))
.op(Op::postfix(EOI)) // discarded below
};
}
impl Calc {
#[inline]
pub fn eval<S: AsRef<str>>(s: S) -> Result<f64, Error> {
let result = Calc::parse(Rule::calc, s.as_ref()).map_err(|_| Error::Pest)?;
eval_expr(result)
}
}
fn eval_single_pair(pair: Pair<Rule>) -> Result<f64, Error> {
use Rule::*;
let result = match pair.as_rule() {
oct | hex | binary => {
let base = match pair.as_rule() {
hex => 16,
oct => 8,
binary => 2,
_ => unreachable!(),
};
u64::from_str_radix(&pair.as_str()[2..], base).map_err(|_| Error::NumberFormat)? as f64
},
float => pair.as_str().parse::<f64>().map_err(|_| Error::NumberFormat)?,
expr | num => eval_expr(pair.into_inner())?,
unary_expr => {
let mut p = pair.into_inner();
let op = p.next().ok_or(Error::ArgCount)?;
let arg = eval_expr(p)?;
match op.as_rule() {
log => arg.ln(),
sqrt => arg.sqrt(),
sgn => arg.signum(),
sin => arg.sin(),
cos => arg.cos(),
tan => arg.tan(),
asin => arg.asin(),
acos => arg.acos(),
atan => arg.atan(),
sinh => arg.sinh(),
cosh => arg.cosh(),
tanh => arg.tanh(),
asinh => arg.asinh(),
acosh => arg.acosh(),
atanh => arg.atanh(),
exp => arg.exp(),
abs => arg.abs(),
ceil => arg.ceil(),
floor => arg.floor(),
round => arg.round(),
_ => unreachable!(),
}
},
binary_expr => {
let mut p = pair.into_inner();
let op = p.next().ok_or(Error::ArgCount)?;
let arg1 = eval_single_pair(p.next().ok_or(Error::ArgCount)?)?;
let arg2 = eval_single_pair(p.next().ok_or(Error::ArgCount)?)?;
assert!(p.next().is_none());
match op.as_rule() {
min => arg1.min(arg2),
max => arg1.max(arg2),
atan2 => arg1.atan2(arg2),
_ => unreachable!(),
}
},
suffix_expr => {
let mut p = pair.into_inner();
let arg = eval_expr(p.next().ok_or(Error::ArgCount)?.into_inner())?;
let op = p.next().ok_or(Error::ArgCount)?;
assert!(p.next().is_none());
match op.as_rule() {
factorial => statrs::function::gamma::gamma(arg + 1.),
_ => unreachable!(),
}
},
_ => unreachable!(),
};
Ok(result)
}
fn eval_expr(p: Pairs<Rule>) -> Result<f64, Error> {
use Rule::*;
PRATT_PARSER
.map_primary(eval_single_pair)
.map_infix(|lhs, op, rhs| {
let lhs = lhs?;
let rhs = rhs?;
let result = match op.as_rule() {
add => lhs + rhs,
sub => lhs - rhs,
mul => lhs * rhs,
div => lhs / rhs,
pow => lhs.powf(rhs),
dice => {
let dice_count = lhs as usize;
let dice_faces = rhs as usize;
let mut rng = rand::thread_rng();
(0..dice_count)
.map(|_| rng.gen_range(1..(dice_faces + 1)))
.sum::<usize>() as f64
},
_ => unreachable!(),
};
Ok(result)
})
.map_postfix(|arg, _post| arg) // discard EOI
.parse(p)
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_calc_basics() {
assert_eq!(3., Calc::eval("1 + 2").unwrap());
assert_eq!(3.0f64.ln(), Calc::eval("log 3").unwrap());
assert!(6. - Calc::eval("3!").unwrap() < 0.0001);
assert_eq!(3., Calc::eval("max 3 2").unwrap());
}
#[test]
fn test_binary_unary() {
assert_eq!(3.0f64.ln(), Calc::eval("max log 3 log 2").unwrap());
}
#[test]
fn test_prefix_suffix() {
assert!(6. - Calc::eval("abs 3!").unwrap() < 0.0001);
}
}
|
