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

use eyre::{eyre, Result};
use serde::{Deserialize, Serialize};
use std::collections::BTreeMap;

mod fasteval;
#[cfg(feature = "savage")]
mod savage;

pub type VarMap = BTreeMap<String, f64>;

#[derive(Debug, Clone, Copy, Deserialize, Serialize)]
#[serde(rename_all = "snake_case")]
pub enum Interpreter {
    Inherit,
    Fasteval,
    #[cfg(feature = "savage")]
    Savage,
}

pub enum Evaluator {
    Fasteval(fasteval::Evaluator),
    #[cfg(feature = "savage")]
    Savage(savage::Evaluator),
}

impl Default for Interpreter {
    fn default() -> Self {
        Interpreter::Inherit
    }
}

impl Interpreter {
    pub fn parse(&self, expr: &str) -> Result<Evaluator> {
        match self {
            Interpreter::Inherit => Err(eyre!("Cannot parse with interpreter=`Inherit`.")),
            Interpreter::Fasteval => Ok(Evaluator::Fasteval(fasteval::Evaluator::new(expr)?)),
            #[cfg(feature = "savage")]
            Interpreter::Savage => Ok(Evaluator::Savage(savage::Evaluator::new(expr)?)),
        }
    }

    pub fn or(&self, other: &Self) -> Self {
        if let Self::Inherit = self {
            *other
        } else {
            *self
        }
    }
}

impl Evaluator {
    pub fn eval(&self, vars: &mut VarMap) -> Result<f64> {
        match self {
            Evaluator::Fasteval(evaler) => evaler.eval(vars),
            #[cfg(feature = "savage")]
            Evaluator::Savage(evaler) => evaler.eval(vars),
        }
    }
}