rust_servo/
engine.rs

1use std::{fmt::Display, time::Instant};
2
3use num_traits::Num;
4
5use crate::servo::{ControlValue, Servo, ServoInput};
6
7pub struct Engine<T: Servo> {
8    pub servo: T,
9    pub last_read_timestamp: Option<Instant>,
10    pub num_reads: u64,
11}
12
13impl<T: Servo + Display> Display for Engine<T> {
14    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
15        write!(
16            f,
17            "Engine runner [{}] has {} total read(s)",
18            self.servo, self.num_reads
19        )
20    }
21}
22
23impl<T: Servo> Engine<T> {
24    pub fn new(servo: T) -> Self {
25        Self {
26            servo,
27            last_read_timestamp: None,
28            num_reads: 0,
29        }
30    }
31
32    pub fn reset(&mut self) {
33        self.last_read_timestamp = None;
34        self.num_reads = 0;
35    }
36
37    pub fn next<N: Num>(&mut self, process_value: N) -> ControlValue {
38        let servo_input = ServoInput {
39            process_value,
40            delta_t: None,
41        };
42        let servo_result = self.servo.read(&servo_input);
43
44        self.num_reads += 1;
45        servo_result.unwrap()
46    }
47}
48
49#[cfg(test)]
50mod tests {
51    use std::fmt::Display;
52
53    use super::Engine;
54    use crate::servo::{ControlValue, Servo};
55
56    struct TestController {}
57
58    impl TestController {
59        fn new() -> Self {
60            Self {}
61        }
62    }
63
64    impl Servo for TestController {
65        fn read<T: num_traits::Num>(
66            &mut self,
67            _servo_input: &crate::servo::ServoInput<T>,
68        ) -> Result<crate::servo::ControlValue, crate::servo::ReadInputError> {
69            Ok(ControlValue { value: 0.0 })
70        }
71    }
72
73    impl Display for TestController {
74        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
75            write!(f, "")
76        }
77    }
78
79    #[test]
80    fn should_instantiate_engine_correctly() {
81        let servo = TestController::new();
82        let engine = Engine::new(servo);
83        assert!(engine.last_read_timestamp.is_none());
84        assert_eq!(engine.num_reads, 0);
85    }
86
87    #[test]
88    fn should_invoke_servo_engine_correctly() {
89        let servo = TestController::new();
90        let mut engine = Engine::new(servo);
91        engine.next(1);
92        engine.next(2);
93        engine.next(3);
94        assert_eq!(engine.num_reads, 3);
95    }
96
97    #[test]
98    fn should_reset_engine_correctly() {
99        let servo = TestController::new();
100        let mut engine = Engine::new(servo);
101        for _ in 0..5 {
102            engine.next(0);
103        }
104        assert_eq!(engine.num_reads, 5);
105        engine.reset();
106        assert_eq!(engine.num_reads, 0);
107    }
108}
rust_servo/engine.rs

rust_servo/
engine.rs
