sad_machine 1.0.0

Sad Machine - a static State Machine macro
Documentation 
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

use proc_macro2::TokenStream;
use quote::{quote, ToTokens};
use std::vec::IntoIter;
use syn::{
    parse::{Parse, ParseStream, Result},
    Ident,
};

#[derive(Debug, PartialEq)]
pub(crate) struct States(pub Vec<State>);

impl ToTokens for States {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        let states = &self.0;

        tokens.extend(quote! {
            #(#states),*
        })
    }
}

#[allow(single_use_lifetimes)] // TODO: how to fix this?
impl<'a> IntoIterator for &'a States {
    type IntoIter = IntoIter<State>;
    type Item = State;

    fn into_iter(self) -> Self::IntoIter {
        self.0.clone().into_iter()
    }
}

#[derive(Clone, Debug, PartialEq)]
pub(crate) struct State {
    pub name: Ident,
}

impl Parse for State {
    /// example state tokens:
    ///
    /// ```text
    /// Locked
    /// ```
    fn parse(input: ParseStream<'_>) -> Result<Self> {
        let name = input.parse()?;

        Ok(State { name })
    }
}

impl ToTokens for State {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        let name = &self.name;
        let struct_name = Ident::new(&format!("{}State", self.name), self.name.span());

        tokens.extend(quote! {
            #name(#struct_name)
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use proc_macro2::TokenStream;
    use syn::{self, parse_quote};

    #[test]
    fn test_state_parse() {
        let left: State = syn::parse2(quote! { Unlocked }).unwrap();
        let right = State {
            name: parse_quote! { Unlocked },
        };

        assert_eq!(left, right);
    }

    #[test]
    fn test_state_to_tokens() {
        let state = State {
            name: parse_quote! { Unlocked },
        };

        let left = quote! {
            Unlocked(UnlockedState)
        };

        let mut right = TokenStream::new();
        state.to_tokens(&mut right);

        assert_eq!(format!("{}", left), format!("{}", right))
    }

    #[test]
    fn test_states_to_tokens() {
        let states = States(vec![
            State {
                name: parse_quote! { Locked },
            },
            State {
                name: parse_quote! { Unlocked },
            },
        ]);

        let left = quote! {
            Locked(LockedState),
            Unlocked(UnlockedState)
        };

        let mut right = TokenStream::new();
        states.to_tokens(&mut right);

        assert_eq!(format!("{}", left), format!("{}", right))
    }
}