mindset 0.1.1

A pure functional state machine library built on Stillwater's Effect system
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
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

//! Core State trait for state machine states.
//!
//! All state machine states must implement this trait, which provides
//! pure methods for inspecting state properties without side effects.

use serde::{Deserialize, Serialize};
use std::fmt::Debug;

/// Trait for state machine states.
///
/// All methods are pure - no side effects. States represent immutable
/// values that describe the current position in a state machine.
///
/// # Required Traits
///
/// - `Clone`: States must be cloneable for history tracking
/// - `PartialEq`: States must be comparable for transition logic
/// - `Debug`: States must be debuggable for diagnostics
/// - `Serialize` + `Deserialize`: States must be serializable for persistence
///
/// # Example
///
/// ```rust
/// use mindset::core::State;
/// use serde::{Deserialize, Serialize};
///
/// #[derive(Clone, PartialEq, Debug, Serialize, Deserialize)]
/// enum TaskState {
///     Pending,
///     Running,
///     Complete,
///     Failed,
/// }
///
/// impl State for TaskState {
///     fn name(&self) -> &str {
///         match self {
///             Self::Pending => "Pending",
///             Self::Running => "Running",
///             Self::Complete => "Complete",
///             Self::Failed => "Failed",
///         }
///     }
///
///     fn is_final(&self) -> bool {
///         matches!(self, Self::Complete | Self::Failed)
///     }
///
///     fn is_error(&self) -> bool {
///         matches!(self, Self::Failed)
///     }
/// }
/// ```
pub trait State:
    Clone + PartialEq + Debug + Serialize + for<'de> Deserialize<'de> + Send + Sync
{
    /// Get the state's name for display/logging.
    ///
    /// Returns a static string reference for zero-cost naming.
    fn name(&self) -> &str;

    /// Check if this is a final (terminal) state.
    ///
    /// Final states represent completion points in the state machine
    /// where no further transitions are expected.
    ///
    /// Default implementation returns `false`.
    fn is_final(&self) -> bool {
        false
    }

    /// Check if this is an error state.
    ///
    /// Error states represent failure conditions in the state machine.
    /// They are typically also final states, but this is not enforced.
    ///
    /// Default implementation returns `false`.
    fn is_error(&self) -> bool {
        false
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[derive(Clone, PartialEq, Debug, Serialize, Deserialize)]
    enum TestState {
        Initial,
        Processing,
        Complete,
        Failed,
    }

    impl State for TestState {
        fn name(&self) -> &str {
            match self {
                Self::Initial => "Initial",
                Self::Processing => "Processing",
                Self::Complete => "Complete",
                Self::Failed => "Failed",
            }
        }

        fn is_final(&self) -> bool {
            matches!(self, Self::Complete | Self::Failed)
        }

        fn is_error(&self) -> bool {
            matches!(self, Self::Failed)
        }
    }

    #[test]
    fn state_name_returns_correct_value() {
        assert_eq!(TestState::Initial.name(), "Initial");
        assert_eq!(TestState::Processing.name(), "Processing");
        assert_eq!(TestState::Complete.name(), "Complete");
        assert_eq!(TestState::Failed.name(), "Failed");
    }

    #[test]
    fn is_final_identifies_terminal_states() {
        assert!(!TestState::Initial.is_final());
        assert!(!TestState::Processing.is_final());
        assert!(TestState::Complete.is_final());
        assert!(TestState::Failed.is_final());
    }

    #[test]
    fn is_error_identifies_error_states() {
        assert!(!TestState::Initial.is_error());
        assert!(!TestState::Processing.is_error());
        assert!(!TestState::Complete.is_error());
        assert!(TestState::Failed.is_error());
    }

    #[test]
    fn state_trait_methods_work() {
        let state = TestState::Initial;
        assert_eq!(state.name(), "Initial");
        assert!(!state.is_final());
        assert!(!state.is_error());

        let complete = TestState::Complete;
        assert!(complete.is_final());
        assert!(!complete.is_error());

        let failed = TestState::Failed;
        assert!(failed.is_final());
        assert!(failed.is_error());
    }

    #[test]
    fn state_serializes_correctly() {
        let state = TestState::Initial;
        let json = serde_json::to_string(&state).unwrap();
        let deserialized: TestState = serde_json::from_str(&json).unwrap();
        assert_eq!(state, deserialized);
    }

    #[test]
    fn state_is_cloneable() {
        let state = TestState::Processing;
        let cloned = state.clone();
        assert_eq!(state, cloned);
    }

    #[test]
    fn state_is_comparable() {
        let state1 = TestState::Processing;
        let state2 = TestState::Processing;
        let state3 = TestState::Complete;

        assert_eq!(state1, state2);
        assert_ne!(state1, state3);
    }
}