1#![allow(clippy::exhaustive_enums)]
2
3use core::mem;
4
5#[derive(Debug, Copy, Clone, PartialEq, Eq)]
6#[repr(u8)]
7#[derive(Default)]
8pub enum State {
9 Anywhere = 0,
10 CsiEntry = 1,
11 CsiIgnore = 2,
12 CsiIntermediate = 3,
13 CsiParam = 4,
14 DcsEntry = 5,
15 DcsIgnore = 6,
16 DcsIntermediate = 7,
17 DcsParam = 8,
18 DcsPassthrough = 9,
19 Escape = 10,
20 EscapeIntermediate = 11,
21 #[default]
22 Ground = 12,
23 OscString = 13,
24 SosPmApcString = 14,
25 Utf8 = 15,
26}
27
28impl TryFrom<u8> for State {
29 type Error = u8;
30
31 #[inline(always)]
32 fn try_from(raw: u8) -> Result<Self, Self::Error> {
33 STATES.get(raw as usize).ok_or(err:raw).copied()
34 }
35}
36
37const STATES: [State; 16] = [
38 State::Anywhere,
39 State::CsiEntry,
40 State::CsiIgnore,
41 State::CsiIntermediate,
42 State::CsiParam,
43 State::DcsEntry,
44 State::DcsIgnore,
45 State::DcsIntermediate,
46 State::DcsParam,
47 State::DcsPassthrough,
48 State::Escape,
49 State::EscapeIntermediate,
50 State::Ground,
51 State::OscString,
52 State::SosPmApcString,
53 State::Utf8,
54];
55
56#[derive(Debug, Clone, Copy, PartialEq, Eq)]
57#[repr(u8)]
58#[derive(Default)]
59pub enum Action {
60 #[default]
61 Nop = 0,
62 Clear = 1,
63 Collect = 2,
64 CsiDispatch = 3,
65 EscDispatch = 4,
66 Execute = 5,
67 Hook = 6,
68 Ignore = 7,
69 OscEnd = 8,
70 OscPut = 9,
71 OscStart = 10,
72 Param = 11,
73 Print = 12,
74 Put = 13,
75 Unhook = 14,
76 BeginUtf8 = 15,
77}
78
79impl TryFrom<u8> for Action {
80 type Error = u8;
81
82 #[inline(always)]
83 fn try_from(raw: u8) -> Result<Self, Self::Error> {
84 ACTIONS.get(raw as usize).ok_or(err:raw).copied()
85 }
86}
87
88const ACTIONS: [Action; 16] = [
89 Action::Nop,
90 Action::Clear,
91 Action::Collect,
92 Action::CsiDispatch,
93 Action::EscDispatch,
94 Action::Execute,
95 Action::Hook,
96 Action::Ignore,
97 Action::OscEnd,
98 Action::OscPut,
99 Action::OscStart,
100 Action::Param,
101 Action::Print,
102 Action::Put,
103 Action::Unhook,
104 Action::BeginUtf8,
105];
106
107/// Unpack a u8 into a State and Action
108///
109/// The implementation of this assumes that there are *precisely* 16 variants for both Action and
110/// State. Furthermore, it assumes that the enums are tag-only; that is, there is no data in any
111/// variant.
112///
113/// Bad things will happen if those invariants are violated.
114#[inline(always)]
115pub(crate) const fn unpack(delta: u8) -> (State, Action) {
116 unsafe {
117 (
118 // State is stored in bottom 4 bits
119 mem::transmute::<u8, State>(src:delta & 0x0f),
120 // Action is stored in top 4 bits
121 mem::transmute::<u8, Action>(src:delta >> 4),
122 )
123 }
124}
125
126#[inline(always)]
127#[cfg(test)]
128pub(crate) const fn pack(state: State, action: Action) -> u8 {
129 (action as u8) << 4 | state as u8
130}
131
132#[cfg(test)]
133mod tests {
134 use super::*;
135
136 #[test]
137 fn unpack_state_action() {
138 match unpack(0xee) {
139 (State::SosPmApcString, Action::Unhook) => (),
140 _ => panic!("unpack failed"),
141 }
142
143 match unpack(0x0f) {
144 (State::Utf8, Action::Nop) => (),
145 _ => panic!("unpack failed"),
146 }
147
148 match unpack(0xff) {
149 (State::Utf8, Action::BeginUtf8) => (),
150 _ => panic!("unpack failed"),
151 }
152 }
153
154 #[test]
155 fn pack_state_action() {
156 match unpack(0xee) {
157 (State::SosPmApcString, Action::Unhook) => (),
158 _ => panic!("unpack failed"),
159 }
160
161 match unpack(0x0f) {
162 (State::Utf8, Action::Nop) => (),
163 _ => panic!("unpack failed"),
164 }
165
166 match unpack(0xff) {
167 (State::Utf8, Action::BeginUtf8) => (),
168 _ => panic!("unpack failed"),
169 }
170 }
171}
172