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
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
use std::{
mem,
rc::Rc,
cell::RefCell
};
use crate::common::data::Data;
use crate::vm::{
tag::Tagged,
slot::{Slot, Suspend},
};
#[derive(Debug)]
pub struct Stack {
pub frames: Vec<usize>,
pub stack: Vec<Tagged>
}
impl Stack {
pub fn init() -> Stack {
Stack {
frames: vec![0],
stack: vec![Tagged::frame()],
}
}
#[inline]
fn frame_index(&self) -> usize {
*self.frames.last().unwrap()
}
#[inline]
fn pop(&mut self) -> Tagged {
self.stack.pop()
.expect("VM tried to pop empty stack, stack should never be empty")
}
#[inline]
fn swap(&mut self, index: usize, tagged: Tagged) -> Tagged {
mem::replace(&mut self.stack[index], tagged)
}
#[inline]
pub fn push_data(&mut self, data: Data) {
self.stack.push(Tagged::new(Slot::Data(data)))
}
#[inline]
pub fn push_tagged(&mut self, tagged: Tagged) {
self.stack.push(tagged)
}
#[inline]
pub fn pop_data(&mut self) -> Data {
let value = self.stack.pop()
.expect("VM tried to pop empty stack, stack should never be empty");
match value.slot().data() {
Data::Heaped(h) => h.borrow().clone(),
d => d,
}
}
#[inline]
pub fn pop_frame(&mut self) -> Suspend {
if let Slot::Frame = self.pop().slot() {} else {
unreachable!("Expected frame on top of stack");
}
self.frames.pop();
let old_slot = self.swap(self.frame_index(), Tagged::frame()).slot();
if let Slot::Suspend(s) = old_slot {
return s;
} else {
unreachable!("Expected frame on top of stack");
}
}
#[inline]
pub fn push_frame(&mut self, suspend: Suspend) {
let frame_index = self.frame_index();
self.stack[frame_index] = Tagged::new(Slot::Suspend(suspend));
self.frames.push(self.stack.len());
self.stack.push(Tagged::frame());
}
#[inline]
pub fn push_not_init(&mut self) {
self.stack.push(Tagged::not_init());
}
#[inline]
pub fn declare(&mut self, decls: usize) {
for _ in 0..decls { self.push_not_init(); }
}
#[inline]
pub fn heapify(&mut self, index: usize) {
let local_index = self.frame_index() + index + 1;
let data = self.swap(local_index, Tagged::not_init()).slot().data();
let heaped = Slot::Data(Data::Heaped(Rc::new(RefCell::new(data))));
mem::drop(mem::replace(&mut self.stack[local_index], Tagged::new(heaped)));
}
#[inline]
pub fn unwind_frame(&mut self) -> bool {
self.stack.truncate(self.frame_index() + 1);
return self.frames.len() > 1;
}
pub fn local_slot(&mut self, index: usize) -> Slot {
let local_index = self.frame_index() + index + 1;
let slot = self.swap(local_index, Tagged::not_init()).slot();
let copy = slot.clone();
mem::drop(self.swap(local_index, Tagged::new(slot)));
return copy;
}
pub fn local_data(&mut self, index: usize) -> Data {
let local_index = self.frame_index() + index + 1;
let data = self.swap(local_index, Tagged::not_init()).slot().data();
let copy = data.clone();
mem::drop(self.swap(local_index, Tagged::new(Slot::Data(data))));
return copy;
}
pub fn set_local(&mut self, index: usize) {
let local_index = self.frame_index() + index + 1;
if (self.stack.len() - 1) == local_index {
return;
} else if (self.stack.len() - 1) < local_index {
unreachable!("Can not set local that is not yet on stack");
} else {
let slot = self.swap(local_index, Tagged::not_init()).slot();
let tagged = match slot {
Slot::Frame => unreachable!("Expected data, found frame"),
Slot::Data(Data::Heaped(ref cell)) => {
mem::drop(cell.replace(self.pop_data()));
Tagged::new(slot)
}
_ => self.stack.pop().unwrap(),
};
mem::drop(self.swap(local_index, tagged))
}
}
}