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
|
use std::collections::BTreeMap;
use std::fmt::{self, Debug, Formatter};
use std::hash::{Hash, Hasher};
use std::iter;
use std::sync::{Arc, RwLock};
use super::{Args, Func, Node, Value};
use crate::diag::TypResult;
use crate::util::EcoString;
use crate::Context;
/// A slot where a variable is stored.
pub type Slot = Arc<RwLock<Value>>;
/// A stack of scopes.
#[derive(Debug, Default, Clone)]
pub struct Scopes<'a> {
/// The active scope.
pub top: Scope,
/// The stack of lower scopes.
pub scopes: Vec<Scope>,
/// The base scope.
pub base: Option<&'a Scope>,
}
impl<'a> Scopes<'a> {
/// Create a new, empty hierarchy of scopes.
pub fn new(base: Option<&'a Scope>) -> Self {
Self { top: Scope::new(), scopes: vec![], base }
}
/// Enter a new scope.
pub fn enter(&mut self) {
self.scopes.push(std::mem::take(&mut self.top));
}
/// Exit the topmost scope.
///
/// This panics if no scope was entered.
pub fn exit(&mut self) {
self.top = self.scopes.pop().expect("no pushed scope");
}
/// Look up the slot of a variable.
pub fn get(&self, var: &str) -> Option<&Slot> {
iter::once(&self.top)
.chain(self.scopes.iter().rev())
.chain(self.base.into_iter())
.find_map(|scope| scope.get(var))
}
}
/// A map from variable names to variable slots.
#[derive(Default, Clone)]
pub struct Scope {
/// The mapping from names to slots.
values: BTreeMap<EcoString, Slot>,
}
impl Scope {
/// Create a new empty scope.
pub fn new() -> Self {
Self::default()
}
/// Define a constant variable with a value.
pub fn def_const(&mut self, var: impl Into<EcoString>, value: impl Into<Value>) {
let cell = RwLock::new(value.into());
// Make it impossible to write to this value again.
std::mem::forget(cell.read());
self.values.insert(var.into(), Arc::new(cell));
}
/// Define a mutable variable with a value.
pub fn def_mut(&mut self, var: impl Into<EcoString>, value: impl Into<Value>) {
self.values.insert(var.into(), Arc::new(RwLock::new(value.into())));
}
/// Define a variable with a slot.
pub fn def_slot(&mut self, var: impl Into<EcoString>, slot: Slot) {
self.values.insert(var.into(), slot);
}
/// Define a function through a native rust function.
pub fn def_fn(
&mut self,
name: &'static str,
func: fn(&mut Context, &mut Args) -> TypResult<Value>,
) {
self.def_const(name, Func::from_fn(name, func));
}
/// Define a function through a native rust node.
pub fn def_node<T: Node>(&mut self, name: &'static str) {
self.def_const(name, Func::from_node::<T>(name));
}
/// Look up the value of a variable.
pub fn get(&self, var: &str) -> Option<&Slot> {
self.values.get(var)
}
/// Iterate over all definitions.
pub fn iter(&self) -> impl Iterator<Item = (&str, &Slot)> {
self.values.iter().map(|(k, v)| (k.as_str(), v))
}
}
impl Hash for Scope {
fn hash<H: Hasher>(&self, state: &mut H) {
self.values.len().hash(state);
for (name, value) in self.values.iter() {
name.hash(state);
value.read().unwrap().hash(state);
}
}
}
impl Debug for Scope {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.write_str("Scope ")?;
f.debug_map()
.entries(self.values.iter().map(|(k, v)| (k, v.read().unwrap())))
.finish()
}
}
|
