rune/compile/ir/
scopes.rs

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1use crate::alloc::prelude::*;
2use crate::alloc::{self, HashMap};
3use crate::ast::Spanned;
4use crate::compile::{self, ErrorKind};
5use crate::hir;
6use crate::runtime::Value;
7
8/// Error indicating that a local variable is missing.
9pub(crate) struct MissingLocal(pub(crate) Box<str>);
10
11/// A hierarchy of constant scopes.
12pub(crate) struct Scopes {
13    scopes: Vec<Scope>,
14}
15
16impl Scopes {
17    /// Construct a new empty scope.
18    pub(crate) fn new() -> alloc::Result<Self> {
19        Ok(Self {
20            scopes: try_vec![Scope::default()],
21        })
22    }
23
24    /// Clear the current scope.
25    pub(crate) fn clear_current(&mut self) -> Result<(), &'static str> {
26        let last = self
27            .scopes
28            .last_mut()
29            .ok_or("expected at least one scope")?;
30
31        last.locals.clear();
32        Ok(())
33    }
34
35    /// Declare a value in the scope.
36    pub(crate) fn decl(&mut self, name: hir::Variable, value: Value) -> Result<(), ErrorKind> {
37        let last = self
38            .last_mut()
39            .ok_or_else(|| ErrorKind::msg("Expected at least one scope"))?;
40        last.locals.try_insert(name, value)?;
41        Ok(())
42    }
43
44    /// Try to get the value out from the scopes.
45    pub(crate) fn try_get(&self, name: &hir::Variable) -> Option<&Value> {
46        for scope in self.scopes.iter().rev() {
47            if let Some(current) = scope.locals.get(name) {
48                return Some(current);
49            }
50
51            // don't look past isolate scopes.
52            if let ScopeKind::Isolate = scope.kind {
53                break;
54            }
55        }
56
57        None
58    }
59
60    /// Get the given variable.
61    pub(crate) fn get_name(
62        &self,
63        name: &hir::Variable,
64        span: &dyn Spanned,
65    ) -> compile::Result<&Value> {
66        for scope in self.scopes.iter().rev() {
67            if let Some(current) = scope.locals.get(name) {
68                return Ok(current);
69            }
70
71            // don't look past isolate scopes.
72            if let ScopeKind::Isolate = scope.kind {
73                break;
74            }
75        }
76
77        Err(compile::Error::new(
78            span,
79            MissingLocal(name.try_to_string()?.try_into_boxed_str()?),
80        ))
81    }
82
83    /// Get the given variable as mutable.
84    pub(crate) fn get_name_mut(
85        &mut self,
86        name: &hir::Variable,
87        span: &dyn Spanned,
88    ) -> compile::Result<&mut Value> {
89        for scope in self.scopes.iter_mut().rev() {
90            if let Some(current) = scope.locals.get_mut(name) {
91                return Ok(current);
92            }
93
94            // don't look past isolate scopes.
95            if let ScopeKind::Isolate = scope.kind {
96                break;
97            }
98        }
99
100        Err(compile::Error::new(
101            span,
102            MissingLocal(name.try_to_string()?.try_into_boxed_str()?),
103        ))
104    }
105
106    /// Push a scope and return the guard associated with the scope.
107    pub(crate) fn push(&mut self) -> alloc::Result<ScopeGuard> {
108        let length = self.scopes.len();
109        self.scopes.try_push(Scope::default())?;
110        Ok(ScopeGuard { length })
111    }
112
113    /// Push an isolate scope and return the guard associated with the scope.
114    pub(crate) fn isolate(&mut self) -> alloc::Result<ScopeGuard> {
115        let length = self.scopes.len();
116        let scope = Scope {
117            kind: ScopeKind::Isolate,
118            ..Default::default()
119        };
120        self.scopes.try_push(scope)?;
121        Ok(ScopeGuard { length })
122    }
123
124    pub(crate) fn pop(&mut self, guard: ScopeGuard) -> Result<(), &'static str> {
125        if self.scopes.pop().is_none() {
126            return Err("expected at least one scope to pop");
127        }
128
129        if self.scopes.len() != guard.length {
130            return Err("scope length mismatch");
131        }
132
133        Ok(())
134    }
135
136    /// Get the last scope mutably.
137    pub(crate) fn last_mut(&mut self) -> Option<&mut Scope> {
138        self.scopes.last_mut()
139    }
140}
141
142#[repr(transparent)]
143pub(crate) struct ScopeGuard {
144    length: usize,
145}
146
147#[derive(Debug, Clone, Copy)]
148enum ScopeKind {
149    None,
150    Isolate,
151}
152
153pub(crate) struct Scope {
154    kind: ScopeKind,
155    /// Locals in the current scope.
156    locals: HashMap<hir::Variable, Value>,
157}
158
159impl Default for Scope {
160    fn default() -> Self {
161        Self {
162            kind: ScopeKind::None,
163            locals: HashMap::new(),
164        }
165    }
166}
rune/compile/ir/scopes.rs

rune/compile/ir/
scopes.rs
