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scope_system.rs
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scope_system.rs
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use super::{
lexical_referent::LexicalReferent,
scope_walker::{ScopeId, ScopeWalker},
};
use crate::{
front::name_resolution::{resolve_builtin_ty, NameReferents},
parse::ANameId,
utils::MapStack,
};
use std::collections::HashMap;
/// スコープの種類 (名前を探すとき)
#[derive(Copy, Clone, Eq, PartialEq, Hash)]
pub(crate) enum FindKind {
Ty,
Value,
}
/// スコープの種類 (名前を導入するとき)
#[derive(Copy, Clone)]
pub(crate) enum ImportKind {
Ty,
Value,
Both,
}
/// スコープ解決の枠組みを提供するもの。
pub(crate) struct ScopeSystem {
scope_walker: ScopeWalker,
ty_env: MapStack<ANameId>,
value_env: MapStack<ANameId>,
defer_map: HashMap<(String, FindKind), Vec<(ANameId, ScopeId)>>,
pub(crate) name_referents: NameReferents,
}
impl ScopeSystem {
pub(crate) fn new() -> Self {
let mut it = Self {
scope_walker: ScopeWalker::new(),
ty_env: MapStack::new(),
value_env: MapStack::new(),
defer_map: HashMap::new(),
name_referents: NameReferents::new(),
};
it.ty_env.push();
it.value_env.push();
it
}
pub(crate) fn enter_scope(&mut self) {
// FIXME: hint をつける
self.scope_walker.enter("");
self.ty_env.push();
self.value_env.push();
log::trace!("enter_scope {}", self.scope_walker.breadcrumbs());
}
pub(crate) fn leave_scope(&mut self) {
log::trace!("leave_scope {}", self.scope_walker.breadcrumbs());
self.scope_walker.leave();
self.ty_env.pop();
self.value_env.pop();
}
fn bind_name(
&mut self,
hint: &str,
name_id: ANameId,
#[allow(unused)] text_opt: Option<&str>,
referent: LexicalReferent,
expected: Option<LexicalReferent>,
) {
log::trace!(
"bind_name({}) {}#{} ({:?} -> {:?})",
hint,
text_opt.unwrap_or(""),
name_id.to_index(),
expected,
referent
);
let old = self.name_referents.insert(name_id, referent);
assert_eq!(old, expected);
}
fn import_name(&mut self, name_id: ANameId, kind: ImportKind, text: &str) {
match kind {
ImportKind::Ty => {
log::trace!("import ty {} -> {}", text, name_id.to_index());
self.ty_env.insert(text.to_string(), name_id);
}
ImportKind::Value => {
log::trace!("import value {} -> {}", text, name_id.to_index());
self.value_env.insert(text.to_string(), name_id);
}
ImportKind::Both => {
log::trace!("import ty/value {} -> {}", text, name_id.to_index());
self.value_env.insert(text.to_string(), name_id);
self.ty_env.insert(text.to_string(), name_id);
}
}
}
fn find_name(&mut self, kind: FindKind, text: &str) -> Option<LexicalReferent> {
match kind {
FindKind::Ty => self
.ty_env
.get(text)
.map(|&name| LexicalReferent::Name(name))
.or_else(|| resolve_builtin_ty(text).map(|ty| LexicalReferent::BuiltInTy(ty))),
FindKind::Value => self
.value_env
.get(text)
.map(|&name| LexicalReferent::Name(name)),
}
}
/// 前方参照を許さない名前が追加される。
pub(crate) fn on_name_def_stacked(&mut self, name: ANameId, kind: ImportKind, text: &str) {
self.import_name(name, kind, text);
self.bind_name("stack", name, Some(text), LexicalReferent::Def, None)
}
/// 前方参照を許す値の名前を追加する。
pub(crate) fn on_name_def_hoisted(&mut self, name: ANameId, kind: ImportKind, text: &str) {
let referent = LexicalReferent::Name(name);
let mut aux = |kind: FindKind| {
// この定義がみえる位置にある前方参照を解決する。
let key = (text.to_string(), kind);
let mut vec = match self.defer_map.remove(&key) {
Some(it) => it,
None => return,
};
vec.retain(|&(name, use_scope)| {
let can_see = self.scope_walker.is_descendant(use_scope);
if !can_see {
// use_scope からこの定義が見えない。(`{ f(); } { fn f() {} }` のようなケース)
return true;
}
let expected = Some(LexicalReferent::Unresolved);
self.bind_name("hoist", name, None, referent, expected);
false
});
if !vec.is_empty() {
self.defer_map.insert(key, vec);
}
};
match kind {
ImportKind::Ty => aux(FindKind::Ty),
ImportKind::Value => aux(FindKind::Value),
ImportKind::Both => {
aux(FindKind::Ty);
aux(FindKind::Value);
}
}
self.import_name(name, kind, text);
self.bind_name("hoist", name, Some(text), LexicalReferent::Def, None);
}
pub(crate) fn on_name_use(&mut self, name: ANameId, kind: FindKind, text: &str) {
let referent = match self.find_name(kind, text) {
Some(it) => it,
None => {
self.defer_map
.entry((text.to_string(), kind))
.or_insert(vec![])
.push((name, self.scope_walker.current()));
LexicalReferent::Unresolved
}
};
self.bind_name("use", name, Some(text), referent, None);
}
}