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//! FIXME: write short doc here
use std::sync::Arc;
use hir_expand::name::Name;
use ra_arena::{impl_arena_id, Arena, RawId};
use rustc_hash::FxHashMap;
use crate::{
body::Body,
db::DefDatabase2,
expr::{Expr, ExprId, Pat, PatId, Statement},
DefWithBodyId,
};
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct ScopeId(RawId);
impl_arena_id!(ScopeId);
#[derive(Debug, PartialEq, Eq)]
pub struct ExprScopes {
scopes: Arena<ScopeId, ScopeData>,
scope_by_expr: FxHashMap<ExprId, ScopeId>,
}
#[derive(Debug, PartialEq, Eq)]
pub struct ScopeEntry {
name: Name,
pat: PatId,
}
impl ScopeEntry {
pub fn name(&self) -> &Name {
&self.name
}
pub fn pat(&self) -> PatId {
self.pat
}
}
#[derive(Debug, PartialEq, Eq)]
pub struct ScopeData {
parent: Option<ScopeId>,
entries: Vec<ScopeEntry>,
}
impl ExprScopes {
pub(crate) fn expr_scopes_query(db: &impl DefDatabase2, def: DefWithBodyId) -> Arc<ExprScopes> {
let body = db.body(def);
Arc::new(ExprScopes::new(&*body))
}
fn new(body: &Body) -> ExprScopes {
let mut scopes =
ExprScopes { scopes: Arena::default(), scope_by_expr: FxHashMap::default() };
let root = scopes.root_scope();
scopes.add_params_bindings(body, root, body.params());
compute_expr_scopes(body.body_expr(), body, &mut scopes, root);
scopes
}
pub fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
&self.scopes[scope].entries
}
pub fn scope_chain(&self, scope: Option<ScopeId>) -> impl Iterator<Item = ScopeId> + '_ {
std::iter::successors(scope, move |&scope| self.scopes[scope].parent)
}
pub fn scope_for(&self, expr: ExprId) -> Option<ScopeId> {
self.scope_by_expr.get(&expr).copied()
}
pub fn scope_by_expr(&self) -> &FxHashMap<ExprId, ScopeId> {
&self.scope_by_expr
}
fn root_scope(&mut self) -> ScopeId {
self.scopes.alloc(ScopeData { parent: None, entries: vec![] })
}
fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
self.scopes.alloc(ScopeData { parent: Some(parent), entries: vec![] })
}
fn add_bindings(&mut self, body: &Body, scope: ScopeId, pat: PatId) {
match &body[pat] {
Pat::Bind { name, .. } => {
// bind can have a sub pattern, but it's actually not allowed
// to bind to things in there
let entry = ScopeEntry { name: name.clone(), pat };
self.scopes[scope].entries.push(entry)
}
p => p.walk_child_pats(|pat| self.add_bindings(body, scope, pat)),
}
}
fn add_params_bindings(&mut self, body: &Body, scope: ScopeId, params: &[PatId]) {
params.iter().for_each(|pat| self.add_bindings(body, scope, *pat));
}
fn set_scope(&mut self, node: ExprId, scope: ScopeId) {
self.scope_by_expr.insert(node, scope);
}
}
fn compute_block_scopes(
statements: &[Statement],
tail: Option<ExprId>,
body: &Body,
scopes: &mut ExprScopes,
mut scope: ScopeId,
) {
for stmt in statements {
match stmt {
Statement::Let { pat, initializer, .. } => {
if let Some(expr) = initializer {
scopes.set_scope(*expr, scope);
compute_expr_scopes(*expr, body, scopes, scope);
}
scope = scopes.new_scope(scope);
scopes.add_bindings(body, scope, *pat);
}
Statement::Expr(expr) => {
scopes.set_scope(*expr, scope);
compute_expr_scopes(*expr, body, scopes, scope);
}
}
}
if let Some(expr) = tail {
compute_expr_scopes(expr, body, scopes, scope);
}
}
fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope: ScopeId) {
scopes.set_scope(expr, scope);
match &body[expr] {
Expr::Block { statements, tail } => {
compute_block_scopes(&statements, *tail, body, scopes, scope);
}
Expr::For { iterable, pat, body: body_expr } => {
compute_expr_scopes(*iterable, body, scopes, scope);
let scope = scopes.new_scope(scope);
scopes.add_bindings(body, scope, *pat);
compute_expr_scopes(*body_expr, body, scopes, scope);
}
Expr::Lambda { args, body: body_expr, .. } => {
let scope = scopes.new_scope(scope);
scopes.add_params_bindings(body, scope, &args);
compute_expr_scopes(*body_expr, body, scopes, scope);
}
Expr::Match { expr, arms } => {
compute_expr_scopes(*expr, body, scopes, scope);
for arm in arms {
let scope = scopes.new_scope(scope);
for pat in &arm.pats {
scopes.add_bindings(body, scope, *pat);
}
scopes.set_scope(arm.expr, scope);
compute_expr_scopes(arm.expr, body, scopes, scope);
}
}
e => e.walk_child_exprs(|e| compute_expr_scopes(e, body, scopes, scope)),
};
}
|
