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|
//! Name resolution algorithm. The end result of the algorithm is an `ItemMap`:
//! a map which maps each module to its scope: the set of items visible in the
//! module. That is, we only resolve imports here, name resolution of item
//! bodies will be done in a separate step.
//!
//! Like Rustc, we use an interactive per-crate algorithm: we start with scopes
//! containing only directly defined items, and then iteratively resolve
//! imports.
//!
//! To make this work nicely in the IDE scenario, we place `InputModuleItems`
//! in between raw syntax and name resolution. `InputModuleItems` are computed
//! using only the module's syntax, and it is all directly defined items plus
//! imports. The plan is to make `InputModuleItems` independent of local
//! modifications (that is, typing inside a function should not change IMIs),
//! so that the results of name resolution can be preserved unless the module
//! structure itself is modified.
pub(crate) mod lower;
use std::{time, sync::Arc};
use ra_db::CrateId;
use ra_arena::map::ArenaMap;
use test_utils::tested_by;
use rustc_hash::{FxHashMap, FxHashSet};
use crate::{
Module, ModuleDef,
Path, PathKind,
HirDatabase, Crate,
Name,
module_tree::{ModuleId, ModuleTree},
nameres::lower::{ImportId, LoweredModule, ImportData},
};
/// `ItemMap` is the result of name resolution. It contains, for each
/// module, the set of visible items.
#[derive(Default, Debug, PartialEq, Eq)]
pub struct ItemMap {
per_module: ArenaMap<ModuleId, ModuleScope>,
}
impl std::ops::Index<ModuleId> for ItemMap {
type Output = ModuleScope;
fn index(&self, id: ModuleId) -> &ModuleScope {
&self.per_module[id]
}
}
#[derive(Debug, Default, PartialEq, Eq, Clone)]
pub struct ModuleScope {
items: FxHashMap<Name, Resolution>,
}
impl ModuleScope {
pub fn entries<'a>(&'a self) -> impl Iterator<Item = (&'a Name, &'a Resolution)> + 'a {
self.items.iter()
}
pub fn get(&self, name: &Name) -> Option<&Resolution> {
self.items.get(name)
}
}
/// `Resolution` is basically `DefId` atm, but it should account for stuff like
/// multiple namespaces, ambiguity and errors.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Resolution {
/// None for unresolved
pub def: PerNs<ModuleDef>,
/// ident by which this is imported into local scope.
pub import: Option<ImportId>,
}
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum Namespace {
Types,
Values,
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct PerNs<T> {
pub types: Option<T>,
pub values: Option<T>,
}
impl<T> PerNs<T> {
pub fn none() -> PerNs<T> {
PerNs {
types: None,
values: None,
}
}
pub fn values(t: T) -> PerNs<T> {
PerNs {
types: None,
values: Some(t),
}
}
pub fn types(t: T) -> PerNs<T> {
PerNs {
types: Some(t),
values: None,
}
}
pub fn both(types: T, values: T) -> PerNs<T> {
PerNs {
types: Some(types),
values: Some(values),
}
}
pub fn is_none(&self) -> bool {
self.types.is_none() && self.values.is_none()
}
pub fn take(self, namespace: Namespace) -> Option<T> {
match namespace {
Namespace::Types => self.types,
Namespace::Values => self.values,
}
}
pub fn take_types(self) -> Option<T> {
self.take(Namespace::Types)
}
pub fn take_values(self) -> Option<T> {
self.take(Namespace::Values)
}
pub fn get(&self, namespace: Namespace) -> Option<&T> {
self.as_ref().take(namespace)
}
pub fn as_ref(&self) -> PerNs<&T> {
PerNs {
types: self.types.as_ref(),
values: self.values.as_ref(),
}
}
pub fn and_then<U>(self, f: impl Fn(T) -> Option<U>) -> PerNs<U> {
PerNs {
types: self.types.and_then(&f),
values: self.values.and_then(&f),
}
}
pub fn map<U>(self, f: impl Fn(T) -> U) -> PerNs<U> {
PerNs {
types: self.types.map(&f),
values: self.values.map(&f),
}
}
}
struct Resolver<'a, DB> {
db: &'a DB,
input: &'a FxHashMap<ModuleId, Arc<LoweredModule>>,
krate: CrateId,
module_tree: Arc<ModuleTree>,
processed_imports: FxHashSet<(ModuleId, ImportId)>,
result: ItemMap,
}
impl<'a, DB> Resolver<'a, DB>
where
DB: HirDatabase,
{
fn new(
db: &'a DB,
input: &'a FxHashMap<ModuleId, Arc<LoweredModule>>,
krate: CrateId,
) -> Resolver<'a, DB> {
let module_tree = db.module_tree(krate);
Resolver {
db,
input,
krate,
module_tree,
processed_imports: FxHashSet::default(),
result: ItemMap::default(),
}
}
pub(crate) fn resolve(mut self) -> ItemMap {
for (&module_id, items) in self.input.iter() {
self.populate_module(module_id, Arc::clone(items));
}
let mut iter = 0;
loop {
iter += 1;
if iter > 1000 {
panic!("failed to reach fixedpoint after 1000 iters")
}
let processed_imports_count = self.processed_imports.len();
for &module_id in self.input.keys() {
self.db.check_canceled();
self.resolve_imports(module_id);
}
if processed_imports_count == self.processed_imports.len() {
// no new imports resolved
break;
}
}
self.result
}
fn populate_module(&mut self, module_id: ModuleId, input: Arc<LoweredModule>) {
let mut module_items = ModuleScope::default();
// Populate extern crates prelude
{
let root_id = module_id.crate_root(&self.module_tree);
let file_id = root_id.file_id(&self.module_tree);
let crate_graph = self.db.crate_graph();
if let Some(crate_id) = crate_graph.crate_id_for_crate_root(file_id.as_original_file())
{
let krate = Crate::new(crate_id);
for dep in krate.dependencies(self.db) {
if let Some(module) = dep.krate.root_module(self.db) {
let def = module.into();
self.add_module_item(
&mut module_items,
dep.name.clone(),
PerNs::types(def),
);
}
}
};
}
for (import_id, import_data) in input.imports.iter() {
if let Some(segment) = import_data.path.segments.iter().last() {
if !import_data.is_glob {
module_items.items.insert(
segment.name.clone(),
Resolution {
def: PerNs::none(),
import: Some(import_id),
},
);
}
}
}
// Populate explicitly declared items, except modules
for (name, &def) in input.declarations.iter() {
let resolution = Resolution { def, import: None };
module_items.items.insert(name.clone(), resolution);
}
// Populate modules
for (name, module_id) in module_id.children(&self.module_tree) {
let module = Module {
module_id,
krate: self.krate,
};
self.add_module_item(&mut module_items, name, PerNs::types(module.into()));
}
self.result.per_module.insert(module_id, module_items);
}
fn add_module_item(&self, module_items: &mut ModuleScope, name: Name, def: PerNs<ModuleDef>) {
let resolution = Resolution { def, import: None };
module_items.items.insert(name, resolution);
}
fn resolve_imports(&mut self, module_id: ModuleId) {
for (import_id, import_data) in self.input[&module_id].imports.iter() {
if self.processed_imports.contains(&(module_id, import_id)) {
// already done
continue;
}
if self.resolve_import(module_id, import_id, import_data) == ReachedFixedPoint::Yes {
log::debug!("import {:?} resolved (or definite error)", import_id);
self.processed_imports.insert((module_id, import_id));
}
}
}
fn resolve_import(
&mut self,
module_id: ModuleId,
import_id: ImportId,
import: &ImportData,
) -> ReachedFixedPoint {
log::debug!("resolving import: {:?}", import);
if import.is_glob {
return ReachedFixedPoint::Yes;
};
let original_module = Module {
krate: self.krate,
module_id,
};
let (def, reached_fixedpoint) =
self.result
.resolve_path_fp(self.db, original_module, &import.path);
if reached_fixedpoint == ReachedFixedPoint::Yes {
let last_segment = import.path.segments.last().unwrap();
self.update(module_id, |items| {
let res = Resolution {
def,
import: Some(import_id),
};
items.items.insert(last_segment.name.clone(), res);
});
log::debug!(
"resolved import {:?} ({:?}) cross-source root to {:?}",
last_segment.name,
import,
def,
);
}
reached_fixedpoint
}
fn update(&mut self, module_id: ModuleId, f: impl FnOnce(&mut ModuleScope)) {
let module_items = self.result.per_module.get_mut(module_id).unwrap();
f(module_items)
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum ReachedFixedPoint {
Yes,
No,
}
impl ItemMap {
pub(crate) fn item_map_query(db: &impl HirDatabase, crate_id: CrateId) -> Arc<ItemMap> {
let start = time::Instant::now();
let module_tree = db.module_tree(crate_id);
let input = module_tree
.modules()
.map(|module_id| {
(
module_id,
db.lower_module_module(Module {
krate: crate_id,
module_id,
}),
)
})
.collect::<FxHashMap<_, _>>();
let resolver = Resolver::new(db, &input, crate_id);
let res = resolver.resolve();
let elapsed = start.elapsed();
log::info!("item_map: {:?}", elapsed);
Arc::new(res)
}
pub(crate) fn resolve_path(
&self,
db: &impl HirDatabase,
original_module: Module,
path: &Path,
) -> PerNs<ModuleDef> {
self.resolve_path_fp(db, original_module, path).0
}
// Returns Yes if we are sure that additions to `ItemMap` wouldn't change
// the result.
fn resolve_path_fp(
&self,
db: &impl HirDatabase,
original_module: Module,
path: &Path,
) -> (PerNs<ModuleDef>, ReachedFixedPoint) {
let mut curr_per_ns: PerNs<ModuleDef> = PerNs::types(match path.kind {
PathKind::Crate => original_module.crate_root(db).into(),
PathKind::Self_ | PathKind::Plain => original_module.into(),
PathKind::Super => {
if let Some(p) = original_module.parent(db) {
p.into()
} else {
log::debug!("super path in root module");
return (PerNs::none(), ReachedFixedPoint::Yes);
}
}
PathKind::Abs => {
// TODO: absolute use is not supported
return (PerNs::none(), ReachedFixedPoint::Yes);
}
});
for (i, segment) in path.segments.iter().enumerate() {
let curr = match curr_per_ns.as_ref().take_types() {
Some(r) => r,
None => {
// we still have path segments left, but the path so far
// didn't resolve in the types namespace => no resolution
// (don't break here because curr_per_ns might contain
// something in the value namespace, and it would be wrong
// to return that)
return (PerNs::none(), ReachedFixedPoint::No);
}
};
// resolve segment in curr
curr_per_ns = match curr {
ModuleDef::Module(module) => {
if module.krate != original_module.krate {
let path = Path {
segments: path.segments[i..].iter().cloned().collect(),
kind: PathKind::Crate,
};
log::debug!("resolving {:?} in other crate", path);
let def = module.resolve_path(db, &path);
return (def, ReachedFixedPoint::Yes);
}
match self[module.module_id].items.get(&segment.name) {
Some(res) if !res.def.is_none() => res.def,
_ => {
log::debug!("path segment {:?} not found", segment.name);
return (PerNs::none(), ReachedFixedPoint::No);
}
}
}
ModuleDef::Enum(e) => {
// enum variant
tested_by!(item_map_enum_importing);
match e.variant(db, &segment.name) {
Some(variant) => PerNs::both(variant.into(), (*e).into()),
None => PerNs::none(),
}
}
_ => {
// could be an inherent method call in UFCS form
// (`Struct::method`), or some other kind of associated
// item... Which we currently don't handle (TODO)
log::debug!(
"path segment {:?} resolved to non-module {:?}, but is not last",
segment.name,
curr,
);
return (PerNs::none(), ReachedFixedPoint::Yes);
}
};
}
(curr_per_ns, ReachedFixedPoint::Yes)
}
}
#[cfg(test)]
mod tests;
|