From b28c54a2c239acd73f2eea80fda9ee3960d2c046 Mon Sep 17 00:00:00 2001 From: Aleksey Kladov Date: Thu, 13 Aug 2020 16:28:27 +0200 Subject: Rename ra_hir_def -> hir_def --- crates/hir_def/src/find_path.rs | 687 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 687 insertions(+) create mode 100644 crates/hir_def/src/find_path.rs (limited to 'crates/hir_def/src/find_path.rs') diff --git a/crates/hir_def/src/find_path.rs b/crates/hir_def/src/find_path.rs new file mode 100644 index 000000000..ac2c54ac5 --- /dev/null +++ b/crates/hir_def/src/find_path.rs @@ -0,0 +1,687 @@ +//! An algorithm to find a path to refer to a certain item. + +use hir_expand::name::{known, AsName, Name}; +use rustc_hash::FxHashSet; +use test_utils::mark; + +use crate::{ + db::DefDatabase, + item_scope::ItemInNs, + path::{ModPath, PathKind}, + visibility::Visibility, + ModuleDefId, ModuleId, +}; + +// FIXME: handle local items + +/// Find a path that can be used to refer to a certain item. This can depend on +/// *from where* you're referring to the item, hence the `from` parameter. +pub fn find_path(db: &dyn DefDatabase, item: ItemInNs, from: ModuleId) -> Option { + let _p = profile::span("find_path"); + find_path_inner(db, item, from, MAX_PATH_LEN) +} + +const MAX_PATH_LEN: usize = 15; + +impl ModPath { + fn starts_with_std(&self) -> bool { + self.segments.first() == Some(&known::std) + } + + // When std library is present, paths starting with `std::` + // should be preferred over paths starting with `core::` and `alloc::` + fn can_start_with_std(&self) -> bool { + let first_segment = self.segments.first(); + first_segment == Some(&known::alloc) || first_segment == Some(&known::core) + } +} + +fn find_path_inner( + db: &dyn DefDatabase, + item: ItemInNs, + from: ModuleId, + max_len: usize, +) -> Option { + if max_len == 0 { + return None; + } + + // Base cases: + + // - if the item is already in scope, return the name under which it is + let def_map = db.crate_def_map(from.krate); + let from_scope: &crate::item_scope::ItemScope = &def_map.modules[from.local_id].scope; + if let Some((name, _)) = from_scope.name_of(item) { + return Some(ModPath::from_segments(PathKind::Plain, vec![name.clone()])); + } + + // - if the item is the crate root, return `crate` + if item + == ItemInNs::Types(ModuleDefId::ModuleId(ModuleId { + krate: from.krate, + local_id: def_map.root, + })) + { + return Some(ModPath::from_segments(PathKind::Crate, Vec::new())); + } + + // - if the item is the module we're in, use `self` + if item == ItemInNs::Types(from.into()) { + return Some(ModPath::from_segments(PathKind::Super(0), Vec::new())); + } + + // - if the item is the parent module, use `super` (this is not used recursively, since `super::super` is ugly) + if let Some(parent_id) = def_map.modules[from.local_id].parent { + if item + == ItemInNs::Types(ModuleDefId::ModuleId(ModuleId { + krate: from.krate, + local_id: parent_id, + })) + { + return Some(ModPath::from_segments(PathKind::Super(1), Vec::new())); + } + } + + // - if the item is the crate root of a dependency crate, return the name from the extern prelude + for (name, def_id) in &def_map.extern_prelude { + if item == ItemInNs::Types(*def_id) { + return Some(ModPath::from_segments(PathKind::Plain, vec![name.clone()])); + } + } + + // - if the item is in the prelude, return the name from there + if let Some(prelude_module) = def_map.prelude { + let prelude_def_map = db.crate_def_map(prelude_module.krate); + let prelude_scope: &crate::item_scope::ItemScope = + &prelude_def_map.modules[prelude_module.local_id].scope; + if let Some((name, vis)) = prelude_scope.name_of(item) { + if vis.is_visible_from(db, from) { + return Some(ModPath::from_segments(PathKind::Plain, vec![name.clone()])); + } + } + } + + // - if the item is a builtin, it's in scope + if let ItemInNs::Types(ModuleDefId::BuiltinType(builtin)) = item { + return Some(ModPath::from_segments(PathKind::Plain, vec![builtin.as_name()])); + } + + // Recursive case: + // - if the item is an enum variant, refer to it via the enum + if let Some(ModuleDefId::EnumVariantId(variant)) = item.as_module_def_id() { + if let Some(mut path) = find_path(db, ItemInNs::Types(variant.parent.into()), from) { + let data = db.enum_data(variant.parent); + path.segments.push(data.variants[variant.local_id].name.clone()); + return Some(path); + } + // If this doesn't work, it seems we have no way of referring to the + // enum; that's very weird, but there might still be a reexport of the + // variant somewhere + } + + // - otherwise, look for modules containing (reexporting) it and import it from one of those + + let crate_root = ModuleId { local_id: def_map.root, krate: from.krate }; + let crate_attrs = db.attrs(crate_root.into()); + let prefer_no_std = crate_attrs.by_key("no_std").exists(); + let mut best_path = None; + let mut best_path_len = max_len; + + if item.krate(db) == Some(from.krate) { + // Item was defined in the same crate that wants to import it. It cannot be found in any + // dependency in this case. + + let local_imports = find_local_import_locations(db, item, from); + for (module_id, name) in local_imports { + if let Some(mut path) = find_path_inner( + db, + ItemInNs::Types(ModuleDefId::ModuleId(module_id)), + from, + best_path_len - 1, + ) { + path.segments.push(name); + + let new_path = if let Some(best_path) = best_path { + select_best_path(best_path, path, prefer_no_std) + } else { + path + }; + best_path_len = new_path.len(); + best_path = Some(new_path); + } + } + } else { + // Item was defined in some upstream crate. This means that it must be exported from one, + // too (unless we can't name it at all). It could *also* be (re)exported by the same crate + // that wants to import it here, but we always prefer to use the external path here. + + let crate_graph = db.crate_graph(); + let extern_paths = crate_graph[from.krate].dependencies.iter().filter_map(|dep| { + let import_map = db.import_map(dep.crate_id); + import_map.import_info_for(item).and_then(|info| { + // Determine best path for containing module and append last segment from `info`. + let mut path = find_path_inner( + db, + ItemInNs::Types(ModuleDefId::ModuleId(info.container)), + from, + best_path_len - 1, + )?; + path.segments.push(info.path.segments.last().unwrap().clone()); + Some(path) + }) + }); + + for path in extern_paths { + let new_path = if let Some(best_path) = best_path { + select_best_path(best_path, path, prefer_no_std) + } else { + path + }; + best_path = Some(new_path); + } + } + + best_path +} + +fn select_best_path(old_path: ModPath, new_path: ModPath, prefer_no_std: bool) -> ModPath { + if old_path.starts_with_std() && new_path.can_start_with_std() { + if prefer_no_std { + mark::hit!(prefer_no_std_paths); + new_path + } else { + mark::hit!(prefer_std_paths); + old_path + } + } else if new_path.starts_with_std() && old_path.can_start_with_std() { + if prefer_no_std { + mark::hit!(prefer_no_std_paths); + old_path + } else { + mark::hit!(prefer_std_paths); + new_path + } + } else if new_path.len() < old_path.len() { + new_path + } else { + old_path + } +} + +/// Finds locations in `from.krate` from which `item` can be imported by `from`. +fn find_local_import_locations( + db: &dyn DefDatabase, + item: ItemInNs, + from: ModuleId, +) -> Vec<(ModuleId, Name)> { + let _p = profile::span("find_local_import_locations"); + + // `from` can import anything below `from` with visibility of at least `from`, and anything + // above `from` with any visibility. That means we do not need to descend into private siblings + // of `from` (and similar). + + let def_map = db.crate_def_map(from.krate); + + // Compute the initial worklist. We start with all direct child modules of `from` as well as all + // of its (recursive) parent modules. + let data = &def_map.modules[from.local_id]; + let mut worklist = data + .children + .values() + .map(|child| ModuleId { krate: from.krate, local_id: *child }) + .collect::>(); + let mut parent = data.parent; + while let Some(p) = parent { + worklist.push(ModuleId { krate: from.krate, local_id: p }); + parent = def_map.modules[p].parent; + } + + let mut seen: FxHashSet<_> = FxHashSet::default(); + + let mut locations = Vec::new(); + while let Some(module) = worklist.pop() { + if !seen.insert(module) { + continue; // already processed this module + } + + let ext_def_map; + let data = if module.krate == from.krate { + &def_map[module.local_id] + } else { + // The crate might reexport a module defined in another crate. + ext_def_map = db.crate_def_map(module.krate); + &ext_def_map[module.local_id] + }; + + if let Some((name, vis)) = data.scope.name_of(item) { + if vis.is_visible_from(db, from) { + let is_private = if let Visibility::Module(private_to) = vis { + private_to.local_id == module.local_id + } else { + false + }; + let is_original_def = if let Some(module_def_id) = item.as_module_def_id() { + data.scope.declarations().any(|it| it == module_def_id) + } else { + false + }; + + // Ignore private imports. these could be used if we are + // in a submodule of this module, but that's usually not + // what the user wants; and if this module can import + // the item and we're a submodule of it, so can we. + // Also this keeps the cached data smaller. + if !is_private || is_original_def { + locations.push((module, name.clone())); + } + } + } + + // Descend into all modules visible from `from`. + for (_, per_ns) in data.scope.entries() { + if let Some((ModuleDefId::ModuleId(module), vis)) = per_ns.take_types_vis() { + if vis.is_visible_from(db, from) { + worklist.push(module); + } + } + } + } + + locations +} + +#[cfg(test)] +mod tests { + use base_db::fixture::WithFixture; + use hir_expand::hygiene::Hygiene; + use syntax::ast::AstNode; + use test_utils::mark; + + use crate::test_db::TestDB; + + use super::*; + + /// `code` needs to contain a cursor marker; checks that `find_path` for the + /// item the `path` refers to returns that same path when called from the + /// module the cursor is in. + fn check_found_path(ra_fixture: &str, path: &str) { + let (db, pos) = TestDB::with_position(ra_fixture); + let module = db.module_for_file(pos.file_id); + let parsed_path_file = syntax::SourceFile::parse(&format!("use {};", path)); + let ast_path = + parsed_path_file.syntax_node().descendants().find_map(syntax::ast::Path::cast).unwrap(); + let mod_path = ModPath::from_src(ast_path, &Hygiene::new_unhygienic()).unwrap(); + + let crate_def_map = db.crate_def_map(module.krate); + let resolved = crate_def_map + .resolve_path( + &db, + module.local_id, + &mod_path, + crate::item_scope::BuiltinShadowMode::Module, + ) + .0 + .take_types() + .unwrap(); + + let found_path = find_path(&db, ItemInNs::Types(resolved), module); + + assert_eq!(found_path, Some(mod_path)); + } + + #[test] + fn same_module() { + let code = r#" + //- /main.rs + struct S; + <|> + "#; + check_found_path(code, "S"); + } + + #[test] + fn enum_variant() { + let code = r#" + //- /main.rs + enum E { A } + <|> + "#; + check_found_path(code, "E::A"); + } + + #[test] + fn sub_module() { + let code = r#" + //- /main.rs + mod foo { + pub struct S; + } + <|> + "#; + check_found_path(code, "foo::S"); + } + + #[test] + fn super_module() { + let code = r#" + //- /main.rs + mod foo; + //- /foo.rs + mod bar; + struct S; + //- /foo/bar.rs + <|> + "#; + check_found_path(code, "super::S"); + } + + #[test] + fn self_module() { + let code = r#" + //- /main.rs + mod foo; + //- /foo.rs + <|> + "#; + check_found_path(code, "self"); + } + + #[test] + fn crate_root() { + let code = r#" + //- /main.rs + mod foo; + //- /foo.rs + <|> + "#; + check_found_path(code, "crate"); + } + + #[test] + fn same_crate() { + let code = r#" + //- /main.rs + mod foo; + struct S; + //- /foo.rs + <|> + "#; + check_found_path(code, "crate::S"); + } + + #[test] + fn different_crate() { + let code = r#" + //- /main.rs crate:main deps:std + <|> + //- /std.rs crate:std + pub struct S; + "#; + check_found_path(code, "std::S"); + } + + #[test] + fn different_crate_renamed() { + let code = r#" + //- /main.rs crate:main deps:std + extern crate std as std_renamed; + <|> + //- /std.rs crate:std + pub struct S; + "#; + check_found_path(code, "std_renamed::S"); + } + + #[test] + fn partially_imported() { + // Tests that short paths are used even for external items, when parts of the path are + // already in scope. + check_found_path( + r#" + //- /main.rs crate:main deps:syntax + + use syntax::ast; + <|> + + //- /lib.rs crate:syntax + pub mod ast { + pub enum ModuleItem { + A, B, C, + } + } + "#, + "ast::ModuleItem", + ); + + check_found_path( + r#" + //- /main.rs crate:main deps:syntax + + <|> + + //- /lib.rs crate:syntax + pub mod ast { + pub enum ModuleItem { + A, B, C, + } + } + "#, + "syntax::ast::ModuleItem", + ); + } + + #[test] + fn same_crate_reexport() { + let code = r#" + //- /main.rs + mod bar { + mod foo { pub(super) struct S; } + pub(crate) use foo::*; + } + <|> + "#; + check_found_path(code, "bar::S"); + } + + #[test] + fn same_crate_reexport_rename() { + let code = r#" + //- /main.rs + mod bar { + mod foo { pub(super) struct S; } + pub(crate) use foo::S as U; + } + <|> + "#; + check_found_path(code, "bar::U"); + } + + #[test] + fn different_crate_reexport() { + let code = r#" + //- /main.rs crate:main deps:std + <|> + //- /std.rs crate:std deps:core + pub use core::S; + //- /core.rs crate:core + pub struct S; + "#; + check_found_path(code, "std::S"); + } + + #[test] + fn prelude() { + let code = r#" + //- /main.rs crate:main deps:std + <|> + //- /std.rs crate:std + pub mod prelude { pub struct S; } + #[prelude_import] + pub use prelude::*; + "#; + check_found_path(code, "S"); + } + + #[test] + fn enum_variant_from_prelude() { + let code = r#" + //- /main.rs crate:main deps:std + <|> + //- /std.rs crate:std + pub mod prelude { + pub enum Option { Some(T), None } + pub use Option::*; + } + #[prelude_import] + pub use prelude::*; + "#; + check_found_path(code, "None"); + check_found_path(code, "Some"); + } + + #[test] + fn shortest_path() { + let code = r#" + //- /main.rs + pub mod foo; + pub mod baz; + struct S; + <|> + //- /foo.rs + pub mod bar { pub struct S; } + //- /baz.rs + pub use crate::foo::bar::S; + "#; + check_found_path(code, "baz::S"); + } + + #[test] + fn discount_private_imports() { + let code = r#" + //- /main.rs + mod foo; + pub mod bar { pub struct S; } + use bar::S; + //- /foo.rs + <|> + "#; + // crate::S would be shorter, but using private imports seems wrong + check_found_path(code, "crate::bar::S"); + } + + #[test] + fn import_cycle() { + let code = r#" + //- /main.rs + pub mod foo; + pub mod bar; + pub mod baz; + //- /bar.rs + <|> + //- /foo.rs + pub use super::baz; + pub struct S; + //- /baz.rs + pub use super::foo; + "#; + check_found_path(code, "crate::foo::S"); + } + + #[test] + fn prefer_std_paths_over_alloc() { + mark::check!(prefer_std_paths); + let code = r#" + //- /main.rs crate:main deps:alloc,std + <|> + + //- /std.rs crate:std deps:alloc + pub mod sync { + pub use alloc::sync::Arc; + } + + //- /zzz.rs crate:alloc + pub mod sync { + pub struct Arc; + } + "#; + check_found_path(code, "std::sync::Arc"); + } + + #[test] + fn prefer_core_paths_over_std() { + mark::check!(prefer_no_std_paths); + let code = r#" + //- /main.rs crate:main deps:core,std + #![no_std] + + <|> + + //- /std.rs crate:std deps:core + + pub mod fmt { + pub use core::fmt::Error; + } + + //- /zzz.rs crate:core + + pub mod fmt { + pub struct Error; + } + "#; + check_found_path(code, "core::fmt::Error"); + } + + #[test] + fn prefer_alloc_paths_over_std() { + let code = r#" + //- /main.rs crate:main deps:alloc,std + #![no_std] + + <|> + + //- /std.rs crate:std deps:alloc + + pub mod sync { + pub use alloc::sync::Arc; + } + + //- /zzz.rs crate:alloc + + pub mod sync { + pub struct Arc; + } + "#; + check_found_path(code, "alloc::sync::Arc"); + } + + #[test] + fn prefer_shorter_paths_if_not_alloc() { + let code = r#" + //- /main.rs crate:main deps:megaalloc,std + <|> + + //- /std.rs crate:std deps:megaalloc + pub mod sync { + pub use megaalloc::sync::Arc; + } + + //- /zzz.rs crate:megaalloc + pub struct Arc; + "#; + check_found_path(code, "megaalloc::Arc"); + } + + #[test] + fn builtins_are_in_scope() { + let code = r#" + //- /main.rs + <|> + + pub mod primitive { + pub use u8; + } + "#; + check_found_path(code, "u8"); + check_found_path(code, "u16"); + } +} -- cgit v1.2.3