From 3fcb28c9428bbc25de1d1f422ec11afa4825c31c Mon Sep 17 00:00:00 2001
From: Yoshitomo Nakanishi <yurayura.rounin.3@gmail.com>
Date: Mon, 17 Apr 2023 16:08:27 +0200
Subject: [PATCH] [WIP] Define `ScopeGraph`

---
 crates/hir/src/hir_def/mod.rs         |   1 +
 crates/hir/src/hir_def/scope_graph.rs | 113 ++++++++++++++++++++++++++
 crates/hir/src/hir_def/use_tree.rs    |   4 +-
 crates/hir/src/lower/use_tree.rs      |   4 +-
 4 files changed, 118 insertions(+), 4 deletions(-)
 create mode 100644 crates/hir/src/hir_def/scope_graph.rs

diff --git a/crates/hir/src/hir_def/mod.rs b/crates/hir/src/hir_def/mod.rs
index af4f5f3939..a4dca66586 100644
--- a/crates/hir/src/hir_def/mod.rs
+++ b/crates/hir/src/hir_def/mod.rs
@@ -5,6 +5,7 @@ pub mod item;
 pub mod params;
 pub mod pat;
 pub mod path;
+pub mod scope_graph;
 pub mod stmt;
 pub mod types;
 pub mod use_tree;
diff --git a/crates/hir/src/hir_def/scope_graph.rs b/crates/hir/src/hir_def/scope_graph.rs
new file mode 100644
index 0000000000..9f284bc7ce
--- /dev/null
+++ b/crates/hir/src/hir_def/scope_graph.rs
@@ -0,0 +1,113 @@
+use cranelift_entity::{entity_impl, PrimaryMap};
+use rustc_hash::FxHashSet;
+
+use super::{IdentId, ItemKind, PathId, Struct, TopLevelMod, UseAlias};
+
+pub struct ScopeGraph {
+    pub top_mod: TopLevelMod,
+    pub scopes: PrimaryMap<LocalScopeId, LocalScope>,
+    pub unresolved: FxHashSet<UnresolvedName>,
+}
+
+pub struct UnresolvedName {
+    pub scope: LocalScopeId,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct LocalScope {
+    kind: ScopeKind,
+    edges: Vec<ScopeEdge>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ScopeKind {
+    Item(ItemKind),
+    Field(usize),
+    Variant(Struct, usize),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ScopeEdge {
+    dest: ScopeId,
+    kind: EdgeKind,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum EdgeKind {
+    Lex(LexEdge),
+    Mod(ModEdge),
+    GlobUse(GlobUseEdge),
+    Use(UseEdge),
+    Type(TypeEdge),
+    Func(FuncEdge),
+    Field(FieldEdge),
+    Variant(VariantEdge),
+    Super(SuperEdge),
+    Ingot(IngotEdge),
+    SelfTy(SelfTyEdge),
+    Anon(AnonEdge),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct LexEdge();
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ModEdge(IdentId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct GlobUseEdge {
+    /// `UsePathSegment` are lowered to a normal `Path`.
+    path: PathId,
+    alias: UseAlias,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct UseEdge {
+    /// `UsePathSegment` are lowered to a normal `Path`.
+    path: PathId,
+    alias: UseAlias,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeEdge(IdentId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct FuncEdge(IdentId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct FieldEdge(IdentId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct VariantEdge(IdentId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct SuperEdge();
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct IngotEdge();
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct SelfEdge {
+    path: PathId,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct SelfTyEdge {
+    path: PathId,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct LocalEdge(IdentId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct AnonEdge();
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ScopeId {
+    top_mod: TopLevelMod,
+    local_id: LocalScopeId,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct LocalScopeId(u32);
+entity_impl!(LocalScopeId);
diff --git a/crates/hir/src/hir_def/use_tree.rs b/crates/hir/src/hir_def/use_tree.rs
index 474a36a3e2..b025d47d88 100644
--- a/crates/hir/src/hir_def/use_tree.rs
+++ b/crates/hir/src/hir_def/use_tree.rs
@@ -16,7 +16,7 @@ pub struct UseTreeId {
 
     //// The alias of this use tree.
     /// `Bar` in `Foo as Bar;`
-    pub alias: Option<Partial<UseTreeAlias>>,
+    pub alias: Option<Partial<UseAlias>>,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -33,7 +33,7 @@ pub enum UsePathSegment {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub enum UseTreeAlias {
+pub enum UseAlias {
     Ident(IdentId),
     Underscore,
 }
diff --git a/crates/hir/src/lower/use_tree.rs b/crates/hir/src/lower/use_tree.rs
index 4080154758..98f4b7a1f1 100644
--- a/crates/hir/src/lower/use_tree.rs
+++ b/crates/hir/src/lower/use_tree.rs
@@ -23,7 +23,7 @@ impl UseTreeId {
         };
         let alias = ast
             .alias()
-            .map(|ast| UseTreeAlias::lower_ast_partial(ctxt, ast));
+            .map(|ast| UseAlias::lower_ast_partial(ctxt, ast));
 
         Self::new(ctxt.db, path, subtree, alias)
     }
@@ -55,7 +55,7 @@ impl UsePathSegment {
     }
 }
 
-impl UseTreeAlias {
+impl UseAlias {
     pub(super) fn lower_ast_partial(
         ctxt: &mut FileLowerCtxt<'_>,
         ast: ast::UseTreeAlias,