Move child_by_source from hir-def to hir

crates/hir-def/src/dyn_map.rs

@@ -21,7 +21,79 @@
 //!
 //! This is a work of fiction. Any similarities to Kotlin's `BindingContext` are
 //! a coincidence.
-pub mod keys;
+
+pub mod keys {
+    use std::marker::PhantomData;
+
+    use hir_expand::{attrs::AttrId, MacroCallId};
+    use rustc_hash::FxHashMap;
+    use syntax::{ast, AstNode, AstPtr};
+
+    use crate::{
+        dyn_map::{DynMap, Policy},
+        BlockId, ConstId, EnumId, EnumVariantId, ExternCrateId, FieldId, FunctionId, ImplId,
+        LifetimeParamId, Macro2Id, MacroRulesId, ProcMacroId, StaticId, StructId, TraitAliasId,
+        TraitId, TypeAliasId, TypeOrConstParamId, UnionId, UseId,
+    };
+
+    pub type Key<K, V> = crate::dyn_map::Key<AstPtr<K>, V, AstPtrPolicy<K, V>>;
+
+    pub const BLOCK: Key<ast::BlockExpr, BlockId> = Key::new();
+    pub const FUNCTION: Key<ast::Fn, FunctionId> = Key::new();
+    pub const CONST: Key<ast::Const, ConstId> = Key::new();
+    pub const STATIC: Key<ast::Static, StaticId> = Key::new();
+    pub const TYPE_ALIAS: Key<ast::TypeAlias, TypeAliasId> = Key::new();
+    pub const IMPL: Key<ast::Impl, ImplId> = Key::new();
+    pub const TRAIT: Key<ast::Trait, TraitId> = Key::new();
+    pub const TRAIT_ALIAS: Key<ast::TraitAlias, TraitAliasId> = Key::new();
+    pub const STRUCT: Key<ast::Struct, StructId> = Key::new();
+    pub const UNION: Key<ast::Union, UnionId> = Key::new();
+    pub const ENUM: Key<ast::Enum, EnumId> = Key::new();
+    pub const EXTERN_CRATE: Key<ast::ExternCrate, ExternCrateId> = Key::new();
+    pub const USE: Key<ast::Use, UseId> = Key::new();
+
+    pub const ENUM_VARIANT: Key<ast::Variant, EnumVariantId> = Key::new();
+    pub const TUPLE_FIELD: Key<ast::TupleField, FieldId> = Key::new();
+    pub const RECORD_FIELD: Key<ast::RecordField, FieldId> = Key::new();
+    pub const TYPE_PARAM: Key<ast::TypeParam, TypeOrConstParamId> = Key::new();
+    pub const CONST_PARAM: Key<ast::ConstParam, TypeOrConstParamId> = Key::new();
+    pub const LIFETIME_PARAM: Key<ast::LifetimeParam, LifetimeParamId> = Key::new();
+
+    pub const MACRO_RULES: Key<ast::MacroRules, MacroRulesId> = Key::new();
+    pub const MACRO2: Key<ast::MacroDef, Macro2Id> = Key::new();
+    pub const PROC_MACRO: Key<ast::Fn, ProcMacroId> = Key::new();
+    pub const MACRO_CALL: Key<ast::MacroCall, MacroCallId> = Key::new();
+    pub const ATTR_MACRO_CALL: Key<ast::Item, MacroCallId> = Key::new();
+    pub const DERIVE_MACRO_CALL: Key<ast::Attr, (AttrId, MacroCallId, Box<[Option<MacroCallId>]>)> =
+        Key::new();
+
+    /// XXX: AST Nodes and SyntaxNodes have identity equality semantics: nodes are
+    /// equal if they point to exactly the same object.
+    ///
+    /// In general, we do not guarantee that we have exactly one instance of a
+    /// syntax tree for each file. We probably should add such guarantee, but, for
+    /// the time being, we will use identity-less AstPtr comparison.
+    pub struct AstPtrPolicy<AST, ID> {
+        _phantom: PhantomData<(AST, ID)>,
+    }
+
+    impl<AST: AstNode + 'static, ID: 'static> Policy for AstPtrPolicy<AST, ID> {
+        type K = AstPtr<AST>;
+        type V = ID;
+        fn insert(map: &mut DynMap, key: AstPtr<AST>, value: ID) {
+            map.map
+                .entry::<FxHashMap<AstPtr<AST>, ID>>()
+                .or_insert_with(Default::default)
+                .insert(key, value);
+        }
+        fn get<'a>(map: &'a DynMap, key: &AstPtr<AST>) -> Option<&'a ID> {
+            map.map.get::<FxHashMap<AstPtr<AST>, ID>>()?.get(key)
+        }
+        fn is_empty(map: &DynMap) -> bool {
+            map.map.get::<FxHashMap<AstPtr<AST>, ID>>().map_or(true, |it| it.is_empty())
+        }
+    }
+}
 
 use std::{
     hash::Hash,