1 files changed, 280 insertions, 0 deletions

diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
new file mode 100644
index 000000000..a09dee8b1
--- /dev/null
+++ b/crates/ra_hir/src/ids.rs
@@ -0,0 +1,280 @@
+use ra_db::{SourceRootId, LocationIntener, Cancelable, FileId};
+use ra_syntax::{SourceFileNode, SyntaxKind, SyntaxNode, SyntaxNodeRef, SourceFile, AstNode, ast};
+
+use crate::{
+    HirDatabase, PerNs, ModuleId, Module, Def, Function, Struct, Enum,
+    arena::{Arena, Id},
+};
+
+/// hir makes a heavy use of ids: integer (u32) handlers to various things. You
+/// can think of id as a pointer (but without a lifetime) or a file descriptor
+/// (but for hir objects).
+///
+/// This module defines a bunch of ids we are using. The most important ones are
+/// probably `HirFileId` and `DefId`.
+
+/// Input to the analyzer is a set of file, where each file is indetified by
+/// `FileId` and contains source code. However, another source of source code in
+/// Rust are macros: each macro can be thought of as producing a "temporary
+/// file". To assign id to such file, we use the id of a macro call that
+/// produced the file. So, a `HirFileId` is either a `FileId` (source code
+/// written by user), or a `MacroCallId` (source code produced by macro).
+///
+/// What is a `MacroCallId`? Simplifying, it's a `HirFileId` of a file containin
+/// the call plus the offset of the macro call in the file. Note that this is a
+/// recursive definition! Nethetheless, size_of of `HirFileId` is finite
+/// (because everything bottoms out at the real `FileId`) and small
+/// (`MacroCallId` uses location interner).
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct HirFileId(HirFileIdRepr);
+
+impl HirFileId {
+    /// For macro-expansion files, returns the file original source file the
+    /// expansionoriginated from.
+    pub(crate) fn original_file(self, db: &impl HirDatabase) -> FileId {
+        match self.0 {
+            HirFileIdRepr::File(file_id) => file_id,
+            HirFileIdRepr::Macro(macro_call_id) => {
+                let loc = macro_call_id.loc(db);
+                loc.source_item_id.file_id.original_file(db)
+            }
+        }
+    }
+
+    pub(crate) fn as_original_file(self) -> FileId {
+        match self.0 {
+            HirFileIdRepr::File(file_id) => file_id,
+            HirFileIdRepr::Macro(_r) => panic!("macro generated file: {:?}", self),
+        }
+    }
+
+    pub(crate) fn hir_source_file(db: &impl HirDatabase, file_id: HirFileId) -> SourceFileNode {
+        match file_id.0 {
+            HirFileIdRepr::File(file_id) => db.source_file(file_id),
+            HirFileIdRepr::Macro(m) => {
+                if let Some(exp) = db.expand_macro_invocation(m) {
+                    return exp.file();
+                }
+                // returning an empty string looks fishy...
+                SourceFileNode::parse("")
+            }
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+enum HirFileIdRepr {
+    File(FileId),
+    Macro(MacroCallId),
+}
+
+impl From<FileId> for HirFileId {
+    fn from(file_id: FileId) -> HirFileId {
+        HirFileId(HirFileIdRepr::File(file_id))
+    }
+}
+
+impl From<MacroCallId> for HirFileId {
+    fn from(macro_call_id: MacroCallId) -> HirFileId {
+        HirFileId(HirFileIdRepr::Macro(macro_call_id))
+    }
+}
+
+/// `MacroCallId` identifies a particular macro invocation, like
+/// `println!("Hello, {}", world)`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct MacroCallId(u32);
+ra_db::impl_numeric_id!(MacroCallId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct MacroCallLoc {
+    pub(crate) source_root_id: SourceRootId,
+    pub(crate) module_id: ModuleId,
+    pub(crate) source_item_id: SourceItemId,
+}
+
+impl MacroCallId {
+    pub(crate) fn loc(
+        self,
+        db: &impl AsRef<LocationIntener<MacroCallLoc, MacroCallId>>,
+    ) -> MacroCallLoc {
+        db.as_ref().id2loc(self)
+    }
+}
+
+impl MacroCallLoc {
+    #[allow(unused)]
+    pub(crate) fn id(
+        &self,
+        db: &impl AsRef<LocationIntener<MacroCallLoc, MacroCallId>>,
+    ) -> MacroCallId {
+        db.as_ref().loc2id(&self)
+    }
+}
+
+/// Def's are a core concept of hir. A `Def` is an Item (function, module, etc)
+/// in a specific module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct DefId(u32);
+ra_db::impl_numeric_id!(DefId);
+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct DefLoc {
+    pub(crate) kind: DefKind,
+    pub(crate) source_root_id: SourceRootId,
+    pub(crate) module_id: ModuleId,
+    pub(crate) source_item_id: SourceItemId,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub(crate) enum DefKind {
+    Module,
+    Function,
+    Struct,
+    Enum,
+    Item,
+
+    StructCtor,
+}
+
+impl DefId {
+    pub(crate) fn loc(self, db: &impl AsRef<LocationIntener<DefLoc, DefId>>) -> DefLoc {
+        db.as_ref().id2loc(self)
+    }
+
+    pub fn resolve(self, db: &impl HirDatabase) -> Cancelable<Def> {
+        let loc = self.loc(db);
+        let res = match loc.kind {
+            DefKind::Module => {
+                let module = Module::new(db, loc.source_root_id, loc.module_id)?;
+                Def::Module(module)
+            }
+            DefKind::Function => {
+                let function = Function::new(self);
+                Def::Function(function)
+            }
+            DefKind::Struct => {
+                let struct_def = Struct::new(self);
+                Def::Struct(struct_def)
+            }
+            DefKind::Enum => {
+                let enum_def = Enum::new(self);
+                Def::Enum(enum_def)
+            }
+            DefKind::StructCtor => Def::Item,
+            DefKind::Item => Def::Item,
+        };
+        Ok(res)
+    }
+
+    /// For a module, returns that module; for any other def, returns the containing module.
+    pub fn module(self, db: &impl HirDatabase) -> Cancelable<Module> {
+        let loc = self.loc(db);
+        Module::new(db, loc.source_root_id, loc.module_id)
+    }
+}
+
+impl DefLoc {
+    pub(crate) fn id(&self, db: &impl AsRef<LocationIntener<DefLoc, DefId>>) -> DefId {
+        db.as_ref().loc2id(&self)
+    }
+}
+
+impl DefKind {
+    pub(crate) fn for_syntax_kind(kind: SyntaxKind) -> PerNs<DefKind> {
+        match kind {
+            SyntaxKind::FN_DEF => PerNs::values(DefKind::Function),
+            SyntaxKind::MODULE => PerNs::types(DefKind::Module),
+            SyntaxKind::STRUCT_DEF => PerNs::both(DefKind::Struct, DefKind::StructCtor),
+            SyntaxKind::ENUM_DEF => PerNs::types(DefKind::Enum),
+            // These define items, but don't have their own DefKinds yet:
+            SyntaxKind::TRAIT_DEF => PerNs::types(DefKind::Item),
+            SyntaxKind::TYPE_DEF => PerNs::types(DefKind::Item),
+            SyntaxKind::CONST_DEF => PerNs::values(DefKind::Item),
+            SyntaxKind::STATIC_DEF => PerNs::values(DefKind::Item),
+            _ => PerNs::none(),
+        }
+    }
+}
+
+/// Identifier of item within a specific file. This is stable over reparses, so
+/// it's OK to use it as a salsa key/value.
+pub(crate) type SourceFileItemId = Id<SyntaxNode>;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct SourceItemId {
+    pub(crate) file_id: HirFileId,
+    /// None for the whole file.
+    pub(crate) item_id: Option<SourceFileItemId>,
+}
+
+/// Maps item's `SyntaxNode`s to `SourceFileItemId` and back.
+#[derive(Debug, PartialEq, Eq)]
+pub struct SourceFileItems {
+    file_id: HirFileId,
+    arena: Arena<SyntaxNode>,
+}
+
+impl SourceFileItems {
+    pub(crate) fn new(file_id: HirFileId, source_file: SourceFile) -> SourceFileItems {
+        let mut res = SourceFileItems {
+            file_id,
+            arena: Arena::default(),
+        };
+        res.init(source_file);
+        res
+    }
+
+    fn init(&mut self, source_file: SourceFile) {
+        source_file.syntax().descendants().for_each(|it| {
+            if let Some(module_item) = ast::ModuleItem::cast(it) {
+                self.alloc(module_item.syntax().owned());
+            } else if let Some(macro_call) = ast::MacroCall::cast(it) {
+                self.alloc(macro_call.syntax().owned());
+            }
+        });
+    }
+
+    fn alloc(&mut self, item: SyntaxNode) -> SourceFileItemId {
+        self.arena.alloc(item)
+    }
+    pub(crate) fn id_of(&self, file_id: HirFileId, item: SyntaxNodeRef) -> SourceFileItemId {
+        assert_eq!(
+            self.file_id, file_id,
+            "SourceFileItems: wrong file, expected {:?}, got {:?}",
+            self.file_id, file_id
+        );
+        self.id_of_unchecked(item)
+    }
+    pub(crate) fn id_of_unchecked(&self, item: SyntaxNodeRef) -> SourceFileItemId {
+        if let Some((id, _)) = self.arena.iter().find(|(_id, i)| i.borrowed() == item) {
+            return id;
+        }
+        // This should not happen. Let's try to give a sensible diagnostics.
+        if let Some((id, i)) = self.arena.iter().find(|(_id, i)| i.range() == item.range()) {
+            // FIXME(#288): whyyy are we getting here?
+            log::error!(
+                "unequal syntax nodes with the same range:\n{:?}\n{:?}",
+                item,
+                i
+            );
+            return id;
+        }
+        panic!(
+            "Can't find {:?} in SourceFileItems:\n{:?}",
+            item,
+            self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
+        );
+    }
+    pub fn id_of_source_file(&self) -> SourceFileItemId {
+        let (id, _syntax) = self.arena.iter().next().unwrap();
+        id
+    }
+}
+
+impl std::ops::Index<SourceFileItemId> for SourceFileItems {
+    type Output = SyntaxNode;
+    fn index(&self, idx: SourceFileItemId) -> &SyntaxNode {
+        &self.arena[idx]
+    }
+}