| //! `AstIdMap` allows to create stable IDs for "large" syntax nodes like items |
| //! and macro calls. |
| //! |
| //! Specifically, it enumerates all items in a file and uses position of a an |
| //! item as an ID. That way, id's don't change unless the set of items itself |
| //! changes. |
| |
| use std::{ |
| any::type_name, |
| fmt, |
| hash::{Hash, Hasher}, |
| marker::PhantomData, |
| }; |
| |
| use ra_arena::{Arena, Idx}; |
| use ra_syntax::{ast, AstNode, AstPtr, SyntaxNode, SyntaxNodePtr}; |
| |
| /// `AstId` points to an AST node in a specific file. |
| pub struct FileAstId<N: AstNode> { |
| raw: ErasedFileAstId, |
| _ty: PhantomData<fn() -> N>, |
| } |
| |
| impl<N: AstNode> Clone for FileAstId<N> { |
| fn clone(&self) -> FileAstId<N> { |
| *self |
| } |
| } |
| impl<N: AstNode> Copy for FileAstId<N> {} |
| |
| impl<N: AstNode> PartialEq for FileAstId<N> { |
| fn eq(&self, other: &Self) -> bool { |
| self.raw == other.raw |
| } |
| } |
| impl<N: AstNode> Eq for FileAstId<N> {} |
| impl<N: AstNode> Hash for FileAstId<N> { |
| fn hash<H: Hasher>(&self, hasher: &mut H) { |
| self.raw.hash(hasher); |
| } |
| } |
| |
| impl<N: AstNode> fmt::Debug for FileAstId<N> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "FileAstId::<{}>({})", type_name::<N>(), self.raw.into_raw()) |
| } |
| } |
| |
| impl<N: AstNode> FileAstId<N> { |
| // Can't make this a From implementation because of coherence |
| pub fn upcast<M: AstNode>(self) -> FileAstId<M> |
| where |
| N: Into<M>, |
| { |
| FileAstId { raw: self.raw, _ty: PhantomData } |
| } |
| } |
| |
| type ErasedFileAstId = Idx<SyntaxNodePtr>; |
| |
| /// Maps items' `SyntaxNode`s to `ErasedFileAstId`s and back. |
| #[derive(Debug, PartialEq, Eq, Default)] |
| pub struct AstIdMap { |
| arena: Arena<SyntaxNodePtr>, |
| } |
| |
| impl AstIdMap { |
| pub(crate) fn from_source(node: &SyntaxNode) -> AstIdMap { |
| assert!(node.parent().is_none()); |
| let mut res = AstIdMap { arena: Arena::default() }; |
| // By walking the tree in breadth-first order we make sure that parents |
| // get lower ids then children. That is, adding a new child does not |
| // change parent's id. This means that, say, adding a new function to a |
| // trait does not change ids of top-level items, which helps caching. |
| bfs(node, |it| { |
| if let Some(module_item) = ast::ModuleItem::cast(it) { |
| res.alloc(module_item.syntax()); |
| } |
| }); |
| res |
| } |
| |
| pub fn ast_id<N: AstNode>(&self, item: &N) -> FileAstId<N> { |
| let raw = self.erased_ast_id(item.syntax()); |
| FileAstId { raw, _ty: PhantomData } |
| } |
| fn erased_ast_id(&self, item: &SyntaxNode) -> ErasedFileAstId { |
| let ptr = SyntaxNodePtr::new(item); |
| match self.arena.iter().find(|(_id, i)| **i == ptr) { |
| Some((it, _)) => it, |
| None => panic!( |
| "Can't find {:?} in AstIdMap:\n{:?}", |
| item, |
| self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(), |
| ), |
| } |
| } |
| |
| pub fn get<N: AstNode>(&self, id: FileAstId<N>) -> AstPtr<N> { |
| self.arena[id.raw].clone().cast::<N>().unwrap() |
| } |
| |
| fn alloc(&mut self, item: &SyntaxNode) -> ErasedFileAstId { |
| self.arena.alloc(SyntaxNodePtr::new(item)) |
| } |
| } |
| |
| /// Walks the subtree in bfs order, calling `f` for each node. |
| fn bfs(node: &SyntaxNode, mut f: impl FnMut(SyntaxNode)) { |
| let mut curr_layer = vec![node.clone()]; |
| let mut next_layer = vec![]; |
| while !curr_layer.is_empty() { |
| curr_layer.drain(..).for_each(|node| { |
| next_layer.extend(node.children()); |
| f(node); |
| }); |
| std::mem::swap(&mut curr_layer, &mut next_layer); |
| } |
| } |