//! FIXME: write short doc here use std::{ hash::{Hash, Hasher}, iter::successors, marker::PhantomData, }; use crate::{AstNode, SyntaxKind, SyntaxNode, TextRange}; /// A pointer to a syntax node inside a file. It can be used to remember a /// specific node across reparses of the same file. #[derive(Debug, Clone, PartialEq, Eq, Hash)] pub struct SyntaxNodePtr { // Don't expose this field further. At some point, we might want to replace // range with node id. pub(crate) range: TextRange, kind: SyntaxKind, } impl SyntaxNodePtr { pub fn new(node: &SyntaxNode) -> SyntaxNodePtr { SyntaxNodePtr { range: node.text_range(), kind: node.kind() } } pub fn to_node(&self, root: &SyntaxNode) -> SyntaxNode { assert!(root.parent().is_none()); successors(Some(root.clone()), |node| { node.children().find(|it| it.text_range().contains_range(self.range)) }) .find(|it| it.text_range() == self.range && it.kind() == self.kind) .unwrap_or_else(|| panic!("can't resolve local ptr to SyntaxNode: {:?}", self)) } pub fn cast<N: AstNode>(self) -> Option<AstPtr<N>> { if !N::can_cast(self.kind) { return None; } Some(AstPtr { raw: self, _ty: PhantomData }) } } /// Like `SyntaxNodePtr`, but remembers the type of node #[derive(Debug)] pub struct AstPtr<N: AstNode> { raw: SyntaxNodePtr, _ty: PhantomData<fn() -> N>, } impl<N: AstNode> Clone for AstPtr<N> { fn clone(&self) -> AstPtr<N> { AstPtr { raw: self.raw.clone(), _ty: PhantomData } } } impl<N: AstNode> Eq for AstPtr<N> {} impl<N: AstNode> PartialEq for AstPtr<N> { fn eq(&self, other: &AstPtr<N>) -> bool { self.raw == other.raw } } impl<N: AstNode> Hash for AstPtr<N> { fn hash<H: Hasher>(&self, state: &mut H) { self.raw.hash(state) } } impl<N: AstNode> AstPtr<N> { pub fn new(node: &N) -> AstPtr<N> { AstPtr { raw: SyntaxNodePtr::new(node.syntax()), _ty: PhantomData } } pub fn to_node(&self, root: &SyntaxNode) -> N { let syntax_node = self.raw.to_node(root); N::cast(syntax_node).unwrap() } pub fn syntax_node_ptr(&self) -> SyntaxNodePtr { self.raw.clone() } pub fn cast<U: AstNode>(self) -> Option<AstPtr<U>> { if !U::can_cast(self.raw.kind) { return None; } Some(AstPtr { raw: self.raw, _ty: PhantomData }) } } impl<N: AstNode> From<AstPtr<N>> for SyntaxNodePtr { fn from(ptr: AstPtr<N>) -> SyntaxNodePtr { ptr.raw } } #[test] fn test_local_syntax_ptr() { use crate::{ast, AstNode, SourceFile}; let file = SourceFile::parse("struct Foo { f: u32, }").ok().unwrap(); let field = file.syntax().descendants().find_map(ast::RecordField::cast).unwrap(); let ptr = SyntaxNodePtr::new(field.syntax()); let field_syntax = ptr.to_node(file.syntax()); assert_eq!(field.syntax(), &field_syntax); }