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use std::{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, Copy, PartialEq, Eq, Hash)]
pub struct SyntaxNodePtr {
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| self.range.is_subrange(&it.text_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 range(self) -> TextRange {
self.range
}
pub fn kind(self) -> SyntaxKind {
self.kind
}
}
/// Like `SyntaxNodePtr`, but remembers the type of node
#[derive(Debug, PartialEq, Eq, Hash)]
pub struct AstPtr<N: AstNode> {
raw: SyntaxNodePtr,
_ty: PhantomData<fn() -> N>,
}
impl<N: AstNode> Copy for AstPtr<N> {}
impl<N: AstNode> Clone for AstPtr<N> {
fn clone(&self) -> AstPtr<N> {
*self
}
}
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
}
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::NamedFieldDef::cast).unwrap();
let ptr = SyntaxNodePtr::new(field.syntax());
let field_syntax = ptr.to_node(file.syntax());
assert_eq!(field.syntax(), &field_syntax);
}
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