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use std::marker::PhantomData;
use crate::{
AstNode, SourceFile, SyntaxKind, SyntaxNode, TextRange,
algo::generate,
};
/// 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 {
range: TextRange,
kind: SyntaxKind,
}
impl SyntaxNodePtr {
pub fn new(node: &SyntaxNode) -> SyntaxNodePtr {
SyntaxNodePtr {
range: node.range(),
kind: node.kind(),
}
}
pub fn to_node(self, source_file: &SourceFile) -> &SyntaxNode {
generate(Some(source_file.syntax()), |&node| {
node.children()
.find(|it| self.range.is_subrange(&it.range()))
})
.find(|it| it.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> {
ptr: SyntaxNodePtr,
_ty: PhantomData<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 {
ptr: SyntaxNodePtr::new(node.syntax()),
_ty: PhantomData,
}
}
pub fn to_node(self, source_file: &SourceFile) -> &N {
let syntax_node = self.ptr.to_node(source_file);
N::cast(syntax_node).unwrap()
}
pub fn syntax_node_ptr(self) -> SyntaxNodePtr {
self.ptr
}
}
#[test]
fn test_local_syntax_ptr() {
use crate::{ast, AstNode};
let file = SourceFile::parse("struct Foo { f: u32, }");
let field = file
.syntax()
.descendants()
.find_map(ast::NamedFieldDef::cast)
.unwrap();
let ptr = SyntaxNodePtr::new(field.syntax());
let field_syntax = ptr.to_node(&file);
assert_eq!(field.syntax(), &*field_syntax);
}
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