rust/crates/syntax/src/ptr.rs

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