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use std::marker::PhantomData;
use ra_syntax::{
File, TextRange, SyntaxKind, SyntaxNode, SyntaxNodeRef,
ast::{self, AstNode},
};
use crate::FileId;
use crate::db::SyntaxDatabase;
salsa::query_group! {
pub(crate) trait SyntaxPtrDatabase: SyntaxDatabase {
fn resolve_syntax_ptr(ptr: SyntaxPtr) -> SyntaxNode {
type ResolveSyntaxPtrQuery;
// Don't retain syntax trees in memory
storage volatile;
}
}
}
fn resolve_syntax_ptr(db: &impl SyntaxDatabase, ptr: SyntaxPtr) -> SyntaxNode {
let syntax = db.file_syntax(ptr.file_id);
ptr.local.resolve(&syntax)
}
/// SyntaxPtr is a cheap `Copy` id which identifies a particular syntax node,
/// without retaining syntax tree in memory. You need to explicitly `resolve`
/// `SyntaxPtr` to get a `SyntaxNode`
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub(crate) struct SyntaxPtr {
file_id: FileId,
local: LocalSyntaxPtr,
}
impl SyntaxPtr {
pub(crate) fn new(file_id: FileId, node: SyntaxNodeRef) -> SyntaxPtr {
let local = LocalSyntaxPtr::new(node);
SyntaxPtr { file_id, local }
}
}
struct OwnedAst<T> {
syntax: SyntaxNode,
phantom: PhantomData<T>,
}
trait ToAst {
type Ast;
fn to_ast(self) -> Self::Ast;
}
impl<'a> ToAst for &'a OwnedAst<ast::FnDef<'static>> {
type Ast = ast::FnDef<'a>;
fn to_ast(self) -> ast::FnDef<'a> {
ast::FnDef::cast(self.syntax.borrowed())
.unwrap()
}
}
/// A pionter to a syntax node inside a file.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub(crate) struct LocalSyntaxPtr {
range: TextRange,
kind: SyntaxKind,
}
impl LocalSyntaxPtr {
pub(crate) fn new(node: SyntaxNodeRef) -> LocalSyntaxPtr {
LocalSyntaxPtr {
range: node.range(),
kind: node.kind(),
}
}
pub(crate) fn resolve(self, file: &File) -> SyntaxNode {
let mut curr = file.syntax();
loop {
if curr.range() == self.range && curr.kind() == self.kind {
return curr.owned();
}
curr = curr.children()
.find(|it| self.range.is_subrange(&it.range()))
.unwrap_or_else(|| panic!("can't resolve local ptr to SyntaxNode: {:?}", self))
}
}
pub(crate) fn into_global(self, file_id: FileId) -> SyntaxPtr {
SyntaxPtr { file_id, local: self}
}
}
#[test]
fn test_local_syntax_ptr() {
let file = File::parse("struct Foo { f: u32, }");
let field = file.syntax().descendants().find_map(ast::NamedFieldDef::cast).unwrap();
let ptr = LocalSyntaxPtr::new(field.syntax());
let field_syntax = ptr.resolve(&file);
assert_eq!(field.syntax(), field_syntax);
}
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