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//! A higher level attributes based on TokenTree, with also some shortcuts.
use std::sync::Arc;
use mbe::ast_to_token_tree;
use ra_cfg::CfgOptions;
use ra_syntax::{
ast::{self, AstNode, AttrsOwner},
SmolStr,
};
use tt::Subtree;
use crate::{hygiene::Hygiene, path::Path};
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Attr {
pub(crate) path: Path,
pub(crate) input: Option<AttrInput>,
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum AttrInput {
Literal(SmolStr),
TokenTree(Subtree),
}
impl Attr {
pub(crate) fn from_src(ast: ast::Attr, hygiene: &Hygiene) -> Option<Attr> {
let path = Path::from_src(ast.path()?, hygiene)?;
let input = match ast.input() {
None => None,
Some(ast::AttrInput::Literal(lit)) => {
// FIXME: escape? raw string?
let value = lit.syntax().first_token()?.text().trim_matches('"').into();
Some(AttrInput::Literal(value))
}
Some(ast::AttrInput::TokenTree(tt)) => {
Some(AttrInput::TokenTree(ast_to_token_tree(&tt)?.0))
}
};
Some(Attr { path, input })
}
pub fn from_attrs_owner(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Option<Arc<[Attr]>> {
let mut attrs = owner.attrs().peekable();
if attrs.peek().is_none() {
// Avoid heap allocation
return None;
}
Some(attrs.flat_map(|ast| Attr::from_src(ast, hygiene)).collect())
}
pub fn is_simple_atom(&self, name: &str) -> bool {
// FIXME: Avoid cloning
self.path.as_ident().map_or(false, |s| s.to_string() == name)
}
// FIXME: handle cfg_attr :-)
pub fn as_cfg(&self) -> Option<&Subtree> {
if !self.is_simple_atom("cfg") {
return None;
}
match &self.input {
Some(AttrInput::TokenTree(subtree)) => Some(subtree),
_ => None,
}
}
pub fn as_path(&self) -> Option<&SmolStr> {
if !self.is_simple_atom("path") {
return None;
}
match &self.input {
Some(AttrInput::Literal(it)) => Some(it),
_ => None,
}
}
pub fn is_cfg_enabled(&self, cfg_options: &CfgOptions) -> Option<bool> {
cfg_options.is_cfg_enabled(self.as_cfg()?)
}
}
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