crates/hir_expand/src/builtin_attr_macro.rs

   1 //! Builtin attributes.
   2
   3 use syntax::ast;
   4
   5 use crate::{
   6     db::AstDatabase, name, AstId, CrateId, ExpandResult, MacroCallId, MacroDefId, MacroDefKind,
   7 };
   8
   9 macro_rules! register_builtin {
  10     ( $(($name:ident, $variant:ident) => $expand:ident),* ) => {
  11         #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
  12         pub enum BuiltinAttrExpander {
  13             $($variant),*
  14         }
  15
  16         impl BuiltinAttrExpander {
  17             pub fn expand(
  18                 &self,
  19                 db: &dyn AstDatabase,
  20                 id: MacroCallId,
  21                 tt: &tt::Subtree,
  22             ) -> ExpandResult<tt::Subtree> {
  23                 let expander = match *self {
  24                     $( BuiltinAttrExpander::$variant => $expand, )*
  25                 };
  26                 expander(db, id, tt)
  27             }
  28
  29             fn find_by_name(name: &name::Name) -> Option<Self> {
  30                 match name {
  31                     $( id if id == &name::name![$name] => Some(BuiltinAttrExpander::$variant), )*
  32                      _ => None,
  33                 }
  34             }
  35         }
  36
  37     };
  38 }
  39
  40 impl BuiltinAttrExpander {
  41     pub fn is_derive(self) -> bool {
  42         matches!(self, BuiltinAttrExpander::Derive)
  43     }
  44     pub fn is_test(self) -> bool {
  45         matches!(self, BuiltinAttrExpander::Test)
  46     }
  47     pub fn is_bench(self) -> bool {
  48         matches!(self, BuiltinAttrExpander::Bench)
  49     }
  50 }
  51
  52 register_builtin! {
  53     (bench, Bench) => dummy_attr_expand,
  54     (cfg_accessible, CfgAccessible) => dummy_attr_expand,
  55     (cfg_eval, CfgEval) => dummy_attr_expand,
  56     (derive, Derive) => dummy_attr_expand,
  57     (global_allocator, GlobalAllocator) => dummy_attr_expand,
  58     (test, Test) => dummy_attr_expand,
  59     (test_case, TestCase) => dummy_attr_expand
  60 }
  61
  62 pub fn find_builtin_attr(
  63     ident: &name::Name,
  64     krate: CrateId,
  65     ast_id: AstId<ast::Macro>,
  66 ) -> Option<MacroDefId> {
  67     let expander = BuiltinAttrExpander::find_by_name(ident)?;
  68     Some(MacroDefId {
  69         krate,
  70         kind: MacroDefKind::BuiltInAttr(expander, ast_id),
  71         local_inner: false,
  72     })
  73 }
  74
  75 fn dummy_attr_expand(
  76     _db: &dyn AstDatabase,
  77     _id: MacroCallId,
  78     tt: &tt::Subtree,
  79 ) -> ExpandResult<tt::Subtree> {
  80     ExpandResult::ok(tt.clone())
  81 }